Multi-Scale Structural Insights into Enzymatically Hydrolyzed Lentil Starch Concentrates Prepared by In Vitro Method Using Different Types of Enzymes.

This study was undertaken to investigate the enzymatic hydrolysis of lentil starch concentrates from conventional cooked seeds (CCLSC) by the action of different types of enzymes, including pancreatin (PC-EHSC), heat-stable α-amylase (HS-EHSC), ß-amylase (ßA-EHSC), amyloglucosidase (AMG-EHSC), and multi-enzymes (ßA-HS-AMG-EHSC); their multi-scale structural characteristics of the enzymatic hydrolysis products of lentil starch concentrates were compared. The morphological features distinguished among different samples. The Fourier-transform infrared spectroscopy and solid-state 13C CP/MAS NMR spectral features indicated the possible formation of a binary and ternary complex among amylose, protein and lipids. The X-ray diffraction results revealed that the V-type characteristic diffraction peaks were more obvious for samples including PC-EHSC and ßA-EHSC, which was in line with their lowest polydispersity index (DPn). PC-EHSC and ßA-EHSC also showed an increased peak intensity of the scattering maximum on the small-angle X-ray scattering spectra, whereas CCLSC exhibited an overall lower peak intensity within the studied q range of scattering. The highest XRD crystallinity and the lowest DPn value obtained for PC-EHSC indicated that the starch polymers modified by pancreatin could produce glucan chains with a comparatively homogenous Mw distribution that are readily recrystallized by hydrogen bonding through chain aggregation. Comparatively, the lowest relative crystallinity for HS-EHSC obtained from XRD suggested that thermostable α-amylolysis was unfavorable for the formation of starch structure with a higher degree of molecular order. This study could provide useful information for the needed research to obtain a deeper understanding of the impact of different amylolysis actions on the structural organization of starch hydrolysates and to provide a theoretical foundation for the development of fermentable enzymatically hydrolyzed starch with well-tailored physiological properties.

Lacticaseibacillus rhamnosus C1 effectively inhibits Penicillium roqueforti: Effects of antimycotic culture supernatant on toxin synthesis and corresponding gene expression.

Recently, consumers are increasingly concerned about the contamination of food by molds and the addition of chemical preservatives. As natural and beneficial bacteria, probiotics are a prospective alternative in food conservation because of their antimycotic activities, although the mechanism has not been explained fully at the level of metabolites. This study aimed at investigating the antifungal activities and their mechanisms of five potential probiotic strains (Lacticaseibacillus rhamnosus C1, Lacticaseibacillus casei M8, Lactobacillus amylolyticus L6, Schleiferilactobacillus harbinensis M1, and Limosilactobacillus fermentum M4) against Penicillium roqueforti, the common type of mold growth on the bread. Results showed that C1 emerged the strongest effectiveness at blocking mycelium growth, damaging the morphology of hyphae and microconidia, decreasing DNA content and interfering in the synthesis of the fungal toxins patulin, roquefortine C and PR-toxin, as well as downregulating the expression of key genes associated with the toxin biosynthesis pathways. Further metabonomic investigation revealed that protocatechuic acid with the minimum inhibitory concentration of 0.40 mg/mL, may be most likely responsible for positively correlated with the antimycotic effects of C1. Thus, C1 is expected to be both a potentially greatly efficient and environmental antimycotic for controlling P. roqueforti contamination in foods.

Preparation of rutin-loaded microparticles by debranched lentil starch-based wall materials: Structure, morphology and in vitro release behavior.

Different treatments of autoclaving, pullulanase debranching and/or ultrasound were applied to prepare debranched lentil starch (DBLS). Their fine structures can affect the retrogradation patterns of DBLSs, which consequently could affect their potential use as delivery carrier of sensitive bioactive compounds. An attempt was made to use these DBLSs as wall materials to encapsulate rutin, aiming to improve the bioaccessibility, meanwhile to enhance the aqueous solubility and stability of rutin molecules. Their encapsulation efficiency, structural characteristics, thermal stability, morphological features, antioxidant activity and in vitro release behavior under simulated upper gastrointestinal tract environment were evaluated. The results suggested that rutin was dispersed in the DBLS polymer matrix, showing the amorphous nature that further authenticates the encapsulation and entrapment of rutin. The structural analyses of microparticles revealed that rutin could interacted with DBLS biopolymer chains by hydrogen bonds, making the starch molecular chains less susceptible to interact with themselves for reordering. The encapsulation efficiency was found to be in an opposite trend with those values obtained for relative crystallinity, melting enthalpy, degree of order/double helices of DBLS wall materials before encapsulation. The release rate results indicated that DBLS carrier with lower Mw, DPn and higher molecular order was beneficial for the slower release of rutin encapsulated in the microparticles.

Insights into the supramolecular structure and techno-functional properties of starch isolated from oat rice kernels subjected to different processing treatments.

Oat rice kernels were subjected to decortication (DOR), decortication and enzyme deactivation (DDOR), decortication and cooking (DCOR), as well as combined decortication, enzyme deactivation and cooking (DDCOR). The starch fractions were isolated and their structural features were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, solid-state 13C nuclear magnetic resonance, small angle X-ray scattering (SAXS), and scanning electron microscope. In the cooked oat rice samples (DCOR and DDCOR), in addition to losing a significant amount of the A-type crystalline structure, there was an enhancement in the proportion of V-type crystallinity. The cooking process completely destroyed the periodic lamellar structure of oat starch on the SAXS profile. The Mw values (1.195 × 107-1.459 × 107 g/mol) were in the following order: DOR > DDOR > DCOR > DDCOR. The data was in line with the results for crystallinity, double helix content, degree of order, melting enthalpy, and those obtained for textural parameters, resistant starch content, and bile acid binding capacity.

Understanding the multi-scale structural changes in starch and its physicochemical properties during the processing of chickpea, navy bean, and yellow field pea seeds.

This study aimed to isolate starch from three types of untreated and autoclaved pulse seeds including chickpea, navy bean, and yellow field pea and to characterize their multi-scale structure and the associated physicochemical properties. Autoclaving of pulse seeds tended to significantly decrease the relative crystallinity, the Mw value, and degree of order of starch samples measured by X-ray diffraction, size exclusion chromatography, and FT-IR. Simultaneously, double helix content, and degree of double helix obtained from solid-state 13CNMR and FT-IR were relatively higher (P < 0.05) for autoclaved pulse seeds than their native counterparts. The structural characteristics also corroborated well with the obtained results of resistant starch content, gelatinization behavior, swelling power, solubility, and bile acid binding capacity. This research gave insights into the structural characteristics of starch from pulses and their changes that occurred following processing of seeds, aiming to provide information for the future study on their processing-structure-function relationship.