Art_15772.indd Journal of Applied Botany and Food Quality 94, 124 - 131 (2021), DOI:10.5073/JABFQ.2021.094.015 1Division of Food and Nutrition Sciences, Ohio University, USA 2 Fox Paw Farm, LLC., Adams County, Ohio, USA A comparative analysis of p awpaw (Asimina triloba) quality and nutritional data Robert G. Brannan1*, Emily E. Anderson1, Ronald L. Powell2, Maria N. Coyle1 (Submitted: February 14, 2021; Accepted: June 1, 2021) * Corresponding author Summary The North American pawpaw (Asimina triloba [L.] Dunal) from sixteen varieties was analyzed for size, pH, oBrix, fi rmness, and pulp and skin color. A varietal composite was used to determine nutrient composition. Data from the current study was compared to previous literature values, and all results fi t well with previous literature. The average weight of the fruits across all varieties was 194 g and ranged from 122 to 292 g, the pH of the fruits ranged from 5.4 to 6.3, the average oBrix ranged from 18.2% to 26.1%, and fi rmness ranged from 0.391 kg to 0.727 kg. The color of the skin and the pulp differed by variety but was well-within previously reported values. Pawpaw pulp nutritional values verifi ed the nutritional values previously reported for pawpaw pulp from fruit harvested in Korea and will be used as the basis for inclusion of pawpaw in the USDA National Nutrient Database for Standard Reference. Several specifi c recommendations are made: 1) fi rmness of 0.2 to 0.7 kg of force can be used to describe ripe pawpaw fruit; 2) the serving size for raw pawpaw pulp is one- half cup (120 g); and 3) pawpaw pulp nutrition compares favorably to that of banana or mango. Introduction The North American pawpaw (Asimina triloba [L.] Dunal), hereafter pawpaw, is the largest edible fruit native to the United States (layne, 1996). The pawpaw is in the Annonaceae family, of which 14 of the 2300 species are native to the United States (cronqUist, 1981), including nine species of Asimina (callaWay, 1993). The pawpaw grows on fruit-bearing trees about 5 to 10 meters tall and often found in clusters (PoMPer et al., 2003; PoMPer and layne, 2005). The leaves are distinctive compared to leaves of other Asmina species because they are long, egg-shaped, and membranous in texture (Kral, 1960; layne, 1996). The buds are dark maroon in color (PoMPer and layne, 2005) and the fl owers are unable to self- pollinate, requiring hand pollination using a genetically different tree (Bois, 2001; layne, 1996; Willson and scheMsKe, 1980) or pollinators such as fl ies, beetles, and other nocturnal insects, which are unreliable for proper pollination (layne, 1996; PoMPer et al., 2008; Willson and scheMsKe, 1980). These pawpaw structures are shown in Fig. 1. More detailed information about the botanical characteristics of the pawpaw can be found in the literature (PoMPer and layne, 2005). The fruit may grow alone or in clusters and are botanically cate- gorized as a pulpy berry, probably an aggregate berry (Jones and layne, 1997; PoMPer and layne, 2005). The fruit’s edible fl esh can range in color from creamy white to bright yellow to orange, has a custard-like texture, and has 12-20 bean-shaped seeds embedded in the pulp in two rows (layne, 1996; Peterson, 2003; PoMPer and layne, 2005). The pawpaw is a climacteric fruit and ethylene and respiratory peaks are seen within three days after the fruit is harvested (archBold and PoMPer, 2003), causing the fruit to become undesirably soft and brown within 5 days of harvest at ambient temperature (galli et al., 2008). Refrigeration at 4 °C can delay the softening of the fruit for several weeks, but does not prevent skin browning (galli et al., 2008; PoMPer and layne, 2005). Food quality research on the pawpaw fruit pulp appearance in the literature has been gradual, with our lab and others reporting on a variety of quality characteristics. Pulp browning and the activity of polyphenol oxidase, the enzyme responsible for pulp browning has been characterized, (Brannan, 2016; zhang et al., 2017), as has the identifi cation of cell wall components and phytochemicals (Brannan et al., 2019, 2015). The utilization of pulp and seed components, especially phytochemicals and antioxidants, as potentially value- added food ingredients has been reported (Brannan et al., 2018; Brannan and salaBaK, 2009; harris and Brannan, 2009; KoBayashi et al., 2008; naM et al., 2019, 2017). Sensory quality of the pulp (Brannan et al., 2012; Mcgrath and Karahadian, 1994) and the application of processing techniques to extend shelf life (Brannan et al., 2019; Brannan and Wang, 2017; zhang et al., 2017) also has been reported. The totality of research about the nutrient composition of pawpaw pulp includes two studies, one that reported nutritional information for whole pawpaws including the pawpaw skin, which is rarely consumed and often considered inedible (Peterson et al., 1982), and a more recent study about pawpaw fruit grown in Korea (naM et al., 2018). Many of these food quality studies sought to differentiate quality parameters by pawpaw variety (Brannan, 2016; Brannan et al., 2015; greenaWalt et al., 2019) or pulp ripeness (harris and Brannan, 2009; KoBayashi et al., 2008; naM et al., 2019). The objective of the present study was to investigate the quality, nutritional, and compositional characteristics of pawpaw pulp from different varieties and compare and contextualize the results to similar characteristics reported previously. Fig. 1: Artists rendition of the parts of the pawpaw (Asimina triloba) plant. A) Mature fruit on the tree; B) mature fruit cut lengthwise to expose the seeds; C) branch with bud; D) blossom. (Artwork © by author M.N. Coyle) Comparative analysis of pawpaw nutrition 125 Materials and methods Pawpaw collection and processing Pawpaw fruit were collected from Fox Paw Farm, L.L.C. in Adams County, Ohio (38°39’N, 83°41’W, 273 m above sea level) in September 2019. Located in USDA Hardiness Zone 6, the climate for Adams County, Ohio shows average rainfall of 1133 mm, snow- fall of 445 mm, 126 days of precipitation, average January tempera- ture of -6.6 °C, and average July temperature of 29.6 °C. The farm is a rural 3.5-acre plot that contains pawpaw trees planted from 2003- 2006 in three blocks. At the time of data collection, the north block contained trees in east-to-west rows with 2.5 m between trees. The east block contained rows running north-south with trees 2.5 m apart. The west block contained nine rows running north-south with 3 m between trees. In all three blocks, rows were planted 4.5 m apart. Sixteen varieties with at least four fruits from each variety were harvested for this study. The varieties were selected at the time of harvest to be sure all fruits were of similar ripeness and were harvested by hand to ensure there was no damage or bruising to the fruits being used in the analysis. The sixteen varieties were 'Estill', 'Green River Belle', 'IXL', 'KSU Atwood™', 'Lynn’s Favorite', 'Mango', 'Mitchell', 'NC-1', 'Overleese', 'Pickle', 'Potomac™', 'Quakers Delight', 'SAA-Zimmerman', 'SAB Overleese', 'Shenandoah™', and 'Wabash™'. The harvested fruits were then transferred to the Food Innovation Laboratory at Ohio University on ice. Fruit weight, size, skin and pulp color, fi rmness of the fruit, and pH of the pulp were recorded for each individual fruit before processing. The skin color (L*, a*, b*) was measured in three places on each fruit using a using a Konica BC-10 colorimeter (Konica Minolta Sensing Americas Inc., Ramsey, NJ), after which the hue angle was calculated according to previous work (Brannan et al., 2015). A ~25 mm circle of skin was removed in three spots on the exterior of the fruit to assess pulp color and fruit fi rmness on the exposed pulp. The fi rmness of the exposed pulp, reported as kg of force, was measured by penetrometry on the fruit situated on a solid platform with a 10-mm diameter cylindrical probe with a crosshead speed of 5 mm/s to a depth of 10 mm using a Ta-XT2i Texture Analyzer (Texture Technologies Corp., Scarsdale NY/Stable Micro Systems, Godalming, Surrey, UK). Varietal composites for nutritional analysis were prepared according to the following scheme. One whole fruit from each of the sixteen varieties was randomly assigned into one of four groups. Pulp from each variety was not pooled before being assigned to a group, rather each individual whole fruit assigned to a group was processed by removing the skin and seeds from the pulp by hand, after which an equal weight of that pulp was used to create a composite from the one fruit of each variety in each group. Thus, the four composites were compositionally identical except that the source of the pulp from each variety was an individual fruit, not a composite of fruits from each variety. After each composite was mixed thoroughly, pulp from the composites was distributed into FoodSaver® bags, which were sealed without any attempt to exclude oxygen from the bags and held at -20 °C. A total of nine of the composite samples, two duplicates from three of the composites and three triplicates from the one remaining composite, were assigned three-digit random codes before being transported on dry ice to the laboratories for analysis. Nutrient Analysis Nutrient analysis was performed by Q Laboratories (Cincinnati, Ohio) except for total dietary fi ber and vitamin D, which were performed by Medallion Labs (Minneapolis, Minnesota). Analysis for each analyte was performed in triplicate from each of the nine randomly-coded bags of pawpaw pulp (described above), according to standard AOAC International methods (aoac international, 2016) except for metals (Ca, Fe, K, Na), which were quantifi ed using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP- OES) after acid digestion of the pulp. The AOAC methods used for each nutrient are as follows: ash (AOAC 923.03), cholesterol (AOAC 994.10), lipid (AOAC 922.06), moisture (AOAC 934.06), fatty acids (monounsaturated, polyunsaturated, saturated and trans) (AOAC 996.06), total dietary fi ber (AOAC 991.43), vitamin D (AOAC 2011.11). Data Analysis Means and standard deviations were generated for the response variables. Inferential statistics were generated to compare varieties using Analysis of Variance and means separation was achieved using Duncan’s post-hoc analysis using IBM SPSS Statistics software. Signifi cance was determined at p<0.05. Results and discussion Of the sixteen varieties of pawpaw analyzed and reported in this study, there was existing literature data for nine of the varieties, which was used for comparative analysis of the attributes for which whole fruit or pulp was not pooled, i.e. fruit size and weight, texture, oBrix, pH, and pulp and skin color. The sixteen varieties were pooled into varietal composites for nutritional analysis. Fruit size by variety and serving size determination Tab. 1 shows the mean weight, length, and width for each of the varieties of pawpaws used for this study. The average weight of the fruits across all varieties was 194 grams and ranged from 122 grams for variety 'Pickle' to 292 grams for variety 'KSU-Atwood'. Although there were signifi cant differences in average fruit weight by variety (p<0.001), with the six heaviest varieties signifi cantly heavier than the ten least heavy varieties (Tab. 1), post-hoc means separations did not elucidate other differences. A recent study that examined average fruit weight from all fruit of 52 varieties collected during 8 harvests from 2005 to 2012 at three sites including Fox Paw Farm, the location of fruit collected for this study, determined that fruit weight is normally distributed across all varieties and the average fruit weight by variety ranged from 72-244 g (greenaWalt et al., 2019). Results of the much smaller sample from this study fi t well with those results. Of the 9 varieties of which comparisons to previous research can be made (Tab. 1), 8 of the varieties from this study, all but 'Lynn’s Favorite', weighed more and all nine varieties had larger dimensions than was reported previously and (Brannan et al., 2015) even though they came from the same location. The average weight of the fruit of the 9 varieties from the comparative study was 136 g, compared to 203 g for the same varieties from the current study. Because the intention of the current study was not to collect all fruit but rather to create composites for nutritional analysis, it is likely that larger fruit were selected. The average fruit weights were used as a basis to determine the serving size of the pawpaw because currently there is none. After some experimentation, the Registered Dietitian on the project team (author E.E. Anderson) determined that one half cup (120 g) was an appropriate serving size. This determination was based on the knowledge that 120 g is similar to the serving size of other popular fruits and can be obtained from the pulp of one large (~240 g) or two small (~120 g) whole pawpaw fruits, assuming a 50% yield of pulp from the skin and seeds. Fruit pH, oBrix, fi rmness, and color by variety As shown in Tab. 2, the pH of the fruits from each variety ranged from 5.4 to 6.3, which categorizes pawpaw as a low acid fruit along 126 R.G. Brannan, E.E. Anderson, R.L. Powell, M.N. Coyle Tab. 1: Mean and standard error (S.E.) for size (weight, length, width) of sixteen varieties of whole pawpaws (Asimina triloba), nine of which can be compared directly to a previous study (BRANNAN et al., 2015). (Different superscript letters within a column indicate significant differences at p<0.05.) Variety Study Weight (g) S.E. Length (cm) S.E. Width (cm) S.E. Varieties for which comparative analysis can be made Green River Belle Current 187 abcde 6.2 16.6 abc 0.2 5.8 a 0.4 Previous 152 10.5 5.7 IXL Current 213 bcdef 63.6 15.6 ab 3.4 8.6 bcde 0.9 Previous 127 9.5 5.4 KSU-Atwood Current 292 f 22.7 18.3 bc 0.5 11.2 g 0.5 Previous 162 11.1 5.2 Lynn’s Favorite Current 130 ab 10.6 13.8 a 0.7 8.6 bcde 0.4 Previous 179 11.5 5.6 NC1 Current 217 cdef 19.5 16.3 abc 0.9 9.3 cdef 0.8 Previous 204 10.5 6.4 Overleese Current 223 def 38.0 14.2 a 0.8 10.4 fg 0.7 Previous 130 9.1 5.8 Quaker’s Delight Current 186 abcde 22.3 16.2 abc 1.0 7.8 abc 0.2 Previous 84 7.9 4.8 SAA-Zimmerman Current 247 def 28.6 19.0 c 0.7 8.3 abcd 0.5 Previous 130 9.8 5.5 Shenandoah Current 133 abc 11.3 13.8 a 0.6 6.8 a 0.3 Previous 123 8.6 5.6 Varieties for which comparative analysis cannot be made Estill Current 188 abcde 24.3 15.0 ab 1.1 9.8 ef 0.4 Mango Current 175 abcd 17.8 14.4 a 1.1 8.0 abcd 0.3 Mitchell Current 195 abcde 32.4 16.3 abc 1.4 9.0 bcdef 0.4 Pickle Current 122 a 10.7 14.3 a 0.6 8.5 bcde 0.2 Potomac Current 267 ef 34.1 15.8 abc 0.9 11.2 g 0.5 SAB Overleese Current 197 abcde 29.1 14.8 a 0.9 9.3 def 0.4 Wabash Current 194 abcde 25.0 15.5 ab 1.2 7.5 ab 0.6 Tab. 2: Mean and standard error (S.E.) for oBrix, firmness, and pH of sixteen varieties of whole pawpaws (Asimina triloba), nine of which can be compared directly to a previous study (BRANNAN et al., 2015) for all values except pH which can be compared to a different study (BRANNAN, 2016). (Different superscript letters within a column indicate significant differences at p<0.05.) Variety Study °Brix S.E. Firmness S.E. Firmness S.E. pH S.E. (kg) (N) Varieties for which comparative analysis can be made Green River Belle Current 21.6 defg 0.3 0.610 bc 0.083 5.17 0.74 6.1 fg 0.0 Previous 25.1 0.419 6.8 IXL Current 22.6 fg 0.5 0.410 ab 0.037 4.10 0.43 5.5 ab 0.1 Previous 22.9 0.643 6.5 KSU-Atwood Current 22.3 efg 0.4 0.603 abc 0.096 4.92 0.81 6.1 fg 0.7 Previous 27.1 0.206 6.3 Lynn’s Favorite Current 20.6 cde 0.7 0.551 abc 0.056 5.47 0.55 5.4 a 0.1 Previous 28.0 0.232 6.2 NC1 Current 21.2 defg 0.5 0.464 ab 0.083 4.55 0.82 5.4 a 0.1 Previous 25.7 0.248 6.1 Overleese Current 20.6 cde 0.3 0.347 a 0.039 3.43 0.38 5.8 cde 0.0 Previous 25.1 0.198 6.5 Quaker’s Delight Current 17.1 a 0.3 0.507 abc 0.057 5.04 0.52 5.5 a 0.0 Previous 20.9 0.499 6.5 SAA-Zimmerman Current 19.2 bc 0.5 0.580 abc 0.054 5.81 0.53 6.3 g 0.0 Previous 19.9 0.551 6.5 Shenandoah Current 22.3 efg 0.6 0.727 c 0.172 7.24 1.68 5.8 cde 0.0 Previous 21.2 0.432 6.7 Varieties for which comparative analysis cannot be made Estill Current 24.7 h 0.6 0.391 ab 0.048 3.94 0.45 5.8 cde 0.1 Mango Current 18.2 abc 0.3 0.421 ab 0.075 4.18 0.78 5.6 abc 0.1 Mitchell Current 20.4 cd 0.4 0.490 abc 0.061 4.86 0.57 5.5 ab 0.1 Pickle Current 21.7 defg 0.2 0.391 ab 0.049 3.91 0.52 6.0 ef 0.1 Potomac Current 21.0 def 0.7 0.623 bc 0.048 6.11 0.47 5.7 cd 0.1 SAB Overleese Current 26.1 h 0.6 0.429 ab 0.046 4.22 0.45 5.8 cde 0.0 Wabash Current 23.0 g 1.1 0.590 abc 0.101 5.79 0.99 5.7 cde 0.1 Comparative analysis of pawpaw nutrition 127 with such fruits as avocado, most melons, mango, papaya, and others. These values are in agreement with previously reported values (Brannan, 2016). Significant differences (p<0.001) for pH among varieties were found in the current study (Tab. 2) but not in the comparative study. The practical impact of the pH of pawpaw relates to the polyphenol oxidase (PPO), the enzyme responsible for skin and tissue browning. All of the varieties in this and previous studies exhibited pulp pH in the range in which pawpaw PPO has been shown to exhibit its highest activity (Fang et al., 2007), suggesting that none of these varieties would be more resistant than any other to PPO activity. The oBrix in the whole fruits were measured using a refractometer calibrated for direct reading of percent sugar and should not be confused with the percent sugar from the composites reported later in this paper. The average oBrix of the varieties ranged from 18.2% to 26.1%, again showing good agreement with previously reported values (Tab. 2). Variation in percent sugar of pawpaw fruit likely is due to an increase in sugars during climacteric ripening, although there is no research to support this hypothesis. In this study, varieties 'Estill' and 'SAB Overleese' exhibited significantly higher oBrix values than the other 14 varieties (p<0.001). The firmness of pawpaw is directly related to the ripeness of the fruit. There is no benchmark firmness value that defines a ripe pawpaw fruit and the current best practice for harvest is to squeeze each fruit by hand, looking for a small amount of give in the skin, an unreliable indicator. The least firm variety at the time of harvest was 'Estill' with a firmness of 0.391 kg, and the firmest variety was 'Shenandoah' with a firmness of 0.727 kg. Although there was a significant difference between these two varieties (p<0.022), post-hoc analysis did not reveal other differences of note (Tab. 2). We have shown that certain cell wall xyloglucans, pectins, and arabinogalactins degrade during refrigerated storage of pawpaw pulp (Brannan et al., 2019) and it is likely that compositional degradation of the cell wall causes loss of turgor during ripening and storage. Whole fruit firmness from nine varieties in the current study compares well to the firmness of fruits from similar varieties measured previously (Tab. 2). One conclusion that can be drawn from this comparison is the certainty that firmness values between 0.2 and 0.7 kg of force using the method described herein would describe ripe fruit because all of the fruits from the comparison studies were in this range and were considered ripe as determined by hand. The CIE color (L*, a*, b*) and hue angle for the skin and pulp of the varieties sampled in this study are shown in Tab. 2 and 3, respective- ly. There were significant differences (p<0.001) between varieties for all of these values, however, the interpretation of these results tends to be descriptive rather than inferential because certain varieties have skin and pulp that tends to be lighter or more yellow than others. The skin color range for all of the varieties (Tab. 3) exhibited a* values (-6.0 to -14.0), b* values (37.0 to 49.3), and hue angles (99.0 to 109.1) indicating that the skin is yellow-green or green-yellow. This range of skin color by variety has led to the conclusion that skin color is not a reliable indicator of fruit ripeness (Mcgrath and Karahadian, 1994). The pulp color range for all of the varieties (Tab. 4) exhibited a* values (1.0 to 11.6), b* values (32.8 to 51.2), and hue angles (76.2 to 88.3) indicating that the pulp is orange to yellow. These results are in strong agreement with previous research (Tab. 4). Nutritional analysis of pawpaw The proximates, vitamins, minerals, and essential and non-essential amino acids for varietal composites of pawpaw pulp from this and comparative studies (naM et al., 2018; Peterson et al., 1982) are Tab. 3: Mean and standard error (S.E.) for CIE L*, a*, b* and hue angle (Hue) of the skin from sixteen varieties of whole pawpaws (Asimina triloba), eight of which can be compared directly to a previous study (BRANNAN et al., 2015) and variety Shenandoah to a different study (ZHANG et al., 2017). (Different superscript letters within a column indicate significant differences at p<0.05.) Variety Study L* S.E. a* S.E. b* S.E. Hue S.E. Varieties for which comparative analysis can be made Green River Belle Current 62.9 ce 0.8 -7.8 def 0.7 43.5 efgc 1.0 100.2 ab 1.0 Previous 65.8 -3.1 34.2 95.1 IXL Current 65.4 de 0.8 -12.7 ab 0.5 49.3 h 1.0 104.5 cde 0.7 Previous 63.4 -9.4 39.5 103.3 KSU-Atwood Current 59.7 ab 0.6 -12.8 ab 0.3 37.4 ab 1.2 108.9 f 0.4 Previous 61.4 -8.6 24.6 109.2 Lynn’s Favorite Current 59.5 ab 0.8 -12.5 ab 0.8 44.5 fg 1.2 105.7 de 1.2 Previous 63.9 -3.8 35.8 96.1 NC1 Current 61.8 abc 0.6 -12.6 ab 0.5 39.5 abcd 1.2 107.6 ef 0.7 Previous 62.9 -4.8 30.2 99.0 Overleese Current 59.9 ab 0.7 -14.0 a 0.7 40.1 abcde 0.8 109.2 f 0.8 Previous 65.1 -8.8 33.0 104.9 Quaker’s Delight Current 67.4 e 0.8 -13.0 ab 0.5 45.1 fg 1.0 106.1 def 0.7 Previous 69.3 -6.8 41.3 99.3 SAA-Zimmerman Current 67.7 e 0.7 -11.0 bc 0.4 41.9 cdef 1.5 104.7 cde 0.8 Previous 65.3 -10.2 36.9 105.4 Shenandoah Current 60.1 ab 0.6 -11.3 bc 0.8 39.8 abcde 1.1 105.9 de 1.0 Previous 61.8 -8.0 31.9 104.0 Varieties for which comparative analysis cannot be made Estill Current 59.3 ab 0.5 -8.0 def 0.5 37.5 ab 1.1 102.3 bc 0.9 Mango Current 62.1 bc 0.4 -9.1 cde 0.8 38.4 abc 0.9 103.5 bcd 1.2 Mitchell Current 64.4 cd 0.8 -8.2 def 1.4 43.2 defg 1.2 100.9 ab 13.8 Pickle Current 64.5 cd 0.5 -6.0 f 0.7 37.0 a 0.9 99.0 a 1.0 Potomac Current 59.8 ab 0.7 -7.6 ef 0.8 41.5 cdef 1.5 100.5 ab 1.1 SAB Overleese Current 59.2 a 1.9 -8.1 def 1.1 41.1 bcdef 1.9 101.1 ab 12.2 Wabash Current 65.2 de 0.7 -10.1 cd 0.9 46.2 gh 1.2 102.4 bc 1.2 128 R.G. Brannan, E.E. Anderson, R.L. Powell, M.N. Coyle Tab. 4: Mean and standard error (S.E.) for CIE L*, a*, b* and hue angle (Hue) of the pulp from sixteen varieties of whole pawpaws (Asimina triloba), eight of which can be compared directly to a previous study (BRANNAN et al., 2015) and variety Shenandoah to a different study (ZHANG et al., 2017). (Different superscript letters within a column indicate significant differences at p<0.05.) Variety Study L* S.E. a* S.E. b* S.E. Hue S.E. Varieties for which comparative analysis can be made Green River Belle Current 70.8 bc 3.5 7.0 de 0.3 45.6 cd 1.1 81.2 cd 0.5 Previous 73.9 10.0 46.2 77.7 IXL Current 82.4 g 1.3 2.4 ab 0.3 32.8 a 1.2 85.9 f 0.4 Previous 77.1 6.3 45.1 82.0 KSU-Atwood Current 78.3 defg 1.0 5.0 cd 0.5 42.6 c 1.3 83.3 de 0.5 Previous 75.0 5.6 44.8 82.8 Lynn’s Favorite Current 75.8 cdefg 4.1 4.5 c 1.1 36.4 ab 2.6 82.9 de 1.4 Previous 72.6 11.1 42.9 75.4 NC1 Current 78.2 defg 1.3 4.3 bc 0.5 37.9 b 1.6 83.5 e 0.5 Previous 77.1 10.1 45.9 77.0 Overleese Current 72.5 bcde 2.1 6.5 cde 0.7 47.3 cde 1.3 82.2 de 0.7 Previous 79.3 2.1 34.6 86.5 Quaker’s Delight Current 82.6 g 1.0 1.0 a 0.2 32.9 a 1.2 88.3 g 0.3 Previous 77.8 6.5 46.1 81.9 SAA-Zimmerman Current 80.3 fg 0.8 7.0 de 0.5 49.9 de 1.0 82.1 de 0.5 Previous 79.8 4.4 44.2 84.3 Shenandoah Current 74.4 bcdef 0.8 9.3 fg 1.0 49.4 de 1.4 79.3 bc 0.8 Previous 64.3 6.3 39.8 81.0 Varieties for which comparative analysis cannot be made Estill Current 68.4 ab 2.0 10.6 gh 0.8 51.2 e 2.9 74.3 ab 2.3 Mango Current 75.9 cdefg 2.7 6.2 cde 1.0 44.7 cd 2.3 82.4 de 1.0 Mitchell Current 63.0 a 2.4 11.3 gh 0.8 46.0 cde 1.7 76.3 a 0.6 Pickle Current 71.8 bcd 1.0 11.3 gh 0.4 48.7 de 0.7 77.0 a 0.4 Potomac Current 73.9 bcdef 1.8 11.7 h 1.0 49.6 de 1.3 76.9 a 0.8 SAB Overleese Current 76.2 cdefg 3.2 7.4 ef 0.5 48.5 de 1.5 81.3 cde 0.6 Wabash Current 79.4 efg 1.8 5.7 cde 1.2 36.8 ab 2.7 81.9 de 1.2 shown in Tab. 5. We were able to locate historical pawpaw nutritional information from the 1963 USDA Agriculture Handbook #8 (Watt and Merrill, 1963), which includes information for the proximates (water, protein, fat, carbohydrate, and ash) and calories. It is unclear whether pawpaw nutritional values were listed in the database before this time. In 1982, a nutritional analysis of pawpaw pulp with skin was reported (Peterson et al., 1982), however, many consider the skin undesirable and only consume the pulp. Nonetheless, including the nutritional information for the pulp with skin in the comparison has value for those who do consume the skin. Recently, Korean researchers published a detailed nutritional analysis of pawpaw pulp (naM et al., 2018) but did not note the variety of pawpaw used. The comparison in Tab. 5 revealed more similarities than differen- ces between the composite from this study and the Korean study. Kilocalories calculated from the proximates were nearly identical (85 v 84) for the two studies. There were similarities in total lipid, ash, dietary fiber, potassium, and iron between the two studies. Nutrient analysis from the current study indicated less moisture and protein but more carbohydrates, especially glucose, vitamin C, and calcium than the Korean study. Pawpaw nutritional quality compared to common fruits To place the nutritional quality of the pawpaw in perspective, a weight-to-weight comparison of pawpaw nutrition information from this study to 100 g of seven common fruits (Us dePartMent oF agricUltUre, 2020) is shown in Tab. 6. On a per weight basis, pawpaw has 33-67% more lipid, 4-68% more carbohydrates, 42-69% more dietary fiber, and 16-70% more sugars than the seven other fruit. On the other hand, pawpaw has 2 to 12-fold less vitamin C than the other fruits, except apple. Prior to this research, which establishes one-half cup (120 g) as a standard serving size for pawpaw, no standard serving size of pawpaw existed. Serving size is an important measure because the ubiquitous NUTRITION FACTS labels on food products in the U.S. are based on serving size. Tab. 7 shows a nutritional comparison of pawpaw to the same seven fruits based on serving size. One serving of the seven other fruits ranges from 118 g (banana) to 182 g (medium apple). On a per serving basis, the pawpaw nutrient composition most resembles the nutritional content provided by a banana or mango. Pawpaw is very similar in calories and carbohydrates, has similar potassium as mango, but has much less vitamin C than both fruit. Pawpaw does have more fat and fiber than banana and mango. It is an interesting coincidence that the pawpaw’s closest nutritional comparisons on a per serving basis are the banana and mango because research has shown that banana and mango are the predominant flavors of pawpaw pulp (Brannan et al., 2012; Mcgrath and Karahadian, 1994). Benefits of up-to-date pawpaw nutritional information It is our intention to use the information from this and the Korean study to petition the USDA for inclusion of pawpaw in the USDA’s National Nutrient Database for Standard Reference. The database will be a boon for disseminating pawpaw’s nutrition information to growers, the food industry, and consumers interested in learning more about the pawpaw. Up-to-date nutritional data that reflects only the edible portion of the fruit can also be used to generate NUTRITION FACTS panels for food labels. Although raw fruits and certain low volume small businesses are exempt from having the NUTRITION FACTS labels, other small businesses and/or foods for sale that make nutrient claims (e.g. “Gluten free”, “Low fat”, etc.) are required to have NUTRITION FACTS labeling, even if they are exempt from the Comparative analysis of pawpaw nutrition 129 Tab. 5: Pawpaw (Asimina triloba) nutritional information for 100 g of pulp, one serving of pulp (1/2 cup, 120 g), and 100 g of pulp with skin. (“n.d.” indicates that the nutrient was not included in the analysis. The “<” symbol indicates the nutrient was analyzed but could not be detected at or above the threshold level.) Pulp (without skin) Pulp and Skin Current Study NAM et al., 2018 PETERSON et al., 1982 Nutrient Unit 100 g 1 serving 100 g 1 serving 100 g Proximates Calories KCal 85 102 841 101 80 Calories KJ 357 428 353 423 335 Moisture g 74.5 89.4 79.1 94.9 73.2 Protein g 0.7 0.9 1.5 1.8 1.2 Total Lipid g 0.6 0.7 0.4 1.7 1.2 MUFA g 0.05 0.06 0.06 0.07 n.d. PUFA g < < 0.06 0.07 n.d. Saturated FA g < < 0.05 0.06 n.d. Trans FA g < < n.d. n.d. n.d. Cholesterol mg < < n.d. n.d. n.d. Ash g 0.4 0.5 0.4 0.5 0.6 Carbohydrates (by difference) g 23.8 28.6 18.6 22.3 18.8 Dietary Fiber g 4.5 5.4 5.8 7.0 2.6 Total Sugars (calculated) g 16.3 19.5 13.1 15.7 n.d. Sucrose g 11.4 13.7 9.3 11.2 n.d. Glucose g 2.7 3.2 2.1 2.5 n.d. Fructose g 2.2 2.6 1.7 2.0 n.d. Lactose g < < n.d. n.d. n.d. Maltose g < < n.d. n.d. n.d. Vitamins Vitamin A IU n.d. n.d. 82 98 87 Vitamin C mg 4.92 5.9 1.0 1.2 18.3 Vitamin D IU < < n.d. n.d. n/a Thiamin mg n.d. n.d. n.d. n.d. 0.01 Riboflavin mg n.d. n.d. n.d. n.d. 0.09 Niacin mg n.d. n.d. n.d. n.d. 1.1 Minerals Calcium mg 13 16 8 10 63 Copper mg n.d. n.d. n.d. n.d. 0.5 Iron mg 0.2 0.2 0.3 0.4 7 Magnesium mg n.d. n.d. 10 12 113 Manganese mg n.d. n.d. n.d. n.d. 2.6 Phosphorus mg n.d. n.d. n.d. n.d. 47 Potassium mg 201 241 239 287 345 Sodium mg 1.0 1.2 n.d. n.d. n.d. Sulfur mg n.d. n.d. n.d. n.d. 70 Zinc mg n.d. n.d. 0.5 0.6 0.9 Essential Amino Acids Cystine mg n.d. n.d. n.d. n.d. 4 Histidine mg n.d. n.d. 44 53 21 Isoleucine mg n.d. n.d. 13 15 70 Leucine mg n.d. n.d. 38 45 81 Lysine mg n.d. n.d. 30 36 60 Methionine mg n.d. n.d. n.d. n.d. 15 Phenylalanine mg n.d. n.d. 28 33 51 Threonine mg n.d. n.d. 24 29 46 Tryptophan mg n.d. n.d. n.d. n.d. 9 Valine mg n.d. n.d. 24 29 58 Non-Essential Amino Acids Alanine mg n.d. n.d. 67 81 n.d. Aspartic Acid mg n.d. n.d. 47 57 n.d. Glutamic Acid mg n.d. n.d. 58 69 n.d. Glycine mg n.d. n.d. 29 38 n.d. Proline mg n.d. n.d. 163 196 n.d. Serine mg n.d. n.d. 35 42 n.d. Tyrosine mg n.d. n.d. 16 20 25 1KCal calculated from proximate analysis (moisture, lipid, protein, carbohydrate) 2Vitamin C value was not determined in this study. It was from a previous study (HARRIS and BRANNAN, 2009). 130 R.G. Brannan, E.E. Anderson, R.L. Powell, M.N. Coyle label for other reasons. Most food companies provide nutrition facts on their labels whether they are required to or not because it provides a layer of transparency for customers. As the popularity of the fruit grows, demand for up-to-date nutritional information likely will increase and the information will be beneficial for health clinicians recommending pawpaw to increase fiber intake, for example. Conclusions Results from this study confirm that the size, pH, oBrix, firmness, color of the skin and pulp, and nutritional information fits well with previous literature. Pawpaw pH is in the high range for PPO activity, so strategies to reduce pawpaw browning that rely on inhibition of PPO activity should take this into account. Variations in firmness of the pawpaw pulp observed in this study are likely are due to differential degradation of cell wall polysaccharides. Pawpaw skin and pulp color fall well-within the previously established values. Pawpaw pulp nutritional values compare to the values from the Korean study and will be used as the basis for inclusion of pawpaw in the USDA’s National Nutrient Database for Standard Reference. Data from this study was used as the basis for several specific recommendations: 1) firmness values between 0.2 and 0.7 kg of force using the method described herein describe ripe pawpaw fruit; 2) the serving size for raw pawpaw pulp is one-half cup (120 g); and 3) pawpaw pulp nutrition should be compared favorably to that of a banana or mango. Acknowledgements Funding provided by generous grants from the Northern Nut Growers Association and the National Pawpaw Foundation. Conflict of interest No potential conflict of interest was reported by the authors. References AOAC International, 2016: Official Methods of Analysis of AOAC International, 20th ed. AOAC International, Rockville, MD. archBold, d.d., PoMPer, K.W., 2003: Ripening pawpaw fruit exhibit respiratory and ethylene climacterics. Postharvest Biol. Tech. 30, 99-103. DOI: 10.1016/S0925-5214(03)00135-2 Bois, J., 2001: Anachronistic relationships. BioScience 51, 318-320. DOI: 10.1641/0006-3568 Brannan, R.G., 2016: Polyphenol oxidase in pawpaw (Asimina triloba [L.] Dunal) fruit pulp from different varieties. J. Food Res. 5, 33-39. DOI: 10.5539/jfr.v5n1p33 Brannan, r.g., FaiK, a., goelz, r., Pattathil, s., 2019: Identification and Tab. 6: Comparison of pawpaw pulp nutritional information from this study (except where noted) to existing nutritional information for seven common fruits on a 100-gram basis. Pawpaw Apple Banana Blueberry Mango Papaya Pineapple Strawberry 100 g 100 g 100 g 100 g 100 g 100 g 100 g 100 g Calories (kcal) 85 52 89 57 60 43 50 32 Protein (g) 0.7 0.3 1.1 0.7 0.8 0.5 0.5 0.7 Total fat (g) 0.6 0.2 0.3 0.3 0.4 0.3 0.1 0.3 Carbohydrate (g) 23.8 13.8 22.8 14.5 15.0 10.8 13.1 7.7 Dietary Fiber (g) 4.5 2.4 2.6 2.4 1.6 1.7 1.4 2.0 Total Sugar (g) 16.3 10.4 12.2 10.0 13.7 7.8 9.8 4.9 1Vitamin C (mg) 4.9 4.6 8.7 9.7 36.4 60.9 47.8 58.8 Calcium (mg) 13 6 5 6 11 20 13 16 Iron (mg) 0.2 0.1 0.3 0.3 0.2 0.3 0.3 0.4 Potassium (mg) 201 107 358 77 168 182 109 153 Sodium (mg) 1 1 1 1 1 8 1 1 1Vitamin C value was not determined in this study. It was from a previous study (HARRIS and BRANNAN, 2009) Tab. 7: Comparison of pawpaw nutritional information from this study (except where noted) to existing nutritional information (US DEPARTMENT OF AGRI- CULTURE, 2020) for seven common fruits per serving. Pawpaw Apple Banana Blueberry Mango Papaya Pineapple Strawberry 1/2 cup, pulp 1 medium fruit 1 medium fruit 1 cup, fruit 1 cup, pieces 1 cup, pieces 1 cup, chunks 1 cup, halves (120 g) (182 g) (118 g) (148 g) (165 g) (145 g) (165 g) (152 g) Calories (kcal) 102 95 105 84 99 62 83 49 Protein (g) 0.8 0.5 1.3 1.0 1.3 0.7 0.8 1.1 Total fat (g) 0.7 0.4 0.4 0.4 0.7 0.4 0.2 0.5 Carbohydrate (g) 28.6 25.1 26.9 21.5 24.8 15.7 21.6 11.7 Dietary Fiber (g) 5.4 4.4 3.1 3.6 2.6 2.5 2.3 3.0 Total Sugar (g) 19.6 18.9 14.4 14.8 22.6 11.3 16.2 7.4 1Vitamin C (mg) 5.9 8.4 10.3 14.4 60.1 88.3 78.9 89.4 Calcium (mg) 16 11 6 9 18 29 21 24 Iron (mg) 0.2 0.2 0.4 0.4 0.3 0.4 0.5 0.6 Potassium (mg) 241 195 422 114 277 264 180 233 Sodium (mg) 1 2 1 1 2 12 2 2 1Vitamin C value was not determined in this study. 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DOI: 10.2307/2484160 zhang, l., dai, s., Brannan, r.g., 2017: Effect of high-pressure processing, browning treatments, and refrigerated storage on sensory analysis, color, and polyphenol oxidase activity in pawpaw (Asimina triloba L.) pulp. LWT − Food Sci. Tec. 86, 49-54. DOI: 10.1016/j.lwt.2017.07.023 ORCID Robert G. Brannan https://orcid.org/0000-0003-0240-6373 Address of the corresponding author: Robert G. Brannan, Division of Food and Nutrition Sciences, E170 Grover Center, Athens, OH 45701, USA E-mail: brannan@ohio.edu © The Author(s) 2021. This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creative- commons.org/licenses/by/4.0/deed.en). http://dx.doi.org/10.1177/1082013219856769 http://dx.doi.org/10.1016/j.foodchem.2014.07.018 http://dx.doi.org/10.1002/jsfa.8706 http://dx.doi.org/10.1016/j.foodchem.2008.09.071 http://dx.doi.org/10.5539/jfr.v1n1p179 http://dx.doi.org/10.1016/j.lwt.2017.07.023 http://dx.doi.org/10.1111/j.1745-4514.2007.00133.x http://dx.doi.org/10.1021/jf801857g http://dx.doi.org/10.1016/j.lwt.2008.05.006 http://dx.doi.org/10.21273/HORTSCI.43.1.268 http://dx.doi.org/10.2307/2805119 http://dx.doi.org/10.21273/HORTSCI.31.5.777 http://dx.doi.org/10.1021/jf00040a025 http://dx.doi.org/10.5073/JABFQ.2018.091.007 http://dx.doi.org/10.1111/1750-3841.13806 http://dx.doi.org/10.1111/1750-3841.14414 http://dx.doi.org/10.21273/HORTTECH.13.3.0449 http://dx.doi.org/10.21273/HORTTECH.13.3.0412 http://dx.doi.org/10.2307/2484160 http://dx.doi.org/10.1016/j.lwt.2017.07.023 https://orcid.org/0000-0003-0240-6373