Gluten-free food is the best choice for patients with celiac disease (CD), which is an autoimmune disease in which gluten triggers the activity of immune system and destroys the intima of small intestine. Abdominal diseases that respond to gluten can be divided into three categories, including celiac disease, wheat allergy without celiac disease and wheat allergy, among which celiac disease is the most serious one.

Under normal circumstances, protein ingested by human body is firstly decomposed into polypeptides under the action of pepsin, then decomposed into single amino acids under the action of digestive protease in small intestine, and finally absorbed by small intestine. However, gluten, that is, gluten, cannot be completely decomposed into single amino acids, but some polypeptide fragments remain, which will not cause diseases and adverse reactions to normal people. However, for celiac disease patients, These peptides can promote immune response in the body, thus destroying the villi of the small intestine and affecting the absorption of nutrients in food by the intestine, thus causing health problems such as slow growth, chronic diarrhea, abdominal distension, constipation, fatigue, weight loss, anemia, irritability, and even death in severe cases.

According to epidemiological studies in Europe and the United States, the incidence of this kind of abdominal diseases is about 1%. Now the effective way to treat this disease is to eat gluten-free food.

1

Gluten-free food and its research and development trend

Gluten-free food refers to food that does not include gluten. Gluten, also known as gluten, is a group of protein which mainly exists in wheat, rye, barley and other grains. It is mainly composed of gliadin and glutenin. Gluten can not only make the dough form a solid structure, but also make the dough have a certain viscosity, elasticity and water absorption, giving the pasta a chewy taste.

Gluten-free food mainly uses some natural and gluten-free raw materials and is made according to standard operation and production regulations. According to the regulations of the European Union, only when the food contains no gluten or the gluten content is less than 2 mg kg-1 can it be marked as "gluten-free" on the food packaging; However, after special treatment to remove most of the gluten, if the gluten content in food is higher than 2 mg kg-1 but lower than 1 mg kg-1, the label "containing trace gluten" can be used on the packaging.

According to a survey, about 3% of Americans are trying to reduce or completely avoid gluten intake. Among the food and beverage products launched around the world, the claimed amount of gluten-free food continues to rise. From 213 to 217, the average annual growth rate of new products with gluten-free labels is 24%. Therefore, the development of gluten-free food has become a direction of product research and development in the food field.

2

Raw materials of gluten-free food

Raw materials of gluten-free food mainly include:

(1) Various cereals. Rice flour, corn flour, quinoa flour, sorghum, buckwheat, almond, millet and grain amaranth.

(2) various starches. Corn starch, rice starch, sorghum starch, cassava starch and potato starch.

(3) plant powder. Chestnut powder, pumpkin powder, chia seed powder, carrot powder, lupine powder, pepper powder, spinach powder and fennel powder.

2.1 rice flour

Rice flour is the most commonly used gluten-free flour, which is easy to digest and absorb, and has low allergy. It is one of the best gluten-free raw materials. Rice flour is rich in amino acids, which can regulate the secretion of insulin and has potential benefits to health. However, rice loses more vitamins and minerals in the finishing process.

There is no gluten in rice, so it can't form a network structure in baking, and it can't retain carbon dioxide gas, which makes the dough less elastic and limits its application in baking. These bad qualities of rice can be improved by mixing ingredients. Lucisano and others added oat fiber and inulin to rice flour in the process of making cakes, and the cakes made were improved in taste and nutrition. Torbica et al. used rice flour and buckwheat flour as raw materials to make biscuits, and determined that the best ratio of rice flour to buckwheat flour was 8: 2. The gluten-free biscuits made were unique in taste and good in flavor.

2.2 quinoa powder

quinoa is native to the middle and high altitude areas of South America, and it is one of the most balanced foods on earth. It is rich in all essential amino acids needed by protein and human body, especially lysine, which is generally lacking in cereals, as well as minerals, unsaturated fatty acids, B vitamins, vitamin E and antioxidant additives.

Quinoa has a significant dietotherapy effect on hypertension, hyperglycemia, hyperlipidemia, prevention and treatment of atherosclerotic diseases and cardiovascular diseases. Pagamunici et al. used different levels of quinoa flour to develop three gluten-free biscuits, and evaluated the physical and chemical indexes, sensory indexes and nutritional value of the three formulas, and determined that the optimal formula was quinoa flour: rice flour of 14∶25. The product had balanced nutrition and excellent sensory quality.

2.3 oat flour

oat flour is made by crushing whole oats, which can make the food have a more crisp taste in the processing of baked goods. Oat flour is the best source of oat β-glucan, which is a kind of soluble fiber beneficial to health. It can reduce LDL (low density lipoprotein cholesterol) and total cholesterol levels without affecting HDL (high density lipoprotein cholesterol), and can also slow down sugar absorption, reduce blood sugar and regulate insulin levels.

2.4 buckwheat flour

buckwheat flour is rich in B vitamins and mineral elements such as iron, magnesium, zinc and manganese, and also contains plant active ingredients such as rutin and quercetin with anti-inflammatory properties, which helps to reduce the risk factors of heart disease. The mixture of buckwheat flour and rice flour is suitable for baking and fermenting bread. Wronkowska and others used 1%, 2%, 3% and 4% buckwheat flour instead of corn starch to produce gluten-free bread respectively. It was found that when the content of buckwheat flour was 4%, the sensory score was the highest and it could be used to produce gluten-free bread.

2.5 Coconut powder

Coconut powder is made by drying coconut meat and grinding it. It has mild coconut flavor and light texture, similar to ordinary flour, and is very suitable for baking bread and dessert. Coconut powder is rich in medium-chain fatty acid lauric acid, which can provide energy for the body and contribute to brain health. It is rich in dietary fiber and helps to regulate blood sugar levels. Coconut powder is an ideal choice for people who are sensitive to nuts and gluten.

2.6 chickpea powder

chickpea powder is rich in cellulose and plant protein. These nutrients can enhance satiety and help control weight. Chickpea powder is rich in mineral elements such as magnesium and potassium, which has a positive effect on heart health. Chickpea powder can be used to make salads, sandwiches, hummus and hummus bread, which is very popular in Middle East and Indian cuisine.

2.7 corn flour

corn flour is made from crushed corn kernels, which is rich in vitamin B6, thiamine, manganese, magnesium and selenium, and rich in dietary fiber. It is also a good source of carotene, lutein and zeaxanthin. These phytochemicals can be used as antioxidants and help to reduce the risk of macular degeneration and cataract. Corn flour can be used to make gluten-free tortillas, corn porridge and so on.

2.8 almond flour

almond flour is one of the most common gluten-free flours. When processing, almonds need to be peeled and then ground into powder, usually with a ratio of 1: 1 instead of ordinary flour. Almond powder contains many minerals, including iron, calcium, magnesium, potassium, copper and manganese, and is also a good source of vitamin E and unsaturated fatty acids, and its fat content is much higher than that of wheat flour.

2.9 Sorghum flour

Sorghum is an ancient grain, which has been planted for more than 5, years. It is a natural gluten-free food. It has a mild sweetness and is usually mixed with other gluten-free flour. Sorghum flour is rich in fiber and protein, which is a food with low glycemic index, and rich in mineral iron and antioxidants, which helps to reduce inflammatory reaction.