Highland Barley Polyphenol Delayed the In Vitro Digestibility of Starch and Amylose by Modifying Their Structural Properties

Elucidating the influence and mechanism of different phenols on the properties, food quality and function of maize starch

This study discusses interaction differences between three phenols (protocatechuic acid, naringin and tannic acid) and starch helix, investigates influences of phenols at different doses on properties of maize starch, and further determines their effects on quality and function of maize-starchy foods. Simulated results indicate variations of phenolic structure (phenolic hydroxyl group amount, glycoside structure and steric hindrance) and dose induce phenols form different complexes with starch helix. Formation of different starch-phenols complexes alters gelatinization (1.65-5.63 J/g), pasting form, water binding capacity (8.83-12.69 g/g) and particle size distribution of starch. Meanwhile, differences in starch-phenols complexes are reflected in fingerprint area (R1045/1022: 0.920 to 1.047), crystallinity (8.3% to 17.0%), rheology and gel structure of starch. Additionally, phenols change texture and color of cold maize cake, giving them different antioxidant capacity and lower digestibility. Findings are beneficial for understanding interaction between starch and different phenols and their potential application.

Exploring the formation mechanism of resistant starch (RS3) prepared from high amylose maize starch by hydrothermal-alkali combined with ultrasonic treatment

In this study, type III resistant starch (RS3) was prepared from high amylose maize starch (HAMS) using hydrothermal (RS-H), hydrothermal combined ultrasonication (RS-HU), hydrothermal-alkali (RS-HA), and hydrothermal-alkali combined ultrasonication (RS-HAU). The role of the preparation methods and the mechanism of RS3 formation were analyzed by studying the multiscale structure and digestibility of the starch. The SEM, NMR, and GPC results showed that hydrothermal-alkali combined with ultrasonication could destroy the granule structure and α-1,6 glycosidic bond of HAMS and reduce the molecular weight of HAMS from 195.306 kDa to 157.115 kDa. The other methods had a weaker degree of effect on the structure of HAMS, especially hydrothermal and hydrothermal combined ultrasonication. The multiscale structural results showed that the relative crystallinity, short-range orderliness, and thermal stability of RS-HAU were significantly higher compared with native HAMS. In terms of digestion, RS-HAU had the highest RS content of 69.40 %. In summary, HAMS can generate many short-chain amylose due to structural damage, which rearrange to form digestion-resistant crystals. With correlation analysis, we revealed the relationship between the multiscale structure and the RS content, which can be used to guide the preparation of RS3.

Starch modification through its combination with other molecules: Gums, mucilages, polyphenols and salts

Apart from its non-toxicity, biocompatibility and biodegradability, starch has demonstrated eminent functional characteristics, e.g., forming well-defined gels/films, stabilizing emulsions/foams, and thickening/texturizing foods, which make it a promising hydrocolloid for various food purposes. Nonetheless, because of the ever-increasing range of its applications, modification of starch via chemical and physical methods for expanding its capabilities is unavoidable. The probable detrimental impacts of chemical modification on human health have encouraged scientists to develop potent physical approaches for starch modification. In this category, in recent years, starch combination with other molecules (i.e., gums, mucilages, salts, polyphenols) has been an interesting platform for developing modified starches with unique attributes where the characteristics of the fabricated starch could be finely tuned via adjusting the reaction parameters, type of molecules reacting with starch and the concentration of the reactants. The modification of starch characteristics upon its complexation with gums, mucilages, salts, and polyphenols as common ingredients in food formulations is comprehensively overviewed in this study. Besides their potent impact on physicochemical, and techno-functional attributes, starch modification via complexation could also remarkably customize the digestibility of starch and provide new products with less digestibility.