Wheat is a crop grown on a large scale in China, and for a long time, various kinds of pasta made of wheat flour are the staple food preferred by people in the north of China.

With the development of the food industry, flour as a major base material continues to be widely used, a variety of varieties of pasta products with its nutritious, unique flavor, convenient and quick characteristics are more and more people accept.

However, the quality of noodle products is affected by the origin and variety of wheat, and there are many problems with the quality of wheat flour in China, so it is often necessary to add some improvers to improve the quality of the products when producing noodle products.

Monoglyceride is currently the world’s largest use of an emulsifier, but also commonly used in China’s food industry emulsifiers.

When used in the production and processing of bread, cookies, cakes, pasta and other pasta products, it can play the role of emulsification and interact with the main components of wheat flour to give the pasta products a good appearance and taste.

Classification and properties of monoglycerides

Monoglycerides is known as monofatty acid glycerides (or glycerol monofatty acid esters), the English name is Monoglycerides (MG), according to the name of the main constituent fatty acids can be further divided into monostearic acid glycerides (Glycerolmonostearate), monolaurate glycerides (Glycerolmonolaurate), Glycerolmonooleate, Glycerolmonosilicate, Glyc- erolmonooleate, etc., of which the most widely used is Glycerolmonostearate.

Glycerol monooleate can be generally oily, fatty or waxy, light yellow or ivory in color, greasy or tasteless, which is related to the size and saturation degree of the fat group, with excellent sensory properties, monoglyceride is insoluble in water and glycerol, but it can form a stable hydrated dispersion in water, and its HLB value is 2~3.

Its HLB value is 2 to 3. By changing the length and saturation of the fatty acid carbon chains that make up the monoglyceride, its HLB value can be adjusted. Similar to fats and oils, monoglycerides exist in a variety of crystalline or metamorphic forms.

Functional properties of monoglycerides

In addition to their typical surface-active effects, monoglycerides have many other functions in food. The combination of these surface-active effects and special effects in food is the basis for the application of monoglycerides in the processing of pasta products.

On this basis, monoglycerides can not only improve the quality of food, extend the storage period of food, improve the sensory properties of food, but also prevent food deterioration, facilitate food processing and preservation, and help the development of new types of food.

2.1 Surface activity of monoglycerides
Monoglycerides are nonionic surfactants with an amphiphilic molecular structure. Its lipophilic group consists of fatty acids and its hydrophilic group consists of glycerol groups.

This amphiphilic molecular structure is a prerequisite for surface activity, and enables monoglycerides to be easily enriched on the surface of the solution to adsorb, and oriented arrangement on the surface and interface, resulting in surface activity and interfacial activity, reducing the surface or interfacial tension.

In addition, the directional arrangement of the monoglycerides at the gas-liquid or gas-lipid interface increases the mechanical strength and elasticity of the air bubbles, thus allowing them to expand more without rupturing.

The most commonly used monostearic acid glycerides, there are two hydrophilic hydroxyl groups, a lipophilic eighteen-carbon alkyl, so it can be adsorbed in the oil and water respectively on the surface of the two mutually exclusive phases, the formation of thin molecular layer, reduce the interfacial tension of the two phases, thus making the original immiscible substances to be uniformly mixed, the formation of a homogeneous state of the dispersion of the system, changing the physical state of the raw materials, and thus improve the internal structure of the food and improve the quality.

2.2 Interaction between monoglycerides and flour components
Carbohydrates, proteins and lipids play a decisive role in the complex process of producing flour products. The role of the various flour components is determined by their composition or the products of their interaction. Monoglycerides may interact with flour components in many ways and can influence the quality of the product accordingly.

2.2.1 Interaction of monoglycerides with starch
When starch is pasted and swollen by heat, monoglycerides, together with water, form a liquid crystalline layered dispersed phase that leaches into the starch granules, interacting with the straight-chained starch that has dissolved out of the starch granules and with the straight-chained starch outside the starch granules.

The monoglyceride is tightly encapsulated in the straight-chain starch helical structure to form a strong complex, i.e., the straight-chain starch is immobilized in the starch granules, the amount of straight-chain starch dissolved into the free water around the starch granules decreases, and the lipophilic group of the monoglyceride enters into the helical structure of the straight-chain starch to form an insoluble complex, which prevents aging from occurring due to recrystallization between the starch granules.

Which molecules can be embedded in starch is determined by chemical and geometrical factors. The ability to form complexes of homologous monoglycerides depends strongly on the chain length of the fatty acid moiety, where hydrocarbon chains with 16 and 18 carbon atoms are preferred.

Unsaturated fatty acid monoglycerides have a low complexation rate, mainly because their molecules are not linear and there is a spatial site barrier that prevents them from entering smoothly into the starch structure. From an energetic point of view, the presence of a cavity within the starch helix structure is an unfavorable conformation, but this conformation can be stabilized by embedding a suitable ligand.

Because the internal diameter of the starch helix is only about 4.5 to 6*10^-10m, it can only preferentially form ring-closing compounds with emulsifiers whose lipophilic groups also have a similar order of magnitude diameter. This condition is optimally realized in the case of monoglycerides of saturated fatty acids.The finding by R. Cui, C. G. Oates_6 that the complexes are not readily decomposed by amylase is also a reason for the above observation. Branched-chain starches have few straight-chained helical structures and are very unlikely to form complexes.

In addition to the anti-aging effect of monoglycerides by forming insoluble complexes with straight-chain starch, they also directly affect the distribution of moisture in the dough and indirectly retard aging.

At the stage of dough mixing, monoglycerides are adsorbed on the surface of starch, producing water-insoluble substances, inhibiting the movement of water and the expansion of starch granules, and preventing the interconnection between starch granules. As the water-absorbing and swelling capacity of starch is reduced, the pasting temperature is raised, thus allowing more water to be transferred to the gluten, thus increasing the softness of the product and delaying aging.

2.2.2 Interaction between monoglycerides and proteins
There are two non-water soluble proteins present in flour, namely, wheat gluten and gliadin. These two proteins absorb water and swell and moisten during the operational engineering of dough formation by adding water to flour. Gliadin forms a small single-chained molecule with strong viscosity and no elasticity; glutenin forms a large multichained molecule with good elasticity and no viscosity.

During dough processing, small molecules of gliadin are dispersed into large molecules of wheat gluten, forming a special network structure with both elasticity and viscosity, i.e. gluten. After adding monoglycerides, monoglycerides can interact with gluten proteins to form complexes, i.e., the hydrophilic group of monoglycerides combines with gliadin, and the lipophilic group combines with wheat gluten, so that gluten proteins molecules dispersed by mechanical mixing during the process are connected with each other, and small molecules become large molecules to form a firm and tight gluten network. It is because of this good “bridging effect”, so that the free protein in the dough is significantly reduced, while the binding protein increased significantly.

2.2.3 Interaction between monoglycerides and lipids
The α-monocrystalline type of fat is the most unstable and has a low melting point, while the β-monocrystalline and β’-monocrystalline types are very stable and have high melting points, and the β’-monocrystalline state of the fat also has good processing properties.

In order to maintain the β’-monocrystalline state, it is necessary to add a crystal modifier. When monoglycerides are eutectic with fats and oils, a stable β’-monocrystalline state can be obtained. β’-monocrystalline state of fats and oils has a high melting point, good plasticity and spreadability.

Monoglycerides can improve the cohesion between fats and oils and the ability to combine with fats to form a crystal network structure with each other, thus improving the crystal crystallization of fats and oils and improving the stability of fats and oils, which is very advantageous for the production of heavy oil cakes and cookies, and prevents the phenomenon of oil-water separation of the dough or products due to placing for a long time, i.e., the phenomenon of “walking away”, and improves the stability of fats and oils, and also improves the stability of fats and oils. It can prevent the phenomenon of oil-water separation of dough or products due to long time, i.e. the phenomenon of “oil leakage”, which improves the storage period and ensures the quality.