Mixed grains is the common name for small grain and bean crops, with medical and food double effect. China’s variety of grains, and nutritious. However, in the market consumption, the utilization of mixed grains situation is not optimistic, mainly due to its rough texture, the lack of gluten protein, so that the quality of the composition of loose, poor appearance, poor palatability, it is difficult to form the market competitiveness, which requires the pre-treatment of mixed grain flour.

This paper introduces the puffing technology, ultra-micro-grinding technology, enzyme processing technology and gas explosion technology in the treatment of grain flour, in order to provide reference for the production of grain flour and quality improvement.

Expansion technology

Expansion technology is mainly extrusion, deep-frying, stir-frying, baking, microwave and other maturation process, so that the volume of the material before and after the obvious changes in the treatment. Expanded materials, the organizational structure becomes fluffy and porous, the texture is crisp, water absorption increases, mixed with water will show a unique flavor.

At the same time, in the puffing process, the composition will also change with the processing of materials, specifically in the protein denaturation, increased sensitivity to protease, starch molecules break hydrogen bonds, starch paste, degradation of some small molecules, fat oxidation rate slows down and so on.

These changes in the state and composition for the preparation of grain flour and in the improvement of taste provides benefits, highlighted in the production of food mixed with flour can increase the amount of addition, the corresponding rheological properties of the dough as well as the textural properties of the product are better than the direct addition of raw grains made of flour products.

At present, China’s puffing technology are mainly the following: deep-frying puffing technology, extrusion puffing technology, microwave puffing technology, airflow puffing technology, as well as carbon dioxide puffing technology, etc., and in the pre-processing of grains flour, is generally the use of baking, extrusion, microwave and other technologies, the market is more mature products (such as potato chips, shrimp crackers) production is the grains flour puffing treatment, and then extruded into shape.

Ultra-micro-grinding technology

Ultra-micro pulverization technology is the use of physical or chemical methods to a variety of solid substances crushed to a diameter of less than 10 um processing mode. After crushing the material according to the size of the diameter can be divided into micron-level crushing, submicron-level crushing and nano-scale crushing of three kinds.

General industrial ultra-micro-grinding has dry crushing and wet crushing 2 kinds of processing, different crushing methods used by different tools, the former is mainly used in hammering, self-grinding, ball milling high-frequency vibration and other ways of processing, the latter is used in colloid mills and homogenizers for the wet crushing of the old. Ultra-micro pulverization used to be used in traditional Chinese medicine pharmaceuticals, the purpose is to specifically crush traditional Chinese medicine, and maximize the retention of active ingredients in the drug.

In recent years, with the development of ultra-micro pulverization technology, equipment cost reduction, ultra-micro pulverization in the food industry applications gradually increased. After the ultra-micro-grinding of flour products, the most prominent performance is the significant increase in the broken starch in the flour, starch particles become smaller.

In addition, the material in the process of ultra-micro-grinding can not just be mechanically considered as a change in geometric dimensions, often accompanied by complex physical and chemical changes in the process.

Ultra-micro crushing, due to the role of mechanical forces so that the starch grain is filled with internal lattice distortions, defects and even nanocrystalline micro-units, fracture generated by the external surface of the unsaturated valence bonds and high surface energy aggregation of chemical activity is stronger. These changes are the direct cause of the changes in the properties of the pasta products, such as a significant increase in water absorption.

Due to the complexity of the composition of grains flour, and some of the grains of the skin is also very rich in nutrients, it is difficult to meet the requirements of ordinary crushing, which requires the use of ultra-micro-crushing technology in the pre-treatment of grains flour.

Enzyme treatment technology

Enzyme processing technology is the use of enzyme preparations on the material in the crude fiber and anti-nutritional factors for specific destruction, so as to achieve the purpose of improving the digestibility and utilization of materials. Enzyme preparations commonly used in the food industry are amylase, protease, cellulase and so on. Because grains flour is rich in crude fiber, ash, a large number of starch and protein and other components, so the enzyme preparation is more widely used in the treatment of grains flour.

After enzyme pre-treatment of grain flour, its cellulose, starch and protein and fat content will often be reduced, while the treatment of grain flour oligosaccharide, amino acids, ash and other components will increase, which is a series of physical and chemical properties of grain flour viscosity, coagulation, solubility, water holding capacity, pasting characteristics will have a greater impact on a range of physical and chemical properties, for the refinement of grains flour to provide the possibility.

Gas explosion technology

Gas explosion technology is a new type of material treatment developed in recent years, the treatment process is the use of steam generated by high heat and high pressure on the internal structure of the material specific degradation process. This treatment originated in the United States, a scholar invented the blast pulping technology, after a large number of other research scholars to explore and verify the experiments followed by the promotion, and in the technology continues to innovate, such as the introduction of continuous gas explosion technology.

The traditional gas explosion technology is mainly for the agricultural reuse of straw, straw gas explosion to extract oligosaccharides and preparation of humic acid, oxalic acid, liquid fuels and ecological fertilizers, etc., is a clean and non-polluting way to deal with.

Although the development of gas explosion technology for nearly 90 years, but this technology is mostly used in the treatment of lignocellulose, in the treatment of miscellaneous grain flour and even the entire grain industry is not common. And because of the unique nature of this technology itself, that is, the role of high temperature and high pressure generated by the gas explosion, the structure of the material to change the larger, so the appropriate process conditions is the key to the quality of the treated material.

In the author’s view, the use of gas explosion technology in the appropriate process conditions can be specific to some of the insoluble ingredients in the grain flour to change, such as crude fiber, ash and other substances. In the process of high temperature, high pressure, high humidity grains powder will occur in a series of complex physical and chemical changes, accompanied by pasting, protein denaturation, intermolecular chemical bond breaking, material structure refinement and some specific components of the transformation of the degradation, such as some of the flavonoids and phenolic acid degradation of substances.