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© 2024 by the authors; licensee Asian Online Journal Publishing Group 
 

Agriculture and Food Sciences Research 
Vol. 11, No. 2, 156-169, 2024 

ISSN(E) 2411-6653/ ISSN(P) 2518-0193 
DOI: 10.20448/aesr.v11i2.6232 

© 2024 by the authors; licensee Asian Online Journal Publishing Group 

 
 

 
 
 
Properties of boiled or steamed Procambarus clarkii girard and Procambarus 
zonangulus crawfish tail meat during refrigerated and frozen storage 

 
John B. Shackelford1   

Kenneth W. McMillin2   
J. David Bankston3   

Marlene E. Janes4   

Lucina E. Lampila5   

 

 
( Corresponding Author) 

 
1Giraffe Foods, OneSYMRISE Toronto, Ontario, Canada. 
1Email: jshack2@gmail.com   
2,3Louisiana State University Agricultural Center, Baton Rouge, LA, USA. 
2Email: kmcmillin@agcenter.lsu.edu  
3Email: entropyrd@gmail.com  
4NorthWest Arkansas Community College, Bentonville, AR, USA. 
4Email: mjanes@nwacc.edu  
5Pactiv Evergreen Packaging, Waynesville, NC, USA. 
5Email: lucinalampila@gmail.com  

 
Abstract 

This research was conducted to address the different cooking methods of crawfish processors and 
determine the refrigerated or frozen shelf-life of cooked product. Live crawfish, (Procambarus clarkii 
girard and Procambarus zonangulus), were either boiled or steamed before storage of 11 days in 
refrigerated (3°C) conditions or six months in frozen storage (-18°C). There were minimal moisture, 
ash, protein, and fat differences with cooking type or storage type. There were no E.coli/coliforms 
in samples and aerobic plate counts were less than 3 log10 colony forming untis (CFU)/g after 6 mo 
frozen storage and higher than 3 log10 CFU/g after 3 days of refrigerated storage. Lipid oxidation 
by TBARS increased, but was less than 0.53 mg MDA/kg during storage. Peak force, total shear 
work, pH, L*, a*, b* color values were variable during storage, but not different between cooking 
treatments at each storage period. Mineral and fatty acid analyses were similarly variable. There 
were no differences between boiling and cooking crawfish for most variables and natural variation 
among the samples might explain variability in refrigerated and frozen storage. Processors can use 
either boiling or steaming to cook crawfish and store cooked crawfish for 3 days in refrigerated 
storage and for 6 weeks in frozen storage with minimal changes in properties. 

 
Keywords: Crawfish, Boiling, Steaming, Nutrient composition, Shelf-life, Yield. 

 
Citation | Shackelford, J. B., McMillin, K. W., Bankston, J. D., Janes, 
M. E., & Lampila, L. E. (2024). Properties of boiled or steamed 
Procambarus clarkii girard and Procambarus zonangulus crawfish 
tail meat during refrigerated and frozen storage. Agriculture and Food 
Sciences Research, 11(2), 156–169. 10.20448/aesr.v11i2.6232 
History:  
Received: 13 November 2024 
Revised: 1 December 2024 
Accepted: 9 December 2024 
Published: 20 December 2024 
Licensed: This work is licensed under a Creative Commons 

Attribution 4.0 License  
Publisher:  Asian Online Journal Publishing Group 
 

Funding: This study received no specific financial support 
Institutional Review Board Statement: Not applicable. 
Transparency: The authors confirm that the manuscript is an honest, accurate, 
and transparent account of the study; that no vital features of the study have 
been omitted; and that any discrepancies from the study as planned have been 
explained. This study followed all ethical practices during writing. 
Competing Interests: The authors declare that they have no competing 
interests. 
Authors’ Contributions: Conceptualization, J.S., D.B., L.L.; methodology, J.S., 
D.B. L.L., M.J.; software, J.S., L.L.; validation, M.J., L.L.; formal analysis, J.S.; 
resources, K.M., M.J., L.L.; data curation, J.S.; writing—original draft 
preparation, J.S., L.L.; writing—review and editing, K.M, L.L.; supervision, 
K.W., D.B., M.J., L.L.; project administration, L.L.; funding acquisition, L.L.  All 
authors have read and agreed to the published version of the manuscript. 
Acknowledgement:  The Louisiana State University Agricultural Center LSU 
Aquaculture Research Station and Tony’s Seafood Market and Deli provided 
the crawfish for this study. 

 

Contents 
1. Introduction .................................................................................................................................................................................... 157 
2. Materials and Methods ................................................................................................................................................................. 157 
3. Results and Discussion ................................................................................................................................................................. 160 
5. Conclusions ..................................................................................................................................................................................... 167 
References ............................................................................................................................................................................................ 167 

 
 

mailto:jshack2@gmail.com
mailto:kmcmillin@agcenter.lsu.edu
mailto:entropyrd@gmail.com
mailto:mjanes@nwacc.edu
mailto:lucinalampila@gmail.com
https://creativecommons.org/licenses/by/4.0/
https://creativecommons.org/licenses/by/4.0/
https://www.doi.org/10.20448/aesr.v11i2.6232
https://orcid.org/0000-0001-9249-6071
https://orcid.org/0000-0002-1644-8841
https://orcid.org/0000-0002-0797-6060


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Contribution of this paper to the literature 
This research compares two different methods of heating two species of crawfish for consumption 
and the subsequent properties of the crawfish during refrigerated and frozen storage. It provides 
data on the composition, texture, color, and microorganism growth during 11 days of refrigerated 
and 6 months of frozen storage of boiled and steamed crawfish tail meat. 

 
1. Introduction 

Crawfish/crayfish have emerged as a highly desirable and valued culinary delicacy because of  their distinctive 
sensory, textural and flavor characteristics [1, 2]. Use of  the term “crawfish” in 1817 predates the term “crayfish” 
used in the Huxley 1880 textbook [3] and so “crawfish” will refer to the crustacean in this manuscript. Of  the many 
species of  crawfish around the world, only two species, Procambarus clarkii, the red swamp crawfish, and Procambarus 
zonangulus, the white river crawfish, are commercially important for harvest in Louisiana, USA [4-6]. The white 
river crawfish is less tolerant of  poor water conditions and warmer temperatures than the red swamp crawfish [5]. 
Consumers and processors prefer the red swamp crawfish to the white river crawfish for appearance and flavor [4, 
7]. 

Crawfish may be purchased live or boiled, if  for immediate consumption, depending upon the preference of  
consumers and restauranteurs [8] and more recently as peeled tail meat, fresh or frozen, of  cooked crawfish. 
Crawfish tail meat possess a high protein content [approximately 20%] and eight essential amino acids for human 
consumption [9]. Crawfish, like other seafood, are a perishable product with postmortem changes occurring rapidly 
that cause off-odors and flavors even before spoilage Miget [10] and Zeng, et al. [11]. Davis [5] suggested that 
crawfish tail meat with adhering hepatopancreas can be frozen, but typically becomes rancid within 30 days of  
storage. A mushy texture may occur after relatively short periods of  iced storage, but deterioration of  texture has 
also been observed in crawfish through extended frozen storage [12]. Freezing rate, frozen storage conditions and 
thawing rate influence frozen food properties [13, 14]. Frozen seafood can experience color changes [15] protein 
denaturation [16] lipid oxidation [17] and ice sublimation and recrystallization [1, 18] which may result in drip 
loss, dehydration, toughening, off-flavor, and lipid oxidation [18, 19]. Drum/belt mechanically separated mince of  
boiled crawfish had 22% less lipid oxidation with cryogenic liquid nitrogen freezing than with air blast freezing after 
180 d of  frozen storage [20]. 

The two most prevalent commercial thermal treatments for cooking of  crawfish are steaming and boiling because 
of  their low cost and large scale efficiency [2]. Raw crawfish meat may have only faint fishy odors while the desirable 
flavor of  cooked crayfish meat is mainly from complex reactions of  flavor precursors, intermediates and their 
interaction products [21]. Crawfish cooking can produce lipid oxidation degradation, the Maillard reaction and the 
interaction between the two reactions, resulting in volatile flavor compounds, such as aldehydes, alcohols, ketones 
and other compounds, that provide a unique flavor [21].  

Microorganisms are also a major concern in the spoilage and safety of  crawfish [11, 22] as farmed or wild caught 
crawfish are apt to come in contact with harmful organisms in their habitats [10]. An added microbiological concern 
with crawfish tail meat is microbial contamination by hand-peeling from the shells if  proper sanitation practices are 
not practiced [23]. An increase in APC to levels exceeding 106 colony forming units(CFU)/g is generally a sign of  
a long period of  time at refrigerated temperatures or temperature abuse before freezing [24]. Aerobic plate count 
(APC) and E. coli/coliform limits have been suggested by the International Commission on Microbiological 
Specifications for Foods [24]. The limits are appropriate for both refrigerated and frozen cooked crawfish. Any 
sample having an APC count exceeding log 7 CFU/g should result in the product being discarded. For E. 
coli/colifoms, any sample exceeding 500 CFU/g should result in product being discarded.  

Procambarus clarkii crawfish harvested from rice fields had higher aroma and texture acceptability scores from a 
consumer panel than those from moist-soil wetlands, but there were no differences in flavor, overall acceptability, 
composition, or fatty acid contents [25]. The total amounts of  protein, fat, and ash increased in tail meat after both 
microwave and frying cooking while water content decreased, especially in the fried samples [26]. 

Steaming and boiling significantly influenced the fatty acids and free amino acids and were highly correlated with 
flavor and key flavor compounds in pulverized freshwater crawfish (Procambarus clarkia) tail meat [2]. Color, texture, 
flavor components, and microorganism growth were measured through 11 days of  refrigerated and 6 months of  
frozen storage of  boiled and steamed crawfish tail meat from Procambarus clarkia and Procambarus zonangulus species. 
 

2. Materials and Methods 
2.1. Procurement and Initial Preparation 

Live freshwater crawfish consisting of  both red swamp crawfish (Procambarus clarkia), and white river crawfish 
(Procambarus zonangulus) were obtained from the Louisiana State University AgCenter Aquaculture Research Station 
in Baton Rouge, Louisiana, USA and from Tony’s Seafood Market and Deli of  Baton Rouge, Louisiana, USA. The 
live crawfish were transported to the Food Science building in Baton Rouge, Louisiana in mesh sacks varying in 
weight from 12 to 18 kg and stored two days at 4°C until processed.  

Prior to cooking the crawfish were removed from the mesh sacks and placed in 1.5m x 0.6m x 0.6m metal 
containers. The crawfish from the different locations were mixed and washed with municipal tap water to remove 
any mud and debris. Dead crawfish were separated from the live crawfish and discarded. The crawfish were then kept 
moist by regularly spraying with municipal tap water until they were processed. 

Two lots of  28.8 kg of  crawfish destined for boiling were removed from the metal lugs and placed in a stainless 
steel basket. Temperatures were obtained with an T-type thermocouple and data logger (Omega OM-DAQPRO-
5300, Omega Engineering Inc., Stamford, CT). The crawfish were placed in approximately 75.7 L of  unseasoned 
municipal tap water that had been brought to a boil at atmospheric pressure in a 150 L jacketed steam kettle (B.H. 
Hubbert & Son, Inc., Baltimore, MD) with university-generated 206.85 cm Hg food-grade steam as the steam source. 
The temperature of  the water in the kettle was measured at periodic (~30 second) intervals during the cook process 
(Comark C28 K-type thermocouple, Comark Instruments, Norfolk, England). Crawfish were lowered into the steam 



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kettle after the water had been brought to a boil, completely submerged in the water, and continuously stirred with 
a plastic paddle to ensure that the crawfish were evenly heated. It took seven minutes for the water to return to a 
boil. The crawfish were then boiled for exactly three minutes. The cook time of  ten minutes (as used by the D&T 
Crawfish Company in Abbeville, Louisiana) satisfied the adequate cook time of  seven minutes or more [4] that would 
ensure the deactivation of  proteolytic enzymes. At the end of  the three-minute boil, steam was immediately turned 
off  and several crawfish were retrieved to measure internal temperature using the Comark C28 K-type thermocouple 
inserted into the thickest part of  the tail. The internal temperature of  the crawfish from the boiling trials ranged 
from 86.7 to 91.1°C. Once the steam was turned off, crawfish were submerged in a sanitized plastic lug (1.2m x 1.2m 
x 0.9m) containing ice-water to rapidly cool the crawfish and prevent continued cooking. After five minutes of  cooling 
crawfish temperatures were measured using the Comark C28 K-type thermocouple before pouring into plastic lined, 
waxed fish boxes (0.6m x 0.3m x 0.3m) for cooling at 5°C for 4 hr prior to being separated into treatments of  3.5°C 
refrigerated storage and frozen storage at -18°C.  

A commercial batch vegetable blancher was used to steam crawfish. Eight trials of  approximately 7.3 kg of  live 
crawfish were conducted because of  the limited blancher capacity. Live crawfish (~7.3kg) were placed in stainless 
steel trays and inserted into the chamber of  the blancher. Thermocouples (Omega OM-DAQPRO-5300 Type-T) 
connected to a data logger (Omega Engineering Inc., Stamford, CT) were placed in the tails of  two crawfish per trial. 
Initial temperatures (uncooked) and final temperature of  the crawfish during the cook process were recorded. The 
crawfish were steamed in the blancher using food-grade steam at 206.86 cmHg to the same internal temperature (90 
to 92.2°C) reached during the boiling process. The crawfish were immediately removed from their trays and placed 
in an ice bath similar for five minutes of  cooling with periodic stirring. Crawfish were placed in plastic containers 
[0.6m x 0.3m x 0.3m] and stored in a cooler at 5°C for 4 hr prior to allotment of  refrigerated storage at 4°C for 11 
d and frozen storage at -18°C for 6 mo. At each month of  frozen storage, crawfish were removed from the boxes, 
placed in shallow trays and thawed at 4°C for analyses. 

Deactivation of  proteolytic enzymes by the heating treatments was determined by a gelatin test [4]. Following 
the 4-hour cooling period at 5°C, five g of  hepatopancreas from each treatment including raw crawfish 
hepatopancreas were obtained by peeling the tails of  5-10 crawfish of  each treatment. The hepatopancreas was then 
minced using a metal spatula and set aside at 5°C until used.  Then, in triplicate for each treatment, 0.2 g of  mince 
was placed into labeled 22 mm tubes (Pyrex®, Corning Corporation, Tewksbury, MA). Concurrently, blanks in 
triplicate, which contained no hepatopancreas, were prepared. Five ml of  cooled 12% unflavored gelatin (Knox®, 
Kraft Foods Group, Inc., Northfield, IL) in water were then added to each tube and the contents homogenized using 
a Vortex-Genie® 2 mixer (Scientific Industries Inc., Bohemia, NY). The samples were then allowed to incubate for 
1h at room temperature followed by holding at 3°C for 23 h. After the 23 hour refrigerated storage, the samples were 
removed and analyzed subjectively to determine the presence of  a firm gel. A loose gel or no gel formation at all 
indicated that proteolytic enzymes present in the hepatopancreas had not been deactivated whereas firm gels revealed 
that the enzymes had been deactivated by an adequate cooking process.  
 

2.2. Microbiological Analysis 
The microbiological analyses conducted on the crawfish included the quantification of  the aerobic plate count 

(APC) and E.coli/coliforms of  refrigerated samples on days 0, 1, 3, 5, 7, 9, and 11 and on frozen samples at months 
0, 1, 2, 3, 4, 5, and 6. Crawfish tail meat with adhering hepatopancreas was removed by hand peeling and placed in 
17.78cm x 19.05cm reclosable storage bags (Qwik Seal®, Reynolds®, Lake Forest, Illinois). Twenty-five gram 
samples [in duplicate for each treatment] were prepared and placed in 1.56kg bags (Whirl-pak®, Nasco, Fort 
Atkinson, WI) along with 25.0 mL of  phosphate buffered saline (PBS), which was composed of  0.24% sodium 
phosphate monobasic [Sigma-Aldrich Corporation, St. Louis, MO], 0.28% sodium phosphate dibasic (Sigma-Aldrich 
Corporation, St. Louis, MO), and 0.85% sodium chloride (Amresco LLC, Solon, OH) in distilled water. The 25 g of  
tail meat and 25 mL of  PBS were homogenized for 60 seconds (EasyMix blender, AES Chemumex, Bruz Cedex, 
France).  From each treatment, serial dilutions were prepared and samples plated on both 3M™ E.coli/Coliform and 
Aerobic Count Petrifilms™ (3M Company, St. Paul, MN), then incubated at 35° ± 1°C. E.coli and coliforms were 
counted and recorded after 24 ± 3 hours as colony forming units and APC was counted and recorded after 48 ± 3 h 
(Official Methods 991.14 and 998.08 for E.coli/coliforms and Official Methods 990.12 for aerobic plate count, [AOAC 
International, Rockville, MD], 2005). 
 

2.3. Color Analysis 
Hunter color scale values (L*, a*, and b*) were measured on ten randomly selected tails with hepatopancreas at 

the widest point at the back of  the peeled tails for both boiled and steamed crawfish [calibrated CM-508d 
Spectrophotometer, Konica Minolta Sensing Americas Inc., Ramsey, NJ]. Measurements on refrigerated samples 
were conducted on days 1, 3, 5, 7, 9, and 11 of  refrigeration (4°C) and on frozen samples on months 1, 2, 3, 4, 5, and 
6 of  frozen storage (-18°C).  
 

2.4. Texture Analysis 
Texture analysis was conducted using a TA-XT Plus Texture Analyzer (Texture Technologies Corporation, 

Scarsdale, NY) with a 5-blade Kramer shear attachment and a 30 kg load cell. Texture of  peeled tails with adhering 
hepatopancreas from both boiled and steamed treatments was measured on days 0, 1, 3, 5, 7, 9, and 11 for refrigerated 
samples and after 0, 1, 2, 3, 4, 5, and 6 months of  frozen storage. Peak shear force (N) and work of  shearing (N/s) 
were measured on 100 grams of  peeled tail meat from each treatment in triplicate. One hundred grams of  sample 
were placed randomly in the Kramer cell, which filled the cell to roughly 40-50% capacity. The blade was set at 45 
mm (~10mm above the sample) and the blade speed was set at 3 mm per second. Following the texture determination, 
the samples were fully homogenized (Oster® Osterizer 14 speed all metal drive blender, Jarden Consumer Solutions, 
Providence, RI) and used for subsequent proximate and TBARS analyses.  
 
 



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2.5. Proximate Analysis 
Proximate analysis (moisture, ash, protein, and fat) was conducted on refrigerated crawfish tail meat with 

adhering hepatopancreas on days 0, 1, 3, 5, 7, 9, and 11 and on frozen crawfish tail meat with adhering hepatopancreas 
at months 0, 1, 2, 3, 4, 5, and 6 for both boiled and steamed samples.  

Moisture analysis was conducted in triplicate for each cooking treatment. Three grams of  homogenized tail meat 
were placed in ceramic crucibles, weighed, and then placed in an oven (Model 20 GC Lab Oven, Quincy Lab Inc., 
Chicago, IL) at 100°C for 24 hours. Samples were removed from the oven and placed in a desiccator to cool before 
weighing. The percent moisture of  tail meat with adhering hepatopancreas was determined by the calculation:  

% Moisture = ((Wet Weight – Dry Weight)/Wet Weight)×100. 
Ash measurements were conducted on the samples after moisture determination. The samples in triplicate were 

heated to 550°C for 18-24 hours (Type 6000 Furnace, Thermolyne Inc., Dubuque, IA), removed from the furnace 
and placed in a desiccator to cool before weighing. The percent ash was determined using the calculation:  

%Ash = (Weight after ashing – Tare Weight of  Crucible)/(Dry Sample Weight after Oven Drying – Tare weight 
of  Crucible) × 100. 

Lipid extraction was performed according to a modified method of  Bligh and Dyer [27] described by Woyewoda, 
et al. [28]. Total lipid quantification was performed in duplicate for each treatment.  Following lipid quantification 
on a wet weight basis, fatty acid analysis was conducted on the lipid. Peeled crawfish tail meat with adhering 
hepatopancreas were homogenized (Oster® Osterizer 14 speed all metal drive blender with a rosin blade, Jarden 
Consumer Solutions, Providence, RI). A measured amount of  homogenized tail meat (approximately 50.0 grams) was 
added to a commercial blender (Waring® model 51BL31, Waring®, Stanford, CT) along with 100.0 mL of  high 
performance liquid chromatography (HPLC) grade anhydrous methyl alcohol (Avantor™ Performance Materials 
Inc., Center Valley, PA) and 50.0 mL of  HPLC grade Chloroform (Mallinckrodt Baker Inc., Phillipsburg, NJ) and 
blended for exactly two minutes. An additional 50.0 mL of  chloroform was added to the blender and the mixture was 
blended for an additional 30.0 seconds. The mixture was then filtered through a Buchner funnel containing a #1 filter 
paper (Whatman,™ GE Healthcare UK Limited, Buckinghamshire, UK). Aspiration was used to expedite the filtering 
process. The filtered product contained lipid, chloroform, and methanol. Fifty mL of  distilled water was added and 
the mixture was then stirred vigorously. The mixture was transferred to a 250-mL separatory funnel and then 
allowed to rest at 5°C overnight. The following day, the chloroform-lipid layer was then filtered from the separatory 
funnel through a glass funnel containing #4 filter paper inside #1 filter paper (Whatman™, GE Healthcare UK 
Limited, Buckinghamshire, UK) that was filled with American Chemical Society (ACS) grade anhydrous sodium 
sulfate (ThermoFisher Scientific, Waltham, MA) into a pre-weighed 250 ml round bottom boiling flask (Corning 
Corporation, Tewksbury, MA). The chloroform was then removed from the round bottom flask using a 
rotoevaporator (Buchi Rotovapor R114, Buchi Corporation, New Castle, DE). To ensure that all solvent was removed 
and only crude lipid remained, ultra- high pure (UHP) nitrogen (Air Liquide Corporation, Paris, France) was sprayed 
into the flask for 10-15 minutes or until no odor or appearance of  solvent remained. The crude lipid remaining was 
weighed and the percent fat was determined by the calculation: % Fat = ((Weight of  Flask Containing Lipid – Weight 
of  Empty Flask)/ Weight of  Sample Used) × 100.  

Protein analysis was conducted on homogenized tail meat with adhering hepatopancreas from each cooking 
method. The samples were dried in the same manner as samples dried for moisture analysis. The dried samples were 
then blended to a fine powder using a mortar and pestle and coffee grinder (Custom Grind™, Hamilton Beach Brands 
Inc., South Pines, NC). Approximately 1.5 grams of  finely ground sample were placed in 15 ml clear, screw top vials 
(Supelco®, Bellefonte, PA) and transported to the Soil Testing & Plant Analysis Laboratory on the LSU campus for 
combustion and total nitrogen determination. Total nitrogen determination was conducted on 0.25 gram samples in 
triplicate using a LECO® TruSpec Micro CHNS analyzer (LECO Corporation, St. Joseph, MI). The results were 
reported as percent total nitrogen in the sample. The total percent protein was determined by multiplying the percent 
total nitrogen by the appropriate conversion factor of  6.25 and converting from a dry weight basis to a wet weight 
basis.  
 

2.6. pH Analysis 
The pH of  crawfish tail meat with hepatopancreas was measured in triplicate for each treatment using a pH 

meter (SMS115, Milwaukee Instruments Inc., Rocky Mount, NC) that had been calibrated at pH values of  4,7, and 
10. Ten grams of  homogenized crawfish tail meat were blended with 90 mL of  distilled/de-ionized water for one 
minute using a commercial blender (Waring® model 51BL31, Waring, Stanford, CT). The samples were then 
transferred to 400 mL beakers (Pyrex, ®Corning Corporation, Tewksbury, MA) and the pH was measured and 
recorded.  
 

2.7. TBARS Analysis 
Thiobarbituric acid reactive substances (TBARS) analyses were conducted on boiled and steamed crawfish tail 

meat refrigerated for 0, 1, 3, 5, 7, 9 and 11 days and on frozen samples at months 0, 1, 2, 3, 4, 5, and 6 using a modified 
method of  Vyncke [29] by Lemon [30]. Solutions were prepared the day prior to analysis. The extraction solution 
consisted of  7.5% trichloroacetic acid (TCA) (ThermoFisher Scientific, Waltham, MA), 0.1% propyl gallate (Sigma-
Aldrich Corporation, St. Louis, MO), and 0.1% ethylene diaminetetraacetic acid (EDTA) (Sigma-Aldrich Corporation, 
St. Louis, MO) in 92.3% deionized water. The thiobarbituric acid (TBA) solution consisted of  2.883 g/L (0.02M) of  
TBA (Sigma-Aldrich Corporation, St. Louis, MO) in deionized water. The standard solution for standard curve 
determination was prepared by dissolving 0.22 grams of  1,1,3,3-Tetraethoxypropane (TEP) (Sigma-Aldrich 
Corporation, St. Louis, MO) in one L of  water.  The working solution to actually obtain the standard curve was 
formed by diluting the standard solution 100 fold. Fifteen grams of  tissue from each treatment [in triplicate] were 
blended with 30 ml of  extraction solution for 30 seconds using a Waring® blender. The samples were then filtered 
through a Whatman #1 filter paper into a 100 ml Pyrex® beaker. Five mL of  the clear filtrate in the beaker was 
added to five ml of  TBA reagent in Pyrex® (120 x 10 mm) test tubes with screw caps. The test tubes were then 
heated in boiling water in 1000 ml beakers (Pyrex®, Corning Corporation, Tewksbury, MA) on a hot plate (Corning 
PC-420D, Corning Corporation, Tewksbury, MA). Test tubes containing only five mL of  water and five ml of  TBA 



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reagent were added to beakers as blanks. After boiling for exactly 40 minutes, the tubes were removed from the beaker 
and cooled in running tap water. Using a transfer pipette, each sample was transferred to a cuvette and their optical 
density was measured at 530nm against the blanks of  water and TBA reagent (Thermo Spectronic Genesys™ 2 
spectrophotometer, ThermoFisher Scientific, Waltham, MA). The TBARS values were calculated from the standard 
curve obtained from the TEP working solution and the values were reported in mg malonaldehyde (MDA) 
equivalent/100 grams of  tissue.   
 

2.8. Mineral Analysis 
Mineral analyses were conducted on the ashed samples remaining from the proximate analysis of  boiled and 

steamed crawfish tail meat that had been refrigerated for days 0,1,3,5,7,9, and 11 and frozen samples on months 
1,2,3,4,5, and 6. Ten mL of  10% nitric acid (Avantor™ Performance Materials Inc., Center Valley, PA) solution in 
distilled water were added to each crucible for ten minutes to solubilize the ash. The solubilized ash samples were 

drawn into a sterile 10 mL tip syringe (Luer-Lok™, Becton Dickinson & Company, Franklin Lakes, NJ). A 0.2μm, 
25-mm surfactant free cellulose acetate membrane, acrylic housing, syringe filter was placed on the syringe 
(Nalgene™, ThermoFisher Scientific, Waltham, MA) and the sample was filtered into labeled 15 ml clear, screw top 
vials (Supelco®, Bellefonte, PA). Two of  the three samples were then transported to the LSU AgCenter’s W.A. 
Callegari Environmental Center Central Research Station in Baton Rouge, Louisiana for analysis in duplicate via 
inductively coupled plasma optical emission spectroscopy (ICP-OES, Varian Vista-MPX CCD Simultaneous ICP-
OES unit, Varian Medical Systems Inc., Palo Alto, CA). The results for minerals present in the samples were reported 
in parts per million [ppm] of  crawfish tail meat with adhering hepatopancreas on a wet weight basis.  
 

2.9. Fatty Acid Analysis 
Fatty acid profiles were obtained from samples of  lipid collected during proximate analysis (2.5). In duplicate, 

1.3-2.0 grams of  crude lipid was solubilized in exactly ten ml of  HPLC grade hexane (Honeywell, Morristown, NJ) 
and transferred to a 15 mL clear, screw top vial (Supelco®, Bellefonte, PA). Samples were then placed in the freezer 
(-18°C) until they were transported to the LSU AgCenter’s W.A. Callegari Environmental Center Central Research 
Station in Baton Rouge, Louisiana for analysis. Fatty acid analysis was conducted using a gas chromatograph with 
an ion trap mass spectrometer (Varian 450 and Varian 240, respectively, Varian Inc., Palo Alto, CA) with a 75 m, 0.18 

mm diameter, 0.14 μm film thickness, silica capillary column (SP2560, Supelco®, Bellefonte, PA) with hydrogen as 
the carrier gas at a flow rate of  40 cm per second.  
 

2.10. Statistical Analysis 
Results were expressed as least squares means (LS-Means) ± standard deviation. The experimental design used 

was a 2x7 factorial design for both refrigerated and frozen studies. Statistical analysis was performed using analysis 
of  variance (ANOVA). Separation of  means and difference between control and treatments were determined by the 
generalized linear model (GLM) procedure with a T comparison for least squares means (SAS Institute, version 9.3). 
Statistical significance was set at P < 0.05. 
 

3. Results and Discussion 
3.1. Cooking, Cooling, and Gelatin Test 

Crawfish were submerged in an ice bath immediately after cooking to retard the cook process and to cool the 
crawfish within recommended guidelines [31] which slowed the rate of  spoilage reactions that include bacterial and 
autolytic enzyme activity and reduced the rate at which bacteria multiply [32].  

An average internal temperature of  87.6° C was obtained [5 crawfish per each of  2 replications] for the boiled 
crawfish, which killed pathogen Listeria monocytogenes [31]. The average chilled temperature of  the crawfish after 
the ice bath for the two trials was 30.11°C. After four hours of  cooling in refrigeration, the temperature of  all the 
crawfish was reduced to an average of  3.5°C.  

The average internal temperature of  the cooked tails in the eight replications of  steaming was 86.9°C. After the 
ice bath, the average internal temperature of  the steamed samples was 29.6°C. The slightly lower internal 
temperature of  the boiled samples might be due to the smaller batch size of  ~7.26 kg versus the boiled batch sizes 
which were ~ 27.22 kg. Once the steamed samples had been boxed and allowed to cool under refrigeration for four 
hours, the average internal temperature was 5.0°, similar to that of  the boiled samples.  

Boiled and steamed crawfish samples contained cooked hepatopancreas and formed stable, firm gels after cooking, 
which indicates that the cook time was sufficient to deactivate the proteolytic enzymes in the hepatopancreas [33].  

The heat-labile proteolytic enzymes present in the hepatopancreas of  crawfish promote the development of  
mushiness in the tail meat [34]. It is important to limit texture deterioration before freezing of  crawfish tail meat 
as Godber, et al. [12] found extended frozen storage would cause poor texture. 
 

3.2. Tail Meat Yield 
The edible tail meat yields for the boiled and the steamed crawfish through refrigerated and frozen storage are 

in Table 1. It was expected that the edible yield would decrease during storage, especially frozen storage from freeze-
thaw transitions and thawing due to purge. Slow freezing causes large ice crystal formation that damages cell walls 
and promotes water loss upon thawing [1, 35].  

Since crawfish are generally hand peeled, there can be variations in the yield obtained from peeling depending 
on the technique and experience of  the peeler. The average abdominal [tail] meat yield for cooked crawfish is about 
15% of  the live weight of  the crawfish [8]. The yield also depends on the sexual maturity of  the crawfish, with 
immature crawfish having a higher yield because they have smaller claws and thinner shells [8]. This is typical of  
crawfish early in the season, when yields can be as high as 22-23%. Later in the season, when the crawfish have 
matured and have larger claws and thicker shells, the yield can be as low as 10 to 11% [8]. The yields obtained in 
this study averaged around 18%. This was higher than expected because these crawfish were harvested later in the 
season and their shells were quite thick. A reason why the yields may have been higher than expected is that the 



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crawfish were very carefully peeled. Also, the hepatopancreas was left attached as well as the vein/intestine that runs 
along the dorsal side of  the abdomen/tail. Typically, this is removed during commercial peeling, but was left on in 
this research because the goal was to mimic how Louisiana consumers typically ingest boiled crawfish. Cooking losses 
of  31.17% and 18.33% from fried and microwave cooking, respectively, were reported [28]. 
 
Table 1. Percent (%) edible yield of  peeled crawfish tail meat with adhering hepatopancreas during refrigerated (3.5°C) storage or after frozen 
(-18°C) storage and thawing. 

Refrigerated Day 0 Day 1 Day 3 Day 5 Day 7 Day 9 Day 11 Avg. % yield 

Boiled 19.14 18.41 20.16 18.09 18.02 19.46 17.43 18.67 ± 0.95 
Steamed 18.58 18.63 18.60 17.84 17.63 19.19 15.80 18.03 ± 1.11 
Frozen Mo. 0 Mo. 1 Mo. 2 Mo. 3 Mo. 4 Mo. 5 Mo. 6 Avg. % Yield 
Boiled 19.14 17.69 17.36 19.16 17.28 18.13 17.52 18.04 ± 0.81 
Steamed 18.58 17.08 17.98 18.71 16.84 18.92 19.45 18.22 ± 0.96 

 

3.3. Proximate Analysis Results 
The proximate analyses LS-means for the boiled and steamed refrigerated and frozen crawfish tail meat with the 

attached hepatopancreas are in Table 2. The proximate analyses from the USDA [36] and Sidwell [37] are also 
shown for comparison. It was not specified whether or not the tail meat samples included hepatopancreas from in the 
USDA [36] or Sidwell [37] studies. 

 
Table 2. Means for % moisture, ash, protein, and fat of  crawfish tail meat during refrigerated (3.5°C) and frozen (-18°C) storage. Proximate 
values from references 26, 36, and 37 are shown for comparison. 

Proximate composition Boiled Steamed 
USDA 
[36] 

boiled 

Sidwell 
[37] 

boiled 

Sidwell [37] 
raw range 

Abou-
Taleb, et 
al. [26] 

raw 

% moisture (3.5°C)  79.29 79.40     
% moisture (-18°C) 77.91 77.86 80.8 75.0 (72.1 - 83.4) 78.61 
% ash (3.5°C)  1.26 1.31     
% ash (-18°C) 1.22 1.32 1.07 1.5 (0.7 - 3.60 1.33 
% protein (3.5°C)  15.89 15.30     
% protein (-18°C) 16.69 16.30 17.5 16.3 (11.9 - 24.10 18.46 
% fat (3.5°C)  2.73 2.96    1.58 
% fat (-18°C) 3.00 3.22 1.3 0.8 (0.5 - 2.5)  

Total (3.5°C/-18°C) 99.17 ⁄ 98.82 98.97 ⁄ 98.70 100.67 98.9  99.98 

 
Moisture, ash, and protein in crawfish boiled for 10 m were 80%, 1.2%, and 17%, respectively, [25] while the 

moisture for crawfish boiled for 5 m was 86% [20]. Lower moisture (38.2 and 58.2%) and higher protein (35.8 and 
35.2), fat (18.9 and 2.73%), and ash (6.35 and 3.25%) were in cooked crawfish by frying and microwaving [26]. 

The moisture content of  the peeled crawfish tail meat with adhering hepatopancreas through refrigerated and 
frozen storage from boiled and steamed treatments did not vary greatly. There was little change in the moisture 
content for the boiled samples through 0 to 11 d refrigerated storage (Table 3). The moisture content for the steamed 
samples varied a bit more than the boiled samples throughout the 11-day storage. The differences in moisture could 
be from natural variation, which corresponds to previously reported large range of  moistures (72.1 - 83.4%) [37]. 

 
Table 3. Percent (%) moisture of  peeled crawfish tail meat with adhering hepatopancreas stored during refrigerated (3.5°C) storage. 

Treatment Day 0 Day 1 Day 3 Day 5 Day 7 Day 9 Day 11 

Boiled 78.23d ± 0.08 78.77cd ± 0.12 
78.93cd 
± 0.05 

80.33ab 
± 2.04 

80.19ab 
± 0.08 

78.46c 
± 0.10 

80.11ab 
± 0.14 

Steamed 79.00cd ± 0.17 79.30abcd ± 0.02 
78.22d 
± 0.05 

79.84abc 
± 0.36 

79.77abc 
± 0.02 

79.27bcd 
± 0.15 

80.38a 
± 0.11 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letter (abcd) are not different (P < 0.05). 

 
A greater difference in moisture content with cooking treatments was observed between frozen samples (which 

were thawed prior to moisture determination) than for samples in refrigerated storage (Table 4). Ice crystal 
formation, protein denaturation, and increases in salt concentration during frozen storage can decrease the moisture 
content of  the thawed product [38, 39]. It was thought that ice crystal formation may have been a factor because 
slow freezing rates cause larger ice crystal formation, which would result in cellular disturbance and rupturing [1, 
40] and increased water loss or drip-loss from the crawfish upon thawing. There was a 13 to 20% drip loss during 
freeze-thaw cycles of  crawfish previously boiled for 15 m [41]. There was a significant difference between the boiled 
and steamed samples at all time intervals except for months four and five. 
 
Table 4. Percent (%) moisture of  peeled crawfish tail meat with adhering hepatopancreas after frozen (-18°C) storage and thawing. 

Treatment Month 0 Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 

Boiled 
78.23bc 
± 0.08 

77.05j 
± 0.13 

78.36bc 
± 0.04 

78.21cd 
± 0.07 

77.90efg 
± 0.06 

77.65h 
± 0.17 

77.95ef 
± 0.10 

Steamed 
79.00a 
± 0.17 

77.72gh 
± 0.06 

77.34i 
± 0.14 

78.42b 
± 0.11 

78.02de 
± 0.26 

77.79fgh 
± 0.12 

76.71k 
± 0.04 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letter (abcdefghijk) are not different (P<0.05). 

 
The ash contents obtained in this study did not exhibit significant differences between the boiled and steamed 

crawfish samples in refrigerated storage, except on d 9 (Table 5). As Sidwell [37] reported, the range for percent ash 
in an unspecified species of  raw crawfish was 0.7-3.6% which indicates quite a large range of  natural variation. 



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Another study had similar results, an ash content of  1.5% [41].  The values for percent ash content of  the 
refrigerated samples (boiled and steamed) are shown in Table 5. 

 
Table 5. Percent (%) ash of  peeled crawfish tail meat with adhering hepatopancreas stored during refrigerated (3.5°C) storage. 

Treatment Day 0 Day 1 Day 3 Day 5 Day 7 Day 9 Day 11 

Boiled 
1.30bcd 
± 0.10 

1.56a 
± 0.16 

1.15e 
± 0.03 

1.25bcde 
± 0.08 

1.21bcde 
± 0.03 

1.17de 
± 0.06 

1.19cde 
± 0.08 

Steamed 
1.25bcde 
± 0.04 

1.56a 
± 0.04 

1.23bcde 
± 0.12 

1.31bc 
± 0.02 

1.28bcde 
± 0.03 

1.33b 
± 0.01 

1.19cde 
± 0.08 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letter (abcde) are not different (P<0.05). 

 
The percent ash contents of  the boiled and steamed samples after frozen storage and thawing were slightly 

higher, on average, than the samples in refrigerated storage (Table 6). This might indicate more leaching of  minerals 
in the boiled samples compared to that of  the steamed samples. Blanching, or boiling, of  foods has a tendency to 
cause leaching of  vitamins and minerals; steaming has the benefit of  less leaching than blanching/boiling [42]. 

 
Table 6. Percent (%) ash of  peeled crawfish tail meat with adhering hepatopancreas after frozen (-18°C) storage and thawing. 

Treatment Month 0 Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 

Boiled 
1.29abc 
± 0.10  

1.01d 
± 0.39 

1.31abc 
± 0.04 

1.15cd 
± 0.02 

1.21bc 
± 0.02  

1.22bc 
± 0.04  

1.33abc 
± 0.00  

Steamed 
1.25abc 
± 0.04  

1.40ab 
± 0.05  

1.22bc 
± 0.08  

1.21bc 
± 0.07 

1.40ab 
± 0.07  

1.34abc 
± 0.03  

1.44a 
± 0.02 

Note: LS-Means ± SD of  3 measurements at each time period. LS-Mean values with the same letter (abcd) are not different (P<0.05). 

 
The protein contents of  boiled samples were significantly higher than for steamed crawfish on day of  refrigerated 

storage, except d 7 (Table 7). Although significant, the actual differences were small. For both the boiled and steamed 
samples, there was an overall decrease in percent protein from d 0 to 11. This may be due to increased microbial 
counts and the hydrolysis and consumption of  free amino acids and other soluble non-nitrogenous substance in the 
crawfish that serve as nutrients for microbial growth [11]. 

 
Table 7. Percent (%) protein of  peeled crawfish tail meat with adhering hepatopancreas stored during refrigerated (3.5°C) storage. 

Treatment Day 0 Day 1 Day 3 Day 5 Day 7 Day 9 Day 11 

Boiled 16.32c ± 0.04 16.46b ± 0.06 16.93a ± 0.04 
15.06g ± 

0.00 
14.95h ± 

0.07 
16.23d ± 

0.04 
15.27f 
± 0.05 

Steamed 16.15c ± 0.03 15.34f ± 0.06 16.02e ± 0.06 
14.56i 
± 0.10 

15.07g 
± 0.04 

15.05g ± 
0.02 

14.91h ± 
0.10 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letter (abcdefgh) are not different (P<0.05). 

 
The protein contents of  the boiled samples during frozen storage were higher (P<0.05) than steamed samples 

at every month except month six. There was a difference between the protein content of  the frozen samples and the 
refrigerated samples. The frozen values were larger by almost one % (Table 8). These values also fall within the range 
(11.9 - 24.1%) for percent protein in raw samples [37]. 

  
Table 8. Percent (%) protein of  peeled crawfish tail meat with adhering hepatopancreas after frozen (-18°C) storage and thawing. 

Treatment Month 0 Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 

Boiled 
16.32ef 
± 0.04 

17.31a 
± 0.06 

16.52d 
± 0.03 

16.71c 
± 0.03 

16.21fg 
± 0.19 

17.26a 
± 0.02 

16.51d 
± 0.04 

Steamed 
16.15gh 
± 0.03 

16.02hi 
± 0.05 

16.32de 
± 0.06 

16.44de 
± 0.16 

15.90i 
± 0.04 

16.37e 
± 0.05 

16.90b 
± 0.01 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letter (abcdefgh) are not different (P<0.05). 

 
There were some differences in the protein content between boiled and steamed crawfish during refrigerated and 

frozen storage. The differences could simply arise from natural variation in the samples that were selected. The 
protein content of  frozen samples tended to be higher than that of  the refrigerated samples.  

The percent fat values obtained in this study (2.12 to 3.76%) were higher than literature values (Table 9). This 
may be due to the inclusion of  the hepatopancreas (fat) with the tail meat in the present study. In Louisiana, crawfish 
are traditionally consumed with the fat [7] and so the hepatopancreas was kept attached to the tail meat to mimic 
the way that crawfish are commonly consumed in Louisiana.  Most studies delineating the fat content of  crawfish 
tail meat do not include the hepatopancreas. The hepatopancreas is roughly 30% fat by weight [43].  Therefore, the 
fat content of  crawfish with hepatopancreas would be expected to be higher than crawfish tail meat without 
hepatopancreas. 

 
Table 9. Percent (%) average fat of  peeled crawfish tail meat with adhering hepatopancreas during refrigerated (3.5°C) storage. 

Treatment Day 0 Day 1 Day 3 Day 5 Day 7 Day 9 Day 11 

Boiled 
2.99cde 
± 0.04 

2.91de 
± 0.04 

2.58f 
± 0.08 

2.27g 
± 0.13 

2.24g 
± 0.06 

3.27bc 
± 0.07 

2.88de 
± 0.11 

Steamed 
2.76def 
± 0.16 

2.75ef 
± 0.27 

3.04cd 
± 0.03 

2.12g 
± 0.11 

3.41a 
± 0.27 

2.90de 
± 0.08 

3.76a 
± 0.06 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letter (abcdefg) are not different (P<0.05). 

 
The average fat content of  the frozen crawfish was higher for both the boiled and steamed treatments than for 

the same treatments with refrigerated storage (Table 10). This might be explained by the reduced moisture in the 
frozen samples compared to the refrigerated samples. The variation is much more pronounced for the steamed 
samples than for the boiled samples. 



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Table 10. Percent (%) fat of  peeled crawfish tail meat with adhering hepatopancreas after frozen (-18°C) storage and thawing. 

Treatment Month 0 Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 

Boiled 
2.99def 
± 0.04 

3.10de 
± 0.0 

2.72h 
± 0.08 

3.13cde 
± 0.10 

3.00def 
± 0.08 

2.95efg 
± 0.01 

3.15cde 
± 0.04 

Steamed 
2.76gh 
± 0.16 

3.07def 
± 0.04 

3.34bc 
± 0.06 

3.87a 
± 0.10 

2.86fgh 
± 0.03 

3.21bcd 
± 0.26 

3.42b 
± 0.11 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letter (abcdefgh) are not different (P<0.05). 

 

3.4. Microbiological Results 
There were no E. coli/coliforms present in any of  the water samples or any of  the boiled or steamed crawfish at 

any time. There was no presence of  E. coli, but there was an average coliform count of  295 colony forming units 
(CFU)/g in raw crawfish. This suggests that the cook procedure for both boiling and steaming was adequate to kill 
these organisms. An APC count of  log 5.7 CFU/g is suggested by ICMSF [24] as the upper limit of  acceptability 
and, in this study, taken as the upper limit for shelf  life determination. As seen in Table 11, the boiled and steamed 
samples in refrigerated storage did not exceed the limit of  log 5.7 CFU/g until after day three. Both the boiled and 
steamed samples exceeded the chosen limit by day 5, the data point immediately after day 3, so the acceptable shelf  
life of  refrigerated crawfish, either boiled or steamed, was taken as three days. It is not clear why the difference in 
APC occurred. Further study with analyses conducted on all days may provide better insight. Total bacteria and 
psychrophilic bacteria counts were 4.6 and 4.7 and 3.3 and 3.5 log CFU/g for fried and microwaved crawfish in 
refrigerated storage [26]. 

 
Table 11. Aerobic plate counts (log10 CFU/g) for peeled crawfish tail meat with adhering hepatopancreas during refrigerated (3.5°C) storage. 

Treatment Day 0 Day 1 Day 3 Day 5 Day 7 Day 9 Day 11 

Boiled 
3.03c 

± 2.87 
3.10c 

± 2.87 
3.03c 

± 2.91 
6.10c 

± 5.36 
6.12c 

± 5.05 
8.10b 
± 7.08 

8.01b 
± 6.94 

Steamed 
2.57c 

± 2.53 
2.78c 

± 1.97 
5.46c 

± 4.89 
6.22c 

± 5.08 
TNC* 

8.62a 
± 7.53 

8.65a 
± 8.00 

Note: LS-means ± SD of  4 measurements at each time period. LS-mean values with the same letter (abc) are not different (P<0.05). * TNC = Too numerous 
to count. 

 
The APC counts were constant during frozen storage and below 5.7 log CFU/g at all data points as shown in 

Table 12 which would be expected during frozen storage at -18°C. This suggests that the shelf  life, based upon APC 
counts, of  crawfish in frozen storage is at least six months. This contrasted with results of  decreased Ca 2 + -ATPase 
activity, salt soluble protein content, total sulfhydryl and reactive sulfhydryl content and increased hardness at week 
4 to suggest that the recommended shelf-life of  frozen crayfish should be 1 month {1]. 

 
Table 12. Aerobic plate counts (log10 CFU/g) for peeled crawfish tail meat with adhering hepatopancreas after frozen (-18°C) storage and 
thawing. 

Treatment Month 0 Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 

Boiled 
3.02a 
± 2.87 

2.27d 
± 2.18 

2.48d 
± 1.98 

2.90abc 
± 2.19 

2.69bcd 
± 2.00 

2.78bcd 
± 2.00 

2.79bcd 
± 2.77 

Steamed 
2.57cd 
± 2.53 

2.70bcd 
±2.02 

2.69bcd 
±1.83 

2.95ab 
± 2.56 

2.56cd 
± 1.70 

2.92ab 
± 2.41 

3.04a 
± 2.41 

Note: LS-means ± SD of  4 measurements at each time period. LS-mean values with the same letter (abcd) are not different (P<0.05). 

 

3.5. TBARS Results 
TBAR values increased during refrigerated storage for both boiled and steamed samples but the level of  TBARS 

measured at the end of  the refrigerated storage was lower than anticipated (Table 13). It was anticipated that the 
values would be higher than previous studies because the crawfish in the current study had the hepatopancreas and 
vein, increasing the amount of  fat that might be oxidized and result in higher TBARS values. Surprisingly, the 
TBARS values obtained in this study were lower than literature values. An average TBARS value of  2.24 mg 
MDA/kg after 7 days [44] and 0.113 after 9 days of  refrigerated storage [26] were obtained on crawfish tail meat. 
 
Table 13. TBARS (mg MDA/kg) for peeled crawfish tail meat during refrigerated (3.5°C) storage. 

Treatment Day 0 Day 1 Day 3 Day 5 Day 7 Day 9 Day 11 

Boiled 
0.19fg 
± 0.02 

0.15h 
± 0.01 

0.24e 
± 0.00 

0.33cd 
± 0.03 

0.34c 
± 0.01 

0.42b 
± 0.04 

0.45b 
± 0.02 

Steamed 
0.16gh 
± 0.01 

0.14h ± 
0.02h 

0.22ef 
± 0.00 

0.29d 
± 0.03 

0.30d 
± 0.04 

0.32cd 
± 0.01 

0.53a 
± 0.03 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letter (abcdefgh) are not different (P<0.05). 

 
During refrigerated storage, TBARS values of  the boiled and steamed samples gradually increased from d 0 to 

11. It was unexpected that TBARS on d 0 were more than on d 1. One possible explanation is that the samples on d 
0 remained at room temperature slightly longer before TBARS analyses than on the other days of  the study. TBARS 
values, as expected, increased with refrigerated storage with boiled samples having slightly higher values than the 
steamed samples on all days except d 11. TBARS of  1.5 mg MDA/kg was the point at which humans can detect any 
off  flavors and 3.0 mg MDA/kg of  TBARS was the level at which crawfish are considered rancid and not desirable 
for consumption [44]. Using these criteria, the fat in the crawfish tail meat and hepatopancreas was not rancid at 
any time during the course of  the study. However, it was noticed that the crawfish in the last 5 to 6 days of  
refrigeration had an odor that was unpleasant. The TBARS values were similar to those of  Abou-Taleb, et al. [26] 
but Cremades, et al. [45] identified much higher levels of  TBARS of  crawfish in refrigerated storage. 
 
 

 



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Table 14. TBARS (mg MDA/kg) for peeled crawfish tail meat with adhering hepatopancreas after frozen (-18°C) storage and thawing. 

Treatment Month 0 Month 1 Month 2 Month 3 Month 4 Month 5 

Boiled 0.19f ± 0.02 0.22def ± 0.02 0.16g ± 0.02 0.21def ± 0.01 0.23cd ± 0.01 0.2cde ± 0.01 
Steamed 0.16g ± 0.01 0.25bc ± 0.00 0.20ef ± 0.00 0.22cde ± 0.01 0.19f ± 0.01 0.26b ± 0.04 

 
 

After frozen storage (Table 14), the TBARS values for both boiled and steamed samples, although having 
statistically significant differences, were essentially stable in contrast to the TBARS values of  the refrigerated 
samples. [46] observed an average TBARS value of  4.00 mg MDA/kg over the course of  10 months of  frozen 
storage, with a maximum value at month ten of  5.60 mg MDA/kg in crawfish tails containing the hepatopancreas. 
TBARS in crawfish tail meat greatly increased after 30 d of  frozen storage [20] and a linear increase in TBARS was 
found with repeated freeze-thaw cycles [41]. 
 

3.6. Texture  
Texture analyses were conducted on crawfish tail meat with adhering hepatopancreas over the course of  

refrigerated and frozen storage. Table 15 shows the peak shear force for boiled and steamed peak shear force values 
for crawfish during 11 days of  refrigerated storage. 

 
Table 15. Peak shear force (kg) for peeled crawfish tail meat with adhering hepatopancreas after refrigerated (3.5°C) storage. 

Treatment Day 0 Day 1 Day 3 Day 5 Day 7 Day 9 Day 11 

Boiled 
231.54abcd 

± 8.63 
240.66abc 
± 20.89 

262.43a 
± 28.24 

218.59bcde 
± 11.77 

230.95bcd 
± 5.28 

248.99ab 
± 33.73 

228.10bcd 
± 8.73 

Steamed 
224.57cd 
± 30.30 

208.39de 
± 14.51 

217.41cde 
± 19.22 

217.81bcde 
± 14.71 

236.14abcd 
± 7.75 

220.65bcd 
± 15.98 

188.19e 
± 14.12 

 
 
The peak shear force (kg) for the boiled samples in refrigerated storage gradually increased from day zero to day 

three even though the values were not different (P<0.05); there was greater variability from day three to eleven. The 
trend was somewhat similar for steamed samples, but the final value for steamed samples was lower than for boiled 
crawfish on d 11. The frozen shear force values (Table 16) are statistically similar but the shear force value on day 
eleven was the lowest which follows previous results [47] that proteolytic enzyme activity and an increased bacterial 
presence through the refrigerated storage caused the deterioration in the texture of  the crawfish. The results 
indicated that toughening due to moisture loss or mushy or deteriorative texture due to residual activity of  native 
proteinases in the hepatopancreas or tail that had not been deactivated by the thermal treatment (cooking) process 
did not substantially influence texture. However, d 7 variations in texture may also be due to the inherent nature of  
crawfish and the Kramer analysis. The uniformity of  the sample and direction of  the muscle fibers plays a role in the 
outcome of  the analysis [48]. That the crawfish were placed in the Kramer cell at random and did not completely 
cover the bottom of  the cell in the present study may have had an impact. The weight of  crawfish added to the cell 
was kept constant for all samples, however the number of  crawfish changed since the weights of  individual crawfish 
tails varied. 

  
Table 16. Peak shear force (kg) for peeled thawed crawfish tail meat with adhering hepatopancreas after frozen (-18°C) storage and thawing. 

Treatment Month 0 Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 

Boiled 
231.54f 
± 8.63 

277.23abc 
± 24.12 

266.15abcde 
± 19.81 

266.05abcde 
± 16.97 

291.06a 
± 26.08 

272.72abcd 
± 3.63 

282.23ab 
± 18.93 

Steamed 
224.57f 
± 30.30 

236.14e 
± 18.63 

242.42def 
± 7.75 

247.52cdef 
± 9.71 

252.62bcdef 
± 27.75 

265.17abcde 
± 16.18 

285.86a 
± 8.34 

 
 

The peak shear forces (kg) for the thawed previously frozen crawfish tail meat with attached hepatopancreas were 
more consistent than for the refrigerated samples, with the boiled samples generally tougher than the steamed 
samples. However, at month six, the steamed sample had a higher peak shear force than the boiled sample. The 
hardness, springiness, and chewiness of  crawfish varied among freeze-thaw cycles [41]. 

The work of  shearing was chosen as a measure of  toughness perceived when biting into a food product by 
measuring the force needed to shear the sample as a product of  time. The results of  the work of  shearing mimic the 
values of  peak shear force, which might be expected considering the measurements were taken simultaneously. Values 
for work of  shearing of  boiled and frozen crawfish tails through refrigerated storage are in Table 17 and through 
frozen storage are in Table 18. The hardness, resilience, cohesiveness, and chewiness changed with the times of  
steaming and boiling of  crawfish tail meat [2]. 

 
Table 17. Total shear work (N/s) for peeled crawfish tail meat with adhering hepatopancreas after refrigerated (3.5°C) storage. 

Treatment Day 0 Day 1 Day 3 Day 5 Day 7 Day 9 Day 11 

Boiled 
1059.31bcde 

± 86.00 
1081.67abcd 

± 152.40 
1241.42a 
± 52.56 

1045.29bcde 
± 133.57 

1045.49bcde 
± 57.07 

1092.56abc 
± 35.01 

1011.07bcdef 
± 89.34 

Steamed 
1105.11ab 
± 147.59 

907.31ef 
± 15.59 

994.69bcdef 
± 110.62 

923.59def 
± 118.56 

1105.80ab 
± 70.51 

933.20cdef 
± 86.00 

849.26f 
± 101.99 

 
 

 
 
 
 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letters (abcdef) are not different (P<0.05). 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letter (abcde) are not different (P<0.05). 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letter (abcdef) are not different (P<0.05). 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letter (abcdef) are not different 
(P<0.05). 



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Table 18. Total shear work (N/s) for peeled thawed crawfish tail meat with adhering hepatopancreas after frozen storage (-18°C) and 
thawing. 

Treatment Month 0 Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 

Boiled 
1059.31cd 
± 86.00b 

1157.48bc 
± 138.57 

1130.41bc 
± 115.72 

1073.44bcd 
± 117.29 

1347.63a 
± 36.38 

1226.71ab 
± 33.05 

1101.48bc 
± 76.3 

Steamed 
1105.11bc 
± 147.59 

832.19e 
± 43.64 

1008.71cde 
± 33.34 

895.94de 
± 52.86 

1170.52abc 
± 181.33 

1182.68abc 
± 200.45 

1138.75bc 
± 54.43 

 
 

3.7. pH Results 
There was no general trend for the pH in the boiled crawfish during refrigerated storage, presented in Table 19. 

For the steamed samples, the initial pH declined during storage to a pH value of  7.77 on day 11. The variable pH for 
boiled and steamed samples through the refrigerated storage can be attributed to changes in production of  basic 
compounds such as ammonia and other biogenic amines [49, 50]. The pH of  fried and microwaved crawfish meat 
were 5.75 and 5.80, respectively, for refrigerated samples [26]. There were also significant decreases from month 
zero to month six (which had the lowest pH values) for both boiled and steamed crawfish tail meat in frozen storage 
(Table 20). Reported pH values were 7.66 to 7.79 during 180 d frozen storage [20] and from 7.35 to 7.85 during 
repeated freeze-thaw cycles [41]. 

 
Table 19. pH of  peeled crawfish tail meat with adhering hepatopancreas during refrigerated (3.5°C) storage. 

Treatment Day 0 Day 1 Day 3 Day 5 Day 7 Day 9 Day 11 

Boiled 
8.10ef 
± 0.00 

8.20cd 
± 0.00 

8.10ef 
± 0.00 

8.17de 
± 0.06 

8.40a 
± 0.00 

8.27bc 
± 0.06 

8.03f 
± 0.06 

Steamed 8.30b ± 0.00 
8.20cd 
± 0.00 

8.10ef 
± 0.00 

8.13de 
± 0.06 

8.17de 
± 0.06 

8.03f 
± 0.06 

7.77g 
± 0.06 

 
 

Table 20. pH of  peeled thawed crawfish tail meat with adhering hepatopancreas after frozen storage (-18°C) and thawing. 

Treatment Month 0 Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 

Boiled 
8.10de 
± 0.00 

8.20bc 
± 0.00 

8.27ab  
± 0.06 

8.23abc 
± 0.06 

8.20bc 
± 0.00 

7.87fg 
± 0.06 

7.87g 
± 0.06 

Steamed 
8.30a 
± 0.00 

8.03e 
± 0.0 

8.20bc 
± 0.00 

8.17cd 
± 0.06 

8.20bc 
± 0.00 

7.93f 
± 0.06 

7.83g 
± 0.06 

 
 

3.8. Color Results   
The results of  the color analyses for lightness (L*), green/red (a*), and blue/yellow (b*) showed only slight 

differences throughout refrigerated and frozen storage.  
For boiled samples during refrigerated storage, the L* values were similar except for the difference (P<0.05) in 

L* between d 7 and 11 (Table 21). 
 

Table 21. L* of  peeled crawfish tail meat with adhering hepatopancreas during refrigerated (3.5°C) storage. 

Treatment Day 1 Day 3 Day 5 Day 7 Day 9 Day 11 

Boiled 
53.30bc 
± 6.26 

54.06abc 
± 3.45 

53.23bc 
± 6.39 

50.61c 
± 6.23 

54.73abc ± 
4.28 

57.84ab ± 
6.70 

Steamed 
53.65bc 
± 5.57 

52.91bc 
± 5.85 

51.34c 
± 3.85 

55.10abc 
± 3.91 

56.06abc ± 
7.20 

59.33a 
± 10.64 

 
 
For the steamed samples, lightness values slowly decreased from day one to day five, then increased to day eleven.  

There were no differences (P<0.05) between the two treatments at each individual day. 
 

Table 22. L* of  peeled thawed crawfish tail meat with adhering hepatopancreas after frozen (-18°C) storage and thawing. 

Treatment Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 

Boiled 
52.32ab 
± 4.28 

54.45ab 
± 5.76 

53.74ab 
± 6.66 

56.60a 
± 7.43 

48.63b 
± 5.91 

48.58b 
± 6.92 

Steamed 
52.12ab 
± 9.18 

53.11ab 
± 4.45 

52.46ab ± 
6.58 

52.84ab 
± 7.29 

49.86b 
± 6.72 

54.23ab 
± 7.71 

 

 
The L* values of  the boiled samples through frozen storage were all similar except that month 4 was higher 

(P<0.05) than months 5 and 6 and the boiled and steamed frozen crawfish L* values were not different (P<0.05) from 
each other at any month, as shown in Table 22.  

These L* values through refrigerated storage were slightly higher than the samples in frozen storage. L* values 
showed a general decrease with increased frozen storage time in the study by Bonilla, et al. [20].   

The a* values or green/red scale of  color showed little differences (P<0.05) in Table 23 for boiled crawfish 
samples throughout refrigerated storage with day 3 having the highest (P<0.05) a* value.  

Values for the steamed samples fluctuated and on day 11 the steamed samples had much smaller values a* values 
than the boiled samples. 

 
 
 
 

Note: LS-means ± SD of  3 measurements at each time period. abcdeLS-mean values with the same letter (abcde) are not different (P<0.05). 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letter (abcdefg) are not different (P<0.05). 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letter (abcedfg) are not different (P<0.05). 

Note: LS-means ± SD of  3 measurements at each time period. LS-mean values with the same letter (abc) are not different (P<0.05). 

Note: LS-Means  ± SD of  10 measurements at each time period.  LS-Mean values with the same letter (ab) are not different (P<0.05). 



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Table 23. a* of  peeled crawfish tail meat with adhering hepatopancreas in refrigerated (3.5°C) storage. 

Treatment Day 1 Day 3 Day 5 Day 7 Day 9 Day 11 

Boiled 32.02bcd ± 6.39 
35.52ab 
± 5.73 

32.58bcd ± 
4.63 

31.65bcd ± 
3.74 

29.35cd ± 
3.63 

31.06bcd ± 5.77 

Steamed 34.18abc ± 8.04 38.23a ± 6.94 
31.47bcd ± 

5.27 
27.35de 
± 4.03 

29.35de 
± 3.63 

22.91e ± 10.45 

 
 

The a* values for the boiled and steamed frozen samples were similar at each month except month 6, where the 
a* values of  the boiled samples were larger than the steamed samples (Table 24). 

 
Table 24. a* of  peeled thawed crawfish tail meat with adhering hepatopancreas after frozen (-18°C) storage and thawing. 

Treatment Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 

Boiled 
25.80bc 
± 4.08 

26.58bc 
± 5.04 

27.24bc 
± 7.27 

24.55bc 
± 8.27 

30.15ab 
± 6.23 

32.93a 
± 5.77 

Steamed 
23.82c 
± 8.18 

30.12ab 
± 3.48 

27.21bc 
± 6.21 

26.99bc 
± 4.83 

28.93abc 
± 7.80 

25.39c 
± 7.40 

 
 
The b* values [blue/yellow color scale] fluctuated during the eleven days of  refrigerated storage (Table 25). 

The b* value of  boiled samples increased (P<0.05) from day one to day three, then decreased from d 3 to 7 when the 
lowest value of  22.91 occurred.  

The b* values then steadily increased to d 11. Steamed crawfish tail meat also had variable b* values in 
refrigerated storage, with a high value of  40.24 on day three and values that decreased from day five through day 9. 
It is not understood what caused the fluctuation in the b* values during the refrigerated storage. 

 
Table 25. b* of  peeled crawfish tail meat with adhering hepatopancreas in refrigerated (3.5°C) storage. 

Treatment Day 1 Day 3 Day 5 Day 7 Day 9 Day 11 

Boiled 32.48c ± 4.66 
37.78ab 
± 5.99 

30.78cd 
± 4.88 

22.91f 
± 3.40 

26.29def ± 
4.63 

32.35c 
± 4.30 

Steamed 34.68bc± 6.31 
40.24a 
± 5.35 

30.10cde ± 4.10 
26.77def 
± 4.98 

25.49ef 
± 3.30 

27.60de ± 8.46 

 
 
During frozen storage, the b* values were lower than the b* values during refrigerated storage (Table 26) which 

corresponds to the differences in the L* and a* values with type of  storage. The steamed and boiled samples were 
the same throughout the six months of  storage at every month. Cryogenically frozen crawfish showed minimal 
changes in b* values while blast frozen crawfish had variation in b* values during 180 d frozen storage [20]. 

 
Table 26. b* of  peeled crawfish tail meat with adhering hepatopancreas after frozen (-18°C) storage and thawing. 

Treatment Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 

Boiled 
22.57ab 
± 5.37 

24.30ab 
± 5.04 

24.24ab 
± 4.73 

25.60a 
± 3.86 

26.12a 
± 5.56 

25.59a 
± 5.13 

Steamed 
20.94b 
± 7.84 

25.03ab 
± 2.22 

22.50ab 
± 2.22 

25.82a 
± 2.13 

24.86ab 
± 4.47 

25.11a 
± 3.78 

 
 

The L*, a*, and b* values all decreased during frozen storage in comparison to their refrigerated samples. L*, 
a*, and b* values varied greatly during consecutive freeze-thaw cycles of  crawfish during frozen storage [13].   
 

3.9. Mineral Results  
Mineral analyses shown in Table 27 were conducted to determine the presence and quantity of  29 different 

minerals and metals that might have caused differences in crawfish properties throughout the refrigerated and frozen 
storage.  

The amount of  arsenic is pertinent as many crawfish are farmed in rice ponds, as in this study, and levels of  
inorganic and organic arsenic are of  concern in rice and rice products [51, 52].  The arsenic levels observed in the 
crawfish in the present study are higher than that which is approved by the Environmental Protection Agency (EPA) 
for allowable limits in drinking water. The limit for arsenic in drinking water is 10 parts per billion (ppb) or 0.01 
parts per million (ppm).  

The mineral values varied greatly from those of  frozen crawfish in the Bonilla, et al. [20] possibly due to the 
inclusion of  the hepatopancreas and veins in the samples analyzed in the current study. 

 
Table 27. Selected minerals (ppm) in tail meat with adhering hepatopancreas. 

Mineral 
Boiled avg. ± 

SD (ppm) 
Boiled range 

(ppm) 
Steamed avg. ± SD 

(ppm) 
Steamed range 

(ppm) 
Other sources 

(ppm) 

Al 9.67 ± 2.98 4.72 – 13.78 8.54 ± 3.68 4.01 – 16.83 _ 
Mg 86.08 ± 4.86 78.02 - 90.36 81.76 ± 4.73 70.97 – 87.64 330 [35] 
Mn 1.04 ± 0.24 0.41 – 1.29 1.06 ± 0.24 0.36 – 1.29 4.2-7.28 [36] 
K 576.32 ± 46.15 641.46 – 494.79 647.13 ± 64.06 535.89 – 738.37 5,000 [36] 
Na 341.98 ± 21.80 300.21 – 364.26 383.51 ± 39.82 325.93 – 431.24 1,820 [36] 
Si 15.77 ± 2.91 11.18 – 21.30 15.71 ± 3.75 10.22 – 21.58 _ 
B 4.27 ± 0.32 3.73 – 4.77 4.43 ± 0.28 3.84 – 4.85 _ 

Note: *LS-means ± SD of  10 measurements at each time period. LS-mean values with the same letter (abcde) are not different (P<0.05). 

 

Note: LS-means ± SD of  10 measurements at each time period. LS-mean values with the same letter (abc) are no different (P<0.05). 

Note: LS-means ± SD of  10 measurements at each time period. LS-mean values with the same letter (abcdef) are not different (P<0.05). 

Note: LS-means ± SD of  10 measurements at each time period. LS-mean values with the same letters (ab) are not different (P<0.05). 
 



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Mineral 
Boiled avg. ± 

SD (ppm) 
Boiled range 

(ppm) 
Steamed avg. ± SD 

(ppm) 
Steamed range 

(ppm) 
Other sources 

(ppm) 

Cu 2.60 ± 0.81 1.48 – 4.47 2.40 ± 0.92 0.73 – 3.98 7-11.21 [36] 
Fe 14.55 ± 2.68 10.32 – 18.61 12.80 ± 2.57 6.53 – 16.22 9-373 [36] 
Ca 416.16 ± 68.71 333.74 – 545.91 371.20 ± 71.10 297.09 – 515.43 650-2,700 [36] 
P 435.74 ± 51.60 346.44 – 506.66 426.01 ± 64.05 308.32 – 524.12 1,010-1,920 [36] 
Zn 5.92 ± 0.72 4.08 – 6.91 5.62 ± 0.90 3.68 – 6.76 16.38 [36] 
As 0.08 ± 0.05 0.01 – 0.15 0.08 ± 0.04 0.01 – 0.13 0.02 [36] 

 

3.10. Fatty Acid Results 
Table 28 gives fatty acids and their levels (%) observed in boiled and steamed crawfish samples through 11 days 

of  refrigerated storage. Table 29 represents the fatty acid values (%) of  boiled and steamed crawfish through six 
months of  frozen storage. This analysis was conducted to add to the body of  knowledge regarding crawfish and the 
types and levels of  fatty acids in crawfish containing hepatopancreas fat. The fatty acid contents of  steamed crawfish 
were determined to be 25.77, 30.86, and 43.36 per cent for SFA, MUFA, and PUFA, respectively [2]. SFA varied 
from 24.37 to 27.00 while MUFA increased from 29.82 to 33.31 and PUFA decreased from 45.42 to 39.68 with 
increased steaming time for crawfish, but SFA, MUFA, and PUFA were variable among boiling times with similar 
ranges in values [2]. Fatty acid composition varied between commercially harvested crawfish and those from moist-
soil wetlands [25]. 

 
Table 28. Percentages of  fatty acid groups in boiled crawfish fat in refrigerated (3.5°C) storage. 

Fatty acid group Day 0 Day 1 Day 3 Day 5 Day 7 Day 9 Day 11 

% SFA boiled 38.33 33.51 36.20 72.86 63.00 42.78 26.05 
% SFA steamed 41.20 24.93 58.39 56.81 56.94 27.55 16.18 
% MUFA boiled 23.34 25.32 24.43 8.47 7.90 18.16 29.67 
% MUFA steamed 24.69 26.29 9.60 9.80 13.71 41.23 37.95 
% PUFA boiled 38.33 41.47 40.36 18.67 29.20 39.07 44.28 
% PUFA steamed 34.10 48.78 32.01 33.39 19.35 31.22 45.86 

Note: Saturated fatty acids [SFA], Mono-unsaturated fatty acids [MUFA], And polyunsaturated fatty acids [PUFA]. 

 
Table 29. Percentages of  fatty acid groups in boiled crawfish fat in frozen (-18°C) storage. 

Fatty acid group Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 

% SFA boiled 41.04 44.58 36.50 45.83 42.21 36.17 
% SFA steamed 32.95 38.24 33.32 37.15 29.67 35.50 
% MUFA boiled 16.01 22.73 26.51 27.05 29.00 26.19 
% MUFA steamed 27.87 24.98 28.32 29.76 30.39 27.12 
% PUFA boiled 42.95 32.65 36.99 27.11 28.78 37.64 
% PUFA steamed 39.18 36.79 38.36 33.09 39.94 37.38 

Note: Saturated fatty acids [SFA], Mono-unsaturated fatty acids [MUFA], And polyunsaturated fatty acids [PUFA]. 

 

5. Conclusions 
The quality and shelf  life of  whole cooked crawfish through refrigerated and frozen storage was similar in 

steamed and boiled crawfish tails with adhering hepatopancreas. These observations suggest that commercial 
crawfish processors would not benefit by investing in commercial steamers and steaming their crawfish, but they 
should continue the traditional boiling processes for crawfish. A further study with analyses conducted on each day 
of  storage would allow for a more precise determination of  the exact shelf  life of  the crawfish regarding aerobic 
counts.  

With either method of  cooking, the refrigerated shelf  life is very short for whole cooked crawfish in most 
marketing channels. Further research on sensory properties would be advantageous to determine consumer 
acceptability on the refrigerated and frozen crawfish to compare with the analytical results observed in this study. 
Also, sensory analysis may reveal a difference between boiling and steaming from consumer perspectives even though 
analytical results in this study do not suggest there would be major differences. 
 

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