Accelerated Test Method for Food Shelf Life

Food is a diverse, active and complex system. Microbial proliferation, enzymatic reactions, and physical and chemical changes related to food quality may occur at the same time, and some external conditions such as temperature and humidity will also affect the progress of these reactions. The chemical composition, processing technology, packaging form and storage conditions of food will all affect the shelf life of food. The shelf life of food stipulates that within this period, the food is completely suitable for sale and meets the quality specified on the label or in the product standard. Through the shelf life of food, manufacturers can specify the correct distribution channel and sales mode, and consumers can also understand the quality status of the purchased products. If consumers eat food that has exceeded the shelf life, it may cause a series of symptoms such as diarrhea, abdominal pain, and even acute food poisoning due to excessive microbial or viral infection.

Principles of Accelerated Test for food

The principle of accelerated food storage period (shelf life) test is to use chemical kinetics to quantify the influence of external factors such as:

temperature,

humidity,

air pressure

light

On the deterioration reaction. By controlling the food in an environment where one or more external factors are higher than the normal level, the rate of deterioration will be accelerated, and whether the product has deteriorated can be judged in a shorter than normal time. Because the external factors affecting deterioration can be quantified, and the degree of acceleration can also be calculated, so the actual storage period (shelf life) of the product under normal storage conditions can be calculated.

Under given conditions, the decline in product quality is inversely proportional to time. The ratio of the storage period (shelf life) at two arbitrary temperatures with a temperature difference of 10°C Q10=storage period when the temperature is T/storage period (shelf life) when the temperature is (T+10°C), for the storage period ( Shelf life) has a great impact see Table 1.

Temperature(℃)	Storage Period(week)
	Q10＝2	Q10＝2.5	Q10＝3	Q10＝5
50	2	2	2	2
40	4	5	6	10
30	8	12.5	18	50
20	16	31.3	54	250

Generally speaking, the Q10 of canned food is 1.1~4, that of dehydrated food is 1.5~10, and that of frozen food is 3~40.

Food Storage Life (Shelf Life) Accelerated Test (ASLT) Procedure

The following steps can be taken to set the shelf life (shelf life) of a food product:

① Determination of microbial safety and quality indicators of products;

② Select the key deterioration reactions, which will lead to product quality degradation, and these quality degradation is unacceptable to consumers, and decide which tests must be carried out during product testing (sensory or instrumental);

③Select the packaging material to be used, and test a series of packaging materials, so that you can choose the most cost-effective material (that is, economical and meet a certain storage period (shelf life);

④ Select which external factors will act on the accelerated reaction, see the recommended temperature in Table 2, and at least 2 must be selected;

frozen food	dehydrated food	canned food
-40	0	5
-15	23	23
-10	30	30
-5	40	35
	45	40

⑤ Use the coordinate curve to record how long the product has been stored at the test temperature. Full ASLT testing is mandatory if Q10 value is unknown

⑥ Determine the number of tests

f2=f1 Q10∆/10

f1: Test time at higher test temperature T1 (days, weeks)

f2: Test time at lower test temperature T2 (days, weeks)

∆: Temperature difference between T1 and T2

Because if a product is tested at 40°C for one month, then at 30°C, Q10=3, the product needs to be tested at least f2=1x3(10/10)=3 months. If Q10 is unknown, it is best to conduct multiple tests, at least 6 data points are required to minimize the error, otherwise the reliability of the obtained storage period (shelf life) will be degraded.

⑦ Calculate the number of stored samples under each test condition.

⑧Start ASLT, draw the obtained data on the coordinate map, and increase or decrease the number of sampling as needed.

⑨ From each test storage condition, evaluate the K value or storage period (shelf life) and establish a storage period (shelf life) graph appropriately, and estimate the storage period (shelf life) under normal conditions accordingly.

Case

①Estimate the possible shelf life of the food by referring to the same type of products through the process conditions.

② Evaluate the shelf life through damage experiments such as heating, humidification, and light.

③ Storage experiment at room temperature. Store the product at room temperature, test it every month, and keep reaching the required shelf life, and the sensory, physical and chemical safety meets the requirements. The shelf life of the product is not as long as possible, and factors such as market turnover and consumer acceptance must also be considered.

1. Test product and data model

Test product: soft bread that is about to enter the market.

Data model: calculated according to formula (1) and formula (2).

Formula (1): f2=f1xQ10△T/10

Where: f1 is the time interval between each test (such as days, weeks) when f1 is the highest test temperature T1; f2 is the time interval between each test when f2 is the lower test temperature T2; ΔT is (T1- T2)°C; Q10 is defined as the ratio of shelf life at two arbitrary temperatures with a temperature difference of 10°C.

Formula (2): θs (T1) = θs (T2) x Q10△T/10

Among them: θs(T1) is the shelf life at a specified temperature T1; θs(T2) is the shelf life at a specific temperature T2; △T is the temperature difference between T and T2.

2. Steps and results

(1) Purpose of the test

In order to understand the shelf life of the corresponding products, to ensure that they can be better applied after being put into the market.

(2) Analyze the composition of food and determine the factors affecting food quality

The test analysis found that the oil content in this product is relatively high. From this point of view, the temperature change is likely to pose a threat to the product and cause the soft bread to deteriorate.

(3) Choose appropriate packaging to protect shelf life products

This product is put on the shelves in small packages, and the weight of each small package is about 20 g.

(4) Determine the optimum temperature

Carry out detailed tests on the appropriate temperature to understand the storage time of products at different temperatures, so that the shelf life of the products can be guaranteed and the sales of products can be more profitable.

Tests have shown that the preservation effect of the product is ideal at 37°C, and it should be ensured that the humidity of the surrounding environment is maintained at about 60%.

(5) Test the changing state of food

Considering the characteristics of the product, it is decided to test the food stored at 47°C every 2 days, and the Q10 is tentatively set at 2. According to the formula, f2(30°C)=1x22/2 is about 2, that is, at 30°C 1 test every 2d.

(6) Detection of kinetic parameters

The test results show that if the product is always kept at 37°C, it can be stored stably for 5 to 6 days, and then there will be deterioration problems. At 47°C, it can only be stored for 2 days.

(7) Speculation and analysis of storage conditions

According to the calculation and analysis of the life of products with different shelf life at 37°C and 47°C, the corresponding Q10 data results are obtained, and specific calculations are made from the aspect of humidity, and the following results are obtained:θs(T1)=θs(T2)xQ10△T/10=5x2.51.7=24d;θs(T1)=θs(T2)xQ10△T/10=6x31.7=39d.

It is calculated that if the temperature of the product is controlled at 20°C and the humidity is kept at about 60%, the shelf life of the product can be maintained for 24 to 39 days.

Accelerated Test Equipment

1.Temperature and Humidity Test Chamber

Temperature and Humidity Test Chamber provide a high-precision test environment for durability testing of food, chemical, pharmaceutical and electronic products

A wide selection of standard and custom Hot And Cold Chamber are available to suit many types of environmental test conditions. Our test cases are available in a variety of sizes and configurations, from 50 litre to 3000 litre, including bench, floor and walk-in. It can perfectly perform a series of environmental tests such as high temperature test, cold test and constant temperature test. Our LIB stability chambers have basic performance and good reliability for long-term continuous operation. The test chamber also has the advantages of easy operation and easy maintenance.

Temperature Range	Model A:-20℃ ~150℃ Model B:-40℃ ~150℃ Model C:-70℃ ~150℃
Humidity Range	20% ~ 98% RH
Cooling Rate	1 ℃ / min
Heating Rate	3 ℃ / min

Big or small, you can choose your own size according to your products.

2.Xenon Accelerated Weathering Test Chamber

There are three factors:

light

The chemical bonds of polymer materials have different sensitivities to different wavelengths of sunlight in sunlight, generally corresponding to a threshold value. The short-wavelength ultraviolet rays of sunlight are the main reason for the aging of most polymer physical properties. For example, the action threshold of C-N (carbon-nitrogen) bond is 393nm. However, some prints and inks can be damaged by long-wave UV or even visible light, causing discoloration or fading.Food packaging materials need to do this test.

temperature

The higher the temperature, the faster the chemical reaction. The aging reaction is a photochemical reaction, the temperature does not affect the photoinduced reaction speed in the photochemical reaction, but affects the subsequent chemical reaction speed. Therefore, the effect of temperature on material aging is often nonlinear.

humidity

Water will directly participate in the material aging reaction. Relative humidity, dew and rain are the main manifestations of water in nature. Studies have shown that outdoor materials are exposed to moisture for extended periods of time each day (up to 8-12 hours per day on average). Dew is the main cause of outdoor humidity. Dew is more damaging than rain because it sticks to materials longer, creating harsher moisture attacks. For indoor materials, generally only the influence of relative humidity is considered.

Model	XL-S-750
Internal Dimension (mm)	950*950*850 mm
Overall Dimension (mm)	1300*1420*1800 mm
Specimen Holder Size(mm)	95*200
Specimen Capacity	42pcs
Chamber Type	Rotating Holder
Irradiation Source	1 piece of 4500w water-cooled xenon arc lamp with inner quartz and outer borosilicate filter
Irradiance Range	35~150 W/㎡
Bandwidth Measurement	300nm~400nm (340nm or 420nm)
Chamber Temperature Range	Ambient ～ 100 ℃ ±2℃
Black Panel Temperature	BPT 35 ～ 85 ℃ ±2℃
Humidity Range	50% ~ 98% RH
Humidity Deviation	± 5% RH
Water Spray Cycle	1~9999H59M (Adjustable)

Summary

Food that is first developed, packaging changes or storage conditions change needs to determine the shelf life, and the food that has already determined the shelf life can also be further demonstrated and verified.

In order to determine the shelf life of the food produced and improve the reliability of food packaging materials, contact LIB now, we’ll provide you with professional test solutions and quality test chambers.