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 American Journal of  
Food Science and Technology (AJFST)

Evaluation of  Celery Juice Powder as a Natural Curing Agent for Tocino
Joshua Ken J. Policarpio1*

Volume 3 Issue 2, Year 2024
ISSN: 2834-0086 (Online)

DOI: https://doi.org/10.54536/ajfst.v3i2.3087
https://journals.e-palli.com/home/index.php/ajfst

Article Information ABSTRACT

Received: June 15, 2023

Accepted: July 09, 2024

Published: July 12, 2024

Artificial food preservatives are a key consideration for consumers purchasing cured meat 
products, which often contain sodium nitrite, a curing salt known to produce carcinogenic 
nitrosamines. To address health concerns, ongoing research seeks natural alternatives that 
maintain product quality. This study investigates the potential of  celery juice powder as 
a natural curing agent for tocino, leveraging its nitrite content. Despite vegetables being 
recognized as natural nitrite sources, their use is limited due to potential impacts on color and 
flavor. Celery juice powder has emerged as the preferred natural nitrite source. According 
to USDA guidelines, celery juice powder can adhere to regulatory limits while effectively 
curing meat products. A 2k factorial design experiment was conducted, incorporating four 
treatments generated through Yates’ table and the Design Expert application. Analysis of  
variance (ANOVA) and linear regression were employed to evaluate the significance and 
relationships of  factors affecting nitrite levels in cured tocino. Results demonstrate the 
statistical viability of  celery juice powder as an alternative curing substance, contributing 
valuable insights into its practical application in the food industry.

Keywords

Curing, Curing Salt, Celery 
Juice Powder or Celery Powder, 
Nitrite

1 Mabalacat City College, Philippines
* Corresponding author’s e-mail: policarpioken1198@gmail.com

INTRODUCTION
Cured meat products, like sausages and bacon, have 
always been on top of  the most bought food products. 
The curing of  meat is an ancient process initially started 
by the Sumerian culture. People believed that the salt 
used to preserve meat was contaminated with saltpeter 
(Potassium nitrate) in the early times. As a result, saltpeter-
treated meat became popular, primarily for its desirable 
reddish color and longer storage life.
Consequently, studies conducted in the late 1800s proved 
that nitrate has favorable properties for preserving meat. 
Subsequent experiments discovered that nitrate-reducing 
bacteria convert nitrate to nitrite.
The United States Department of  Agriculture (USDA) 
has set regulations on the usage of  Sodium nitrite for 
different cured products and curingwhich has additional 
regulations because of  other factors for the formulation 
of  nitrosamine. The USDA had established standard 
limits on sodium nitrite - 120 ppm (0.012%) for bacon, 
200 ppm (0.02%) for dry-cured bacon, less than or 
equal to 156 ppm (0.0156%) for cured meats like ham, 
not more than 625 ppm (0.0625%) for dry-cured meat 
products (Sullivan, 2016).
Additionally, Potassium and Sodium nitrate/nitrite are 
approved food additives in the European Union, with 
limits of  150 mg/kg in meat products. Adding an extra 
50-60 ppm to the meat could ensure longer preservation. 
As the salt inhibits the growth of  Clostridium (Cl.) 
Botulinum, where nitrite improves the microbial safety 
of  meat products. (Siekmann et al., 2021)
Meanwhile, various reports highlighted concerns 
about the potential of  the curing substance to produce 

nitrosamines, which are carcinogenic substances. 
Moreover, in recent years, research on the development 
of  curing methods has been ongoing, focusing on 
eliminating nitrosamines (Lijinsky & Epstein, 1970).
In addition, the World Health Organization associated 
carcinogenicity with the consumption of  processed meat 
products and red meat. Studies suggested that the intake 
of  50 grams of  processed meat daily heightens the risk of  
colorectal cancer by 18%.
As a result, the belief  that organic foods are safer 
remained in the market. Consumers prefer to spend 
10% to 40% more to avoid chemical additives, owing 
to concerns about exposure to synthetic nitrate. As a 
result of  the increased  demand  for  natural  alternatives, 
various studies have been conducted to discover artificial 
nitrate substitutes.
Natural nitrate or nitrite sources include various 
vegetables, although their use is limited due to their colors 
and flavors attributes. Nitrate is abundant in vegetables; 
however, the amount varies depending on the type 
(Lorenz, 1978).
According to Sebranek (2006), celery juice powder was 
the best substitute for curing salt, producing up to 2,114 
ppm nitrate. He also noted that is compatible with meat 
products as it does not affect the desired physicochemical 
property. The concentration for the use of  celery juice 
powder as a curing substance is only ¼ to ½ of  the 
ingoing sodium nitrite (Sullivan, 2016).
Tocino is a known cured meat product in Pampanga, 
Philippines, because of  its sweet or sour taste that satisfies 
the desired taste of  the consumers. A Kapampangan 
native, Mrs. Lolita Hizon, was asked by her neighbor, a 



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meat vendor, to help cook the unsold meat during the end 
of  market day. As this regularly happens, she eventually 
came up with the formula in making Tocino that caused 
the birth of  Pampanga’s Best Tocino - a meat processing 
company, now known as Pampanga’s Best, Inc - a multi-
million meat processing corporation.
Therefore, this paper examined the potential of  celery 
powder as an alternative curing salt for Tocino. Celery 
powder solution must be prepared prior to the Tocino 
making process. Four treatments were used to identify 
the effect and interaction between the celery powder 
and the curing period of  the meat. Then, the treatments 
underwent a colorimetric test method to analyze their 
respective nitrite content.

1. The curing time significantly contributes to the 
amount of  nitrite content of  the processed meat.

2. The optimal level of  the curing time that produces 
the acceptable amount of  nitrite is the lowest level of  the 
factor to be tested in the experiment.

3. There are interactions between the factors.

METHODOLOGY
The study utilized the 2k factorial design as the experimental 
framework. Moreover, during the experiment, the use of  
the Colorimetric test method (AOAC Official Method 
935.48, Xylenol Method) specified the nitrite content of  
each treatment. (Wood et al., 2000)

Figure 1: Experimental Procedure

Problem
This paper aims to address the following problems:

1. To what extent does the curing time affect the nitrite 
content?

2. What level of  curing time will produce an acceptable 
amount of  nitrite?

3. What minimum amount of  celery powder and curing 
time is needed to meet the standard nitrite content?
The above problems are postulated on the following 
hypotheses:

Table 1: Factors and Levels
Factors Low Level High Level
(A) Amt. of  Celery 
Powder (g)

-1 (0.5g) 1 (1g)

(B) Curing Time (days) -1 (1) 1 (2)

Factors and Level
Experimental Procedures and Setup
The ingredients to be used with their amounts held 
constant are meat (250 g), salt (8 g), refined sugar (45 
g), water (15 ml), and pineapple juice (15 g) (Manalo & 
Benedicto, 2014). The amount of  celery powder will have 
two levels based on the total weight of  meat - low level 
(0.2% or 0.5 g) and high level (0.4% or 1 g) (Sebranek & 
Bacus, 2007). The study will start with the preparation of  
the celery powder by mixing it with water and salt. 
Moreover, the mixture will then be combined with the 
meatand added refined sugar and pineapple juice. The 
curing time will also have two levels at refrigerated 
temperature – low level (1 day) and high level (2 days) 
(Manalo & Benedicto, 2014).

Table 2: Treatments and Concentration
Treatment Specifications
1 Amt. of  celery powder: 0.5g 

Curing time: 1 day
2 Amt. of  celery powder: 0.5g 

Curing time: 2 days
3 Amt. of  celery powder: 1g Curing 

time: 1 day
4 Amt. of  celery powder: 1g Curing 

time: 2 days

After the specified curing period, 5g of  sample  per  
treatment  underwent  the colorimetric test method, 
known specifically as AOAC Official Method 935.48, 
Xylenol Method. The nitrite analysis process lasted for 
six (6) hours. Four (4) treatments were made for the 
experimental runs with two replicates each.



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Findings
The experiment exhibit eight (8) results of  nitrite content 
from different levels of  the two factors.

Result of  Experiment

Table 3: Yates Table and Results
Std.Order Run Amt. of  Celery Powder (g) Curing Time (day/s) Nitrite Content (ppm)
4 1 1 -1 0.2487
6 2 -1 1 0.2421
5 3 -1 1 0.2424
8 4 1 1 0.2440
7 5 1 1 0.2439
2 6 -1 -1 0.2452
1 7 -1 -1 0.2454
3 8 1 -1 0.2487

Table 4: ANOVA Table
Source Sum of  Squares DF Mean Square F Value Prob > F
Model 4.487E-005 3 1.496E-005 854.67 < 0.0001 Signifi cant
A 1.300E-005 1 1.300E-005 743.14 < 0.0001 Signifi cant
B 3.042E-005 1 3.042E-005 1738.29 < 0.0001 Signifi cant
AB 1.445E-006 1 1.445E-006 82.57 0.0008 Signifi cant
Pure Error 7.000E-008 4 1.750E-008
Cor Total 4.494E-005 7

Analysis of  Variance (ANOVA)
The Analysis of  Variance indicates that all the factors are 

significant in the amount of  nitrite content of  cured meat. 
The model F- value also implies that the model is significant.

Curing Time (B) has the highest effect in the response, 
followed by the Amount of  Celery Powder (A), and then, 
the interaction of  the Two factors (AB) based on the half  
normal plot (Figure 5). Also, no violations were done 
on the ANOVA theory based on the results of  different 
studentized diagnostic procedures (Figure 6).

Regression Model
Regression results have confirmed and expound the 
results in the analysis of  variance. The adjusted R-squared 
decreases from 99.84% to 99.73%. The decrease indicates 
that the current setup of  the model is well-designed, and 
other inputs will have no value in the model.
The linear regression model designed for this experiment 
is as follows:
Y = 0.25 + 1.275E-003 * A - 1.950E-003 * B - 4.250E - 
004 *A* B
where:
Y = Nitrite Content
A = Amount of  Celery Powder
B = Curing Time
The coefficients in the regression equation indicate that 

(A) is directly proportional to the resulting factor (Figure 
2). On the other hand, as (B) will increase, the nitrite 
content will decrease (Figure 3).

CONCLUSION
This study statistically proved that the factors used 
significantly affect the nitrite content in Tocino using a 
natural substance - the celery juice powder.
Nitrite is a time-dependent variable that depletes quickly, 
upon use, for the next 24 hours and depletes slower the 
succeeding time before the standard curing time is met 
(Merino et al., 2015) that, causes (B) to have the highest 
effect on the response. This also causes the interaction 
of  the two factors to be indirectly proportional to the 
response.
It was also showed that the celery juice powder is rich 
with nitrite based on the results of  the experiments. It is 
significant to consider the study, stated in the introduction, 
to use only
¼ to ½ concentration of  celery juice powder based on 
the standard of  ingoing nitrite to meet the regulatory 
limit on the use of  nitrite in curing meat products.



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Figure 2: One Factor Plot – Amount of  Celery Powder

Figure 3: One Factor Plot – Curing Time

Figure 4: Interaction Graph



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Figure 5: Half  Normal Plot

Figure 6: Diagnostics (Studentized)



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