Comprehensive investigation into the effects of yeast dietary fiber and temperature on konjac glucomannan/kappa-carrageenan for the development of fat analogs.

In this study, yeast dietary fiber (YDF) was incorporated into konjac glucomannan/kappa-carrageenan (KGM/κ-KC) for the development of fat analogs, and the impact of YDF on the gelation properties and behavior of KGM/κ-KC composite gels was assessed. YDF improved the composite gel whiteness value, and affected the mechanical properties of the composite gel, especially enhancing its hardness, and decreasing its chewiness, elasticity, and gel strength, making it more similar to porcine back fat. When the yeast dietary fiber content was 0.033 g/mL and the heating temperature was 80 °C (T80-2), the textural properties of the composite gel were closest to porcine back fat. The frequency sweep results suggested that YDF incorporation led to enhancement of the intermolecular interaction and intermixing and interaction among more easily at higher processing temperatures (80 °C and 90 °C). By scanning electron microscopy, the fatty surface of porcine back fat was flat and covered with a large amount of oil, while KGM/κ-KC/YDF composite gels developed a dense, stacked network structure. YDF caused more fragmented, folded, and uneven structures to emerge. Overall, YDF could influence the gel behavior of KGM/κ-KC composite gels, and change their colors and mechanical properties. This work could serve as a guide for preparing fat analogs with KGM/κ-KC composite gels.

Alaska pollock surimi-based meat analogs by high-moisture extrusion: Effect of konjac glucomannan/curdlan/carrageenan/sodium alginate on fibrous structure formation.

This study investigated the effects of the addition of konjac glucomannan (KGM), curdlan (CD), carrageenan (CA), and sodium alginate (SA) on fibrous structure formation in surimi-based meat analogs to livestock meat. Meat analogs were prepared using high-moisture extrusion with Alaskan pollock surimi and soy protein isolate at a ratio of 7:3 (w/w). The meat analogs samples were labeled as SSP. Macrostructure observation showed that the best fibrous structure was obtained in SSP containing 2% SA. Mesostructure and microstructure observations revealed that 2% CD, CA or SA promoted the formation of a less tight three-dimensional network structure, which contributed to the formation of fiber filaments. Increased ß-sheet structure content, ordered degree, fractal dimension and thermal stability were observed in SSP with the three colloids. Moreover, fibrous texture was closely associated with the thermal stability and fractal dimension. This study has provided useful information for colloid application in surimi-based meat analogs.

A mechanistic investigation into combined influences of NaCl and extrusion temperature on fibrous structures of high-moisture textured yeast protein.

NaCl and extrusion temperature have an important influence on the qualities of high-moisture textured proteins, but the influence mechanism is still unclear. Therefore, this study prepared high-moisture textured yeast protein (HMTYP) with different NaCl contents (0%-4%) under different extrusion temperatures (170 °C, 180 °C) and characterized their physicochemical properties. The results showed that the HMTYP containing 1% and 2% NaCl prepared at 180 °C contained a strong fibrous structure. The possible mechanism was as follows: YP could not be sufficiently melted at 170 °C after adding NaCl, causing a decrease in the structural strength; however, at 180 °C, YP still reached a fully molten state even though 1%-2% NaCl was added. After YP sufficiently melted, NaCl enhanced the cross-linking and aggregation of proteins during cooling, which improved the textural properties of HMTYP. Accordingly, NaCl and extrusion temperature could combine to adjust the fibrous structure and texture of HMTYP.

Developing a High-Umami, Low-Salt Soy Sauce through Accelerated Moromi Fermentation with Corynebacterium and Lactiplantibacillus Strains.

The traditional fermentation process of soy sauce employs a hyperhaline model and has a long fermentation period. A hyperhaline model can improve fermentation speed, but easily leads to the contamination of miscellaneous bacteria and fermentation failure. In this study, after the conventional koji and moromi fermentation, the fermentation broth was pasteurized and diluted, and then inoculated with three selected microorganisms including Corynebacterium glutamicum, Corynebacterium ammoniagenes, and Lactiplantibacillus plantarum for secondary fermentation. During this ten-day fermentation, the pH, free amino acids, organic acids, nucleotide acids, fatty acids, and volatile compounds were analyzed. The fermentation group inoculated with C. glutamicum accumulated the high content of amino acid nitrogen of 0.92 g/100 mL and glutamic acid of 509.4 mg/100 mL. The C. ammoniagenes group and L. plantarum group were rich in nucleotide and organic acid, respectively. The fermentation group inoculated with three microorganisms exhibited the best sensory attributes, showing the potential to develop a suitable fermentation method. The brewing speed of the proposed process in this study was faster than that of the traditional method, and the umami substances could be significantly accumulated in this low-salt fermented model (7% w/v NaCl). This study provides a reference for the low-salt and rapid fermentation of seasoning.

Effects of the soy protein to wheat gluten ratio on the physicochemical and structural properties of Alaska pollock surimi-based meat analogs by high moisture extrusion.

Surimi products have attracted much attention and are widely used in the food industry. Currently, the processing and exploitation of surimi products are mostly based on their gel characteristics. However, the abundant protein in surimi can be rearranged and integrated by high-temperature melting to generate a new surimi product with fibrous structures. In this study, meat analogs (new surimi product) were produced by high moisture extrusion (HME) using Alaska pollock surimi and plant protein (8:2), where the plant protein consisted of different ratios of soy protein and wheat gluten (9:1, 7:3, 5:5, 3:7 and 1:9). The product was marked as SSG because it was composed of Alaska pollock surimi, soy protein and wheat gluten. The structure and color results showed that the hardness and ΔE of SSG decreased, while the fibrous degree and lightness increased with increasing WG content. The observation of the macrostructure and microstructure also showed that the skeleton structure of SSG was more obvious with increasing WG addition, but the viscosity reflected a decreasing trend. Furthermore, an increase in the WG content raised the free water ratio and the total content of ß-sheets, whereas the appropriate plant protein ratio reduced the SSG's thermal stability. In conclusion, Alaskan pollock surimi and the appropriate proportion of plant protein can form structurally stable meat analogs by high moisture extrusion.

Physicochemical and structural properties of meat analogues from yeast and soy protein prepared via high-moisture extrusion.

In this study, yeast and soy protein at different ratios (0:1, 1:9, 2:8, 3:7, 4:6, and 5:5) were used to produce meat analogues (MA) via high-moisture extrusion. According to color analysis, the addition of yeast protein (YP) increased the lightness of MA from 43.12 ± 0.26 (the control) to 50.37 ± 0.46 (50 g/100 g, dry basis). Textural results indicated that when the YP content was 40 g/100 g (dry basis), the hardness, chewiness, and fibrous degree of MA reached the maximum (523.94 ± 11.91 N, 724.55 ± 22.89 N, and 2.06 ± 0.15, respectively), which were higher than the control (419.63 ± 7.52 N, 618.02 ± 14.82 N, and 1.43 ± 0.03, respectively). Furthermore, YP increased the free water ratio, SS bond, and total ß-sheets structure content, while reducing the ß-turn structure content and thermal stability of MA. Overall, YP is a promising protein source for preparing high-quality MA.

High-moisture extrusion of yeast-pea protein: Effects of different formulations on the fibrous structure formation.

The demand of meat analogues (MAs) is consistently increasing. The protein materials for MAs are primarily soy, pea, and wheat protein which can not completely meet the growing demand. Hence, this study is focused on the preparation of MAs with up to 50 % yeast protein (YP) instead of pea protein isolate (PPI). In the present study, 0 %, 10 %, 30 %, and 50 % YP powder in dry matter basis were combined with PPI; then the mixtures were used to prepare MAs with fibrous structures using high-moisture extrusion (55 % moisture). The involvement of YP significantly enhanced the hardness of MAs (P < 0.05). The optical and microstructural images illustrated that when YP ratio reached 30 %, obvious fibrous structures still were observed in MAs. Furthermore, MAs containing YP became whiter, which is conducive to reprocessing. With an increase in YP, the bound water content, sheet structures, and exposure of tryptophan residues in MAs increased, whereas the free water content, ß-turn, and random coil structures decreased. Analysis of thermal and rheological behaviors indicated that YP lowered the denaturation temperature of MAs and the viscosity of protein dispersions, which was related to the formation of protein aggregates. Overall, YP can be used to prepare MAs and regulate the fibrous structure in MAs by acting on protein conformations.

Yeast protein as a novel dietary protein source: Comparison with four common plant proteins in physicochemical properties.

Currently, with the preference for a healthy diet and increased awareness of reducing the carbon footprint, the demand for protein is becoming more and more diversified. In this study, the physicochemical properties of yeast protein (YP) and four common plant proteins (soy protein isolate, pea protein isolate, wheat gluten, and peanut protein) were compared. The most prevalent secondary structure in YP is the ß-sheet. Furthermore, YP is in an aggregated state, and it has a high surface hydrophobicity. The tryptophan residues are primarily exposed on the polar surface of YP. The results of in vitro digestibility indicated that YP (84.91 ± 0.52%) was a high-quality protein. Moreover, YP has a higher thermal stability and relatively stable low apparent viscosity, which provides ample possibility for its application in food processing and in foods for people with swallowing difficulties. This study provides theoretical basis in the potential of YP as an alternative protein source.

Binding and distribution regularity of water molecules in high-moisture textured Antarctic krill (Euphausia superba) meat.

High-moisture extrusion technique with the advantage of high efficiency and low energy consumption is a promising strategy for processing Antarctic krill meat. Consequently, this study aimed to prepare high-moisture textured Antarctic krill meat (HMTAKM) with a rich fiber structure at different water contents (53 %, 57 %, and 61 %) and to reveal the binding and distribution regularity of water molecules, which is closely related to the fiber structure of HMTAKM and has been less studied. The hydrogen-bond network results indicated the presence of at least two or more types of water molecules with different hydrogen bonds. Increasing the water content of HMTAKM promoted the formation of hydrogen bonds between the water molecules and protein molecules, leading to the transition of the ß-sheet to the α-helix. These findings offer a novel viable processing technique for Antarctic krill and a new understanding of the fiber formation of high-moisture textured proteins.