A multihole nozzle controls recrystallization of high-moisture extruded maize starches: Effect of cooling die temperature.

Hot extrusion is utilized for starch modification due to its high mechanical input and product output. Amylose recrystallization commences and primarily depends on intermolecular interactions after conventional extrusion. Hence, the design of a new component based on the existed extrusion system was aimed at facilitating molecular aggregation, potentially accelerating starch recrystallization. In this study, a nozzle sheet comprising 89 holes was integrated into the cooling die. The impact of the multihole nozzle on the structure and in vitro digestibility of extruded maize starches after retrogradation was examined at varying cooling die temperatures. The results showed that the nozzle-assembled extrusion system operated effectively without additional mechanical or yield losses. At 50 °C, the crystallinity of nozzle-produced starch was approximately 70 % higher than that of conventionally extruded starch, predominantly owing to the B-type allomorph of the amylose double helix. Recrystallized amylopectin was also found in these nozzle-produced starches, indicating that multihole nozzle-induced uniaxial elongational flow resulted in the rapid starch crystallization. The increased formation of recrystallized amylose led to improved molecular order in starch structures while reducing their digestibility. These findings revealed a new approach to improve starch crystallinity by incorporating a nozzle sheet in the extrusion process.

Advances in the Interaction between Food-Derived Nanoparticles and the Intestinal Barrier.

The maintenance of the intestinal barrier is crucial for the overall balance of the gut and the organism. Dysfunction of the intestinal barrier is closely associated with intestinal diseases. In recent years, due to the increased presence of nanoparticles (NPs) in the human diet, there has been a growing concern regarding the safety and potential impact of these NPs on gastrointestinal health. The interactions between food-derived NPs and the intestinal barrier are numerous. This review provides an introduction to the structure and function of the intestinal barrier along with a comprehensive summary of the interactions between food NPs and the intestinal barrier. Additionally, we highlight the potential connection between the food NPs-induced dysfunction of the intestinal barrier and inflammatory bowel disease. Finally, we discuss the enhancement of food NPs on the repair of the intestinal barrier damage and the nutrients absorption. This review holds significant importance in furthering our understanding of the regulatory mechanisms of food-derived NPs on the intestinal barrier.

High-moisture extrusion of curdlan: Texture and structure.

High-moisture extrusion is a promising thermomechanical technology extensively employed in manufacturing fibrous meat analogues from plant-based proteins, garnering considerable research attention. However, polysaccharide-based extrusion has been rarely explored. The present study investigates the effects of varying extruder barrel temperatures (130 °C-200 °C) on the texture and structure of curdlan extrudates, and highlights the formation mechanism. Results showed that the single chain of curdlan aggregates to form triple-helix chains upon extrusion, consequently enhancing the crystallinity, particularly at 170 °C. The hardness, chewiness, and mechanical properties improved with increasing barrel temperature. Moreover, barrel temperatures affected the macrostructure, the extrudates maintained intact morphologies except at 160 °C due to the melting of curdlan gel as confirmed by the differential scanning calorimetry thermogram. Microstructural analysis revealed that curdlan extrudates transited through three phases: original gel (130 °C, 140 °C, and 150 °C), transition state (160 °C), and regenerated gel (170 °C, 180 °C, 190 °C, and 200 °C). The steady state of regenerated gel (170 °C) exhibited higher crystallinity and smaller fractal dimension, resulting in a more compact and crosslinked gel network. This study elucidates the structure transition of curdlan gel at extremely high temperatures, offering valuable technical insights for developing theories and methods with respect to polysaccharide-based extrusion that may find applications in food-related fields.

High Viscosity Slows the Utilization of Rapidly Fermentable Dietary Fiber by Human Gut Microbiota.

In the present study, the influence of viscosity on the fermentation characteristics of fructooligosaccharides (FOS) by gut microbiota was examined. Different concentrations of methylcellulose (MC) were added to create varying viscosities and the mixture was fermented with FOS by gut microbiota. The results demonstrated that higher viscosity had a significant impact on slowing down the fermentation rate of FOS. Specifically, the addition of 2.5 wt% MC, which had the highest viscosity, resulted in the lowest and slowest production of gas and short-chain fatty acids (SCFAs), indicating that increased viscosity could hinder the breakdown of FOS by gut microbiota. Additionally, the slower fermentation of FOS did not significantly alter the structure of the gut microbiota community compared to that of FOS alone, suggesting that MC could be used in combination with FOS to achieve similar prebiotic effects and promote gut health while exhibiting a slower fermentation rate.

Concentration-Regulated Fibrillation of Soy Protein: Structure and In Vitro Digestion.

The impact of protein types, heating temperatures, and times on protein fibrillation has been widely studied. However, there is little understanding of the influence of protein concentration (PC) on the protein fibril assembly. In this work, the structure and in vitro digestibility of soy protein amyloid fibrils (SAFs) were investigated at pH 2.0 and different PCs. Significant increases in fibril conversion rate and parallel ß-sheets proportion were observed in SAFs upon increasing the PC from 2 to 8% (w/v). The AFM images showed that curly fibrils were prone to form at 2-6% PCs, while rigid, straight fibrils developed at higher PCs (≥8%). As evidenced in XRD results, increasing PC led to a more stable structure of SAFs with enhanced thermal stability and lower digestibility. Moreover, positive correlations among PC, ß-sheet content, persistence length, enthalpy, and total hydrolysis were established. These findings would provide valuable insights into concentration-regulated protein fibrillation.

Core-shell starch as a platform for reducing starch digestion and saturated fat intake.

Ill-balanced diets, especially high-carbohydrate and high-fat diets, have led to an explosion of diabetes and cardiovascular diseases worldwide, posing great threats to human health. The structural design of functional foods can offer promising solutions to these afflictions. Here, we introduce a versatile core-shell starch made from food-grade starch and alcohol-soluble protein to reduce starch digestion and saturated fat intake. The fabrication of core-shell structure is realized through an anti-solvent method, assisted by electrostatic interaction, which is generalizable to starches and proteins from different sources and feasible for scale-up production. The protein shell imparts a higher gelatinization temperature and a lower pasting viscosity to the starch, suggesting restricted granule swelling, which leads to a reduced starch digestibility as proved by in vitro digestion studies. The hypoglycemic effect of core-shell starch is demonstrated in vivo. We also show that the application of core-shell starch can be extended to oil encapsulants and saturated fat replacers due to the impact of protein shell on the surface hydrophobicity of the starch. These results may advance the establishment of healthy diets and the tackling of diet-related diseases.

Understanding the differences in heat-induced gel properties of twelve legume proteins: A comparative study.

This study aimed to investigate the rheological and textural properties of heat-induced gels from twelve legume protein isolates at pH 3.0 and 7.0, including black kidney bean (BKPI), speckled kidney bean (SKPI), panda bean (PDPI), cowpea (CPPI), mung bean (MPI), adzuki bean (API), rice bean (RPI), black soybean (BPI), soybean (SPI), chickpea (CPI), broad bean (BRPI) and pea (PPI). SDS-PAGE revealed that 7S globulin was prominent protein in BKPI, SKPI, PDPI, CPPI, MPI, API and RPI, the main protein fraction of CPI was 11S globulin, and BPI, SPI, BRPI and PPI contained both 7S and 11S globulins as major components. Based on the gel's Power Law constant (K') and hardness, twelve legume proteins were divided into three categories with high, medium and low gel strength. BKPI, SKPI and PDPI with Phaseolin being the major protein fraction showed high gel strength regardless of pH. Electrostatic interactions, hydrophobic interactions and hydrogen bonds were the most important intermolecular forces in the formation of legume protein gel networks, of which gel strength at pH 3.0 and pH 7.0 was significantly affected by electrostatic interactions and hydrogen bonds, respectively. Moreover, gel strength was also remarkably negatively influenced by the non-network proteins. SEM observation indicated that the microstructure of gels at pH 7.0 was denser and more homogeneous than that at pH 3.0, leading to better water holding capacity. These findings would be of great importance for understanding the differences in legume protein gels, and also laid the scientific support for expanding applications of legume proteins in gel-based foods.

Doubling growth of egg-box structure during Calcium-mediated molecular assembly of alginate.

Ca2+-mediated molecular assembly of alginate underpins its wide range of applications in foods, pharmaceutics, biomedicines, tissue engineering and environmental treatments. The mode of growth of egg-box structure of alginate in the presence of Ca2+ is a long-standing fundamental problem to be concluded. In this work, we investigate the Ca-induced structural evolution of alginate in dilute solution using atomic force microscopy and dilute solution viscometry. It is demonstrated that the structural evolution follows the three critical steps of monocomplexation, dimerization and multimerization, upon binding with Ca2+. Interestingly, the alginate single chains grow into dimers and multimers via a doubling mode, i.e., successive emerging of dimer, tetramer, octamer, and hexadecamer. Compared with lower guluronate (G) alginate, higher G alginate exhibits a more pronounced multimerization process occurring at a lower ratio of Ca/G. A mechanistic model depicting the evolution of egg-box structure is proposed. The results would add new knowledge to the current egg-box model regarding the molecular assembly and gelation of an important biopolymer alginate, and provide fundamental basis for molecular engineering of alginate for more advanced applications.

Fibrillization kinetics and rheological properties of panda bean (Vigna umbellata (Thunb.) Ohwi et Ohashi) protein isolate at pH 2.0.

Recently, research interests are growing regarding the formation and mechanisms of amyloid fibrils from plant proteins. This study investigated the fibrillization kinetics and rheological behaviors of panda bean protein isolate (PBPI) at pH 2.0 and 90 °C for various heating times (0-24 h). Results showed that PBPI formed two distinct classes of fibrils after heating for 10 h, including flexible fibril with a contour length of ∼751 nm, and rigid fibril with periodicity of ∼40 nm. The secondary structural changes during fibril formation were monitored by circular dichroism spectroscopy and indicated that ß-sheet content increased first (0-12 h) and then decreased (>12 h), which coincided with similar changes in thioflavin T fluorescence. The gel electrophoresis revealed that the polypeptides of PBPI were progressively hydrolyzed upon heating, and the resulting short fragments were involved in fibril formation rather than PBPI monomer. PBPI-derived fibrils showed extremely high viscosity and storage modulus. A plausible molecular mechanism for PBPI fibrillation process was hypothesized, including protein unfolding, hydrolysis, assembly into matured fibrils, and dissociation of the fibrils. The findings provide useful information to manipulate the formation of legume proteins-based fibrils and will benefit future research to explore their potential applications.

Structure analysis and quality evaluation of plant-based meat analogs.

The growing world's population increases the demand of proteins. Meat products as the major source of high protein food are facing environmental impacts and animal welfare issues. Therefore, plant-based meat analogs are developed and gain a foothold in global markets. The structure design, sensory attributes and nutrient characteristics of meat analogs are crucial points to match the real meat. This review aimed to systematically introduce the structural analysis methods and evaluate meat analog products from quality-related attributes. First, various strategies of analyzing the fibrous structure of meat analogs were illustrated, including microscopic imaging and several optical techniques. Then, representative techniques such as NMR and AFM-IR for analyzing the distribution of moisture and lipid in meat analogs are introduced. In terms of quality, we elaborated on the texture and sensory evaluation methods and dialectically analyzed meat analogs' nutrition, which can provide a guidance for the advanced development of meat analogs.

Heat-induced pea protein isolate gels reinforced by panda bean protein amyloid fibrils: Gelling properties and formation mechanism.

The roles of panda bean protein amyloid fibrils (PDPF) in modifying the textural and rheological properties of heat-induced pea protein isolate (PPI) gels were investigated. It was found that the incorporation of PDPF significantly enhanced (p < 0.05) the strength of PPI gel. This effect was PDPF concentration-dependent and was predominantly attributable to the enhanced intermolecular interactions between PDPF and PPI through hydrogen bonds and hydrophobic interactions. Synchronously, the non-network proteins content in PPI-PDPF gels decreased from 23.6 % to 6.6 % when PDPF concentration increased from 0 to 1.50 % (w/w). Cryo-scanning electron microscopy proved that PDPF was filled in the PPI gel network leading to more compact and interconnected gel structure. However, the water holding capacity and secondary structures of PPI gel were not significantly affected. The findings of this study showed that PDPF was effective in improving the PPI gel functional quality, which provided scientific support for PDPF as a promising gel ingredient in food industrial applications.

Gelation behavior and mechanism of alginate with calcium: Dependence on monovalent counterions.

The present work investigates the calcium-induced gelation behavior and gel properties of alginate samples of lithium-, sodium-, and potassium-forms. It was found that the effect of the alkali metal counterions varied greatly with the calcium concentration regime, namely, the molar ratio of calcium to guluronate (R = Ca/G). Four different regions were identified, including R < 0.25, 0.25 < R < 0.55, 0.55 < R < 1.0, and R > 1.0. The counterion dependence was interpreted by the relative interaction strength of the monovalent cations with COO- groups and their exchange reaction with Ca2+ ions. A mechanistic model depicting the role of counterions was proposed in relation to different steps of the binding and gelation of alginate with calcium. The knowledge gained in the study would further advance the understanding of the gelation mechanism of the industrially important alginate and guide its specific utilizations.

Comparison of cellulose derivatives for Ca2+ and Zn2+ adsorption: Binding behavior and in vivo bioavailability.

Cellulose with distinct colloidal states exhibited different adsorption capability for ions and whether the intake of cellulose would bring positive or negative influence on the mineral bioavailability is inconclusive. This work investigated the binding behavior of carboxymethyl cellulose (CMC), TEMPO-oxidized nanofibrillated/nanocrystalline cellulose (TOCNF/TOCNC), and microcrystalline cellulose (MCC) with Ca2+and Zn2+ and compared their effects on mineral bioavailability in vitro and in vivo. The results suggested that CMC displayed a higher adsorption capability (36.6 mg g-1 for Ca2+ and 66.2 mg g-1 for Zn2+) than the other types of cellulose because of the strong interaction between carboxyl groups of cellulose and the ions. Although the cellulose derivatives had adverse effects on ion adsorption in vitro, the fermentability endowed by TOCNF/TOCNC counterbalanced the negative impacts in vivo. The findings suggested that the colloidal states of cellulose affected the bioavailability of minerals and could provide useful guidance for applications of specific cellulose.

In Vitro Colonic Fermentation Profiles and Microbial Responses of Cellulose Derivatives with Different Colloidal States.

Although cellulose derivatives are widely applied in the food industry, the effects of their structural properties on colonic health is unknown. Here, four types of cellulose derivatives, including microcrystalline cellulose (MCC), TEMPO-oxidized nanofibrillated cellulose (TOCNF), TEMPO-oxidized nanocrystalline cellulose (TOCNC), and carboxymethyl cellulose (CMC) were selected to investigate their in vitro fermentation profiles. TOCNF exhibited the highest production of total short-chain fatty acids (SCFAs), followed by TOCNC. The results suggested that reduced particle size and increased aspect ratio improved the fermentability of insoluble cellulose derivatives. MCC and CMC were barely fermented with similar total SCFAs production as the blank. 16S rRNA sequencing revealed that the fermentation of cellulose derivatives resulted in divergent microbial community structures. Moreover, Bacteroides cellulosilyticus showed high specificity to utilize TOCNF and TOCNC. The findings demonstrated that the colloidal states of cellulose derivatives, such as size and solubility, were important factors governing microbial community composition and metabolites.

Introducing panda bean (Vigna umbellata (Thunb.) Ohwi et Ohashi) protein isolate as an alternative source of legume protein: Physicochemical, functional and nutritional characteristics.

Panda bean protein isolate (PDPI), a legume-protein with Chinese characteristics, was investigated as an alternative potential food protein source. The physicochemical characteristics, functional properties and amino-acid composition of PDPI were determined and compared with soybean (SPI) and pea protein isolate (PPI). Results showed that PDPI was rich in phaseolin (mainly 7S vicilin), and its molecular weight was lower than that of SPI and PPI which were rich in legumin and vicilin. In comparison to SPI and PPI, PDPI showed the lowest solubility, surface-charge and surface-tension at pH 3.0, 7.0 and 9.0, but it exhibited comparable or even superior functionalities, especially in emulsifying and foaming abilities, gelling behaviour, rheological and textural properties. Moreover, the amino-acid composition and protein efficiency ratio of PDPI were excellent. The knowledge gained in the study is expected to provide reliable scientific science data for the potential application of PDPI in the food industry.

Recent advances in the structure, synthesis, and applications of natural polymeric hydrogels.

Hydrogels, polymeric network materials, are capable of swelling and holding the bulk of water in their three-dimensional structures upon swelling. In recent years, hydrogels have witnessed increased attention in food and biomedical applications. In this paper, the available literature related to the design concepts, types, functionalities, and applications of hydrogels with special emphasis on food applications was reviewed. Hydrogels from natural polymers are preferred over synthetic hydrogels. They are predominantly used in diverse food applications for example in encapsulation, drug delivery, packaging, and more recently for the fabrication of structured foods. Natural polymeric hydrogels offer immense benefits due to their extraordinary biocompatible nature. Hydrogels based on natural/edible polymers, for example, those from polysaccharides and proteins, can serve as prospective alternatives to synthetic polymer-based hydrogels. The utilization of hydrogels has so far been limited, despite their prospects to address various issues in the food industries. More research is needed to develop biomimetic hydrogels, which can imitate the biological characteristics in addition to the physicochemical properties of natural materials for different food applications.

Evolution of physicochemical and antioxidant properties of whey protein isolate during fibrillization process.

Whey protein isolate (WPI) fibrils have great potential for applications in future food manufacture due to their improved properties. However, the evolution of their properties during fibrillization is still not fully understood. Here, we investigate variational characteristics of WPI fibrils during formation process. WPI fibrils with a semiflexible and linear structure were formed and showed high aspect ratio after heat treatment. The conversion, fluorescence intensity and isoelectric point of WPI were increased with heating time. Moreover, the antioxidant activity of WPI was improved after fibrillization and was dependent on heating time. This could be attributed to the structure transformation of protein and the exposed amino acids with sulfur groups or aromatic side chains in the fibrillated system. Our findings move a step forward for a detailed understanding on the dynamical changes of WPI properties during fibrillization, which would provide a guidance for WPI fibril applications and future food technology development.

The role of amyloid fibrils in the modification of whey protein isolate gels with the form of stranded and particulate microstructures.

Adding fibers to hydrogels is a modern strategy for producing tough hydrogels. Nanofibers usually perform well in hydrogels due to their unique properties. The purpose of this study was to investigate the effects of whey protein amyloid fibril (WPF) on the properties ofheat-set whey proteinisolate (WPI)gels with fine-stranded or particulate microstructure (at pH 7). The results show that by adding WPF, a homogenous and dense network was observed in fine-stranded gel, while the formation of a coarse and amorphous structure with microphase separation intensified in particulate gel. By adding 1% WPF, the elastic modulus of gels increased about 10.6 and 3.6 times in the case of fine-stranded and particulate gels, respectively. In fine-stranded gels, adding WPF to the gel led to a decrease in the Tg value (from 66.33 to 59.36 °C) and a decrease in tan δ (from 0.2328 to 0.0837), indicating an increase in gel strength because of WPF. In contrast, adding WPF to particulate gels did not cause significant changes in the Tg and tan δ. There was a decrease in the water holding property of particulate gels when WPF was added, whereas it did not change significantly in fine-stranded gels. These findings imply that the efficiency of WPF in WPI gels depends not only on the WPF concentration but also on the type of the WPI gel. In sum, WPF enhances order in the structural network of fine-stranded gels, while accelerating the formation of inhomogeneous random aggregates in particulate gels. Creating fiber-hydrogels with different microstructures and rheological properties can be possible by controlling WPI aggregation (as in amyloid fibril, fine-strand or particulate aggregates).

Prolamin-based complexes: Structure design and food-related applications.

Prolamins are a group of safe food additives that are biocompatible, biodegradable, and sustainable. Zein, gliadin, kafirin, and hordein are common prolamins that have been extensively studied, particularly as these form colloidal particles because of their amphiphilic properties. Prolamin-based binary/ternary complexes, which have stable physicochemical properties and superior functionality, are formed by combining prolamins with polysaccharides, polyphenols, water-soluble proteins, and surfactants. Although the combination of prolamins with other components has received attention, the relationship between the structural design of prolamin-based complexes and their functionalities remains uncertain. This review discusses the production methods of prolamin-based complexes, the factors influencing their structural characteristics, and their applications in the food industry. Further studies are needed to elucidate the structure-function relationships between prolamins and other biopolymers, as well as the toxicological effects of these complexes in food.

Cellulose and cellulose derivatives: Different colloidal states and food-related applications.

Development of new sources and isolation processes has recently enhanced the production of cellulose in many different colloidal states. Even though cellulose is widely used as a functional ingredient in the food industry, the relationship between the colloidal states of cellulose and its applications is mostly unknown. This review covers the recent progress on illustrating various colloidal states of cellulose and the influencing factors with special emphasis on the correlation between the colloidal states of cellulose and its applications in food industry. The associated unique colloidal states of cellulose like high aspect ratio, crystalline structure, surface charge, and wettability not only promote the stability of colloidal systems, but also help improve the nutritional aspects of cellulose by facilitating its interactions with digestive system. Further studies are required for the rational control and improvement of the colloidal states of cellulose and producing food systems with enhanced functional and nutritional properties.