Debranching facilitates malate esterification of waxy maize starch and decreases the digestibility

Effect of ultrasound-pretreated starch on the formation, structure and digestibility of starch ternary complexes from lauric acid and β-lactoglobulin

Starch, lipids, and proteins are key macronutrients in starchy foods. Their interactions during processing can form starch-lipid-protein ternary complexes, significantly affecting food quality. Ultrasonic treatment, as a common processing method, is expected to regulate the quality of starchy foods by influencing the formation of ternary complexes. This study aimed to understand the effect of ultrasonic pretreatment on the formation of starch-lipid-protein ternary complexes using various types of starches. Wheat starch (WS), maize starch (MS), and potato starch (PS) were gelatinized and treated with ultrasound at various power densities (0-40 W/L) to form complexes with lauric acid (LA) and β-lactoglobulin (βLG), respectively. Ultrasound increased the amylose content of gelatinized WS, MS, and PS and shifted their chain length distribution towards the short chains. Results from Fourier transform infrared spectroscopy, laser confocal micro-Raman, X-ray diffraction, and differential scanning calorimetry showed that the largest amount of WS-LA-βLG complexes was formed at the ultrasonic power density of 10 W/L, and MS-LA-βLG and PS-LA-βLG complexes at 20 W/L. Additionally, ultrasound enhanced the content of resistant starch (RS) in the starch-LA-βLG complexes. The RS content increased from 14.12 % to 18.31 % for WS-LA-βLG, and from 19.18 % and 20.69 % to 27.60 % and 28.63 % for MS-LA-βLG and PS-LA-βLG complexes, respectively. This study presents an approach for facilitating the formation of ternary complexes, contributing to the development of low-GI functional foods.

Physiochemical characterization and ameliorative effect of rice resistant starch modified by heat-stable α-amylase and glucoamylase on the gut microbial community in T2DM mice

In the presented study, natural rice containing high resistant starch content was used as a raw material to produce rice resistant starch (RRS) through enzymatic hydrolysis with heat-stable α-amylase and glucoamylase. The chemical composition, structural characteristics and in vitro glycemic index (GI) of RRS were evaluated. The effects of RRS at different doses on the body weight, serum biochemical levels, pathological indexes, production of short-chain fatty acids (SCFAs) in the gut and the intestinal microbial composition in T2DM mice were investigated. The results of physiochemical characterization indicated that, relative to rice flour, RRS mainly comprising resistant starch had higher crystallinity (25.85%) and a more stable structure, which contributed to its lower digestibility and decreased GI in vitro. Compared with the model control group, 1 g per kg BW and 2 g per kg BW oral gavage dosages of RRS effectively enhanced the SCFA productivity in the T2DM mouse gut, as well as alleviating T2DM symptoms, involving an increase in body weight, reduction in fasting blood glucose, total cholesterol, triglyceride, low-density lipoprotein cholesterol, alanine transaminase and aspartate aminotransferase, and an increase in serum insulin and high-density lipoprotein cholesterol. Besides, 1 g per kg BW and 2 g per kg BW dosages of RRS mitigated T2DM-induced pancreas damage. Furthermore, up-regulation in the abundance of probiotics (Lactobacillus, Ruminococcus, etc.) and down-regulation in the number of harmful bacteria (Desulfovibrio, Prevotella, etc.) were observed in all RRS-treated groups. In summary, this work suggested that RRS prepared using heat-stable α-amylase and glucoamylase could be a potential functional component for amelioration of T2DM applied in the fields of food and pharmaceutics.

Understanding synchronous regulating effects of starch-protein interactions on starch digestion and retrogradation under thermal shear processing

Although starch-protein interactions have been widely used to regulate starch digestibility and retrogradation during food processings, their synchronous regulating effects on both properties still remain largely unexplored. The effects of interactions with pea protein (PP) under thermal shear processing on the digestion and retrogradation properties of modified chestnut starch were investigated. Results show that thermal shear processing broke starch multi-scale structure, leading to the reduction in molar mass, short-range ordered structure, crystallinity, and starch compactness, in turn increasing starch digestibility and accelerating starch retrogradation. However, PP molecules would interact with chestnut starch through hydrogen bonding to form the starch-protein complexes during thermal shear processing, which caused an increased resistant starch. These starch-protein interactions also inhibited the formation of short-range, long-range ordered structure, aggregate structure during storage, causing a reduced degree of retrogradation. The results provided new insights into the synchronously regulating effects of starch-protein interactions under thermal shear processing on starch digestion and retrogradation, which would facilitate the development of starch-based foods with high nutrition and quality.

Effect of plasma-activated water on the formation of endogenous wheat starch-lipid complexes during extrusion

The aim of this study was to investigate the effect of plasma-activated water (PAW) during extrusion on the formation of endogenous starch complexes with wheat starch (WS) as a model material. Using PAW during the extrusion process resulted in an increase in amylose content from 27.87 % to 30.07 %. Results from Fourier transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry indicated that the PAW facilitated the formation of endogenous starch-lipid complexes during extrusion. PAW120 (distilled water treated by plasma for 120 s) showed a better promotion effect than PAW60 (distilled water treated by plasma for 60 s). EWS120 (WS extruded using PAW120) exhibited lower peak viscosity and swelling power, but higher solubility, particle size, and resistant starch content compared with EWS0 (WS extruded using distilled water) and EWS60 (WS extruded using PAW60). In a word, the acidic substances in PAW may lead to hydrolysis of starch and generate more amylose, thus improving the amount of endogenous starch-lipid complexes. The present study provides a novel extrusion method to obtain modified starch with higher RS content than common extrusion, which has potential application in the industrial production of functional foods with low glycemic index.