Food industry requirements for drying technology

September 18 13:01:36, 2018

Since the 1990s, the food industry in China has continued to grow rapidly and has achieved remarkable results, basically satisfying the requirements for the continuous improvement of the living standards of urban and rural residents. In 2002, the food industry realized sales revenue of RMB 1,021.055 billion, second only to the manufacturing of communications equipment, computers and electronic equipment, and became an important pillar industry in the manufacturing industry. The quality of some major products such as: meat, edible oil, beer, monosodium glutamate, instant noodles, etc. ranks first in the world, and vegetables and fruits have become the world's largest producer. In 2000, the output of vegetables reached 440 million tons, accounting for 66% of world production. The output of apples and pears ranked first in the world for eight consecutive years. The processing of fruits and vegetables, all kinds of special flour, special fat milk and dairy products are rapidly growing. Convenient foods, meat products, frozen foods, and juice drinks are gradually entering the residents' table. The relationship between the development of the food industry and the nutrition and health of the residents is increasing. The closer it comes.
Experts are very concerned about the development trend of the food industry. In November 1992, a 21st Century Chinese Food Symposium was held in Beijing. A total of more than 150 experts, scholars and entrepreneurs from home and abroad participated in the seminar and discussed the development of the food industry in depth and extensively. The topics were summarized.
First of all, the basic understanding of 21st century Chinese food is summarized as 11 issues. It is believed that the main food in the 21st century is no longer the concept of agricultural food. Industrial food will play a major role in food consumption. The proportion of food in food consumption is generally around 80%, while in China it is only 25%. China's food industry has traditionally been an extension and continuation of agriculture, and the scope of the food industry in the future will be expanded to the initial processing and deep processing of agricultural and sideline products. The food industry should focus on making full use of and developing food resources and avoid undue losses. In addition to safety and hygiene, food in the 21st century will see increased demand due to low calorie, low fat, low cholesterol, low salt foods, and no harm to food flavors.
The assumptions for the development of Chinese food in the 21st century are also discussed in 11 aspects. The Minute thinks that the planting structure and culture structure of agriculture should be adapted to the processing requirements of modern food: the preservation, preservation, and storage of vegetables, fruit, aquatic products, and livestock products, entering the consumption field in the form of semi-finished products and finished products, and actively developing new food resources; Industrialized production of traditional diets enables industrialized products to enter the family's three meals a day; suits functional combination foods at different levels of consumption; vigorously develops the dairy industry; alcoholicity should reduce alcohol levels, and wines should be purely natural high-grade unsweetened types. Development and so on.
Experts believe that the current industrial structure of the food industry does not meet the requirements of the people's nutrition and health, that is, the degree of deep processing of food is low; the food production enterprises do not have a reasonable mix of nutrition and health requirements for residents; the structure of meat production is irrational, and the average urban residents The meat consumption of people has reached 31.8 kilograms, which is comparable to that of European countries. However, the proportion of pork is too high, and the ratio of beef, mutton and poultry is low; the production of fortified foods has not received due attention; and there is insufficient publicity and development of nutritious foods such as soybeans. Wait. All these issues deserve attention.
In the food processing process from raw materials to finished products, almost always a certain process needs to be dried, so the food industry has a close relationship with the drying technology. China's modern drying technology has developed rapidly since the 1950s, and almost all types of drying equipment can now be produced in China to meet the needs of food processing companies. From the perspective of drying technology, the drying technology in the food industry is similar to that in the pharmaceutical and chemical industries, but food drying does have some special places. First of all, food drying should maintain the nutrition of the product and minimize the nutritional loss of the finished product. That is, the food drying must study the reaction kinetics law of nutrient loss, and determine the thermal degradation physical data of accumulation of various nutrients to guide the drying operation control in the material can withstand Below the temperature, and make the heating time as short as possible. Although freeze-drying can keep the nutrients at their best, the high cost makes the freeze-dried products uncompetitive in the market. The vacuum drying and dynamic rapid drying technology can ensure the quality on the basis of cost reduction. If the vegetables in the belt dryer can take about 2 hours to dry, and in a vibrating fluidized bed, drying takes only half an hour, both of the beta-carotene content is 3 times higher than the former.
In processed foods, baked goods, fried foods are also popular varieties, and they are subject to high temperature processing of such foods, to limit the temperature does not exceed a certain limit, or Mailer reaction after eschar (more than 200 kinds of chemical reactions) may produce Carcinogens.
In food processing, fresh fruits and vegetables are often slurried and then dried to make powdered products, some of which are liquid materials, such as milk, which is the most commonly used spray-drying process. The most common fault in spray drying is the sticking of the powder and taking appropriate measures can reduce or prevent sticking. Therefore, people must pay attention to a new concept, namely "glass transition temperature." The higher the glass transition temperature of the material, the less sticky the wall is when drying. For example, the glass transition temperature of tomato powder is below 52°C. Therefore, when the temperature of the cone below the spray tower is still above 52°C, the tomato powder is very dry. Now. But still sticky wall. The glass transition temperature of water is -135 °C, so when the ice cube is above -135 °C, its surface is still sticky. The higher the water content of the material, the glass transition temperature of the material is also affected by the lower water, so the greater the viscosity. In order to dry the sticky Chinese herbal extracts, the use of vacuum belt dryers and microwave vacuum dryers saves a lot of trouble than spray drying. There are also applications in food drying, such as vacuum drying with bananas. Best product.
With the development of new products in the food industry, there will inevitably be new requirements for drying technology, and the same people need to constantly explore and develop drying technologies.