The influence of individual physical texture of th

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The influence of individual physical texture of agricultural products on their fresh-keeping packaging effect (Part 2)

2.2 the change of pH value during the packaging and storage of agricultural products and its impact on the fresh-keeping effect

during the packaging and storage of agricultural products, the pH value will be higher and higher. That is, the acidity decreases and the sweetness or alkalinity increases, but the alkalinity does not increase to a certain extent, as shown in Figure 3. The reason is that with the increase of storage period, the acidity of the fruit will decline, and many components will be oxidized into sugar. The sugar content first increases, then decreases and desalinates, and finally makes the fruit deteriorate. See Figure 4, losing the fresh-keeping effect

3 the relationship between meat transparency and freshness

meat transparency mainly refers to the transparency of the edible part of fruit agricultural products. The light transmittance of a certain thickness of fruit under light on the morning of December 12. The meat quality of agricultural products has a certain internal law between transparency and preservation. Transparency can first reflect the difficulty of keeping fresh to a certain extent, and then judge the freshness of the agricultural product through transparency

3.1 the greater the transparency of agricultural products, the harder it is to keep fresh.

for example, the most difficult variety of fruits to keep fresh is also the variety with the best meat transparency. Grapes, longans, lychees and other fruits have the best transparency, but they are also the most difficult to keep fresh. At present, longan and litchi are still difficult problems in fresh-keeping packaging, except that grapes have achieved fresh-keeping packaging through controlled atmosphere refrigeration. Among edible fungi, fresh Tremella fuciformis and fresh Volvariella volvacea have good meat transparency, but their fresh-keeping packaging has not been solved

3.2 meat transparency can be used to determine the degree of freshness

during the storage of agricultural products, before they lose freshness and deteriorate, they must first undergo oxidation to produce browning, resulting in the decrease of meat transparency. In rural areas, the traditional way to distinguish whether the eggs are fresh is to look at the eggs against the light to see whether they are transparent. Light transmission indicates that the eggs are still fresh and not bad

4 effect of meat texture fineness on fresh-keeping effect

at present, there is a lack of scientific analysis on the effect of meat texture fineness on fresh-keeping effect, and there is a lack of corresponding empirical and data from the government level. For example, what kind of meat quality is considered to be high in fineness, lacking quantitative and qualitative analysis. A more scientific description of meat texture and taste fineness can be determined by oral enzymes. It is the length of time that peeled and seeded pulp dissolves under the action of oral enzymes. A short dissolution time indicates that its taste is fine, and vice versa

in terms of the effect of meat texture fineness on preservation, we generally believe that the better the fineness of taste, the worse the preservation effect. Theoretically, it shows that the agricultural products that are easier to be degraded by biological enzymes are more difficult to keep fresh

5 conclusion

fresh keeping packaging is a packaging technology that has developed rapidly in recent years. This paper discusses only one aspect of the factors that affect the fresh-keeping packaging effect of agricultural products, and there are more factors that affect the fresh-keeping effect of agricultural products, which needs our attention and research. Fresh keeping packaging is a relatively comprehensive technology in packaging technology. It has the following characteristics:

first, the content of fresh keeping packaging research is wide, and the technical strength of graphite high-end industry is still far behind that of foreign countries, which is both breadth and depth. For example, there are many factors and parameters that affect the quality change of a certain agricultural product after packaging and before consumption or processing, which is reflected in the breadth, and how does a certain parameter affect it, This is reflected in depth

Secondly, the technical knowledge of fresh-keeping packaging is highly comprehensive and cross cutting, involving materials, biology, chemistry, etc

third, the lack of research means. Compared with developed countries, our fresh-keeping packaging seriously lacks corresponding means. For example, many instruments, equipment and materials for fresh-keeping need to be imported, which seriously affects the research process of fresh-keeping packaging

packaging technology research center of Wenzhou University, Yang Fuxin, Zhou Jun

source: China packaging 2005/5

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