New technology of straw feed
Release time: 2001-1-29 Article Source: Author: []
Crop straw is a by-product of agricultural production and a precious resource endowed by nature. China produces more than 600 million tons of crop straw every year. The state and governments at all levels attach great importance to the reuse of crop straw, constantly increase capital investment, and study ways to effectively use crop straw. One of the important ways is to convert crop straw into animal feed, which opens up a new feed source for aquaculture. However, due to the high fiber content and low nutrient content of crop straw, it is generally not suitable for direct feeding of livestock and poultry, and it must be properly treated. For example, the storage and ammoniation methods of bluish yellow are mostly used in ruminants such as cattle and sheep. However, how to further improve the nutritional composition of straw feed and expand the application scope of straw feed must adopt new technologies and methods. The production method of 1. Straw feed 1 During preparation, corn straw, rice straw, wheat straw, bean straw and other mildew-free crop straws are selected and appropriately crushed according to feeding objects. The finer the straw particles for pigs, geese and ducks, the better. Straw for cattle and sheep should be cut into sections 0.5-2 cm long. According to the scale of culture, plastic bags, plastic buckets, tanks, cement tanks and so on can be used as fermentation containers. 2. Production method (1) strain activation: dissolve 2.5 kg of sugar in warm water of about 30 degrees, add 1 kg of starter, fully stir and let stand for 1-2 hours. The accelerator 1 kg and 2 kg of salt were fully dissolved in 50 kg of water, and then mixed with the activated starter. (2) Fermentation method: put the cut straw on the cement floor, or add a proper amount of corn flour and soybean meal. The prepared starter, accelerator and straw are evenly mixed, packed into plastic bags for compaction, and sealed for fermentation for 5- 12 days. The fermentation time depends on the environmental temperature, the lowest fermentation temperature is 65438 00℃, and the fermentation time is shortened with the increase of temperature. The fermented straw feed is golden or light yellow in color, has the aroma of wine or apple, and feels soft. 3. Feeding method: After straw fermentation, the dry matter digestibility increased by more than 40%, the crude protein content increased by 8- 12%, the organic acid and sugar increased by 30-40%, and the crude fat increased by 3-7%. At the same time, it produces a large number of physiologically active program-controlled substances such as vitamins and amino acids, so it can be directly used to feed livestock instead of some concentrated feed. It can replace 30% concentrate for fattening pigs, 50% concentrate for fattening cattle and 90% concentrate for fattening ducks and geese. 4. Some suggestions were put forward to avoid frequent opening of straw during fermentation and use. After opening the straw, it should be sealed again immediately to prevent mildew. If there is mildew or odor, stop using it. All kinds of straws can be used individually or in combination, and the priority of straw selection is corn straw, rice straw and wheat straw, and bean straw can be added in the proportion of 5- 15%. Green straw and dry yellow straw can be used, while moldy straw and sorghum straw can't be used as feed. 2. Straw biological feed 1 application example. Examples of pig raising: scale: 300 fattening pigs, sows 10. Dosage: 30% fermented corn stalk for fattening pigs and 50% for sows. Effect: The fattening pigs were slaughtered in 4 months, and the feed/meat ratio was 2.8-3. 1: 1, which saved the feed cost per pig on average, 80 yuan. The feed intake was normal during the growth period, and no intestinal diseases occurred. 2. Example of raising cattle: scale: 30 heads. Eight-month-old calves were selected, including 3 calves in the demonstration group and 3 calves in the control group. Dosage: the concentrate is the same, the coarse material demonstration group uses fermented straw, and the control group uses hay. Results: After feeding for 2 months, the average daily gain of each cow in the demonstration group was 0.79 kg, while that in the control group was 0.355 kg. The average net profit of each cow in the demonstration group was 155.48 yuan, while that in the control group was 3 1.24 yuan.
Yogurt is fermented with fresh milk inoculated with lactic acid bacteria under certain conditions. After fermentation, the original lactose was partially converted into lactic acid, but some lactose remained, thus forming a unique sweet and sour flavor. Different varieties may have different degrees of fermentation, and the ratio of lactose to lactic acid is different, so some varieties will be slightly sweet and some varieties will taste slightly sour. But not very sweet. If it is really sweet, sugar may be added.
At present, there are two kinds of yogurt on the market: solidified yogurt and stirred yogurt. The latter was partially denatured by protein in acidic environment to form curd. On this basis, the former also added a small amount of chymosin to promote protein coagulation. There are two kinds of yogurt and fresh milk, and there is not much difference in nutrients. However, please note that yogurt is different from lactic acid drinks on the market. The latter is to add a certain amount of sour agent to various drinks to make them sour and have low nutritional value.
Yogurt is a kind of food with high nutritional value, and there is no strict limit on how much healthy people can eat a day. Experts believe that it is ok for healthy adults to drink less than 1000 ml per day. You can drink it at any time of the day.
Yogurt is a traditional fermented dairy product with rich nutritional value and good health care function. With the popularization of refrigerator and cold chain system, the improvement of people's consumption level and civilized quality, and the popularization of health concept, the output of yogurt has increased at an average annual rate of 25%, and it has become the largest fermented dairy product and the industry with the most profit and development potential in China.
Yogurt is a dairy product fermented by fresh milk and yogurt starter. Yogurt starter is a special microbial culture material used to make yogurt. Starter plays a very important role in yogurt production, which is the basis and main reason for sour taste and fragrance of yogurt products. The quality of yogurt mainly depends on the quality type and activity of yogurt starter.
Types of yogurt starter
Yogurt starter can be divided into three types according to different physical forms: liquid yoghourt starter, frozen yoghourt starter and direct-throw yoghourt starter. Liquid yogurt starter is relatively cheap, but the strain activity often changes, and it is easy to be contaminated with miscellaneous bacteria during storage, and the storage time is short, and the strain activity drops rapidly after long-distance transportation. Frozen yogurt starter is made by deep freezing, which is cheaper than direct-throwing yogurt starter, with higher strain activity and shorter activation time, but it needs special environmental conditions of -45~-55℃ during transportation and storage. Direct-throw yogurt starter can not only be directly put into fermentation tank to produce yogurt, but also be stored in ordinary refrigerator, with low transportation cost and storage cost, and its convenience, low cost and quality stability in the use process are particularly prominent.
At present, liquid yogurt starter has been gradually eliminated by large yogurt production enterprises because of its unstable quality and easy pollution. Only some small and medium-sized yogurt factories are still producing in conjunction with some universities or research institutes. Because of the high cost of deep frozen yogurt starter, its wide application is limited. However, after the price of direct-throw yogurt starter was gradually accepted by domestic manufacturers, it was widely used in some large yogurt production enterprises.
In the previous yogurt production process, the strains of yogurt starter should be set up in a separate strain workshop of yogurt manufacturers, and the process of "pure bacteria → activation → expanded propagation → mother starter → intermediate starter → working starter" was completed, with many procedures and strict technical requirements. General manufacturers often have quality problems due to limited production conditions. Therefore, in developed dairy countries, yogurt production enterprises do not make their own leavening agents, but enterprises specializing in leavening agents provide yogurt leavening agents to meet the requirements of fermented dairy production enterprises. At the end of 1988, the Danish Hanson Central Laboratory produced a super concentrated yogurt starter.
DVS Directed Vat Set refers to a series of highly concentrated and standardized freeze-dried starter strains, which can be directly added to the heat-treated raw milk for fermentation without other pretreatment such as activation and expansion. Generally, the number of viable bacteria in direct-cast yogurt starter is101012 cfu/g. Because direct-cast yogurt starter has strong vitality and many kinds, yogurt producers can choose it at will according to their needs, which enriches the varieties of yogurt products, omits the strain workshop and reduces personnel, investment and investment. Direct-throw yogurt starter can be used directly, and it is easy to manage without expanding culture. The production and application of direct-throw yogurt starter can make the production of starter professional, socialized, standardized and unified, thus standardizing the production of yogurt, improving the quality of yogurt and ensuring the interests and health of consumers.
Method for making direct-throwing yogurt starter
A breakthrough in yogurt production technology is to change the production mode of traditional liquid starter and use direct-throwing yogurt starter. The product quality of direct-throw yogurt starter is uniform, its activity can be determined in advance, the inoculation amount can be accurately controlled, and it is easy to mix evenly, so the quality of starter and yogurt can be guaranteed to be stable. The production process of direct-throw yogurt starter mainly includes the following steps:
1) and its preservation. The key to producing high-quality commercial koji is to use excellent strains. At present, the research and development center of yogurt starter production has been established abroad, and the functional requirements of starter strains have basically formed standards. The main screening directions of lactic acid bacteria are: ① screening strains with strong freezing, drying and shearing resistance, because freeze drying, deep freezing storage and spray drying are the main methods to prepare commercial starter; ② Screening positive strains with high utilization rate of lactose and galactose and producing more lactic acid; ③ Screening viscous strains to produce high-yield viscous substances such as extracellular polysaccharide, so as to increase the viscosity of the product, improve the thick texture of the product and reduce the occurrence of quality defects such as gel breakage and whey precipitation; ④ In the process of yogurt fermentation, phage pollution often leads to slow fermentation or even failure, but there are still no effective preventive measures, so each yogurt factory requires the corresponding anti-phage strains to rotate; ⑤ Citric acid can be decomposed into diacetyl and other unique flavor substances of yogurt, and citric acid utilization bacteria can enhance the unique flavor of yogurt; ⑥ When screening probiotics such as Bifidobacterium and Lactobacillus acidophilus, it is best that the strains come from human body and can tolerate bile salts and acidic environment to enhance their effectiveness.
The pure culture obtained by screening is stored in ultra-low temperature refrigerator or liquid nitrogen tank for a long time to maintain its activity and stability.
2) Transplantation of strains. Before the industrial production of starter cultures, the strains were activated and transplanted in the laboratory and strain workshop, and the seed solution was expanded.
3) Preparation and sterilization of culture medium. In order to make direct-throw yogurt starter, lactic acid bacteria should be cultured in high concentration first. After selecting the basic culture medium (generally skim milk powder culture medium), we should find a suitable enhancer to strengthen the culture medium, get an optimized culture medium, and reproduce lactic acid bacteria to the maximum extent.
4) Inoculation and culture. There are several methods of high concentration culture of lactic acid bacteria: ① Constant pH culture method: During the fermentation process, lactic acid, acetic acid and other substances produced by metabolism have feedback inhibition on its growth. The pH value of the culture solution in the fermentor is maintained at 5.8-6.0, so as to reduce the inhibitory effect of lactic acid and other substances on bacterial growth, prolong the culture time and prepare the fermentation solution with high number of viable bacteria. In the process of culture, chemical neutralization method or buffer salt method is used to keep the pH value of culture solution stable. (2) Membrane dialysis method: exchange components between culture solution and nutrient solution by using membrane selectivity, so that lactic acid in the culture solution partially oozes out, and components in the nutrient solution permeate into the culture solution to maintain the normal growth and reproduction of lactic acid bacteria.
5) Cell concentration. It is the best time to harvest lactic acid bacteria cells from the late logarithmic growth period to the early stable period, because the survival rate, freezing resistance and drying resistance of the harvested bacterial cells are the strongest at this time. At this time, the lactic acid bacteria culture solution can be separated by centrifugation, and bacterial cells can be collected to concentrate the concentration of the bacterial solution. Membrane separation can also be selected. The concentration multiple is more than 20-50 times, and the operation process is as gentle as possible to minimize the influence of shear force and air.
6) freeze drying. After freezing lactic acid bacteria, water was removed by sublimation in a reduced pressure environment. When most of the water in bacteria is removed, the physiological activities of cells will stop, thus achieving the purpose of long-term preservation. Ice crystals produced in the freezing process will damage the cell membrane, leading to a large number of cell deaths, so it is necessary to add antifreeze protection agents before freeze-drying to reduce cell damage.
7) packaging. Bags and aseptic packaging are generally used to facilitate storage and transportation.