The design elements for accelerated destructive tests and long-term stabilization tests based on temperature conditions are given for the information of food producers. In determining the shelf life of the food, one of the two options may be chosen or used in combination。
Accelerating destructive trials
By placing a food sample in an environment where one or more external factors, such as temperature, humidity, air pressure and light, are above normal levels, the accelerated destruction test enables the sample to reach a bad end within a period shorter than normal bad times, and then calculates, after analysis, the shelf life of the food under the expected storage environmental parameters through regular testing and collection of data in the poor process。
Temperature is the most critical factor influencing poor foods. Temperature is often used as a key factor, or even the only factor, in designing accelerated destructive tests。
As a rule, temperatures are doubled for each 10°c increase. The ratio of two preservation periods with a temperature difference of 10°c is defined as q10, see formula (1)。
Form (1): q10 = t1 / t2
Q10 is the ratio of the shelf life at two temperatures (test temperature t2 and t1) with a temperature difference of 10°c under the accelerated destructive test
(b) the shelf life of gills (t1) for accelerated destructive testing at t1 temperatures
Tritium (t2) is the shelf life obtained for accelerated destructive tests at t2 temperatures。
2. The shelf life under the physical storage environmental parameter is related to the preservation period under the accelerated destructive test temperature, as described in formula (2)。
Type (2): θ (t)= q (t1)xq10ta/10
Zirconium(t) is the shelf life of foods at actual storage temperature t
(b) the shelf life of gills (t1) for accelerated destructive testing at t1 temperatures
Ta is the difference (t1-t) between the higher temperature (t1) and the actual storage temperature (t), in °c。
Q10 is calculated by replacing the test data with (1), and the preservation periods (t) at the actual storage temperature are calculated by means of (2)。
The advantages of double-test temperature are simplicity and time saving, with the disadvantage being greater error. T1 and t2 shall be above the actual storage temperature。
1 accelerated destructive experiments at t1, t2 at test temperatures of any of the two 10 °c are conducted, and the established indicators are examined at each test point of time, as required, until the end of the poor. The primer period at the test temperature is the time at which the poor end is reached。
2. The selection of time points for the examination may be determined on the basis of food characteristics, test conditions and previous studies, and may also be calculated in formula (3)。
(1) the frequency of the study under the higher test temperature t2 is first set and the frequency of the study under the pilot projects under the lower test temperature t1 is calculated in the q10 and f2 proxy (3). F。
F1 is the frequency of visits (e. G., days, weeks) for each pilot project at a lower test temperature of t1
F2 is the frequency of visits (e. G., days, weeks) for each pilot project at a higher test temperature of t2 hours
Q10 to accelerate the ratio of the preservation period at the destructive test temperature of t2 and t1
Tb is the difference between t2 and t1, i. E. (t21-t1), in degrees celsius (°c)。
(2) q10 values can be determined by available research, e. G. Q10 for most food items is 2, q10 for canned foods is 1. 1 to 4, q10 for dehydrated foods is 1. 5 to 10 and q10 for frozen foods is 3 to 40, etc。
(3) q10 is calculated for q10 and q(2) is calculated for the preservation period at the actual storage temperature。
1 more precise q10s can be obtained by conducting separate accelerated destructive tests of samples at multiple test temperatures, and more accurate q10 results can be obtained by analysing calculations or establishing mathematical models. The multi-test temperature method should select multiple test temperatures above the actual storage temperature for accelerated destructive testing and at least two temperature differentials of 10°c. In order to obtain accurate data, at least three temperatures should be selected for testing within sensitive temperature ranges。
The frequency of the examination may be determined on the basis of experience, depending on the food characteristics and test conditions; it may also be calculated in order (3) after determining the maximum test temperature. At least six time points should be taken for testing at each test temperature。
3 in calculating the shelf life under the actual storage environmental parameter, q10 at either temperature at any 10 °c is calculated in formula (1); in proxy (2), the shelf life under the actual storage temperature is calculated。
4. The shelf life at the actual storage temperature calculated in formula (2) is usually a series of values within a range, and it is desirable to determine the shelf life of foods under actual storage conditions, taking into account factors such as food properties, production processes, food packaging, transport and storage. Computation tools, such as excel, can be used to form a proposed conical equation of the shelf life and temperature, which can then be calculated on the basis of actual storage temperature。
Long-term stability test
Poor changes in food during storage can be measured directly or indirectly. The long-term stabilization test, by modelling the parameters of environmental conditions such as temperature, humidity, light, etc. During physical storage, transport, sale, consumption, etc., rationalizes laboratory tests, sensory evaluation points, examines selected test indicators at various points of time and analyses and compares variations between points of time, summarizes patterns of change and discovers unacceptable endpoints for poor foods, which is the shelf life。
The long-term stability test is appropriate for the duration of the warranty derived from the results of the accelerated destructive test, setting the test time point at a certain length of time, the closer it is to the end of the preservation period, the smaller the interval between the detection time points. If the time point for the examination is set at 25 per cent, 50 per cent, 75 per cent, 82 per cent, 89 per cent, 100 per cent, 105 per cent and 110 per cent of the expected shelf life, and if the test results are acceptable at 110 per cent, the duration is extended by a gradient of 5 per cent until the test results are unacceptable。
3. Steps for determining the shelf life
(1) at various points in time, the time when the food reaches the unacceptable end of its poor state, i. E., the period of preservation of the food at the actual storage temperature, is determined by a combination of the full results of the detection or sensory evaluation of the food by the selected project。
(2) if the test results for different batches are less varied, take the average time and, if the difference is greater, the shortest time. Source: t/cnfia 001 - 2017 general guidelines for food security
