Shelf-life prediction of chicken nuggets based on the thickness level of composite plastic packaging using accelerated shelf-life testing (ASLT) method by the Arrhenius equation approach

The packaging of ground chicken meat, known as chicken nuggets, generally experiences a very rapid rate of deterioration caused by microorganisms. To determine the shelf life of chicken nuggets, shelf life measurements are made by accelerating product degradation through environmental conditions such as temperature, humidity, gas atmosphere, and light. In this study, the thickness level of composite plastic packaging was tested using the accelerated shelf-life testing (ASLT) method with the Arrhenius equation approach. The study looked at the critical period of chicken nuggets packed in 15μm nylon and LLDPE composite plastic packaging with a thickness of 40μm and 50μm stored in an incubator at 45°C for two days, then sensory evaluation once a day and calculated the shelf life, where chicken nuggets were packed in 15μm nylon and LLDPE composite plastic packaging with a thickness of 40μm and 50μm and stored in an incubator with temperature variations of -15, 5 and 25 °C for 25 days, every five days analyzed for moisture content and TPC. The best shelf life of chicken nuggets is found in 50μm thickness composite plastic packaging at a temperature of -15 °C, lasting 136 days.


Introduction
Chicken nuggets are processed chicken meat that has been ground and mixed with binders and fillers, with or without food additives permitted according to BPOM (Food and Drug Administration) regulations, which are then molded in various forms, cooked, and served in the form of frozen food [1].Moreover, chicken nuggets are perishable as made from chicken meat, which has the potential to trigger the growth of spoilage and pathogenic microbes [2], thus having a short shelf life.Therefore, it is necessary to extend the shelf life of chicken nuggets with specific methods and the appropriate type and thickness of packaging [3].
A commonly used method in predicting the shelf life of food products is Accelerated Shelf-life Testing (ASLT).Arrhenius indicates the shelf life of food products susceptible to damage due to chemical reactions by accelerating product degradation by regulating environmental conditions such as temperature, humidity, gas atmosphere, and light [4,5].The parameter commonly manipulated in this method is temperature, as high temperatures can increase the rate of chemical reactions in the product and accelerate product deterioration.Thus, the testing time can be shortened, making this method suitable for predicting the shelf life of food products with a long shelf life.
The determining shelf life of packaging plays an important role in maintaining product quality because it can protect from physical, chemical, and biological contamination.In this study, the packaging used is a composite plastic Linear Low-Density Polyethylene (LLDPE) and nylon, a multilayer packaging consisting of two materials [6].LLDPE is plastic with low strength and stiffness but is flexible and resistant to cracking.Thus, it is used as the outer layer [6].Meanwhile, nylon is a more robust plastic, wear-resistant, and has good resistance to pressure and tension, so it is used as the inner layer to provide additional strength and dimensional stability [7]; this combination makes the composite packaging more robust and more resistant to damage that can accelerate product deterioration [8].
In addition to the type, plastic thickness is one of the factors affecting product shelf life.The results showed that different thicknesses of plastic packaging can affect the moisture content of parang-parang fish pempek, and the analysis showed that after 12 days of storage, the thickness of the packaging has a significant effect on the moisture content of the product [9].Therefore, this study will estimate chicken nuggets' shelf life based on different composite plastic packaging thicknesses.

Materials
The materials used in this study are chicken nuggets from PT Belfoods Indonesia for analysis, 70% ethanol, Plate Count Agar (PCA) planting media, and distilled water.The tools used were freezer (Rainbow brand), chiller (Fujidenzo brand), incubator (Changsu brand), and composite plastic packaging with different thicknesses of 15μm nylon/ 40μm LLDPE and 15μm nylon/ 50μm LLDPE as packaging.

Methods 2.2.1. Simple linier regression.
The sample used was taken from the company PT Belfoods Indonesia.This study uses simple linear regression and measurement of the ASLT method with the Arrhenius equation.y = a + bx and correlation (R

Determination of critical quality
Critical quality determination aims to identify the critical condition or point at which the product reaches an unacceptable quality limit.This can help determine the product's shelf life, which is when the product comes in a condition that does not meet the predetermined quality standards.Based on research on critical quality, the results as listed in Table 1 will be used as an essential quality for shelf-life calculations The analysis of water content and TPC (Total Plate Count) is carried out so that the analysis results are used as the final quality characteristics (At) [10].It can be seen that the critical limits of water content in chicken nuggets in nylon 15μm/LLDPE composite plastic packaging of 40μm and 50μm thickness are 60.13% and 60.30%, while the critical limits of TPC in chicken nuggets in nylon 15μm/LLDPE composite plastic packaging of 40μm and 50μm thickness are 9.86 x 103 cfu/g and 9.91 x 103 cfu/g.These results will then be used as standards in the primary research.

Quality Characteristics of Chicken Nugget 3.2.1. Total Plate Count (TPC).
The presence of microbes in chicken nuggets is an essential indicator in determining the safety of food products.The presence of microorganisms in food is familiar, and most foods contain some amount of microbes.However, it is essential to ensure that the level of microbial company is within safe limits for human consumption [11].After analyzing the data plotted into a graph, a linear equation and coefficient of determination (R2) were obtained to determine order 0 and 1. TPC order 0 chicken nuggets can be seen in Table 2.
Based on Table 2, the initial TPC of chicken nuggets was 7,06 x 10 2 cfu/g, still below the standard that has been carried out in the study of determining critical quality, namely 9,91 x 10 3 cfu/g.During storage, there was an increase in TPC in chicken nuggets, both stored at -15, 5, and 25 o C. The longer chicken nuggets are stored, the growth of microorganisms increases because long storage provides sufficient time for microbes to multiply [12].This is by research conducted by Amanda, 2021 [7] regarding the estimation of the shelf life of beef sausage based on packaging variations of the ASLT method stored at incubator temperatures of -15 o C and 5 o C with a time interval of 25 days, the TPC test results showed that there was no significant microbial growth from day 0 to day 25 at both temperatures, where day 0 at -15 o C the number of TPC was 2,0 x 10 2 cfu/g and 2,38 x 10 3 cfu/g on day 25.While at 5 o C day 0 was 2,0 x 10 2 cfu/g, and day 25 was 2,2 x 10 3 cfu/g.
The results of this study are also reinforced by research conducted by Yorah (2018) [13] regarding the estimation of the shelf life of sangkuriang catfish nuggets with various packaging ASLT methods stored for 20 days at temperatures of -5 o C, 5 o C, and 15 o C, the TPC test results showed no significant microbial growth during the storage process, at -5 o C the number of TPC day 0 was 2.50 x 10 2 cfu/g and day 20 was 9.20 x 10 2 , at 5 o C the number of TPC day 0 was 2.50 x 10 2 cfu/g and day 20 was 1.05 x 10 3 cfu/g.At 15 o C, TPC day 0 was 2.50 x 10 2 cfu/g, and on day 20 was 1.47 x 10 3 cfu/g.They were also reinforced by Farokhzad et al. ( 2023) [14] regarding chicken burgers during storage incubated at 35 for 72 hours and 7 o C for 10 days.The results showed no significant differences in growth between mesophilic, psychrophilic, Pseudomonas, Enterobacteriaceae, Staphylococcus aureus, mold, and yeast bacteria.In addition, based on research conducted by Amanda [7] regarding the estimation of the shelf life of frozen food products, the growth of TPC in chicken nuggets is due to the water content; if the higher the humidity in the air, the microbes can grow well, which requires more than 85% wet air to develop and a water content of around 65-80%.In this study, the water content did not reach 65%, and all chicken nugget samples were stored in closed packaging and incubator temperatures.
In addition, the use of ascorbic acid as an antioxidant also has an effect in inhibiting TPC growth; the antiseptic properties of ascorbic acid can help inhibit bacterial growth in chicken nuggets; this is because ascorbic acid can destroy or prevent the development of microorganisms, besides ascorbic acid also acts as an effective antioxidant when oxidized ascorbic acid will release free electrons that can destroy bacterial cell structures and inhibit their growth, ascorbic acid can also reduce the pH on the surface of chicken nuggets, making it a less favorable environment for the development of microorganisms, where lower acidic conditions can inhibit the growth of bacteria and other organisms [14], Table 2. Linear equation and coefficient of determination (R2) TPC.Based on Table 2, the R2 value in order 0 is more significant than in order 1.Hence, the determination of the shelf life of chicken nuggets based on TPC parameters follows order 0 using the shelf-life formula t = (Q0-Qt)/k.After obtaining the value of k = b in each equation of order 0 TPC parameters as listed in Table 3.The longer the time and the higher the storage temperature, the total number of microbes increases every time because the temperature influences the development of microbes in food.Temperature changes can affect enzyme activity and microbial metabolism; at an optimal temperature, microorganisms will multiply and produce microbial colonies.In addition, temperatures that are too low or too high can inhibit microbial growth or even destroy the field [14].

Water content.
Moisture content is an essential parameter in the food industry because it can affect physical properties, chemical changes, enzymatic and microorganism growth.Appropriate moisture content can maintain food products' quality, durability, and safety.Food moisture content dramatically affects the quality and shelf life of the food [14].Data analysis plotted into a graph, obtained a linear equation and coefficient of determination (R2) to determine order 0 and 1.The moisture content of order 0 chicken nuggets can be seen in Table 4.
Based on Table 4, the initial moisture content of chicken nuggets is 47.70%, still below the standard that has been done in the research to determine critical quality, which is 6.30%.During storage, there was an increase in the moisture content of chicken nuggets, whether they were stored at -15, 5, or 25 o C. Increased water content in chicken nuggets can cause texture instability, making the surface of chicken nuggets a suitable medium for microbial growth [15].The results of this study are research conducted by Pebriansyah, 2022 [16] on estimating the shelf life of beef meatballs based on differences in packaging thickness of the ASLT method that changes in moisture content can occur when beef meatballs are stored at temperatures of -18 o C, 5 and 25 o C. Initially, the moisture content in beef meatball products was 58.79%, which is still the maximum limit of moisture content of meatballs set by SNI standards, which is 70%.After being stored for 25 days, the moisture content increased by 63.16%.The moisture content of beef meatballs is influenced by the length of storage because, over time and storage, moisture content can increase.This increase in moisture content impacts the instability of the meatball texture so that the surface of the product becomes more vulnerable as a place for microbial growth and can cause damage to the product due to the activity of microorganisms.
In addition, based on the research of Ariyanti et al. (2022) [17] regarding the quality characteristics of tempeh nuggets during storage, the results of the analysis of variability show that the length of storage influences the moisture content of tempeh nuggets.It was indicated that the highest moisture content in tempeh nuggets occurred in treatment A (storage for three days), with a percentage of 54.99%.From the results of this study, it can be concluded that the longer the storage time, the more moisture content of tempeh nuggets will increase.This is to the journal by Laksono et al. (2012)Field [18] that moisture content influences the quality of chicken nuggets.If the water content is high, then it is likely that microorganisms such as bacteria, molds, and yeasts will quickly multiply.Furthermore, the data that has been plotted on order 0 and order 1 in Figure 4 and Figure 5 is seen as a linear equation and coefficient of determination (R2).Then, in Table 4, the most significant coefficient of determination (R2) is determined.Based on Table 4, the R2 value in order 0 is more significant than in order 1, so the determination of the shelf life of chicken nuggets based on the moisture content parameter follows order 0 using the shelflife formula t = (Q0-Qt)/k.After obtaining the value of k = b in each order 0 equation for the moisture content parameter as listed in Table 5.Based on Table 5, the constant rate of quality loss in chicken nuggets is related to temperature; the higher the temperature, the higher the rate of quality loss.This shows that temperature influences the rate of quality reduction of chicken nuggets.The decrease in the quality of the water content parameter in chicken nuggets follows the reaction order 0 and 1.The length of storage influences the water content in chicken nuggets; with increasing storage time, there is a tendency to increase water content.This occurs due to the migration or transfer of water from the surrounding environment into the product or due to processes that cause an increase in water content, such as water vapor absorption.In addition, the relationship between moisture content and storage time can also be influenced by storage temperature.Chemical reactions and microorganism activity in food products are faster at higher temperatures, which can impact increasing water content [19].

Approximate shelf life of chicken nuggets.
To determine the shelf life, the linear regression equations 1/T and ln k, which are linear regression equations, are listed in the table for each chicken nugget observation parameter, as shown in Table 6.From the linear regression equation in Table 6, the activation energy (Ea) value was determined as shown in Table 6, from which one parameter was selected that most influenced the deterioration of chicken nugget quality during storage in various temperature variations.
The lower the activation energy value of a reaction, the more it will contribute to chicken nugget damage [18].The lowest activation energy (Ea) based on Table 6 is the moisture content parameter of nylon15μm/LLDPE 40μm packaging of 4407.529cal/mol.Therefore, the estimated shelf life in this study is 88 days at -15 o C, 47 days at 5 o C, and 27 days at 25 o C, as shown in Table 7.
Based on Table 7, chicken nuggets have different shelf lives for each packaging thickness used; this is because the thickness of the plastic packaging used affects the length of storage of a product.Based on research conducted by Wulandari et al. (2013) [20] regarding the prediction of the shelf life of kemplang crackers in polypropylene plastic packaging with a thickness of 0.3 mm, 0.5 mm, and 0.7 mm stored in a room with a temperature of ± 30 o C for 24 hours that the shelf life of kemplang crackers with various thicknesses of PP plastic packaging is as follows, 0.3 mm thickness can last for 12 days, 0.5 mm thickness can last for 14 days, and 0.7 mm thickness can last for 33 days.The higher the RH and thinner the plastic, the shorter the shelf life.The thickness of the plastic affects the product's shelf life; this is because the thickness of the product's primary packaging significantly affects the product's shelf life.The thicker the primary packaging, the more difficult it is for water and gas to escape from the packaging.This is because the thickness of the primary packaging is related to the level of permeability, which regulates the entry or exit of substances from the packaging.With thicker primary packaging, the packaging layer becomes sturdier and tighter, preventing water access and contaminants from the external environment.Thus, the product remains protected from moisture, spoilage, microorganism growth, and changes in product quality.Thick primary packaging can also retain the gases produced by the product during production, ensuring the product stays fresh and quality for longer.Overall, the optimal thickness of primary packaging is critical in maintaining the freshness and quality of the product during its shelf life [21].

Conclusions
Determination of the best shelf life is the Nylon15μm/LLDPE 50μm composite plastic at -15 o C 136 days, 5 o C 31 days, and 25 o C eight days.Moreover, Nylon 15μm/LLDPE 50μm composite plastic has a longer shelf life than nylon 15μm/LLDPE 40μm composite plastic.Therefore, the thickness and type of plastic packaging affect chicken nuggets' shelf life.
Observations were made in the Industry and then sampled for this study.The critical point analysis carried out is Moisture content and Total Plate Count (TPC).

Table 1 .
Critical quality results of 40μm and 50μm composite packaging.

Table 3 .
Result of 1/T and ln k TPC.

Table 4 .
Linear equation and coefficient of determination (R2) of moisture content.

Table 5 .
Results of 1/T and ln k moisture content.

Table 6 .
Linear regression equation of 1/T and ln k for each parameter.

Table 7 .
Shelf life of chicken nuggets per parameter.