What Is Perishability?

Perishable food refers to the abnormal quality problems such as the death or deterioration of animal food and the decay and mildew of plant food under the influence of temperature and humidity in a natural temperature environment.

(1) Prosperity of frozen food production and sales. Data show that frozen food production in foreign countries (such as Australia, Germany, the United States, Japan, Thailand, etc.) is very strong and the consumption is large. The scale of frozen food production equipment, transportation equipment, and storage equipment is large, and the technology level is high. It has become a new economic growth point for these countries. The demand for frozen foods is growing, and high-quality frozen foods are popular because they maintain good nutrition.

(2) The consumption of meat products has accelerated. Recent USDA publications analyze world meat consumption, trade prospects, world economic situation and its impact on poultry markets. The analysis believes that the world economy is promising in the next 10 years, especially the continued increase in people's income in emerging markets will increase the demand for meat and trade. With the economic recovery in Asia and increasing market consumption, the consumption of meat in the world will exceed the average annual growth rate of 4% over the past 10 years.

(3) Increase in milk production growth rate. The daily growth rate of global milk production has accelerated, with buffalo milk increasing the fastest, but numerically, milk production has grown faster. The regions with the fastest growth in milk production are Oceania, Asia, and South Africa, while milk production in Europe has not changed; Central and Eastern European countries vary from country to country. ^[1]

China

The easy deterioration of perishable foods is caused by a variety of reasons, firstly determined by the nature of the goods themselves, and secondly by

The main principle of the antisepsis method is to inhibit the life activities of harmful microorganisms or kill all bacteria and molds. The preservative methods generally used are: high temperature treatment, dry, smoked, salted or sugared, and refrigerated. The various antiseptic methods are briefly introduced below.

1. The food is sealed in a tinplate can under high temperature treatment. It is required that the canister does not leak air. Then the canister is placed in a pressure-resistant impregnator and heated to 120 for sterilization. The sterilization time needs 1.5 hours to make harmful bacteria in food And all the microorganisms are killed.

2. Drying Fish, meat, fruits, vegetables, etc. are roasted or dried to make fish floss, meat floss, dried fruit, dried fish, and dehydrated vegetables. Fish and meat are usually slightly salted before they are grilled. Mainly to make microorganisms lose the conditions for growth, development and reproduction, almost all perishable goods can be protected by this method.

3. Smoked is usually used for preservation of fish and meat. Salting is usually performed before smoking. The food is dried during smoking and covered with a preservative produced by burning.

4. Salted and sugared Salt and sugar have a high osmotic pressure, which can reduce the moisture in food cells, which makes it difficult for microorganisms to move and even die. The salted preservative method is the most common and cheapest preservative method.

5. Refrigeration treatment is to reduce the temperature of the food, thereby freezing the water contained in the food, causing dehydration, or reducing the temperature of the food to about 0 ° C. Although the use of this method can hinder the growth and reproduction of microorganisms, the microorganisms have not died at this time. They are only temporarily in a dormant state. After the temperature rises and the external temperature and humidity conditions are appropriate, the microorganisms can quickly recover Its life activities still pose a very serious threat to the quality of the custody of the goods. Therefore, for long-term transportation and storage, the goods must be kept at a low temperature to ensure that the goods will not be damaged and the food will maintain its original quality.

Among the five preservative methods mentioned above, the first four preservative methods have all changed the flavor of the food, reduced the nutritional content of the food, and even produced substances that are not good for the health during the preservative process, which is not worthy of promotion. Therefore, only refrigerated processing is possible to maintain the original freshness and flavor of the food, which is the most ideal and widely used preservative method. From the perspective of the cargo itself, there are two types of refrigerated processing: cooling and freezing. The cooling process is to reduce the temperature of the refrigerated goods to 4 to 0 ° C. During the cooling process, the heat of the goods is taken away, and the surface will have moisture.

Freezing treatment is to freeze the whole of the refrigerated goods and freeze most of the water and juice in the food. This kind of processing should be frozen at a low temperature below -20 , and the faster the freezing speed, the better.

The method of using refrigerated processing to prevent perishable foods is not only simple in process, convenient in operation, economical in packaging, and reduced in cost, but also has the following advantages:

(1) After cooling, when the temperature drops to a certain level, fruits and vegetables are in a state of "false sleep". Respiration slows, metabolism decreases, and low temperature slows the growth and reproduction of microorganisms. These two extend the shelf life of fruits and vegetables. And once it returns to normal temperature, it can restore the original flavor and freshness.

(2) When the temperature of meat food drops to about 0 , even if it does not freeze, the low temperature will slow down the growth and reproduction of spoilage microorganisms, extending the shelf life of this type of food.

(3) When the food is frozen, its juice changes from water to ice, and it can no longer supply the water necessary for the living of microorganisms, and the low temperature further hinders the growth and reproduction of microorganisms, thereby greatly improving the storage resistance.

(4) Sugars, proteins, fats, and inorganic salts contained in foods during the freezing process will hardly be lost; and among vitamins, except vitamin C, which is highly oxidizable, the rest of the vitamins change very little. If during the treatment process, try to destroy or inhibit the enzyme activity for a long time, freeze below -25 , and keep it at -18 , the loss of vitamin C is very small.

Therefore, the preservation of food by the cooling method can maintain the nutrition, flavor and freshness of the food, but the disadvantage is that the storage time cannot be too long. With the development of cooling technology. At present, there is a new method of modified atmosphere refrigerated transportation. This refrigerated transportation method is mainly used to preserve fruit and vegetable goods. After adopting this method, it can reach the freshness that could not be achieved by the previous cooling treatment method, thereby ensuring the highest quality of food during transportation. . The content of modified atmosphere refrigerated transportation will be described in a later chapter.

Foods preserved by the freeze processing method will damage the cell tissue due to freezing, which affects the nutritional value and taste of the food. It cannot guarantee that the original color, aroma and taste remain unchanged, which is a great disadvantage.

1. Livestock and poultry meat

Pork ^[2]

(1) Increasing demand for refrigerated food: Consumers demand that food be easy to prepare, can be stored for a long time, hygienic and safe, delicious and diverse, have traditional ethnic styles and local characteristics, and have a balanced nutrition. Although the situation varies slightly from country to country, frozen foods are generally sold much faster than frozen foods.

The reasons are: first, frozen food is more fresh and natural; second, frozen food consumption has reached a high level in many countries; third, the interval between purchase and consumption of frozen food is very short (about 3 days in France); fourth, frozen food It takes longer to prepare than refrigerated food. Half of frozen food is used in restaurants, and demand is growing. Food manufacturers are using frozen foods to produce frozen foods.

(2) Products should have uniform standards and reliable quality, and be supplied throughout the year: food should be diversified to meet the needs of various consumer objects: such as different ages, uneven fat and thinness, patients and athletes.
(3) Increase all kinds of ignorance and transparency. Consumers increasingly want to know the ingredients of food, how to make it, calories, storage temperature, and expiration date. It is best to use the expiration date of various ingredients). Due to concerns about storage temperature, many consumers buy top brand products (they are protected by the cold chain throughout the entire production, transportation and sales process).
(4) Superior sensory characteristics (color, fragrance, taste): In this regard, consumers like cooked food, but generally they are cooked at a relatively low temperature (57 ~ 60 ° C). Because this does not change the quality of the food due to cooking (of course they are also more fragile and need to be double protected). Refrigeration alone cannot always maintain food quality, so food safety must require safeguards linked to refrigeration and other protection methods.
(5) Cleanliness of equipment: People pay more and more attention to the cleanliness of equipment to prevent food pollution.
(6) Energy saving: Energy consumption is a very important issue. Because it affects decision-makers' decisions and also affects the quality of the cold chain. Refrigerated storage has the trend of large capacity and rapid cooling, but it must have the characteristics of low energy consumption.
(7) Coordination of interfaces. The temperature control and operation coordination of the interfaces of the refrigeration chain are the key to ensure the overall quality and efficiency.
(8) Temperature control. Temperature control is an essential endogenous factor that determines the safe transport of many foods. In many cases, temperature control is also the key to determining the best quality and economic benefits of food. Several food poisoning incidents in the United Kingdom were caused by the temperature of foods not being properly controlled during production, transportation and marketing. Temperature is a key factor affecting microbial growth. Understanding how temperature affects microbial growth is necessary to understand temperature control.
(9) Temperature legislation: Consumers are increasingly demanding food quality, and food poisoning incidents caused by poor temperature control have attracted people's attention. Temperature control has become an important issue. Therefore, temperature legislation is necessary. Developed countries in Europe and the United States have enacted legislation on the temperature control of refrigerated food from production to consumption.
(10) Refrigerant replacement: countries around the world recognize

(1) The demand for convenience food and meat products is increasing.
(2) Less time to buy food. Telemarketing or home food delivery via the Internet is another new sales method, and supermarkets are promoting it this way.
(3) Be wary of specially processed foods. If you do not accept or oppose the production and sale of foods that have been subjected to ionizing radiation, genetically modified foods.
(4) Demand for fruits and vegetables is increasing. In particular, the demand for fruits and vegetables with special characteristics in vitamins, plant fiber, low energy value, and anti-cancer is increasing.
(5) Reduce the content of additives in food. Mainly because such products are more susceptible to microbial contamination. ^[1]

1. Buy two thermometers

Put one thermometer in the freezer and the other in the freezer. You need to know the temperature inside the refrigerator to know if the food is properly stored.

2. Check the temperature in the refrigerator every week. The temperature of the refrigerator compartment should be maintained at 1C to 3 ° C, and the temperature of the freezer compartment should not exceed minus 15 ° C.

3. Don't overfill the refrigerator. Air must be kept in the refrigerator to keep every food at the optimal temperature.

4. Raw meat, fresh chicken and seafood should be placed in sealed containers for refrigerating. To prevent the contamination of raw meat, poultry, and seafood from contamination of other foods, put them in sealed containers or wrap them properly when refrigerated .

5. Keep the refrigerator clean. If there is any spillage, wipe it off immediately. Regularly clean all surfaces of the refrigerator with hot soapy water, then wipe with water.

6. Refrigerated and frozen food should be put in the refrigerator as soon as possible. When you buy refrigerated or frozen food from the supermarket, you should put it in the refrigerator as soon as you get home. Whenever possible, use supermarket-supplied packaging with ice cubes.

7. Leftovers and leftovers cannot be left for more than 4 days. Foods cannot be stored in the refrigerator and freezer for a long time. For leftovers, generally do not stay for more than 4 days.

8. Do not re-frozen frozen food. Once the frozen food is thawed, it should not be frozen again. This is because bacteria can resume growth after thawing frozen foods, and food safety cannot be guaranteed.
Food is frozen to slow down bacterial growth. When bacteria are in the environment with food, a certain humidity and a temperature above 4 ° C, they will grow rapidly. Surprisingly, the number of bacteria can double in just 20 minutes. Keeping the recommended temperature inside the refrigerator (below 4 ° C) helps to inhibit the growth of bacteria and thus improves food safety. ^[1]