Keywords: Xiaomi; Nutritional value; Medical care; Flour products
China's millet has many producing areas, high yield, low price, rich nutrition and easy digestion and absorption. It contains dietary fiber, hydrolyzed peptides, millet polyphenols and other ingredients, and is an active ingredient with many health-care functions such as antioxidation, blood lipid lowering, blood pressure lowering and blood sugar lowering. At present, the way people eat millet is mainly millet porridge. However, flour products involve almost every field of people's daily diet. Adding millet into flour products can promote the application of millet products in a wide range, fundamentally improve people's diet structure and give full play to the health care function of millet. The flour products added with millet have good health care value, but it will have a certain impact on the structural processing characteristics of flour products. The research status of nutritional value and health care efficacy of millet was summarized, and its application in flour products was discussed. At the same time, some problems existing in its application are put forward and the solutions are discussed. Finally, the development prospect of millet in flour products was prospected.
With the improvement of people's living standards, food and clothing is no longer a problem. In this era of abundant food, some "rich diseases" (mainly hypertension, hyperglycemia and hyperlipidemia, commonly known as "three highs", and obesity in general patients) have become important diseases that endanger people's health. Bad diet is the main cause of people's illness, and it is particularly important to improve this situation through the adjustment of diet structure. In recent years, it has been found that increasing the proportion of miscellaneous grains in the dietary structure is conducive to reducing the risk of "three highs" and improving people's health.
Coarse cereals mainly include millet, sorghum, mung beans and so on. It has always had the reputation of "whole grains, millet first". Millet is called "foxtail millet" after hulling. It originated in the Yellow River valley of China and has a history of more than 7300 years. It is cultivated all over the world at present. Millet has short growth period, strong resistance and easy preservation of seeds. Central Africa, Southeast Asia and Central Asia, which are arid and barren and have great demand for grain, are the main planting areas of millet. The output of millet in China ranks first in the world, accounting for 4/5 of the total output. Millet is a gluten-free and nutritious whole grain food. Compared with our current staple food rice and wheat, millet contains a variety of vitamins, minerals and a high level of protein%. It is not only nutritious, but also has a lower glycemic index than the staple food made of rice and flour. In addition, some polyphenols in millet have the function of adjuvant treatment of diabetes, cancer and cardiovascular diseases. Therefore, any food based on millet has the potential to become a functional food. At present, the main processing and eating methods of millet are still limited to the traditional primary processing (cooking processing), and instant products, fermented drinks and composite products with millet as raw materials have also appeared in the market. However, due to the extremely low gluten content of millet, it is difficult for millet dough to have good processing quality like wheat dough, which greatly limits the production and development of millet products. Adding millet into flour products can not only improve the quality of food processing, but also reflect the nutritional and health care value of millet. In this paper, the nutritional and health value of millet was summarized, and the application of millet in flour products was discussed.
Nutritional and health value of 1 millet
1. 1 nutritional value of millet
Generally, carbohydrates, protein, vitamins, zinc, magnesium, iron and calcium are selected for nutritional evaluation of cereals. From the content of nutrients in millet alone (table 1), the carbohydrate content of millet is lower than that of wheat and rice, and the lower carbohydrate content is more conducive to the control of human blood sugar. Dietary fiber accounts for about 5% of total carbohydrates. The protein content of millet is equivalent to that of wheat and higher than that of rice, and the protein of millet (mainly alcohol protein, globulin, albumin and glutenin) is a hypoallergenic compound protein, and the protein of millet has good digestibility, so it is very suitable for people who are weak. The content of amino acids in protein, especially essential amino acids, is also an important index to evaluate its nutritional value. Millet contains many kinds of amino acids, among which 8 essential amino acids are rich in tryptophan and methionine. Like other grains, lysine is its restrictive amino group. In addition, the proportion of other amino acids in millet has also reached the standards recommended by the World Health Organization, which is suitable for the proportion of human amino acids and is a good source of amino acids. The fat content of millet is almost twice that of rice and wheat, and it contains a lot of unsaturated fatty acids, with the highest content of linoleic acid and oleic acid. Linoleic acid is the precursor of arachidonic acid, which is the precursor of most prostaglandins. Prostaglandins play an important role in regulating cell function. Millet is rich in trace elements such as calcium, iron, zinc, magnesium and phosphorus, which plays an indispensable role in human growth and immune regulation. Vitamin is a low molecular weight microbial substance with biological activity. Many physiological processes of human growth and metabolism need vitamins, but most vitamins cannot be synthesized in the body and must be obtained from food. Millet is rich in vitamins, and the content of vitamin B2 is twice that of wheat and rice. Vitamin B2, also known as riboflavin, will affect the biological oxidation of the body and cause metabolic disorder when it is deficient. On the whole, the nutritional composition of millet is almost the same as that of wheat, but much higher than that of rice.
1.2 the health care function of millet
Millet contains a variety of health care ingredients, including dietary fiber, amino acids, peptides, unsaturated fatty acids and so on. Different ingredients have different effects. Table 2 lists the main health functions of various components of millet.
The content of high-quality dietary fiber in millet is about 2.5 times that of rice, especially the bran of millet is rich in high-quality dietary fiber. By combining polyphenols, it can stabilize the intestinal flora of mice and inhibit cancer. Millet protein will produce a polypeptide without toxic side effects after hydrolysis. Different hydrolysis methods will have different properties. The research shows that millet peptide produced by hydrolyzing millet protein with alkaline protease has good oxidation resistance, which can relieve fatigue and enhance immunity. Peptides obtained by hydrolyzing millet protein with trypsin have a strong scavenging effect on free radicals. Millet is rich in polyphenols and has high biological activity. Millet polyphenol extract has strong antioxidant capacity, and can effectively scavenge ABTS free radicals, DPPH free radicals and superoxide anion free radicals. The polyphenol extract of millet can also effectively inhibit the proliferation of cancer cells.
In recent years, there are many researches on the health care function of millet, among which the main health care functions focus on anti-cancer, anti-oxidation, anti-inflammation, lowering blood pressure and blood sugar, and most of the researches stay in in vitro experiments, cell simulation and animal experiments, while the research on clinical experiments and its health care mechanism is limited. In most experiments, the extract is directly used to test its health care effect. However, in practical application, it is undoubtedly necessary to make millet into corresponding products. In the process of making millet health care products, we should not only make the products meet people's sensory requirements, but also keep all kinds of health care functions of millet. However, the research on the activities of various health components of millet in food production is still limited.
With its numerous health functions, Xiaomi's health care products can not only meet the needs of the "three highs" and other people, but also develop mature industrial products, so that Xiaomi's health care products can enter people's daily lives and achieve the purpose of adjusting people's diet structure and improving people's health level.
2 millet in the application of flour products
Noodle products involve almost every field of people's daily diet. Adding millet into flour products can promote millet products from a large range, fundamentally change people's diet structure and give full play to the health care function of millet. Therefore, millet steamed bread, bread, noodles, biscuits and so on with health care function can be developed. However, adding millet to flour products will not only affect the production and sensory aspects of flour products themselves, but also affect the nutrition of millet during the production process.
2. Application of1millet in steamed bread
Steamed bread is one of the traditional pasta in China, and it is also the daily staple food of people in northern China. The sugar index of white flour steamed bread is very high, which brings great trouble to patients with hyperglycemia. Xiaomi steamed bread is not only lower in glycemic index than white flour steamed bread, but also more suitable for people with hyperglycemia, which can effectively improve people's dietary structure.
Adding millet to steamed bread will have a great influence on the quality structure of steamed bread. From the macroscopic quality, millet flour (80%) was added, and the noodle texture was elastic, with low viscosity, extremely low cooking loss and good taste. At present, some scholars use 0.2% calcium hydroxide as an improver to make pure millet noodles. This may be because the addition of calcium hydroxide can promote the cross-linking of protein in millet dough, thus playing a role similar to gluten network. This method provides a feasible idea for millet to make noodles directly. As can be seen from the above, millet flour is a good raw material for making noodles. Generally, the addition of millet flour should not exceed 50%. Perhaps by changing the milling method of millet flour (superfine powder, extruded powder) and adding modifiers (calcium hydroxide, glutamine transaminase) to promote the formation of gluten or gluten network, the processing quality of millet flour can be effectively improved and the addition of millet flour in noodle making can be increased.
2.4 Application of Millet in Cookies
Cookies are a very common convenience food. Millet biscuits can not only enrich the types of biscuits, but also have certain health care functions.
It proves that Xiaomi has the potential to make puffed biscuits. The texture and sense of puffed biscuits made by rice cake machine are very close to those of Wangwang ice cream on the market. Puffed millet flour can also be used as raw material to make crispy biscuits, among which hardness and crispness are important indexes to evaluate the quality of crispy biscuits. The addition of millet puffed powder will increase the hardness of biscuits, and the brittleness will first increase and then decrease. The brittleness of millet puffed powder is the largest when the addition amount is 30%, and it is easier to form when the addition amount is 30%. In the study of millet biscuits, with the increase of millet flour addition, the hardness of biscuits showed a U-shaped curve that first decreased and then increased. When 50% millet flour was added, the biscuit was the least hard and crisp. When the addition of millet flour is 80%, the hardness of biscuits is the highest. At this time, the biscuit is hard, and the increase of hardness is not conducive to the palatability of the biscuit, so the addition of millet flour in the biscuit is about 50%. Besides being added to other biscuits, we can also make gluten-free biscuits with millet to meet the needs of special people. Some scholars compounded millet flour and whey protein according to the ratio of 9: 1, and made gluten-free millet flour muffins with the same quality as wheat flour muffins, which were verified by immunology. Safe and reliable, the gluten content is within the allowable range, and it can be used in the diet of celiac disease patients. The functional characteristics of biscuits can be improved by compounding millet with other food raw materials with health care function. For example, biscuits made of millet and carrot residue fiber not only have high dietary fiber content and rich nutrition, but also have health care functions such as reducing hypertension, coronary heart disease, stroke, type II diabetes, obesity and various metabolic syndromes after long-term consumption. It can be seen that millet biscuits are rich in nutrition and good in texture, which meets people's needs. However, the addition of millet flour has a great influence on the hardness of biscuits, which is also the main factor affecting the quality of millet biscuits, and there is still a certain gap between the biscuits made and the biscuits sold in the market.
3 millet problems and solutions in practical application
3. 1 lack of gluten.
The content of gluten in flour determines the processing quality of dough. Millet itself does not contain gluten protein, which has become the biggest obstacle to the development of millet in flour products. How to improve the content of millet flour and ensure the quality of flour products is the key to promote the development of millet in the field of flour products. Modification of millet flour is helpful to improve its processing performance. It is proved that extrusion modification can increase the addition of millet flour in noodles. Although millet flour does not contain gluten, the extruded millet flour has good formability, and its addition in noodles can reach 80%. Ultrafine grinding is also a common modification method in food. It was found that the particle size of millet decreased and the surface area increased after ultrafine grinding. With the decrease of particle size, the fluidity of millet flour has been obviously improved; The solubility of ultrafine millet powder increased and the gelatinization temperature decreased; Freeze-thaw stability, enzymatic hydrolysis characteristics and sedimentation characteristics can also be significantly improved. Some scholars have also explored the influence of fermentation on the properties of millet starch. Millet starch was modified by lactic acid bacteria and yeast fermentation. It was found that the crystallization structure of millet starch would not be changed by two kinds of bacteria fermentation, but the final viscosity of starch would increase compared with that without fermentation. In addition, it is also a feasible method to modify millet starch with amylase. Q- amylase modified millet flour can improve the texture characteristics of millet bread products and reduce the hardness of bread. Moreover, the addition of α -amylase can shorten the dough fermentation time and increase the volume and height of bread. In addition to modifying millet, adding modifiers can also improve the processing characteristics of millet. It is pointed out that 0.2% calcium hydroxide is beneficial to the cross-linking of protein in millet flour dough and can increase the plasticity of dough.
3.2 Low lysine content
Lysine is one of the essential amino acids for human body to maintain normal growth and metabolism. The body cannot synthesize itself, and it must be obtained from food. The content of lysine in millet food is extremely low, which is easy to be destroyed and lost during processing, and it is the first restrictive amino acid. At present, the methods to solve lysine deficiency are mainly divided into adding nutritional fortifier and compounding with other raw materials with high lysine content. Compared with adding nutritional fortifier, compounding is more popular. Mao Junwei 63 soybean, corn and millet compound. The rich lysine in soybean and corn supplements the lysine in the product and strengthens the nutritional characteristics of the product. Houtao No.6 was compounded with buckwheat and oat bran and supplemented with millet by the rich lysine content of buckwheat. At the same time, oat bran is rich in dietary fiber, which can further improve the nutritional value of products.
4 outlook
In recent years, the research on the health care function of millet is very rich. Extraction, purification and processing of functional components (such as peptides, polyphenols, yellow pigments, etc.) of millet. With mature technology, the research on anti-cancer, anti-oxidation, anti-inflammation, lowering blood pressure and blood sugar has achieved initial results. The application research of millet in flour products mainly focuses on optimizing the process and increasing the addition amount. Most studies have also proved that the processing quality of millet food can be improved by some additives and modifications. At present, the commonly used modification methods, such as extrusion, low-temperature extrusion, moist heat treatment, superfine grinding and microbial fermentation, are seldom applied in food, which is not deep enough. And the effects of these modification methods on the main health components in millet; Can we produce special millet flour for different products by different modification methods like wheat? Whether different modification methods will affect the health care effect of the final product; In view of the different health care functions of modified millet, whether it can be divided into raw materials with different health care functions, so as to make different products for different people, these problems need further study. In addition, in view of the low machinability of millet, it may be a new breakthrough to explore new and effective improvers.
Millet is rich in nutrition and has high health care value. People are very concerned about the development and application of millet products. Researchers have made a lot of achievements in the application of millet flour products, but at present, there are few types of millet food in the market, the content of millet ingredients is low, and the sensory quality is poor, which can not meet people's needs. Turning more research results into products can not only satisfy people's pursuit of healthy diet, supplement the types of health food, improve the national diet structure, but also increase farmers' income.