Research on Modified Starch

The interest of researchers in modified starches has gradually increased in recent years. Based on the digestive behavior, starch can be classified into rapidly digestible starch (RDS) which causes a sudden increase in blood glucose level after ingestion, slowly digestible starch (SDS) which is slowly but completely digested in the small intestine and resistant starch (RS) which is not digested in the small intestine but fermented in the large intestine depending on the rate and extent of digestion [1], which is usually positively correlated with the degree of starch regeneration. Currently, foods are usually modified to increase the content of resistant and chronically digestible starch in starch using enzymatic modification, physical modification [2] and chemical modification [3].

Zhu [4] and others studied the relationship between amylase sensitivity and starch regrowth from different sources such as quinoa, and, found that the higher thermal stability and enthalpy of melting changes of starch reflect a more ordered structure, which is related to the higher resistance of regrowth starch to enzymatic hydrolysis.Ding [5] and others, in a study of the effect of ultrasonication on the molecular structure and digestive properties of starch, showed that the the original order of starch molecules was disrupted and rearranged, and this new arrangement of starch molecules increased the content of resistant starch.Kim [6] et al. used sodium trimetaphosphate / sodium tripolyphosphate (STMP / STPP) to cross-link with maize starch and acetylate by acetic anhydride, which effectively retarded the aging process of maize starch.

Whether it is enzyme modification, physical modification or chemical modification, all of them affect starch pasting and regrowth by changing the internal structure of starch molecules, which have been applied industrially, and now the research direction is beginning to turn to the cross-linking effect of different starch modification methods, which will be another idea to explore the starch regrowth process in the future.

Application of new anti-regrowth components

The investigation of new antireturning components has been the focus of people’s attention, many natural and chemically synthesized antireturning components can play a good effect in the starch regeneration process, but at present it only stays in the theoretical research, if it is further applied to industrial production, some new antireturning components are suitable to be added to the food need to be further demonstrated.

Diao [7] et al. found in their study of the effects of ascorbic acid and sodium sulfite on the texture of cooked rice that, as reducing agents, both sodium sulfite and ascorbic acid restored the texture of cooked rice in terms of viscosity, hardness and viscosity, and hardness ratio to the level of fresh rice, indicating a significant improvement in the texture of cooked rice. Sodium sulfite promotes the separation of starch granules leading to a reduction in particle size and reduces the recrystallization probability of starch granules, thus improving the texture of rice; ascorbic acid, as a safe food additive, not only promotes the separation of starch granules, but also promotes the swelling of starch granules and improves the texture of cooked rice, which is of obvious effect in improving the edible quality of rice.

Yu [8] et al. demonstrated that the addition of 2.0% NaBH4 reduced the relative crystallinity of corn starch and glutinous corn starch by 62.22% and 100%, respectively, in a study of the inhibitory effect of sodium borohydride on the regrowth of normal and glutinous corn starch. However, sodium borohydride does not belong to the additives permitted in the GB 2760-2014 standard for the use of food additives, and its safety needs to be investigated.

Lü [9] et al. by studying the role of tea products (tea polyphenols and catechins) in wheat starch regrowth process found that tea polyphenols and catechins complexed with wheat starch provide wider O-H stretching and C-O-H bending vibration Tea products may form hydrogen bonding with wheat starch, which interferes with the recombination of the starch chain during storage, thus delaying regrowth. Therefore, tea products can be used as potential anti-degradation additives in the food industry. Tea polyphenols are common natural antioxidants, and the addition of small amounts of tea polyphenols to suitable starch-based food products may both delay starch regrowth and protect the oxidation-prone components of the product.