Modification mechanism of protein in rice adjuncts upon extrusion and its effects on nitrogen conversion during mashing

Transforming oilseed blends: the impact of low-moisture extrusion on antinutritional factors, protein structure, and nutritional value

Oilseed cakes from hemp, rapeseed, and flaxseed are protein-rich, sustainable sources but are limited in food applications by antinutritional factors. This study blended meals from these oilseeds with pea or hemp protein ingredients (50:50 w/w) and applied low moisture extrusion (10 % and 20 %) at 122 °C to investigate their impact on physicochemical characteristics of oilseeds blends. Extrusion preserved protein content, reduced protein solubility by up to 44.5 %, and improved in vitro digestibility by up to 13.5 %. Antinutritional factors, including polyphenols (-10.18 % to -52.80 %), saponins (-4.48 % to -21.31 %), condensed tannins (-20.37 % to -41.05 %), and trypsin inhibitors (-2.26 TIU/mg to -13.31 TIU/mg), were significantly reduced, though phytic acid content was less affected. Extrusion decreased surface hydrophobicity, disrupted protein-protein interactions, altered secondary structures, and retained protein profiles under reducing conditions. These findings provided valuable scientific insights into the application of extrusion in enhancing nutritional value and modifying structure of plant-based meat alternatives.

Understanding the anti-browning mechanism and physicochemical properties in potato pulp during the magnetic field processing

To reduce the detrimental effects of enzymatic-browning on potato pulp quality, this study investigated the anti-browning potential of magnetic field at varying intensities. The magnetic field (4 mT) enhanced the structural integrity of potato pulp cells, with the highest hardness (119.37 g). Furthermore, the potato pulp subjected to a magnetic field treatment of 4 mT for 60 min at a temperature of 32 °C (PP-MF-4) shown an orderly macromolecular aggregation, increased viscoelastic properties of potato pulp. The PP-MF-4 demonstrated excellent anti-browning capability, as evidenced by the highest L⁎ value (59.18), reduced browning index, and lower accumulation of browning-products. Furthermore, the PP-MF-4 exhibited a significant reduction in oxidative damage, attributed to enhanced antioxidant activity and total phenolic content. Besides, the PP-MF-4 inhibited browning enzymes and improved the molecular structure orderliness. Consequently, magnetic field presents a viable approach for mitigating enzymatic-browning in potato pulp, offering a promising methods for preserving its quality.

Enrichment of Trypsin Inhibitor from Soybean Whey Wastewater Using Different Precipitating Agents and Analysis of Their Properties

Recovering valuable active substances from the by-products of agricultural processing is a crucial concern for scientific researchers. This paper focuses on the enrichment of soybean trypsin inhibitor (STI) from soybean whey wastewater using either ammonium sulfate salting or ethanol precipitation, and discusses their physicochemical properties. The results show that at a 60% ethanol content, the yield of STI was 3.983 mg/mL, whereas the yield was 3.833 mg/mL at 60% ammonium sulfate saturation. The inhibitory activity of STI obtained by ammonium sulfate salting out (A-STI) was higher than that obtained by ethanol precipitation (E-STI). A-STI exhibited better solubility than E-STI at specific temperatures and pH levels, as confirmed by turbidity and surface hydrophobicity measurements. Thermal characterization revealed that both A-STI and E-STI showed thermal transition temperatures above 90 °C. Scanning electron microscopy demonstrated that A-STI had a smooth surface with fewer pores, while E-STI had a rough surface with more pores. In conclusion, there was no significant difference in the yield of A-STI and E-STI (p < 0.05); however, the physicochemical properties of A-STI were superior to those of E-STI, making it more suitable for further processing and utilization. This study provides a theoretical reference for the enrichment of STI from soybean whey wastewater.

Understanding the mechanism for sodium tripolyphosphate in improving the physicochemical properties of low-moisture extrusion textured protein from rapeseed protein and soybean protein blends

Our previous experiments found that rapeseed protein (RP) has applicability in low-moisture textured proteins. The amount of RP added is limited to <20 %, but the addition of 20 % RP still brings some negative effects. Therefore, in order to improve the quality of 20%RP textured protein, this experiment added different proportions of sodium tripolyphosphate (STPP) to improve the quality of the product, and studied the physical-chemical properties and molecular structure changes of the product to explore the possible modification mechanism. The STPP not only improved the expansion characteristics of extrudates, but also increased the brightness of the extrudates, the rehydration rate. In addition, STPP increased the specific mechanical energy during extrusion, decreased the material mass flow rate. Furthermore, STPP decreased the starch digestibility, increased the content of slow-digesting starch and resistant starch. STPP increased the degree of denaturation of extrudate proteins, the proportion of β-sheets in the secondary structure of proteins, as well as the intermolecular hydrogen bonding interactions. The gelatinization degradation degree of starch molecules also decreased with the addition of STPP. STPP also increased the protein-starch interactions and enhanced the thermal stability of the extrudate. All these indicate that STPP can improve the physical-chemical properties of extrudate.

Effect of high moisture extrusion on the structure and physicochemical properties of Tartary buckwheat protein and its in vitro digestion

Tartary buckwheat is rich in nutrients and its protein supports numerous biological functions. However, the digestibility of Tartary buckwheat protein (TBP) poses a significant limitation owing to its inherent structure. This study aimed to assess the impact of high moisture extrusion (HME, 60 % moisture content) on the structural and physicochemical attributes, as well as the in vitro digestibility of TBP. Our results indicated that TBP exhibited unfolded and amorphous microstructures after HME. The protein molecular weight of TBP decreased after HME, and a greater degradation was observed at 70 °C than 100 °C. In particular, HME at 70 °C caused an almost complete disappearance of bands near 35 kDa compared with HME at 100 °C. In addition, compared with native TBP (NTBP, 44.53 µmol/g protein), TBP subjected to HME at 70 °C showed a lower disulfide bond (SS) content (42.67 µmol/g protein), whereas TBP subjected to HME at 100 °C demonstrated a higher SS content (45.70 µmol/g protein). These changes endowed TBP with good solubility (from 55.96 % to 83.31 % at pH 7), foaming ability (20.00 %-28.57 %), and surface hydrophobicity (8.34-23.07). Furthermore, the emulsifying activity (EA) and in vitro digestibility are closely related to SS content. Notably, extruded TBP (ETBP) obtained at 70 °C exhibited higher EA and digestibility than NTBP, whereas ETBP obtained at 100 °C showed the opposite trend. Consequently, HME (especially at 70 °C) demonstrated significant potential as a processing technique for improving the functional and digestive properties of TBP.

Caffeic Acid Phenethyl Ester Encapsulated in Self-Assemble Rice Peptides Nanoparticles: Storage Stability, In Vitro Release, and Their Interaction Mechanisms

Caffeic acid phenethyl ester (CAPE) is an important active component of propolis with many bioactivities. However, its efficiency and practical application are restricted due to its poor aqueous solubility and storage stability. In this study, a nanocarrier was fabricated to encapsulate CAPE using self-assembled rice peptides obtained by controllable enzymolysis. The physicochemical properties, encapsulation efficiency, and loading capacity of rice peptides nanoparticles (RPNs) were characterized. The storage stability, in vitro release, and interaction mechanisms between CAPE and RPNs were investigated. The results showed that RPNs, mainly assembled by disulfide bonds and hydrogen bonds, possessed an effective diameter of around 210 nm and a high encapsulation efficiency (77.77%) and loading capacity (3.89%). Importantly, the water solubility of CAPE was increased by 45 times after RPNs encapsulation. Moreover, RPNs encapsulation also significantly increased CAPE stability, about 1.4-fold higher than that of unencapsulated CAPE after 18-day storage. An in vitro release study demonstrated that RPNs could delay the release of CAPE, implying a better CAPE protection against extreme environments during digestion. Hydrogen bond and van der Waals force are the predominant interaction forces between RPNs and CAPE. Therefore, the newly developed nanoparticle is a potential delivery system that could effectively improve the aqueous solubility and stability of CAPE.

Authentication of ST25 rice using temperature-perturbed Raman measurement with variable selection by Incremental Association Markov Blanket

A temperature-perturbed transmission Raman measurement was demonstrated for the discrimination of ST25 and non-ST25 rice samples. ST25 rice is a premium long-grain Vietnamese rice with the aroma of pandan leaves and the scent of early sticky rice. Raman spectra of rice samples were acquired with temperature perturbation ranging from 20 to 50 °C, and the variables (intensities of peaks) with greater discrimination were selected from the spectra using Incremental Association Markov Blanket (IAMB) for authentication. The combination of four, seven, and four variables selected from the spectra at 20, 30, and 50 °C, respectively, yielded the highest accuracy of 97.9%. The accuracies in the single-temperature measurements were lower, suggesting that the combination of mutually complementary spectral features acquired at these temperatures is synergetic to recognize the compositional differences between two sample groups, such as in the amylose/amylopectin ratio and the protein constituent.

Properties of texturized protein and performance of different protein sources in the extrusion process: A review

The need for protein is increasing due to the rapid growth of the global population. However, conventional animal meat production has caused severe environmental, land usage, and other issues. Meat substitutes can provide consumers with a high-quality alternative to protein. Texturized protein (TP) is a critical ingredient in meat substitutes and is mainly obtained through extrusion processing. Therefore, this review first discussed the essential physical properties of TP, including appearance and structure, water-holding capacity (WHC) and oil-holding capacity (OHC), texture, and sensory properties. The performance of plant and novel source proteins in extrusion processing is also summarized. The properties of the desired TP should be considered first before extrusion processing. Under different extrusion parameters, proteins from the same source can exhibit varying properties. Although the novel source proteins can adversely affect TP quality, their high yield and environmental protection are worthy of further study. This paper aims to review the impact of proteins from different sources on the properties of TP during the extrusion process and discuss practical research methods for TP.

Carbon and nitrogen sources consumption by ale and lager yeast strains: a comparative study during fermentation

The rapid and efficient consumption of carbon and nitrogen sources by brewer's yeast is critical for the fermentation process in the brewing industry. The comparison of the growth characterizations of typical ale and lager yeast, as well as their consumption preference to carbon and nitrogen sources were investigated in this study. Results showed that the ale strain grew faster and had a more extended stationary phase than the lager strain. However, the lager strain was more tolerant to the stressful environment in the later stage of fermentation. Meanwhile, the ale and lager yeast strains possessed varying preferences for metabolizing the specific fermentable sugar or free amino acid involved in the wort medium. The lager strain had a strong capacity to synthesize the extracellular invertase required for hydrolyzing sucrose as well as a strong capability to metabolize glucose and fructose. Furthermore, the lager strain had an advantage in consuming Lys, Arg, Val, and Phe, whereas the ale strain had a higher assimilation rate in consuming Tyr. These findings provide valuable insights into selecting the appropriate brewer's yeast strain based on the wort components for the industrial fermentation process. KEY POINTS: • The lager strain is more tolerant to the stressful environment. • The lager strain has the great capability to synthesize the extracellular invertase. • The assimilation efficiency of free amino acid varies between ale and lager.

Further Interpretation of the Volatile, Microbial Community and Edible Quality of Fresh Fermented Rice Noodles with Different Selected Strains

Understanding bacteria and yeasts can reduce unpredictable changes in fresh fermented rice noodles (FFRN). The effects of selected strains (Limosilactobacillus fermentum, Lactoplantibacillus plantarum, Lactococcus lactis and Saccharomyces cerevisiae) on the edible quality, microbial community, and volatile component of FFRN were studied. The results indicated that the fermentation time could be shortened to 12 h when Limosilactobacillus fermentum, Lactoplantibacillus plantarum, and Lactococcus lactis were added, whereas it still required approximately 42 h after adding Saccharomyces cerevisiae. Only a steady bacterial composition was provided by adding Limosilactobacillus fermentum, Lactoplantibacillus plantarum, and Lactococcus lactis, and only a steady fungal composition was provided by adding Saccharomyces cerevisiae. Therefore, these microbial results indicated that the selected single strains cannot improve the safety of FFRN. However, the cooking loss was decreased from 3.11 ± 0.11 to 2.66 ± 0.13 and the hardness of FFRN was increased from 1186 ± 178 to 1980 ± 207 when it was fermented with single strains. Finally, a total of 42 volatile components were determined by Gas chromatography-ion Mobility Spectrometry and 8 aldehydes, 2 ketones, and 1 alcohol were added during the entire fermentation process. The main volatile components were different during fermentation depending on the added strain, and there was the greatest variety of volatiles in the group with added Saccharomyces cerevisiae.