This study aimed to develop a product that closely replicates the texture and appearance of tripe. The effect of three different proteins (soy protein isolate (SPI), pea protein isolate (PPI), and whey protein isolate (WPI)) at different protein levels and processing conditions (heating (90 °C, 1 h) followed by cooling (4 °C, 12 h) and heating (90 °C, 1h) followed by freezing (-18 °C, 12 h)) of konjac glucomannan (KGM) was analyzed. The optimal formulations for simulating tripe were screened by examining their similarity to real tripe in terms of texture, color, and sensory experience. The screened formulations were also subjected to a preliminary mechanistic investigation. The results show that all three proteins improved the gel\'s textural properties to varying degrees. At the same concentration, the hardness and chewiness of the KGM/WPI composite gel were significantly higher than those of the other two KGM/protein composite gels, among which the composite gel obtained by adding 8% WPI and 5% KGM heating-frozen (FWK4) had the greatest hardness and chewiness of 4338.07 g and 2313.76, respectively, and the springiness differences in all of the composite gels were small. In addition, the addition of protein increased the whiteness of the hybrid gels, with WPI having the most significant effect on the whiteness of the composite gels (whiteness increased from 30.25 to 62.80 as the concentration of WPI increased from 0 to 10%). Freezing increased composite gel hardness and chewiness, but reduced gel springiness and whiteness. Cluster analysis showed that the composite gel obtained by heating-cooling 8% WPI and 5% KGM (WK4) was very similar to the real tripe in terms of chewiness and whiteness, and WK4 had the highest sensory scores for color, tissue morphology, tactile sensation, taste, and odor. The acceptability score in terms of tissue morphology reached 4.3. Meanwhile, the characterization results of WK4 indicate the presence of large junction areas in the gel network. Fourier transform infrared spectroscopy (FTIR) analysis, X-ray diffraction, and intermolecular force contributions indicated that the incorporation of WPI promoted integral interactions, and that hydrophobic interactions and disulfide bonding played a key role in the WK4 composite gel system. Moreover, scanning electron microscopy (SEM) also showed that the combination of WPI and konjac glucan resulted in a more compact gel structure. This study is informative for the development of the field of bionic tripe processing.

BACKGROUND: The increasing demand for sustainable alternatives to traditional protein sources, driven by population growth, underscores the importance of protein in a healthy diet. Pecan (Carya illinoinensis (Wangenh.) K. Koch) nuts are currently underutilized as plant-based proteins but hold great potential in the food industry. However, there is insufficient information available on pecan protein, particularly its protein fractions. This study aimed to explore the physicochemical and functional properties of protein isolate and the main protein fraction glutelin extracted from pecan nuts.
RESULTS: The results revealed that glutelin (820.67 ± 69.42 g kg-1) had a higher crude protein content compared to the protein isolate (618.43 ± 27.35 g kg-1), while both proteins exhibited amino acid profiles sufficient for adult requirements. The isoelectric points of protein isolate and glutelin were determined to be pH 4.0 and pH 5.0, respectively. The denaturation temperature of the protein isolate (90.23 °C) was higher than that of glutelin (87.43 °C), indicating a more organized and stable conformation. This is further supported by the fact that the protein isolate had a more stable main secondary structure than glutelin. Both proteins demonstrated improved solubility, emulsifying, and foaming properties at pH levels deviating from their isoelectric points in U-shaped curves. Compared to the protein isolate, glutelin displayed superior water and oil absorption capacity along with enhanced gelling ability.
CONCLUSIONS: The protein isolate and glutelin from pecan nuts exhibited improved stability and competitive functional properties, respectively. The appropriate utilization of these two proteins will support their potential as natural ingredients in various food systems. © 2024 Society of Chemical Industry.

In this study, fava bean protein (FPI) was isolated from flours prepared from dehulled seeds and compared to FPI extracted from whole flours; in the latter case, flours were prepared either by dry- or wet-milling. Significant differences in composition and functionality were observed between the three FPIs produced. Dehulling maximized protein purity, oil-absorption capacity, solubility, foamablity and minimized both starchy and non-starchy carbohydrate contents. Protein isolated from wet-milled whole beans provided higher mass and extraction yields, better water-absorption capacity, and exhibited higher surface charge (zeta potential) compared to other samples. The protein extracted from dry-milled whole seed exhibited a higher least gelation concentration, emulsifying activity and zeta value compared to its dehulled counterpart. Dehulling was also found to be a useful process to increase the lightness/whiteness of protein powder. Overall, the present findings provide useful technological information relating to the production of FPI with and without a dehulling step.

Germination is a natural green technology to improve the nutritional and techno-functional quality of plant-based proteins. In this study, the mechanism of improving the functional and antioxidant properties of black and white sesame protein isolates (SPI) through germination process was investigated. Results showed that the surface hydrophobicity and sulfhydryl content increased significantly after germination, which were supported by multispectral analysis suggesting the exposed and unfolded conformational transition of germinated SPI. Moreover, the increased particle size was observed by microscopy analysis and reducing electrophoresis, which indicated that depolymerized protein molecules were rearranged to form protein aggregates during germination. The structural modification induced by germination contributed to the superior solubility (increased to 3.15-fold and 2.36-fold at pH 8 for black and white SPI, respectively), foaming capacity (increased to 3.99-fold and 1.69-fold, respectively), emulsifying ability (increased to 2.84-fold and 2.71-fold, respectively), and diverse chemical antioxidant activities (increased up to 5.60-fold) of SPI in both varieties. This was the first comprehensive study to investigate germination as a promising technology for obtaining high-quality SPI.

The aim of this study was to interpret the interaction of phenolics with walnut protein and determine their effects on protein functional properties. The phenolic profiles of walnut meal (WM) and walnut meal protein isolate (WMPI) were established using UPLC-Q-TOF-MS. A total of 132 phenolic compounds were detected, including 104 phenolic acids and 28 flavonoids. Phenolic compounds bound to protein via hydrophobic interactions, hydrogen bonds, and ionic bonds were identified in WMPI. They were also present as free forms, but the hydrophobic interactions and hydrogen bonds were the main non-covalent binding forces between phenolics and walnut proteins. The interaction mechanisms were further supported by the fluorescence spectra of WMPI with ellagic acid and quercitrin. In addition, changes in the functional properties of WMPI after removal of phenolic compounds were evaluated. Dephenolization significantly increased water holding capacity, oil absorptive capacity, foaming capacity, foaming stability, emulsifying stability index, and the in vitro gastric digestibility. However, in vitro gastric-intestinal digestibility was not significantly affected. These results provide insights into the interactions between walnut protein and phenolics, which indicates potential strategies for removing phenolics from walnut protein.

The aim of this study was to investigate the effect of gellan gum (GG) on the cold gelation of large yellow croaker roe protein isolate (pcRPI). The water-holding ability and storage modulus of the pcRPI-GG binary gels increased with the GG concentration, where the storage modulus of the pcRPI-0.2% GG gel was approximately 30.7 times that of the pure pcRPI gel. Compare to the other binary gels, pcRPI-0.2% GG gels exhibited a lower lacunarity and higher junction density, with a denser, more aggregated microstructure. Consequently, curcumin was embedded in pcRPI-0.2% GG gels, and simulated gastrointestinal digestion test results showed that GG addition effectively protected and slowed curcumin release in the gastrointestinal environment. These findings may contribute to elucidating the interaction of pcRPI with GG and demonstrate the potential of binary gels for the embedding and delivery of active substances.

The aim of this study was to investigate the effects of hydrothermal treatment at different temperatures and times on the structure and functional properties of quinoa protein isolate (QPI). The structure of QPI was investigated by analyzing changes in the intrinsic fluorescence spectrum, ultra-violet (UV) spectrum, and Fourier transform infrared spectrum. The solubility, water/oil-holding capacity, emulsifying activity, and emulsion stability of QPI were studied, as were the particle size and the thermogravimetric properties of QPI. The results showed that the average particle size of QPI gradually increased with the increase in hydrothermal treatment time and temperature, and reached a maximum value of 121 °C for 30 min. The surface morphology also became rough and its thermal stability also increased. The endogenous fluorescence and UV spectral intensity at 280 nm decreased gradually with increasing hydrothermal treatment time and temperature, and reduced to the minimum values at 121 °C for 30 min, respectively. After hydrothermal treatment, the secondary structure of QPI tended to be disordered. The functional properties of QPI after treatment were all superior to those of the control. The results of this study might provide a basis for the processing and utilization of QPI.

Rana chensinensis ovum (RCO) is the major waste/by-product of Oviductus Ranae. This study investigated physicochemical characteristics and stability of emulsified Rana chensinensis ovum oil (RCOO) with Rana chensinensis ovum protein isolates (RCOPI) by particle size, zeta potential, scanning electron microscopy (SEM), visual appearance, confocal laser scanning microscopy (CLSM), rheology and antioxidant capacity. The emulsified RCOO demonstrated great stability, antioxidant capacity and rheological properties. The potential application of the emulsified RCOO as a delivery system was studied using quercetin as an example. The stability of encapsulated quercetin was investigated through storage stability, thermal stability and photostability. The bioaccessibility of encapsulated quercetin was explored by in vitro digestion simulation experiments. The results showed the stability and bioaccessibility of quercetin encapsulated in emulsified RCOO was greatly improved. This study showed that the emulsified RCOO is a promising edible delivery system for hydrophobic bio-actives.

The physicochemical, structural, and functional properties of albumin, globulin, glutelin, and protein isolate (JSPI) extracted from jackfruit seeds were investigated. Protein fractions and JSPI were rich in amino acids, which can be comparable to soy protein. Other essential amino acids except histidine met the FAO/WHO/UNO-recommended intake for infants and adults. Jackfruit seed proteins were mainly composed of 17-26 kDa polypeptides, β-sheet, and random coil were the main secondary structures. Glutelin (572.55) and JSPI (246.14) have higher H0 under neutral conditions, consistent with the solubility and emulsification properties results. Albumin and globulin had good solubility and were mostly soluble under neutral or weak alkaline conditions. In general, protein fractions and JSPI exhibited good foaming and emulsification properties. Therefore, jackfruit seed proteins have the potential to be nutritious functional ingredients in the food industry. PRACTICAL APPLICATION: Jackfruit seed proteins had high essential amino acids content and good functional properties. They can be used as a new type of functional ingredients in the food industry, which can not only reduce the environment pollution of discarded seeds but also improve use of plant protein.

The goal of this work is to explore if pH-shift processing could be used as a cold refinery technique to manufacture pig brain protein isolate (PI). Pig brain protein had the highest solubility at pH 2 (acid method) and pH 12 (alkaline method). As the protein solution\'s zeta-potential was near 0 with the lowest solubility, pH 5.0 was chosen as the precipitation pH. Alkaline process produced a 32% dry matter yield with phospholipid content of 35 mg/100 g. The alkaline-made PI was better at forming soft gels and had good emulsifying and foaming capabilities. Although the acid-made PI included less residual lipid and total haem protein and was whiter in colour, it could not be gelled. Acid-made PI was more prone to lipid oxidation with a poorer ability to function as an emulsifier and foaming agent. Thus, functional proteins from pig brain may be isolated using the alkaline pH-shift technique.