Effects of the hottest cold storage on milk compos

Effects of cold storage on milk composition and somatic cell determination (Part 1)

Abstract

this paper studied the changes of fat, protein, lactose, total milk, solids and SCC (system cell count) in milk during cold storage. This change was determined by series 300 comfoss. The samples were placed for 1, 2, 3, 6 and 8 days with or without preservatives. The paper drew the milk placement map and judged the availability of the data after placement. The conclusion of this paper is only applicable to the dairy cow energy determination program

preface

rapid cooling of milk is the condition for obtaining high-quality raw milk. The temperature of the milk produced by the rigid agent is about 36 degrees, which is the appropriate temperature for microbial reproduction. If it is not cooled in time, the microorganisms in the milk multiply in large numbers, and the acidity increases rapidly, which not only reduces the quality of milk, but also leads to milk suspicion. Scientists' research shows that when the acidity of milk reaches 60 ℃, it solidifies by itself when it is wet in the room

in the cow performance measurement project, it needs to finish three shifts of sampling early and middle, so it takes three 2 hours (about 2 hours per shift) and the milk is not in the cooling state (i.e. 0?/font 5 ℃), so isn't the milk sample bad? In fact, there is no, because there is an antibiotic substance in fresh milk that can inhibit the reproduction of microorganisms - lactenin, which can inhibit or even destroy microorganisms falling into milk. This property is called the antibacterial property of milk. Antibacterial substances are formed inside the mother, The relationship between milk temperature and the duration of antibacterial properties of milk is as follows:

table of relationship between milk temperature and the duration of antibacterial properties of milk

milk temperature (℃)

37

30

25

10

5

0

-10

-25

duration of antibacterial properties

2

3

6

24

36

48

240

720 p>

the International Dairy Federation believes that the reason for the vibration of milk in 4.4 general testing machine is usually the following: ℃ storage has the best quality. Therefore, in the dairy cow determination items, it is generally stipulated that the samples must be cooled and maintained at ℃, and 36 small and mostly sent for inspection in May and June

(the distance between the thick wires should be longer, so that the wires have a tensile force of about 15 (2) 5kg) turn the main grip handle to clamp the lower end of the wires. In summer, due to high temperature, bacterial activity is rampant, and the duration of the antibacterial properties of milk is shortened. Various adverse factors that cause the deterioration of milk, such as the role of microorganisms, the intelligent role of enzyme automobile detection equipment, the role of self oxidation and other synergistic effects, increase the difficulty of sample collection, Milk sample rancidity also occurred. In order to successfully determine the performance of dairy cows and make the samples accurately reflect the production performance of the mother, we designed this experiment on the basis of previous experience. Using the advanced equipment and computer technology of Beijing dairy center, we deeply studied the changes of milk composition and SCC in the process of milk refrigeration, and provided the most basic data for the scientific improvement of sampling procedures, It is also expected to provide scientific and technological workers with new ideas on milk storage

milk sample preparation

more than 300 samples (5 ℃, 24 hours, without preservatives) from five cattle farms of the state-owned farm in the southern suburbs of Beijing. The sample is processed as follows:

the sample is heated to ℃, and the milk composition and somatic cell count are measured

according to the determination results, the samples are divided into 8 groups, as shown in Table 2 below

then give sensory evaluation to all samples in each group. Those with excellent results will be added to the prepared plastic bottle (500ml) and mixed evenly (do not shake to prevent fat balls from precipitation). In this way, 8 groups of mixed samples are obtained

the sample is bathed in water to ℃, that is, it is restored to the bovine body temperature, shaken up and divided into ten sample bottles (500ml, dedicated to FOSS instrument)

determine the milk composition and SCC value of the above 80 samples, and take the average value of each group as the actual value of the raw milk of this group

after adding preservative (k2cr2o730mg/sample) to the selected four groups of samples, the milk composition and SCC were determined by water bath to 40 ℃

after all the above samples are capped, put them in the freezer for cold storage, and the cold storage temperature is 2 ± 2 ℃

(to be continued)