From experience to precise and controllable food fermentation technology, the future may meet personalized and digital nutrition customization

　　In 2099, spacecraft’s canteen during the space migration.
　　”Please voice input what do you want to eat today?”
　　”I was a little tired after exercising. I want to eat a piece of chili-flavored sugar-free chocolate with a spiciness of about 50,000, a little more cellulose, and no more than 300 kJ of calories. “I 　　am
　　3D printing food for you…”
In the future interstellar travel, ensuring adequate food and nutritious food is the first priority. If you put several years or even more than ten years of food reserves into the spacecraft from the beginning, it seems Somewhat impractical. If the carbon dioxide or other metabolites produced by humans can be converted into food, these problems may be solved.
　　In fact, these issues have been studied by scientists. Recently, Chinese scientists have realized the artificial synthesis of starch using carbon dioxide as the raw material. The first step of carbon dioxide conversion into organic matter is chemical catalysis, followed by the catalysis of various enzymes to extend the carbon chain, and finally realize the synthesis of starch. .
　　In addition, many researchers have used autotrophic microorganisms (a kind of microorganisms that use carbon dioxide as the main or only carbon source, inorganic nitrides as nitrogen sources, and obtain energy through bacterial photosynthesis or chemical energy synthesis) to convert carbon dioxide Converted to organic matter, and subsequent synthetic manufacturing of various foods also relies on fermentation engineering using various microorganisms.
　　Microbial engineering:
　　also called fermentation engineering, refers to a technology that uses modern engineering techniques to use certain specific functions of microorganisms to produce useful products for humans, or to directly apply microorganisms to industrial production processes. Biological engineering of microorganisms, including genetic engineering technology, genetically modified biological technology, synthetic biology technology, and industrial application of microbial fermentation production engineering, etc.
1 New generation food fermentation technology

　　Throughout the history of human development, people have already begun to use microbial fermentation technology, such as the use of microbes to brew wine, beer, and soy sauce. However, traditional fermentation mostly relies on experience. The microorganisms used are natural fermentation flora, whose stability and efficiency cannot be guaranteed, fermentation conditions are greatly affected by natural factors, and quality cannot be guaranteed.
　　In some cases, natural microorganisms can also produce substances that are harmful to human health, such as monascus used in fermented bean curd and vinegar brewing. During the metabolism, they can produce a fungalmycin with similar toxicity to aflatoxin-orange Mycin; in fermented foods such as sauerkraut, fruit wine, cheese, etc., microbial decarboxylated amino acids can form biogenic amines.

Multi-level reconstruction of food fermentation research methods and production methods

　　With the emergence of biotechnology such as gene editing and synthetic biology, fermentation engineering has also entered a new era, overcoming the uncertainties in traditional fermentation, and gradually entering the stage of precise fermentation. The penetration and crossover between disciplines, mathematics, kinetics, chemical engineering principles and computer technology have begun to be used in the research of fermentation process, and all the parameters of automatic recording and automatic control of fermentation process have been applied to production.
　　Food bioengineering has also entered a new stage of development, promoting the development of the food industry to scale, standardization, and functionality.
　　The overall technical idea of ​​food synthetic biotechnology is to build a specific “cell factory” to synthesize milk, meat, sugar, oil, eggs, and various food additives in a “workshop” production method. Design-build-test-learn, the cycle is usually used to build high-efficiency cell factories with a wide range of applications, including applications in the food industry. At present, various synthetic biology methods and tools have been developed to promote the design-build-test-learn cycle of cell factory construction. These technologies are reforming the food industry in the future.
　　With the help of the innovative development of food synthetic biology technology and biotechnology, information technology and engineering technology, the research methods and fermentation process of food fermentation have realized multi-step optimization and reconstruction, including: isolation and identification of original flora, artificial synthesis of flora , Analysis of microbial metabolism characteristics and functions in fermented food, prediction of fermentation process, intelligentization of fermentation equipment, etc.
　　Microbial fermentation can produce almost any kind of food, such as protein, fat, sugar, starch, seasonings, additives, etc. For example, one of the most popular manufacturing methods of “plant meat” is to use microorganisms to ferment plant protein, and “artificial milk” is also used It is a combination of various nutrients of microbial fermentation.
2 Microbial fermented meat and artificial milk

　　Microbial fermented meat refers to the single-cell protein produced by fermenting microorganisms (such as yeast and bacteria) using synthetic biology methods. The protein content in these microorganisms is as high as 40% to 80%, far exceeding that of soybeans and peanuts.
　　Single-cell protein has many advantages, including short production cycle, high nutritional value, even more than pork, fish, etc.; it can be industrialized and mass-produced; it contains a variety of amino acids necessary for the human body, such as leucine, lysine, iso Leucine etc.
　　At this stage, the fermentation technology used in the food industry includes traditional fermentation and new fermentation. The difference between the two fermentation methods is whether the target product is a microorganism or a host. The so-called new fermentation technology is the use of the main products obtained from microbial fermentation to produce milk-like proteins.
　　Artificial milk
　　In 2014, the American biotechnology start-up Perfect Day proposed the concept of artificial milk based on “cell agriculture”. Through the design and transformation of yeast cells, industrial fermented milk proteins (such as whey protein and casein) and corresponding nutrients were used to achieve the development of artificial milk products. Precise nutrition and green manufacturing.
　　Artificial milk, that is, synthetic milk, is a milk-like beverage made by mixing about 20 kinds of nutrients. Its main ingredients include 6 kinds of milk protein, 8 kinds of fatty acids, minerals, vitamins, and sugars, and about 87% of water. By adjusting its composition and ratio, this artificial milk can have a composition and flavor similar to that of milk, and does not contain lactose, cholesterol, antibiotics, allergens and other undesirable factors. The production process does not require breeding animals, which can effectively save resources. And energy is a new mode of future dairy production that will subvert the traditional aquaculture industry, and will lead the future development of the food industry and cellular agriculture.
　　Milk is rich in protein and has complex ingredients. The total content is about 3.2%, mainly including casein and whey protein. In addition, there are more than 40 other trace proteins, accounting for about 2%. Among them, except for serum albumin and immunoglobulin from blood, all casein and whey protein are synthesized products of milk secreting cells in the mammary gland. Therefore, the core step in the production of artificial milk is to develop a milk protein that is basically the same as milk.

　　(1) Researchers first extract chromosomes from dairy cow cells and obtain target genes that can synthesize milk proteins. Then the target gene is connected to a vector called a cell plasmid outside the cow’s body to form recombinant DNA. Afterwards, this recombinant DNA is transferred to yeast, and the transformed yeast is screened to select individuals who obtained the recombinant DNA. These selected yeasts can synthesize milk protein.
　　(2) Put the recombined yeast at an appropriate temperature and concentration for industrial cultivation. Yeast can produce enough protein in a few days. Finally, by refining protein from yeast, a large amount of milk protein can be obtained.
　　(3) In order to ensure that the taste similar to milk can be obtained, it is necessary to go through the necessary food processing process of emulsification. That is, the casein and fatty acid can be formed into micelles by using emulsification processing technology, emulsifiers and other chemical means or high pressure homogenizers and other mechanical means, and then the two are surrounded by water to form micelles with a size of about micrometers. Make casein, fatty acid and water form a uniform system to ensure the color and uniformity of artificial milk.
3Used as 3D printing raw materials to make personal customized food

CNC machining (subtractive) VS 3D printing (additive)

　　When microorganisms can be used to produce any food nutrient molecules, there may be a subversive change in the way people make food, such as using nutrient molecules as raw materials and using 3D printing to make food.
　　The traditional food preparation method is similar to numerical control processing, which is a subtractive method. In the process of making grains or animals into food, some inedible wastes such as wheat bran, bones, and internal organs will be discarded. The way of making food with molecules as raw materials and 3D printing is an additive method that can greatly reduce food waste.
　　Around 2000, 3D printing technology was introduced into the food field. The original printing materials were various food powders, such as protein powders, and food molecules were not yet used for printing. With the continuous deepening of research, scientists can use cells, hydrogels, etc. to create 3D printed meat.
　　Scientists have further used food nutritional molecules as raw materials for 3D printing. For example, the Bhandari Bhesh team at the University of Queensland in Australia used dark chocolate, beef sauce, pig fat or egg white protein as printing materials to develop chocolate, meat and protein foods.
　　In China, the team of Professor Zhang Han of Jiangnan University has researched 3D printing covering starches, algae, fruits and vegetables, proteins, fish and other usable materials. Through computer simulation, printing material pretreatment and printing process optimization, more than 20 kinds of materials have been realized. Accurate printing of edible materials, and protective printing of ingredients rich in probiotics, cordyceps pollen, anthocyanins, vitamin D, etc., have obtained more than 20 printed foods with good functionality.
　　Compared with ordinary foods, one of the advantages of 3D printed foods is that they have controllable nutritional content and can seamlessly integrate nutrients to produce personalized foods to meet people’s food needs under different circumstances.
　　For example, the artificial milk technology mentioned above can make artificial milk components closer to natural breast milk by adding breast milk ingredients. When the mother’s breast milk secretion is insufficient, it can be used as a substitute; for people with lactose intolerance, it can be reduced The lactose or allergic ingredients in artificial milk are more suitable for people with lactose intolerance.
　　In the future, combined with computer technology and big data analysis, people can also upload their own health data, the software will use algorithms to match healthy recipes, and then use 3D printing to make food. Athletes, astronauts, the elderly, children, pregnant women and everyone can personalize and digitally customize nutrition in this way.