During the period of 1998, AACC established a special committee on the definition of dietary fiber. During the period of 1999, academic circles held a series of meetings and special discussions on the unification of the definition of dietary fiber. March 7th 1999 World Wide Web online about the definition of dietary fiber. In less than 10 days, more than 100 scientists from the United States, Canada, Argentina, Australia, Brazil, Germany, New Zealand, Finland, Peru and other countries discussed the definition of dietary fiber online. These members represent academia, public welfare, law and policy respectively. 1On June 2-3, 1999, AACC and the International Society for Life Sciences (ILSI) jointly established a working committee on the definition of dietary fiber to discuss the exact definition of dietary fiber and reach an agreement. On July 26th, 1999, IFT held a special forum on this issue in Chicago. In the same year 1 1.2, a special meeting was held at the 84th AACC annual meeting to discuss the definition of dietary fiber. The final definition is as follows:
Dietary fiber refers to the sum of edible plant components, carbohydrates and similar substances that can resist digestion and absorption in human small intestine and can be partially or completely fermented in human large intestine, including polysaccharides, oligosaccharides, lignin and related plant substances. Dietary fiber has one or more physiological functions, such as relaxing bowels, regulating blood sugar concentration and reducing blood fat. The above definition defines the main components of dietary fiber. Dietary fiber is an edible plant component, not an animal component, which mainly includes cellulose, hemicellulose, pectin and hydrocolloid substances, such as gum and seaweed polysaccharide. In addition, it also includes lignin contained in plant cell walls; Substances that are not decomposed by human digestive enzymes, such as resistant starch, resistant dextrin, resistant oligosaccharide, modified cellulose, mucus, oligosaccharide and a small amount of related components, such as wax paper, keratin, cork resin, etc.
Function of dietary fiber
Dietary fiber was first proposed by H.C.Trowell in 1972 and defined in 1976 as "refers to polysaccharides, carbohydrates and lignin that are not digested and absorbed by human body", and is called "the seventh largest nutrient". Dietary fiber is not digested and absorbed in human small intestine, but can be fermented by bacteria in human large intestine.
In recent years, researchers at home and abroad have found that dietary fiber has potential beneficial effects in preventing "civilized diseases" such as coronary heart disease, arteriosclerosis, hyperlipidemia, diabetes and obesity. Dietary fiber can also reduce the incidence of dental caries, delay the residence time of food in the stomach, shorten the time of food passing through the intestine, and prevent colorectal cancer and its lesions. Promote the growth of probiotics in the intestine.
Dietary fiber can be divided into insoluble dietary fiber and soluble dietary fiber, and soluble dietary fiber includes hydrocolloid substances such as pectin and part of hemicellulose; Insoluble dietary fiber includes cellulose, lignin and part of hemicellulose.
The physical properties of dietary fiber are mainly water absorption and adsorption, and dietary fiber has strong oil holding capacity. Water retention and compatibilization can accelerate the frequency and time of intestinal peristalsis; In addition, fiber has other functional characteristics. Such as good sensory characteristics and chewiness, good water dispersibility, thickening and stabilizing functions, and extraordinary baking resistance.
There are many kinds of raw materials for dietary fiber, such as wheat, citrus and oats. Generally speaking, soluble fiber is mostly used in drinks and other products, such as citrus fiber; Insoluble fiber is mostly used in baking and other products, such as wheat fiber. The advantages of dietary fiber in baked products are: 1) strong water absorption. The high water absorption of dietary fiber depends largely on different fiber types. Wheat fiber and citrus fiber have strong water absorption, while wheat bran and oat bran have weak water absorption. 2) reduce heat; 3) Stabilize the organizational structure and prolong the shelf life of baked goods; 4) improve the taste; 5) color standardization; 6) Reduce the generation of debris.
Application of Dietary Fiber in Cookies
Cookies are a kind of food with high sugar and fat. With the improvement of people's living standards. The intake of high-fat and high-oil foods is too high, while the intake of dietary fiber is decreasing, and the incidence of "civilized diseases" related to diet structure is increasing day by day. Therefore, it is of positive significance to develop the application of dietary fiber in biscuits.
Taking advantage of the water absorption and oil retention of dietary fiber, adding this raw material can make biscuits soft and bulky, and can effectively reduce fat and calories.
In order to embody the concept of "reinforced fiber" in the product, it is necessary to add an appropriate proportion of fiber in the formula design to meet the requirements of the label. If "reinforced fiber" is marked, it must meet the requirements of every 100g product >: 3g fiber, if marked as "high fiber or rich in fiber", it must meet the requirements of every 100g product >: 6g fiber, and its addition amount in the product is calculated according to the fiber content. The following is an application example of dietary fiber produced for an enterprise in biscuits. We selected dietary fiber with fiber content of 90% (calculated by dry matter), and the product was labeled as "high fiber or rich in fiber", that is, every 100g product contained 6g fiber.
Formulation design, such as: (based on 500g product)
Ingredients: low-gluten flour 180g, ghee 60g, butter 70g, powdered sugar 100g, dietary fiber 33g, milk powder 12.5g, eggs 50g, sodium bicarbonate 2.5g, essence1.2g. 50 grams of water.
If the product is labeled as "reinforced fiber", that is, 3g fiber per 100g product.
Then the formula is designed as follows: (based on 500g product)
Material: low-gluten flour180g, ghee 60g; ; 70g butter, powdered sugar100g. Dietary fiber 16g, milk powder 12.5g eggs 50g, sodium bicarbonate 2.5g,10.2g essence and water 50g.
Process flow:
Flour, dietary fiber? Butter and shortening? Premixed? Send (powdered sugar, eggs, laxatives)? Mixed powder? Molding? Baking? Cooling? Final result
Key operation points:
Raw material treatment: flour should be sieved before use, and sugar powder should be used for sugar.
Send: It is indispensable to make cookies and fully decompose butter. Before sending, take it out of the freezer and soften it at room temperature; Then pour it into the eggbeater in proportion. Beat quickly for 10 minute, let the air fully dissolve in the butter, then add the eggs, milk powder, powdered sugar and other raw materials in turn, and finally add baking powder.
Powder mixing: dietary fiber and flour are premixed in proportion. Put it into an egg beater and mix it with butter and other raw materials properly.
Dietary fiber is a general term for edible plant components, carbohydrates and similar substances that cannot be digested and absorbed by the small intestine but can be fermented in the large intestine. Known as the seventh largest nutrient, it is a healthy food in the functional food era of 2 1 century. The development of dietary fiber has attracted international attention, and its application is more and more extensive.
First, the classification of dietary fiber
According to different solubility, dietary fiber can be divided into water-soluble and insoluble dietary fiber, and can be divided into insoluble fiber, soluble fiber, indigestible oligosaccharide and resistant starch according to physical and chemical characteristics and physiological functions.
Insoluble fiber is a component of polymer cell wall, which can form polymers with protein, such as insoluble dietary fiber and hemicellulose, especially insoluble pentosan and insoluble β- 1, 3 and 1, 4 glucan in cereals, insoluble protopectin and pectin in fruits and vegetables, insoluble dough kneading and insoluble phytic acid. Some plants contain polysaccharides, pentoses (xylans, arabinans) and glucose, such as galactans and mannans. These sugars can be degraded by microorganisms and partially fermented in colon and large intestine, while lignin and cell wall wax in insoluble fibers cannot be fermented.
Soluble fiber includes most macromolecular oligosaccharides that can be precipitated by ethanol, molecular oligosaccharides that cannot be precipitated by ethanol and multi-branched molecules (such as arabinan). Macromolecular oligosaccharides include pentosan, β- 1, 3 and 1, 4 glucan, soluble protopectin and pectin, indigestible oligosaccharides and so on.
Resistant starch is a special dietary fiber, which will produce several hydrolyzed forms in the small intestine as fermentation substrates and enter the large intestine. In the fermentation process, butyric acid will be produced to prevent intestinal cancer, which is also of great significance to human health.
Second, the characteristics and physiological functions of dietary fiber
1. High water retention and expansibility and function: There are many hydrophilic genes in the structure of dietary fiber, which have strong water absorption, high water retention and high expansibility. It can increase the amount of feces and defecation speed, relieve the pressure of rectum and urinary system, relieve the symptoms of urinary system diseases such as cystitis, bladder stones, kidney calculi, etc., make toxins excreted quickly, and prevent constipation and rectal cancer. The high water-holding capacity and high expansibility of dietary fiber delay gastric emptying, make people feel full, reduce food intake, and help prevent obesity and lose weight.
2. Adsorption boiling and function: There are many active genes on the surface of dietary fiber, which can boil and adsorb organic molecules such as cholesterol and bile acids, inhibit the increase of total cholesterol concentration, reduce the synthesis and absorption of human cholesterol and salts, and reduce cholesterol in human serum and liver, thus preventing coronary atherosclerosis and cardiovascular diseases. One of the mechanisms is that bile acids are metabolites of cholesterol. In order to supplement bile acids absorbed by fiber and excreted from the body, more cholesterol metabolism is needed, so the cholesterol content in the body decreases obviously, which can increase the intake of dietary fiber, increase the absorption of fat and reduce the cholesterol in the body. Dietary fiber can absorb bile acid and excrete it, which can reduce the absorption of bile acid, change the digestion speed of food and the secretion of digestive tract hormones, and prevent gallstones. Dietary fiber can also adsorb enterotoxin and chemical toxin, and urge them to be excreted.
3. Regulating the function of intestinal flora: Dietary fiber can be fermented by beneficial bacteria in the large intestine into organic acids such as acetic acid and lactic acid, which can reduce the pH of the intestine, promote the growth of beneficial bacteria Bifidobacterium in the intestine, prevent intestinal mucosa from shrinking, and maintain the balance and health of intestinal microorganisms. Organic acids produced by fermentation can accelerate the peristalsis and digestion of food in gastrointestinal tract, promote fecal excretion, prevent toxic substances in intestinal tract from stimulating intestinal wall and toxins from staying too long, and prevent colon cancer. Because of the laxative effect of cellulose, it is conducive to the reduction of intestinal internal pressure and can prevent constipation, hemorrhoids and varicose veins of lower limbs caused by long-term constipation. Metabolites of intestinal bacteria, carcinogens such as deoxycholic acid and variant source substances transformed from bile acid are also excreted with fibers, which shortens the contact time between poisons and intestinal mucosa and plays a role in preventing intestinal cancer.
Other functions: Soluble dietary fiber has viscosity, which has great influence on food viscosity. Due to the increase of viscosity, the contact between intestinal contents and intestinal mucosa decreases, thus delaying the absorption rate, stabilizing the blood sugar content of diabetic patients after eating, promoting the secretion of insulin by pancreas, and benefiting the supply and metabolism of sugar. Increasing dietary fiber in food can improve the sensitivity of peripheral tissues to insulin and regulate the blood sugar level of diabetic patients. The cellulose can effectively reduce low-density cholesterol in serum and increase high-density cholesterol, and can effectively prevent and treat diabetes complicated with hyperlipidemia and cardiovascular diseases. According to French reports, dietary fiber can also resist diseases such as breast cancer, duodenal ulcer and ulcerative colitis.
Third, the development of dietary fiber.
1. Dietary fiber of rye: rye contains high soluble fiber, of which about 2-3~3-4 is pentosan (arabinoxylan). Rye also contains 2% fructan, which is higher than other cereals. Soluble rye fiber is a pure natural isolate, and it also contains low molecular carbohydrate monosaccharides, disaccharides, water-soluble VB family, water-soluble minerals and polyphenols, phytoestrogens, tannins and protein. It can reduce blood sugar and cholesterol after eating. It can be used to strengthen baked goods, make bread to increase water content, soften and increase volume. As a feed additive, it can reduce the cholesterol content of pork.
2. Oat dietary fiber: Oat contains 10.5% dietary fiber, among which there are many water-soluble components, accounting for about 40%(β- glucan, etc. ), with high swelling power and viscosity, can hinder the digestion and absorption of starch and protein, reduce blood sugar and cholesterol, prevent arteriosclerosis, and maintain smooth blood circulation. When used in baked goods, it can improve the texture, taste and moisture of food.
Oat fiber in the United States is processed from oats, and there are many varieties. There are high-grade oat fibers, which can make baked products increase the strength and volume of dough, and have high water holding capacity and are not affected by freezing and high temperature; There is also Shellet oat fiber, which has long taste, good water absorption, baking property, processing stability and long shelf life, and can prevent baked products from aging during storage; The content of β -glucan in oat fiber is high, and the total dietary fiber content is as high as 35%.
3. Wheat bran dietary fiber: Wheat bran fiber is made of wheat bran. According to the determination, it contains pectin 4%, cellulose 35%, cellulose 18%, lignin 13%, protein ≤8%, fat ≤5%, minerals ≤2%, phytic acid ≤0.5, total dietary fiber content above 80%, water holding capacity 67%, and temperature 20℃. It can be used as a quality improver and dietary fiber enhancer to be added to bread, biscuits, noodles, cakes and grains.
4. Dietary fiber of malt grain: American Easy Company used mixed fermentation residues of three kinds of grains (beer barley, rice and corn) as raw materials, washed with hot water to remove residual starch, and then dehydrated, dried and crushed to obtain high-value malt grain fiber. It contains 42%-48% dietary fiber, 22% protein, 8% fat (mainly linoleic acid) and 4% water. It is also rich in mineral elements such as calcium, phosphorus, potassium, magnesium and iron. It has obvious malt aroma and mild grain baking aroma, which can improve the unique aroma of baked food and reduce the dosage of sweetener (the product is sweet). Adding food can not only increase the content of dietary fiber.
5. Barley dietary fiber: Barley is rich in dietary fiber, which mainly exists in the cortex. Contains cellulose, hemicellulose, wheat gum (β-glucan) and pentosan.
Barley dietary fiber can be produced from distiller's grains after barley germination to prepare wort. Barley fiber powder produced by American Mill Brewing Company contains 35% ~ 65% fiber (mainly insoluble fiber) and protein 18% ~ 35%. As a food additive, it can produce good temperature effect, endow food with flavor and strengthen food fiber when added to baked food.
6. Rice bran dietary fiber: Rice bran is the main by-product of polished rice processing, which is rich in dietary fiber and oil.