Special wheat flour is respectively bread special powder, biscuit special powder, pastry special powder, steamed bread special powder, dumpling special powder, noodle special powder, starch special powder and so on.
General wheat flour is divided into special first class flour, special second class flour, standard flour and ordinary flour. The quality indexes involved in general purpose flour are mainly processing precision index and storage index.
The further processing of wheat starch is mainly wheat starch and gluten, the value of gluten is much higher than that of wheat starch, and wheat starch is often hydrolyzed into glucose in the industry, and then it is used in fermentation or food.
Wheat starch hydrolysis sugar production using continuous spray liquefaction double enzymatic sugar production process, the production process is different from corn starch sugar production, roughly in the following aspects:
1.The liquefaction feed is difficult;
2. Saccharification time is long;
3. Filtration is difficult, despite participating in a variety of influence ingredients [Mucilage remover, Filter-aid enzymes, Filter aid], on average about 3 times slower than corn sugar;
4. The light transmittance of sugar liquid is too low, it is about 50%, which mainly manifested as high 0D, and color is red and dark;
5. Low conversion rate.
Compared with wheat starch and corn starch, wheat starch raw materials are used for dry milling production, it is lack of sulphurous acid soaking this key link ,which cause more damaged starch, and embryo extraction is difficult. There are many unfavorable factors, such as easy corruption of the product starch, etc, and it seriously affect the sugar-making effect.
From the analysis of the composition of the filter residue, it can be seen that the main factors affecting the filtration speed are two categories of substances:
The first category is dextrins [insoluble starch particles and aging dextrins, of which insoluble starch particles are mainly composed of fat, protein and starch.
The second category is proteins. To improve the filtration speed, it is necessary to eliminate the presence of dextrins as much as possible and make the proteins as cohesive as possible.
Wheat starch can be divided into two types. The first type is the small round ball with a diameter of about 2-10nm, which is called B starch, and the second type is the large disc shape with a diameter of about 20-35um, which is called A starch.
In the process of wheat processing, due to mechanical milling, part starch grains are damaged, and the harder the raw material is, the more damaged it is.
As a result, when mixing flour paste, there must be a large amount of damaged starch in the main product wheat starch, and the degree of damage is different.
There is a cell membrane on the surface of the complete starch particles, which can protect the starch from the invasion of external substances, enzymes, water and acids, so the complete starch particles are not easy to be affected by a-amylase and β-amylase.
However, after it is damaged, it is easy to be affected by amylase, and the deeper for the damage, the easier it is to be affected. And theshed essence, maltose, glucose, etc., are produced ,so that in the initial stage of liquefaction, a large number of small molecule precursors substance of maltose will be produced.
As we all know, starch liquefaction is to create conditions for the use of saccharifying enzyme, and when saccharifying enzyme hydrolyzes dextrin , oligosaccharides, etc,it needs to form firstly the complex with the substrate molecule , and then the action occurs, so that the glucose unit is split from the glucoside bond one by one.
This requires that the substrate molecules to have the certain size & range in order to facilitate the production of this complex by the saccharifying enzyme.
Due to the different degrees of damage and the huge amount of starch, it is difficult to reach uniformity in the liquefaction process, and the phenomenon of uneven drought and flood seriously exists. The result of liquefaction is that the molecular size is different, the difference is large, and the effect is of course very poor.
Such liquefaction liquid has dextrin at the end of saccharification, the protein is difficult to coagulate, and the sugar liquid produced is not only difficult to filter but also has a low conversion rate of light transmission. A considerable amount of protein and dextrin substances are mixed into the sugar solution, resulting in an increase in foam until it is difficult to extract and refine.
Compared with corn, sorghum and potato starch, wheat starch paste has the most serious aging degree, which is bound to be another factor which affects liquefaction.
The aging of starch is actually the process in which gelatinized starch which has broken hydrogen bonds between molecules rearranges to form new hydrogen bonds, that is a process of recrystallization.
In the process of sugar production, it is difficult for amylase to enter the crystallization zone of aging starch, and it is difficult for starch to liquefy.
Wheat germ in wheat grain content is about 3%, it contains 30% protein,30% fat (accounting for 28.5% of the total fat in wheat grains and mostly phospholipids) and quite a lot of sugar, it also contains more than 60% of the total wheat vitamin B1, 2%-25% of vitamin B2, Vitamin B6 and vitamin E, 10%-25% of minerals exist in the germ.
Some data show that the quality of degerm in the production of flour is directly related to the filtration speed of starch and sugar produced, and the difference between the two rates is more than 2 times.
Between the current situation of production and the structure of wheat itself, only 10%-15% of the total amount can be raised after the embryo extraction operation during flour processing, and a large number of germs are mixed into flour. In the process of further processing, there will inevitably be partial fat and other substances brought into the starch.
It has been shown in some references that the insoluble starch particles produced by enzymatic liquefaction are amylopectin (Amylopectin content accounts for 75% of wheat starch) and fatty acids.
Wheat lipids are mainly composed of unsaturated fatty acids. During the storage of starch, partial fats will be oxidized and experience enzymolysis to produce fatty acids to form complexes with helical structure and tight organization. It is difficult to dissolve in the process of Saccharification and can not be hydrolyzed by glycation enzymes.
The existence of this substance will seriously block the pores of the filter cloth and delay the filtration speed. When the filter cake is very thin, the frame has to be removed in advance, and a considerable amount of sugar is lost, which affects the extraction yield.
However, through analysis, the insoluble starch particles produced by acid liquefaction are linked by hydrogen bonds, and belong to the structure of coagulated starch, which can be almost completely dissolved in the process of saccharification.
Acid liquefaction method is not affected by the type of starch, no matter what kind of starch can get a good effect. Zhang Litian mentioned in the book starch sugar that different liquefaction methods were applied to different starches. He pointed out that wheat starch is the most suitable for acidase liquefaction, which can effectively reduce the glycosylation and filter insoluble matter by 1%, it is fast filtration and high DE value.
In the production process, we usually call the large grain starch A-starch, the small grain starch is called B-starch.
B-starch is often mixed with small proteins, which is difficult to separate and has the certain viscidity. Most wheat starch manufacturers use it as the feed compound or for alcohol fermentation.
If B-starch is mixed with A-starch to make sugar, the total protein of the starch is higher by an average of about 1.8%. In the liquefaction process, due to the damage of starch causes the liquefaction to be uneven, the protein is difficult to condense together, suspended in the liquid surface, resulting in filtration difficulties. It cause the phenomenon of difficult filtration and low yield in saccharification process.
Another factor which affects filtration is the presence of non-starch polysaccharides such as pentosan ,dextran and so on. Pentosan is one kind of non-starch colloidal mucopolysaccharide, mainly composed of arabinose and xylose. Besides pentosan, it also contains hexose, uronic acid, phenolic acid and some proteins, etc. It has the nature of high water absorption, water retention and oxidation crosslinking to form gels.
At 2% concentration, the viscosity of its solution reaches a high level, which is extremely difficult to filter. Its content in flour is about 3%. Due to the limitations of the separator, some pentosan can not be prevented from entering the starch, among that there is more B-starch.