The mold and rot microorganisms on the items continuously absorb the nutrients and wastes from the items. Therefore, at the same time as they are multiplying, the objects are gradually decomposed and destroyed. Therefore, the process of material metabolism by the moldy and rot microbes on the objects is also a product mold. The process of rot occurs. This is the nature of the rot of the item.
Items are mildly rotted through the following four steps:
(1) Moisture in wet items is a key factor in the growth and reproduction of mold. When the article absorbs moisture from the outside, the moisture content of the article exceeds the limit of the safe moisture of the article, providing the article with mildew conditions.
(2) When the heat-producing article is exposed to moisture, the moldy microorganisms begin to grow and multiply, and heat is generated. Some of the heat it generates is used by itself, and the rest is distributed in the item. Since the outside of the article is easily radiated from the inside, the internal temperature is higher than the outside temperature.
(3) Mildew As mold grows and thrives on items, it begins to grow hyphae and can be seen as white hairs, called pili. Molds continue to grow and reproduce to form small colonies, known as moldy spots. Colonies increase or colonies fuse to form a lawn, known as mildew. The pigments in the fungal metabolites make the lawn yellow, red, purple, green, brown, and black.
(4) After moldy decay, mold ingests nutrients in the product, and the internal structure of the product is destroyed by the action of mold-secreting enzymes, causing moldy deterioration. The mouldy smell of the moulded articles, the appearance of stains or the appearance of various colours, the internal structure was completely destroyed, the elasticity disappeared and the use value was lost.
From the nature and process of mildew, we can see that the mildew of an item is not only related to the composition of the item itself, but also related to the influence of many environmental factors in the production, packaging, transport, and storage of the item, such as the environment. Humidity, ambient temperature, air, chemical factors, radiation, pressure, etc.
First, the impact of the composition of the article on the product's mildew The rot of the article is the result of the growth and reproduction of the fungal microorganisms on the article. The different nutrients required for the growth and reproduction of different fungal microorganisms are different, but all must have a certain proportion. The sources of carbon, nitrogen, water, and energy constitute a certain culture base. Microbial microbiology obtains carbon sources from sugar-containing articles (such as animal muscles, honey, fruits, dairy products, cotton fiber, and products thereof) and organic acids (such as apples, grapes, citrus, etc.) Its growth and reproduction use. A nitrogen source is obtained from the protein-containing articles (such as meat and fish milk and its products, leather and its products, yarns and wool products) for its need to synthesize bacteria. The carbon source and energy contained in the fat-containing article and the moisture contained in the article itself constitute a good medium, and the mold and rot microbes are prone to growth and reproduction.
Different packaged articles contain different proportions of organic and inorganic substances, which can provide carbon and nitrogen sources, as well as moisture and energy, which are different from the mold and rot microbes. Some bacteria can normally grow and multiply, while others will not adapt and their growth is inhibited. Therefore, the form and degree of mildew rot are different. Therefore, the influence of different compositional items on the mildew of the item is decisive.
Second, the external factors of the mold rot microorganisms get some nutrients from the items, but to reproduce and growth also need suitable external conditions.
(1) Ambient humidity and the moisture content of the item Moisture is the key to the growth and reproduction of mold and rot microbes. Microbial humic microorganisms complete their metabolism through a series of biochemical reactions, and this process must also have the participation of water. When the water content of the article exceeds its safe moisture, it is likely to become mildewed, and the greater the relative humidity is, the easier it is to become mildewed. The relative humidity conditions of various kinds of common molds that make the item mild and rot are listed in Table 3-1. Therefore, to prevent the product's mildew, it is required to control the safety of the item's moisture within 12% and the relative humidity of the environment under 75%.
Table 3-1 Relative humidity and moisture content of all kinds of molds that make things rot
(2) Ambient temperature The temperature and humidity of the microorganisms are different because of the different types. However, the temperature plays an important role in the growth and reproduction of microorganisms. Molds are saprophytic microorganisms and have a wide range of growth temperatures, between about 10°C and 45°C. They belong to mesophilic microorganisms. The main effect of temperature on mold is the action of various enzymes in the bacteria, the temperature level, affecting the activity of the enzyme. The most suitable temperature for enzymes in most molds is 25°C-28°C. At this temperature, the activity of the enzyme is the strongest, the metabolism is also accelerated, and growth and reproduction are also vigorous. When the temperature exceeds or falls below the proper temperature for mold growth, the life of the mold is stopped and growth and reproduction are inhibited.
(3) Influence of air The growth and reproduction of molds also requires sufficient amount of oxygen. During the catabolic process (or respiration) of the moldy microorganisms, microorganisms need to use molecular oxygen or oxygen in the body to decompose organic matters and make them It becomes carbon dioxide, water and energy. When the supply of oxygen in the air is sufficient, it will be beneficial to the life activities of the anaerobic mold and inhibit the growth and reproduction of anaerobic mold. On the contrary, when the oxygen in the air is relatively small, it is beneficial to the activities of anaerobic mold.
(4) Chemical factors Chemical substances have three effects on microorganisms: first, as a nutrient; second, inhibition of metabolic activity; thirdly, destroying the structure of the bacteria or destroying the metabolic mechanism. The role played by chemical substances in the above-mentioned manner depends on the concentration of chemical substances and the physical properties of the environment, the sensitivity of bacteria, the length of contact time, and the temperature level. Different chemicals have different effects on the bacteria. These chemicals mainly include acids, alkalis, salts, oxides, organic compounds and sugar compounds.
(5) Other factors In addition to the above-mentioned major influencing factors, in the process of storage and distribution of articles, they will also be affected by ultraviolet light, radiation, microwaves, electromagnetic oscillations, and pressure, which will affect the mildew. The life activities of microorganisms affect the mildew and spoilage of items.