Phenolic substances are one of the important functional components in black garlic, and the total phenolic content largely reflects the functional role of black garlic. The water content is closely related to the shape and mouthfeel of black garlic. It can be seen from Figure 1 that as the steaming temperature increases, the total phenol mass ratio increases almost linearly. This may be because of the higher the steaming temperature, the higher the pressure and the synergy of pressure and high temperature in garlic. Other compounds can be converted to polyphenols. At the same time, the increase of pressure destroys the structure of garlic, and the loose and porous form makes water molecules more easily enter the garlic. Therefore, the higher the steaming temperature, the greater the water content. The moisture content is too high, the texture of black garlic is soft and rotten, affecting the taste and not easy to store; the moisture content is too low, the black garlic is hard and the chewing property is poor. Considering comprehensively, 125 ° C is a suitable steaming temperature. It can be seen from Fig. 1 that when the steaming temperature is 125 °C, the polysaccharide in garlic is gradually decomposed into monosaccharides and disaccharides due to the synergistic effect of pressure and high temperature, and the -OH of some reducing sugars is oxidized to organic acids. COOH gives black garlic a sweet and sour taste. Taizy black garlic machine can process all kinds of black garlic.
2, steaming time
The heat-sensitive fruits and vegetables have a porous, anisotropic cell structure and high water content. As shown in Fig. 2, when the steaming time is 40 min, the moisture content of the obtained black garlic finished product is as high as 47.81%, which is because the steaming time is short, the garlic cells have not completely died, and the water holding capacity is certain. When the steaming time was 60min, the garlic cells were broken, and some of them were exposed to water. When the baking was performed, the water dispersion was faster, and the water content reached the lowest value of 28.76%. Then, as the steaming time prolongs, more water molecules enter the garlic tissue, and the moisture content of the finished black garlic is also slightly improved. Combined with Fig. 2, it can be found that the total phenol mass ratio, the total acid mass ratio, and the reducing sugar mass ratio increase with the prolongation of the steaming time, and a higher level can be achieved at 60 min. Considering the factors such as the taste, texture and tissue state of black garlic and the production cost, 60min is the most suitable steaming time.
3, baking temperature
The drying process of materials is often accompanied by biological, physical, and chemical reactions that depend on moisture. The reducing sugar and total acid content directly affect the taste and browning of black garlic. It can be seen from Fig. 3 that as the baking temperature increases, the mass ratio of reducing sugar to total acid shows a tendency to increase first and then decrease. This may be because high temperature is beneficial to the decomposition of polysaccharides in garlic, the formation of more reducing sugars, the process of Maillard reaction, and the oxidation of -OH of reducing sugars to COOH. When the baking temperature is lower than 90 °C, the polysaccharide decomposition rate is higher than the Maillard reaction rate, the reducing sugar mass ratio is higher than the total acid mass ratio, and then the Maillard reaction speed increases as the baking temperature increases, and there is also A part of the reducing sugar is oxidized to an organic acid, and the mass ratio of the reducing sugar is rapidly lowered.
Therefore, when the baking temperature is 90 ° C, the mass ratio of reducing sugar and total acid in black garlic is the highest, which is favorable for the formation of sweet and sour taste and accumulation of black sperm. In Fig. 3, the moisture content and total phenol mass ratio of black garlic at 90 °C was 29.18% and 8.58 mg/g, respectively, and the sensory morphology of black garlic was the best.
4, baking time
During the drying process, the food material generally undergoes a constant-speed drying stage and then enters a slow-drying stage. In Fig. 4, as the baking time increases, the water content of black garlic decreases first and then decreases rapidly, and the total phenol mass ratio tends to increase gradually. Acetic acid, formic acid, succinic acid, hydroxy propionic acid and the like do not exist in fresh garlic but gradually form and accumulate with the processing time. It can be seen from Fig. 4 that the total acid mass ratio in black garlic is continuously increased with the extension of the baking time, and it can be inferred that the baking process is an important stage of the formation of acid substances. However, the mass ratio of reducing sugar is only slightly reduced. It may be because during the baking process, the decomposition of polysaccharide is synchronous with the Maillard reaction, and the effect on the mass ratio of reducing sugar is not significant. Only a small part of reducing sugar is oxidized. Organic acid. Considering the influence of baking time on four factors of total phenol, water content, total acid and reducing sugar, it is determined that 7.0h is the best baking time.
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