Recent years, puffing effect during micro heating has become one of hot researches at home and abroad. As micro wave heats quickly, water in the materials evaporates in a short time and accumulates to form pressure gradient. If the materials cannot bear the pressure, it will lead to volume expansion. Take deep corn processing equipments produce resistant starch as an example. First, in puffing treatment, hydrogen bond disconnects and forms during cooling process, which is called retrogradation. Second, evaporation is the inner dynamic of puffing. Starch gelatinizes to form porous net structure, beneficial for enzyme to take effect. Third, micro wave treatment is efficient and secure, greatly shortening processing time.Currently, micro wave puffing technology is mainly used in post processing of starch and protein puffing food, etc. It has become mature as a post processing technology, however, as a pretreatment, it is seldom seen. Hence, it is beneficial for enzymolysis of amylase and pullulanase by pre-treating RS with deep corn processing equipments to make starch gelatinize and puff. RS is increased by controlling enzymolysis conditions.
Micro wave treatment is affected by heating temperature and moisture content, particularly, moisture has a obvious relationship with temperature increase speed which is fast with low moisture and slow with high. Property changes caused are similar to those by heat-moisture treatment. Micro wave processing takes shorter time in low temperature. It is a new technology that has not been carried out in production.
Ultrasound is a high frequency sonic wave. Strong ultrasound will bring about degradation of polymer. On one hand, it speeds up fiction of solvent and polymer molecules, leading to split of 0-0 bond; on the other, cavitation effect causes high temperature and pressure to break apart bond. Compared with other degradation methods, ultrasound makes light molecular weight and high purity.
During RS processing, it is inevitable for degradation and enzymolysis. Ultrasound technology can speed up enzymolysis all together with degradation, shortening processing time and obtaining optimized condition by controlling reaction.
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