Wheat germ is part of the wheat grain, accounting for 2.6% of the wheat grain, is high protein, high vitamin E, low heat, low fat and low cholesterol nutrients, germ has anti-cancer, lower cholesterol, lowering blood sugar, tonic deficiency blood and other efficacy; Wheat flour layer is located in the inner layer of the wheat grain cortex, between the seed coat and the endosperm, accounting for about 6-8% of the wheat grain, the flour layer does not generally contain starch, and contains a lot of protein, lipid, mineral and B vitamins and fiber. Contains a large number of proteins, lipids, minerals and B vitamins and fiber.

Wheat germ is the root of wheat life, the flour layer is the main source of nutrition of wheat grain, they are the essence of the wheat grain, is the highest nutritional value of wheat in the structure, known as the “human natural nutritional treasury”. Although rich in nutrients, they are not fully and effectively utilized, and are even mixed into the bran and disposed of as cheap feed.

The main idea of this paper:
(1) in the original flour to add a certain percentage of germ flour, paste powder layer powder production of steamed bread, noodles;
(2) As a kind of natural functional food and grain nutrition additives, germ and flour paste layer can be added back to the refined flour, standard flour, common flour in a certain proportion to produce whole wheat flour or germ wheat flour, wheat flour paste layer, and other functional specialty flours, which can comprehensively improve the nutritional composition of the flour and health care functions and flour milling rate.

Main nutrients and value of wheat germ and flour paste layer

Comparison of the main chemical composition content of standard flour, germ, and paste layer is shown in Table 1.
Table 1 The main chemical composition of standard flour, germ, paste flour layer

Physical structure
Ratio
Protein/%
Fat/%
Crude fiber/%
Ash/%
Moisture/%

Germ
2.7
29.7
12.2
2.7
3.80
15.0

Paste Layer
9.3
32.0
6.0
6.05
7.35
14.5

Seeds
100
13.5
1.80
2.25
1.70
14.5

Medium Gluten Flour
100
11.2
1.50
0.75
0.78
14.0

As can be seen from Table 1, the protein content of wheat germ and pasty layer is as high as about 30%, which is second only to soybean and many times higher than other animal and vegetable proteins.

Wheat germ and flour layer are noted for their richness in linoleic acid, sterols and other trace physiologically active substances. Linoleic acid can react with the cholesterol in human blood vessels, with the efficacy of preventing atherosclerosis of the human body, the regulation of human blood pressure, lowering serum cholesterol, the prevention of cardiovascular disease has a positive preventive and inhibitory effect.

Sterol has strong anti-inflammatory effect on human body, can inhibit the absorption of cholesterol, promote the degradation of cholesterol metabolism, inhibit the biochemical synthesis of cholesterol and other roles, with the lowering of serum cholesterol, prevention of cardiovascular and cerebral vascular disease function.

Wheat germ oil is so far known as one of the foods with the highest content of Ve, Ve is 1 times that of soybean oil, 2-2.5 times that of corn oil, 3-4 times that of cottonseed oil, and 3-8 times that of rice bran oil, and it is recognized as a treasure trove of Ve in the country, especially B vitamins which are more necessary for the human body.

Table 2 Wheat germ, paste layer protein and other animal and plant protein content

Name
Soybean
Medium gluten flour
Standard one meter
Lean beef
Lean pork
Eggs
Germ
Batter layer

Protein/%
36.3
11.2
6.2
20.3
16.7
14.7
29.7
32.0

Analyzed from the point of view of the physiological process of the dextrination layer, the nutrients of the grouting material transported from the mother must pass through the dextrination layer in order to enter the endosperm cells, the endosperm cells hoard starch, soluble sugars and proteins, and the earliest interception of dextrination layer accumulates other mineral elements, fatty acids, as well as some of the amino acids and proteins, which are then hoarded in the dextrination layer cells. That is, phytonutrients that are beneficial to physiological health are mainly concentrated in the dextrin layer, which is an extremely nutrient-rich structure in the wheat grain.

Pretreatment of wheat germ and dextrin layer

2.1 Wheat germ extraction and stabilization treatment
Development and utilization of wheat germ, the first thing to solve is the germ extraction and stabilization treatment. Utilizing the characteristics of looser combination of germ and endosperm, large and medium-sized flour enterprises across the country have the ability to extract the germ.

Wheat germ is complex, containing a variety of enzymes and active ingredients, untreated germ placed a few days will be oxidation rancidity deterioration, not easy to store, so it is necessary to pre-enzymatic passivation of the germ stabilization of the enzyme treatment, to maintain the stability of its traits.

At present, microwave technology is widely used in the stabilization of wheat germ. This technology inactivates the enzyme in a short time, the effect is good. The microwave treatment of wheat germ in the vitamin E and other heat-sensitive nutrients in the destruction of a smaller degree, wheat germ protein invariant. The shelf life of wheat germ is more than half a year.

2.2 Separation of pasty layer
Because the dextrin layer is located between the seed coat and endosperm of the wheat grain and is tightly bonded to the seed coat, it makes it difficult to separate the dextrin layer from the cortex of the wheat seed coat, which in turn becomes the composition of the bran.

Now the domestic large and medium-sized flour mills using the peeling process, and has achieved certain results. But the constraints of the separation technology makes the wheat flour paste layer can not be large-scale industrialized application.
The Chinese Academy of Sciences has realized the cyclone eddy current micro-nano separation technology will be purely physical high purity separation of wheat bran layer of paste flour layer enriched, the preparation of safe natural nutritional food raw materials, for China’s industrialization of wheat paste flour layer, industrialization has created the possibility.

According to the experts, due to the separation of the paste powder particle size is fine, the average particle size of 36µm. the paste powder cell structure is complete, the purity is very high, maximize the retention of the paste layer of the original characteristics, nutrients, and other characteristics, can be added to the flour in the proportion of 20% -30%. Test results show that this method of production of wheat paste layer flour, about 30% of the share, it is equivalent to the whole grain nutrition, paste layer flour is a staple food can be used as a nutritional product.

Wheat germ flour, paste flour layer flour staple food pasta products

Wheat germ, paste flour layer as a supplementary powder added to the flour to make steamed buns, noodles, buns, dumplings, bread and other staple food in the field of staple food in the mass of staple food. Take steamed buns and noodles as an example to explore the effects of adding wheat germ powder and dextrin layer powder to the original flour on the characteristics of the dough, and on the production quality and eating quality of steamed buns and noodles.

3.1 The effect of the addition of wheat germ and flour paste layer on dough characteristics
The proportion of 0% to 20% of wheat germ fine powder, paste layer fine powder added to wheat flour, through the measurement and texture analysis and other means to explore the physical and chemical index characteristics of mixed dough.

The results showed that the addition of a small amount of wheat germ fine powder increased the water absorption, ductility and toughness of the dough, strengthened the gluten structure, and made the organization structure uniform; with the increase of the proportion of the addition of glutathione, the glutathione in the germ protein is a protease activator, which destroys the structure of the gluten in the dough, and the tendon force decreases, resulting in a gradual decrease in the tensile ability, viscosity, and elongation; the degree of weakening increased, the formation time of dough increased and the stabilization time decreased, and the stretching ability and the elongation of dough increased. Prolonged, stabilization time is reduced, tensile resistance, maximum tensile resistance increased with the increase in the content of germ flour, this is because the germ contains more fat and enzymes, affecting the fermentation ability of the dough, and in the fat contains carotene such as yellow pigments and affects the baidu of the dough.

With the increase in the amount of fine powder added to the paste layer, the dough’s protein, ash, wet gluten, water absorption, formation time, stabilization time are gradually increasing trend, while the degree of weakness, viscosity, extensibility, dispersibility is gradually decreasing trend, which is due to the dietary fibers contained in the paste layer, resulting in the strengthening of the flour gluten, but the quality of gluten deterioration, so that the spatial network of the gluten structure changes, resulting in dough In addition, the proteins in the flour paste layer contain wheat protein and globulin, which are not involved in gluten shaping, and their quality is also very low. Adequate addition of germ flour, paste layer powder, can improve the properties of the dough, and add nutrients and unique flavor, mixed dough still has good processing characteristics.

3.2 The effect of wheat germ addition on the quality of steamed bread and noodles
3.2.1 The effect of the addition of wheat germ on the quality of steamed buns
The experimental results show that the steamed bread with wheat germ powder added has better taste, smell and color. However, with the increase of the amount of wheat germ added, the characteristics of the dough, the organization of the buns will be affected, so that the overall changes in the volume of the buns, the specific volume of the buns show a downward trend, the hardness increased significantly, the internal organization is not delicate, the elasticity and flexibility of the decline in the color of the white to light yellow to dark yellow, but give the buns unique wheat germ aroma is gradually strengthened.

Conclusion: The best process parameters of wheat germ steamed bread, namely: medium gluten flour, wheat germ coarseness and fineness of 50µm, wheat germ powder suitable addition of 10%, and the amount of water added to the flour 55%, and the temperature of water 32 ℃, and the temperature of the fermentation 32 ℃, the fermentation time of 70min, the time of 60min, the temperature of 36 ℃, and the relative humidity of 80%. The surface of the finished buns has a light yellow, full appearance, uniform internal organization, good puffiness and flexibility, good taste, volume and no wheat embryo buns similar.

3.2.2 The effect of wheat germ addition on noodle quality
Dough gluten, crude fiber, ash content is high or low, directly affecting the processing performance and eating quality of noodles. The experimental results show that: see Table 3, with the increase of wheat germ powder, the dough ash, hardness, elasticity increased, whiteness, toughness decreased, the dough wet gluten content showed a downward trend, the water absorption rate of the noodles decreased, the addition of wheat germ in the right amount has little effect on the overall performance of the noodles.
Table 3 Dough chemical composition content after adding wheat germ powder

Addition of wheat germ (%)
0
5
10
15
20

Wet gluten content %
31.3
31.1
29.0
28.8
27.5

Crude Fiber %
0.75
0.76
0.81
0.85
0.90

Ash %
0.78
0.79
0.82
0.85
0.89

Conclusion: The optimal process parameters of wheat germ noodles, namely: medium gluten flour, wheat germ coarseness 50µm, appropriate addition of wheat germ flour 8%, the amount of water added to the noodles was 30%~34%, the temperature of the water was 30℃, and the amount of salt added was 1.5%.

Before cooking: yellow color, obvious germ flavor, smooth surface, good elasticity and toughness, no merging, not easy to break, good tensile elongation.

After cooking: milky yellow color, germ flavor, smooth surface, sharp taste, texture tendon, good flexibility, non-stick, not muddy soup, a small number of broken strips, good resistance to cooking. During the cooking process, the water absorption rate of the noodles showed a decreasing trend, and the elasticity and toughness had a tendency to improve.

3.3 The effect of the added amount of flour paste layer on the quality of steamed bread and noodles
Table 4 Main chemical composition content of flour after adding paste layer

Batter layer fine powder
Addition amount/%
Crude fiber/%
Protein/%
Fat / %
Ash/%

0
0.75
11.2
1.5
0.78

5
0.80
11.4
1.25
0.81

10
0.93
12.0
1.38
0.92

15
0.12
12.3
1.42
0.95

20
1.20
12.5
1.45
0.98

As can be seen from Table 4, with the increase of the addition of fine flour in the paste layer, the dietary fiber, protein and fat of the flour showed a gradual increase in the trend of the indexes are in line with the standard of the special one powder, due to the loose texture of this powder, the amount of digestible protein is better than that of the protein of the refined white flour. Therefore, it plays a nutritional strengthening role in steamed bread and noodles.

The rise of ash directly affects the uniformity of water absorption of dough, thus affecting the formation of gluten network, but also the intrinsic quality of dough and the appearance of buns, noodles, and edible quality decline, the relevant research shows that the ash content of ≤ 1.0% of the characteristics of the flour does not have much impact.

3.3.1 Influence of adding amount of flour paste layer on the quality of steamed buns
Based on the experimental results show that: in the steamed bread main and auxiliary ingredients ratio determination, adding water, steamed bread production process, rousing, steaming time and other identical conditions remain unchanged, were measured and recorded in the paste layer of fine powder with different additions to the quality of the steamed bread: with the increase in the paste layer of powder additions, the specific volume, volume, shape of the steamed bread, such as the trend of micro-decrease, the internal structure, elasticity and toughness, viscosity gradually rising trend, the buns more wheat flavor and smell, and the quality of the steamed bread is not affected. The steamed bread has more wheat flavor and odor.

Conclusion: When the amount of fine flour added to the paste layer is 15%, there is no obvious change in the indicators of bun color, appearance and shape, internal organization, texture and flavor, and the total score of sensory evaluation is the highest. When the additive amount was 20% and 25%, there was a decreasing trend in the indexes of steamed bread.

3.3.2 Effect of the addition amount of batter layer on noodle quality
The addition of fine flour in the batter layer slightly increased the amount of protein in the flour, but had little effect on the gluten quality of the mix. For the same flour, the gluten content also increased.

Protein is the main indicator of the quality of flour for noodles, and its content directly affects the water absorption and tensile strength of the dough; the processing performance of noodles with high gluten dough is good, and the elasticity and toughness of noodles is strong; for noodles with a good sense of taste, it is not desired to have too high a gluten content; in addition, the paste layer contains high cellulose, which makes the elongation and plasticity of noodles weak, and there are broken strips of wet noodles. The increase in ash content was unfavorable to the quality, processing, appearance, and palatability of the noodles.

Conclusion: The optimum process parameters for the pasty layer flour noodles were: medium gluten flour, 50µm particle size of pasty layer flour, 10% addition of pasty layer flour, 32%-36% of water addition for mixing, 30-35℃ of mixing water temperature, and 1.5% of salt addition. The content of wet gluten is 26-30%. The processed noodles were glutenous and resistant to cooking, with very few broken strips, no mixed soup, slightly longer cooking time, more delicate and smooth texture, and the elasticity and toughness were comparable to that of the original noodles, which fully met the requirements for consumption.

Conclusion

Wheat germ flour, paste layer powder directly added to the flour, the production of popular staple food steamed buns, noodles, from the nutritional value and sensory quality to determine, germ flour, paste layer powder steamed buns, noodles, the ratio of nutritional comprehensiveness and rationality, is a nutritional and health care as one of the staple food.

In the face of modern people because of the consumption of refined rice, refined noodles produced by a variety of diseases, knocked people awake to the future of food nutrition orientation and dietary structure adjustment and re-selection, eat out of health and safety is the first place, germ, paste layer contains our body needs protein, minerals, vitamins and dietary fiber, almost all wheat flour as raw material for pasta food can be added to the germ flour, paste powder layer powder. It can also be processed into food-specific flour, i.e., nutritional fortification of flour, which is easier to digest and absorb in consumption, with large market potential, wide sales and high value-added.