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Maillard reaction products (MRPs) of soybean protein isolate (SPI) and sugars (glucose and maltose) were prepared by heating in the aqueous dispersion at 95°C for 15 min with ultrasonic pretreatment (ultrasonic power of 200 W) for 20 min. Effect of ultrasonic pretreatment on physicochemical characteristics and rheological properties of SPI/sugar MRPs was investigated. SPI/sugar MRPs prepared with ultrasonic pretreatment had higher degree of glycation (DG), lower browning and less compact tertiary conformation than that with non-ultrasonic pretreatment. Surface hydrophobicity (H 0 ), particle size and rheological properties were measured by fluorescence spectrophotometry, laser particle size analysis and dynamic oscillatory rheometry, respectively. Glycation reduced H 0 and particle size as well as weaken the gel network formed by the acidification of GDL. However, ultrasound increased H 0 and decreased particle size. This is desirable for the formation of acid-induced gel structure. The ultrasonic pretreatments reduced/eliminate the weakening effect of glycation on the gel network of SPI/sugar MRPs, and even improved the gel properties.

The effect of mixture and conjugation with maltodextrin (MD) in aqueous solution on the structural and physicochemical properties of soya bean protein isolate (SPI) was investigated. Although the mixing of MD would not change the distribution of secondary structure and tertiary conformation of SPI, the protein aggregation was promoted through hydrophobic interaction, which resulted in the decrease in solubility and the improvement of gel strength and water holding capacity (WHC) of SPI/MD mixture. However, glycosylation decreased a-helix and increased b-structure. The bathochromic shift of the fluorescence emission maximum wavelength for SPI/MD conjugates was promoted, resulting in less compact tertiary conformation. These structural modifications might be the reason for the changes in the physicochemical properties of conjugates. After glycosylation, the surface hydrophobicity and solubility were increased, the average particle size was decreased, and the gelation properties were weakened including gel strength and WHC.

The structure and functionalities of rice bran protein (RBP) oxidized by peroxyl radicals were analyzed in this study. The thermal decomposition of 2,2′-azobis [2-amidinopropane] dihydrochloride (AAPH) was used to generate peroxyl radicals. Increased oxidation of RBP by AAPH gradually generated more carbonyl (COOH) groups, which resulted in a loss of protein sulfhydryl groups. Low oxidization (≤0.2 mmol/L AAPH) could cause structural unfolding with an increase in surface hydrophobicity and emulsion properties but reducing the solubility and disulfide bonding. Moderate and high oxidization (>0.2 mmol/L AAPH) could result in soluble aggregates formed by subunits with molecular weights of 53, 49, and 36 kDa, attributed to globulin, albumin, and glutelin, increasing the solubility and disulfide bonding but decreasing the surface hydrophobicity and emulsion stability. Oxidization by low concentration AAPH induced a more unordered structure and transformation from β-turn to β-sheets, while a more ordered structure increased with aggregation.

Ultrasonically modified soybean lipophilic protein has improved solubility and emulsifying properties, which are advantageous for preparing emulsions that improve the bioavailability of vitamin E while protecting its biological activity.

Corn starch, one of the important components of corn, accounts for about 70% of the total mass usually. Starch has a positive effect on maintaining human life and movement, which play a key role obtaining energy from the diet for human. However, long-term consumption of high glycemic index food was positively associated with obesity, hyperglycemia, diabetes typeⅡ, and other metabolic complications (Brand-Miller et al., 2007), prompted researches to reduce digestibility and glycemic index of starch. The protein and phenolic compounds are regarded as safe, eco-friendly, and effective substance that modified digestion and glycemic index of starch, effectively, by