Protein Hydrolysis Research Articles

Discovery of a temperature-dependent protease spoiling meat from Pseudomonas fragi: Target to myofibrillar and sarcoplasmic proteins rather than collagen

Chilled meat frequently suffered microbial spoilage because bacteria can secrete various proteases that break down the proteins. In this study, Pseudomonas fragi NMC 206 exhibited a temperature-dependent secretion pattern, with the ability to release the specific protease only below 25 °C. It was identified as alkaline protease AprA by LC-MS/MS, with the molecular weight of 50.4 kDa, belonging to the Serralysin family metalloprotease. Its significant potential for meat spoilage in situ resulted in alterations in meat color and sensory evaluation, as well as elevated pH, total volatile basic nitrogen (TVB-N) and the formation of volatile organic compounds (VOCs). The hydrolysis of meat proteins in vitro showed that AprA possessed a considerable proteolysis activity and degradation preferences on meat proteins, especially its ability to degrade myofibrillar and sarcoplasmic proteins, rather than collagen. These observations demonstrated temperatures regulated the secretion of AprA, which was closely related to chilled chicken spoilage caused by bacteria. These will provide a new basis for the preservation of meat products at low temperatures.

Degree of hydrolysis of chicken versus plant-based chicken analogues: An in vitro digestion comparison

The adoption of plant-based meat analogues is increasing as an alternative to real meat products among consumers because they offer a more ecologically friendly and sustainable source of protein while also alleviating the ethical concerns related to livestock rearing and slaughter (1). However, there are concerns regarding plant-based meat analogues in terms of its nutritional quality, particularly their protein digestibility. This study aims to compared between chicken and plant-based chicken analogues in terms of nutritional composition and degree of protein hydrolysis.Proximate analyses were performed for raw and cooked samples to assess protein, fat, and energy concentrations in two chicken samples (breast and thigh) and four commercial plant-based chicken (P-C1[Wheat Protein 37%, Pea Protein 10%], P-C2 [ Soya Protein 63%], P-C3 [ Soya and Wheat Protein 83%], and P-C4 [Soya Protein 30%, Pea Protein 2%]). As a first step, the proximate analyses were assessed for the averaged samples, then the product-cooking interactions was assessed using a one-way ANOVA followed by Tukey test (p <0.05). In vitro digestion was performed following the INFOGEST harmonised static in vitro digestion model (2) for cooked samples. After digestion, o- Phthaldialdehyde (OPA) assay was carried out to measure the degree of protein hydrolysis for each sample, and two-way ANOVA test was performed.Protein content of chicken was higher compared with the plant-based chicken, whereas fat content and energy concentrations were higher in plant-based chicken. The protein content of chicken was higher for raw and cooked samples (raw: 19.8 ± 0.38 g/100 g; cooked: 30.55 ± 4 g/100g), compared with plant-based chicken (raw: 13.8 ± 5.3 g/100 g; cooked: 23.4 ± 4.5 g/100g). Plant-based chicken have a higher fat content and energy concentrations for raw and cooked samples (raw:6.52 ± 1.5 g/100 g; cooked: 9.6 ± 3.17 g/100g) and (raw:189.4 ± 28.1 g/100 g; cooked: 291.3 ± 48.1 g/100g) respectively; compared to chicken fat content (raw:4.6 ± 2.7 g/100 g; cooked: 6.1 ± 4 g/100g) and energy concentration (raw:150.9 ± 25.4 g/100 g; cooked: 228.3 ± 20.7 g/100g). The product-cooking interactions showed a significant increase (P ≤0.0001) in the protein content (raw: 15.6 ± 2.3g/100g to 19.8 ± 0.74 g/100g; cooked: 21.4 ± 0.55 g/100g to 33.06 ± 0.71 g/100g), and fat content P<0.001 (raw: 2.7 ± 0.06 g/100g to 8.3 ± 0.27 g/100g; cooked: 3.29 ± 0.19 g/100g to 13.22 ± 0.33 g/100g) in both chicken and plant-based chicken samples. No significant product-cooking interactions on energy content was found. The results from a two-way ANOVA test of the OPA and the degree of hydrolysis analyses demonstrated a significant increase in the degree of hydrolysis of chicken samples compared with plant-based chicken (P<0.0001).The degree of hydrolysis and digestibility of chicken and chicken analogues was influenced by protein type, nutrient composition, and processing. These findings would provide substantial information for the improvement of plant-based chicken products with enhanced nutritional profiles. This work will be extended to investigate the availability and digestibility of individual amino acids.

Effect of transglutaminase crosslinking combined with lactic fermentation on the potential allergenicity and conformational structure of soy protein.

Food allergies are a growing concern worldwide, with soy proteins being important allergens that are widely used in various food products. This study investigated the potential of transglutaminase (TGase) and lactic acid bacteria (LAB) treatments to modify the allergenicity and structural properties of soy protein isolate (SPI), aiming to develop safer soy-based food products. Treatment with TGase, LAB or their combination significantly reduced the antibody reactivity of β-conglycinin and the immunoglobulin E (IgE) binding capacity of soy protein, indicating a decrease in allergenicity. TGase treatment led to the formation of high-molecular-weight aggregates, suggesting protein crosslinking, while LAB treatment resulted in partial protein hydrolysis. These structural changes were confirmed by Fourier transform infrared spectroscopy, which showed a decrease in β-sheet content and an increase in random coil and β-turn contents. In addition, changes in intrinsic fluorescence and ultraviolet spectroscopy were also observed. The alterations in protein interaction and the reduction in free sulfhydryl groups highlighted the extensive structural modifications induced by these treatments. The synergistic application of TGase and LAB treatments effectively reduced the allergenicity of SPI through significant structural modifications. This approach not only diminished antibody reactivity of β-conglycinin and IgE binding capacity of soy protein but also altered the protein's primary, secondary and tertiary structures, suggesting a comprehensive alteration of SPI's allergenic potential. These findings provide a promising strategy for mitigating food allergy concerns and lay the foundation for future research on food-processing techniques aimed at allergen reduction. © 2024 Society of Chemical Industry.

Insights into the starch and proteins molecular structure changes of foxtail millet sourdough: Effect of fermentation from grains of cereal to pre-meal

This study investigated the effects of foxtail millet sourdough fermentation time (0, 8, 16, and 24 h) on the protein structural properties, thermomechanical, fermentation, dynamic rheological, starch granules crystalline regions molecular mobility, and starch microstructural characteristics. The fermentation led to a significant increase in the concentration of free amino acids from protein hydrolysis. Fourier transform infrared spectroscopy (FTIR) revealed changes in protein secondary structure and the presence of functional groups of different bioactive compounds. The result of thermomechanical properties showed a significant increase in the stability (0.70–0.79 min) and anti-retrogradation ability (2.29–3.14 Nm) of lactic acid bacteria (LAB) sourdough compared to the control dough, showing a wider processing applicability with radar profiler index. In contrast, sourdoughs with lower tan δ values had higher elasticity and strength. Scanning electron microscopy showed that the surface of the starch appeared from smooth to uneven with patchy shapes and cavities, which declined the crystallinity from 34.00 % to 21.57 %, 23.64 %, 25.09 %, and 26.34 % respectively. Fermentation changed the To, Tp, Tc, and ΔH of the starch. The results of the study will have great potential for application in the whole grain sourdough industry.

Tomato (Solanum lycopersicum) leaf juice as enzyme source: A study on the impact of endogenous proteases on plant proteins

Tomato leaves are by-products of tomato production and can be considered as source of enzymes due to its endogenous proteolytic activity. The endogenous proteases can alter the functionality of other proteins. In this study, we investigated the effect of tomato leaf juice on the properties of a selected number of plant proteins, with focus on the endogenous proteases. The effect was analyzed at molecular scale using SDS-PAGE and HPSEC and at colloidal scale in terms of protein dispersibility, particle size distribution and viscosity. Lastly, the effects on the gelation behavior and rheological properties were characterized. We observed partial hydrolysis of all plant proteins under the tested conditions. The hydrolysis was specific for each protein and incomplete. The partial hydrolysis resulted in significant changes in protein dispersibility and particle size. For plant proteins with low protein dispersibility, dispersibility increased due to size reduction of the swollen particles. For plant proteins with high protein dispersibility, dispersibility decreased due to the formation of larger aggregates. The partial hydrolysis also resulted in small increase of viscosity, with exception of soy protein isolate, of which the viscosity decreased. Finally, the partial hydrolysis resulted in reduction of the least gelling concentration for all plant proteins, while some of the formed gels exhibiting higher gel strength than the corresponding water gels. This suggests that partial hydrolysis led to formation of more interactions, but these interactions were mostly weak. To conclude, our findings provided a comprehensive overview of the effects of tomato leaf juice proteases on plant proteins.

Effect of silk fibroin protein hydrolysis on biochemistry, gelation kinetics, and NF-kB bioactivity in vitro

Fibroin is a structural protein derived from silk cocoons, which may be used in a variety of biomedical applications due to its high biocompatibility and controllable material properties. Conversely, fibroin solution is inherently unstable in solution, which limits its potential utility. Fibroin hydrolysates possess enhanced aqueous solubility and stability, with known anti-inflammatory bioactivity. Here, silk-derived protein (SDP) was produced through controlled time, temperature, and pressure conditions to generate a novel and reproducible hydrolysate population. Both regenerated fibroin and SDP solution stability were characterized for MWD, amino acid content, solubility, viscosity, surface interaction, secondary structure formation, and in vitro assessment of NF-kB pathway activity. Mechanistic studies indicate that hydrolysis processing is required to enhance material stability by abolishing fibroin's ability to self-associate. In vitro assays using HCLE cells indicate SDP has dose dependent potency for inhibiting NF-kB driven gene expression of TNF-α and MMP-9. Collectively, the results support SDP's use as an anti-inflammatory wetting agent compatible with a wide range of both biomedical and industrial applications. Furthermore, the conditions used to generate SDP hydrolysates are readily accessible, produce a highly consistent material from batch-to-batch, and permit widespread investigation of this novel population for these purposes.

Gelatinization and fermentation synergy: investigating the protein digestibility, mineral bioaccessibility and microstructural transformations of black mash beans through Saccharomyces cerevisiae and Lactobacillus spp

ABSTRACT This study explored the nutritional qualities of black mash bean flour impacted by fermentation, gelatinization and their combination. Protease activity, in vitro protein digestibility (IVPD), and protein solubility were evaluated for both fermented and unfermented black mash bean flour samples. Interestingly, when compared to fermented samples and gelatinized mash bean flour (GMBF), raw mash bean flour (RMBF) showed the highest protein solubility. Due to enzymatic activity and protein hydrolysis, fermentation with Lactobacillus E14 and Saccharomyces cerevisiae MK-157 enhanced protein solubility. Prolonged fermentation timeframes were positively correlated with protease activity and IVPD, suggesting the degradation of complex proteins. The highest levels of IVPD (90.12%) and protease activity (5546.78 U/g) were detected in GMBF fermented by S. cerevisiae MK-157, indicating the impact of fermentation on protein breakdown. The Lactobacillus E14-fermented RMBF exhibited 5521.45 U/g of protease activity and 87.54% IVPD. The mineral content of the fermented samples was substantially greater than that of the unfermented GMBF. The increased calcium, magnesium, potassium, sodium, iron, zinc, and copper levels for the GMBF fermented by S. cerevisiae MK-157 indicated that fermentation facilitated the release of minerals from chelated compounds. Microscopic examination revealed higher protein quantities in the fermented flour as well as hydrolyzed and broken starch granules embedded in the protein matrix. Large mash bean proteins were shown to be proteolyzed during fermentation into smaller peptides by SDS PAGE. Storage proteins were extensively broken down during fermentation with S. cerevisiae MK-157, whereas Lactobacillus E14 displayed a more focused pattern of hydrolysis. The nutritional profile of black mash bean flour was improved by fermentation with Lactobacillus E14 and S. cerevisiae MK-157.

In vitro digestion of starch and protein aerogels generated from defatted rice bran via supercritical carbon dioxide drying

This study investigated the in vitro digestibility of starch and protein aerogels produced from defatted rice bran (DRB), an underutilized rice processing byproduct, using supercritical carbon dioxide (SC-CO2) drying. The extracted starch (i.e., purified starch), crude starch, and proteins were used for the aerogel formation at 15% (w/w) concentration and further characterized. All aerogels exhibited three-dimensional open porous structures with high surface areas of 36–47 m2/g, densities lower than 0.3 g/cm3, and porosities higher than 84%. The starch hydrolyses in starch and crude starch aerogels were 86 and 73%, respectively, while the protein hydrolysis in protein aerogels reached up to 82% after sequential oral, gastric, and intestinal digestion. Thus, the hydrolysis rates achieved in simulated digestions suggest that the developed aerogels from DRB have the potential to serve as vehicles for delivering bioactive compounds and add value to the underutilized DRB.

Characteristics of infant formula consumed in the first months of life and allergy in the EDEN mother-child cohort.

The evidence regarding the association between infant formula (IF) composition and the prevention of allergy and respiratory diseases remains sparse and inconclusive. This study aimed to evaluate whether some IF characteristics were associated with the risk of allergy or respiratory diseases in childhood. Among1243 formula-fed children from the EDEN mother-child cohort, IF characteristics concerning long-chain polyunsaturated fatty acids (LCPUFAs) enrichment, prebiotic/probiotic enrichment, and hydrolysis of proteins were identified from the ingredients list. Eczema, wheezing, food allergy, asthma, and allergic rhinitis up to age 8 years were prospectively collected and summarized into four allergic and respiratory multimorbidity clusters. Associations between 4-month IF characteristics and risk of allergy or respiratory diseases were tested using logistic regressions adjusted on main confounders. The consumption of LCPUFA-enriched formula was not linked to allergic and respiratory multimorbidity clusters, but to a lower risk of any allergy, eczema, and wheezing. Probiotic-enriched formula consumption was associated with a lower risk of belonging to the 'Allergy without asthma' cluster (odds ratio [OR][95% confidence interval,CI] = 0.63 [0.40-0.99]), and consumption of a formula enriched in Bifidobacterium lactis was associated with a lower risk of any allergy (OR[95% CI] = 0.59 [0.41-0.85]). Partially hydrolysed formula (pHF) consumption was associated with a higher risk of belonging to the 'Allergy without asthma' cluster (OR[95%CI] = 2.73 [1.65-4.51]). This study confirms the positive association between pHFconsumption and the risk of allergy found in previous observational studies and suggests that consumption of LCPUFA-enriched or probiotic-enriched formula was associated with a lower risk of allergy.

New insights into the destabilization of fat globules in ultra-instantaneous UHT milk induced by added plasmin: Molecular mechanisms and the effect of membrane structure on plasmin action

Residual plasmin activity in whole ultra-instantaneous UHT (UI-UHT) milk causes rapid fat rise during storage, seriously affecting consumers' purchase intentions. In this work, the molecular mechanisms underlying fat destabilization in whole UI-UHT milk by added plasmin were investigated based on the hydrolysis behavior of interfacial proteins. By using SDS-PAGE and peptidomic analysis, we found that the hydrolysis of interfacial proteins by plasmin led to a decrease in the amount and coverage of interfacial proteins and an increase in zeta-potential value, causing the flocculation and coalescence of fat globules. Moreover, the hydrolysis pattern varied in different categories of interfacial proteins by plasmin. In total, 125 peptides in all samples were identified. Plasmin tended to hydrolyze most major milk fat globule membrane (MFGM) proteins into protein fragments (>10 kDa) rather than peptides (<10 kDa). In contrast, peptides derived from caseins were more preferentially identified within a relatively short incubation time. It was the co-hydrolysis of caseins and some major MFGM proteins as anchors that destroyed the stability of MFGM. Furthermore, studies on the effect of trilayer membrane structure remaining at the interface on the hydrolysis rate of major MFGM proteins by plasmin revealed that ADPH and BTN were very sensitive to plasmin action, while PAS 7 was very resistant to plasmin action. Overall, membrane structure reduced the susceptibility of some major MFGM proteins to plasmin and provided protective effects. Therefore, this study provided important insights into the hydrolysis behavior of interfacial proteins in whole UI-UHT milk induced by plasmin.

Ultrasonic monitoring of enzymatic hydrolysis of proteins. 2. relaxation effects

The paper investigates the occurrence of relaxation processes in enzymatic hydrolysis of whey proteins in phosphate buffer using high-resolution ultrasonic spectroscopy. The hydrolysis produces a frequency-dependent evolution of ultrasonic velocity and attenuation originated by the proton transfer between the phosphate ions and the terminal −NH2 group of protein hydrolysates. Such frequency dependence is absent in other systems, e.g., Tris buffer. Real-time profiles of ultrasonic velocity and attenuation measured during the hydrolysis of β–lactoglobulin, α–lactalbumin and bovine serum albumin by α–chymotrypsin were employed in quantitative analysis of the relaxation mechanisms, relaxation times, determination of the proton transfer rate constants and the reaction volume. The proton transfer is characterised by the rate constant 9.4 × 107 L mol−1 s−1 and the adiabatic reaction volume 24 × 10−6 m3 mol−1. The obtained reaction volume agrees well with thermodynamic data for ionisation volumes and enthalpies of the terminal amino group and phosphate. The described methodology for estimating the relaxation contribution to ultrasonic characteristics allows for precision real-time ultrasonic measurements of the concentration of peptide bonds cleaved during protein hydrolysis in a broad range of environmental conditions.

Effects of sourdough-type fermentation and sorghum type on the techno-functional properties of the batter used for kisra, a fermented flatbread

Techno-functional properties of six sorghum types were determined during spontaneous sourdough batter-type fermentation for Kisra production. All sorghum types showed a progressive decrease in pH to about 3.3 with fermentation for 40 h, accompanied by an increase in titratable acidity and free amino nitrogen. Fermentation increased pasting viscosity at 16 and 24 h, but decreased at 40 h due to starch hydrolysis. Protein hydrolysis as shown by SDS-PAGE leads to disaggregation of flour particles and the release of starch granules to increase the pasting viscosity. Thus, starch was more freely available to absorb water to paste and produce a higher viscosity from zero to 40 h. The decrease in pasting viscosity from 24 h to 40 h of fermentation was related to starch hydrolysis, as there was a reduction in total starch in the batter and pitting of starch granules, as shown by scanning electron microscopy. Fermentation had a more significant effect on techno-functional properties than sorghum types. Low protein and high tannin contents among the sorghum type also showed higher pasting viscosity. The techno-functional changes of sorghum batter during fermentation, especially the high pasting viscosity, might be helpful for structure design of kisra and other gluten-free sorghum-based products.

Influence of flour extraction rate on static in vitro gastrointestinal digestion characteristics of wheat protein during conventional milling

SummaryThe flour extraction rate determines the components of wheat flour. However, the correlation between variations in components resulting from flour extraction rate and the protein digestion characteristics remains to be clarified. In this study, digestion characteristic of wheat flour protein influenced by flour extraction rates was investigated. The results indicated that the degree of protein hydrolysis, the number of peptides at the intestinal stage and the digestive rate constant (k) at the gastric stage exhibited a significant increase as the flour extraction rate increased (35%–85%). Moreover, wheat flour with 85% extraction rate presented the highest protein hydrolysis degree (25.85%), the most peptides (n = 79) and the maximum intestinal digestion rate constant (k = 0.0285). Therefore, increasing the flour extraction rate from 75% to 85% can improve the wheat flour protein digestibility in conventional milling, thereby establishing a fundamental basis for nutritional control of flour products.

Integrative Single-Cell Analysis of Cardiomyopathy Identifies Differences in Cell Stemness and Transcriptional Regulatory Networks among Fibroblast Subpopulations.

Cardiomyopathy encompasses a broad spectrum of diseases affecting myocardial tissue, characterized clinically by abnormalities in cardiac structure, heart failure, and/or arrhythmias. Clinically heterogeneous, major types include dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), restrictive cardiomyopathy (RM), ischemic cardiomyopathy (ICM), among which DCM is more prevalent, while ICM exhibits higher incidence and mortality rates. Myocardial injury during cardiomyopathy progression may lead to myocardial fibrosis. Failure to intervene early and inhibit the process of myocardial fibrosis may culminate in heart failure. Cardiac fibroblasts constitute crucial cellular components determining the extent and quality of myocardial fibrosis, with various subpopulations exerting diverse roles in cardiomyopathy progression. Despite this, understanding of the cellular plasticity and transcriptional regulatory networks of cardiac fibroblasts in cardiomyopathy remains limited. Therefore, in this study, we conducted comprehensive single-cell analysis of cardiac fibroblasts in cardiomyopathy to explore differences in cellular plasticity and transcriptional regulatory networks among fibroblast subpopulations, with the aim of providing as many useful references as possible for the diagnosis, prognosis, and treatment of cardiomyopathy. Cells with mitochondrial gene expression comprising >20% of total expressed genes were excluded. Differential expression genes (DEGs) and stemness genes within cardiac fibroblast subpopulations were subjected to Gene Ontology (GO) analysis of biological processes (BP) and AUCell analysis. Monocle software was employed to analyze the pseudo-temporal trajectory of cardiac fibroblasts in cardiomyopathy. Additionally, the Python package SCENIC was utilized to assess enrichment of transcription factors and activity of regulators within cardiac fibroblast subpopulations in cardiomyopathy. Following batch effect correction, 179,927 cells were clustered into 32 clusters, designated as T_NK cells, endothelial cells, myeloid cells, fibroblasts, pericytes, SMCs, CMs, proliferating cells, EndoCs, and EPCs. Among them, 8148 fibroblasts were further subdivided into 4 subpopulations, namely C0 THBS4+ Fibroblasts, C1 LINC01133+ Fibroblasts, C2 FGF7+ Fibroblasts, and C3 AGT + Fibroblasts. Results from GO_BP and AUCell analyses suggest that C3 AGT + Fibroblasts may be associated with immune response activation, protein transport, and myocardial contractile function, correlating with disease progression in cardiomyopathy. Transcription factor enrichment analysis indicates that FOS is the most significant TF in C3 AGT + Fibroblasts, also associated with the M1 module, possibly implicated in protein hydrolysis, intracellular DNA replication, and cell proliferation. Moreover, correlation analysis of transcriptional regulatory activity between fibroblast subpopulations reveals a more pronounced heterogeneity within C3 AGT + Fibroblasts in cardiomyopathy. C3 AGT + Fibroblasts exhibit increased sensitivity towards adverse outcomes in cardiomyopathy, such as myocardial fibrosis and impaired cardiac contractile function, compared to other cardiac fibroblast subpopulations. The differential cellular plasticity and transcriptional regulatory activity between C3 AGT + Fibroblasts and other subgroups offer new perspectives for targeting fibroblast subpopulation activity to treat cardiomyopathy. Additionally, stemness genes EPAS1 and MYC, along with the regulator FOS, may play roles in modulating the biological processes of cardiac fibroblasts in cardiomyopathy.

Amino acid profile behavior during the fermentation of Criollo cocoa beans

The study investigated the behavior of seventeen amino acids during spontaneous (SF) and starter culture (SC) fermentation of Criollo cocoa beans from Copallín, Guadalupe and Tolopampa, Amazonas-Peru. For this purpose, liquid chromatography (UHPLC) was used to quantify amino acids. Multivariate analysis was used to differentiate the phases of the fermentation process. The percentage of essential amino acids during SC fermentation (63.4%) was higher than SF (61.8%); it was observed that the starter culture accelerated their presence and increased their concentration during the fermentation process. The multivariate analysis identified a first stage (day 0 to day 2), characterized by a low content of amino acids that increased due to protein hydrolysis. The study showed that adding the starter culture (Saccharomyces cerevisiae) to the fermentation mass increased the concentration of essential amino acids (63.0%) compared to the spontaneous process (61.8%). Moreover, this addition reduced the fermentation time (3–4 days less), demonstrating that the fermentation process with a starter culture allows obtaining a better profile of amino acids precursors of flavor and aroma.

Fibrillation of soy protein isolate in the presence of metal ions: Structure and gelation behavior

The structure and functional properties of protein fibrils are closely related to environmental factors in fibrillation. Herein, soy protein isolate fibrils (SPIFs, 22 mg/mL) were prepared under acid-heating conditions in the presence of 100 mM metal ions (K+, Na+, Ca2+, Mg2+, and Fe3+). Except for Fe3+, fibrillation and subsequent larger fibril aggregates were promoted, ultimately leading to gel formation. Compared with K+ or Na+, the addition of Ca2+ or Mg2+ resulted in more organized SPIF structures with increased β-sheet contents and higher ThT fluorescence intensities. Furthermore, both of them resulted in longer fibrils with an average contour length of 700–800 nm, which significantly enhanced the storage modulus. However, the presence of Fe3+ accelerated protein hydrolysis and inhibited SPIF formation, resulting in samples consistently exhibited liquid behavior. These findings provide a foundation for understanding the influence of metal ions on regulating the fibrillation and gelling properties of SPIFs.

Antioxidant and Anti-Inflammatory Properties of Hydrolyzed Royal Jelly Peptide in Human Dermal Fibroblasts: Implications for Skin Health and Care Applications.

Hydrolyzed royal jelly peptide (RJP) has garnered attention for its health-promoting functions. However, the potential applications of RJP in skincare have not been fully explored. In this study, we prepared RJP through the enzymatic hydrolysis of royal jelly protein with trypsin and investigated its antioxidant and anti-inflammatory properties on primary human dermal fibroblasts (HDFs). Our results demonstrate that RJP effectively inhibits oxidative damage induced by H2O2 and lipid peroxidation triggered by AAPH and t-BuOOH in HDFs. This effect may be attributed to the ability of RJP to enhance the level of glutathione and the activities of catalase and glutathione peroxidase 4, as well as its excellent iron chelating capacity. Furthermore, RJP modulates the NLRP3 inflammasome-mediated inflammatory response in HDFs, suppressing the mRNA expressions of NLRP3 and IL-1β in the primer stage induced by LPS and the release of mature IL-1β induced by ATP, monosodium urate, or nigericin in the activation stage. RJP also represses the expressions of COX2 and iNOS induced by LPS. Finally, we reveal that RJP exhibits superior antioxidant and anti-inflammatory properties over unhydrolyzed royal jelly protein. These findings suggest that RJP exerts protective effects on skin cells through antioxidative and anti-inflammatory mechanisms, indicating its promise for potential therapeutic avenues for managing oxidative stress and inflammation-related skin disorders.

Honey induces changes in the molecular structure and microstructure of gluten in wheat-rye sourdoughs.

Chemical oxidizers and redox enzymes have traditionally been used to enhance the quality of baked goods. However, consumers now seek natural and clean-label ingredients, avoiding those with chemical-sounding names. Honey, a natural source of glucose oxidase (GOX), represents a promising alternative to purified enzymes for baking purposes. This study aimed to evaluate the effect of honey on the molecular structure and microstructure of gluten proteins in sourdough fermented by different lactic acid bacteria (LAB) strains. Four wheat-rye (1:1) sourdoughs were prepared, each supplemented with honey and inoculated with a different LAB strain. Additionally, two uninoculated doughs, one with honey (honey dough) and the other without (control dough), were prepared under identical conditions. Electronic paramagnetic resonance spectroscopy revealed the presence of hydrogen peroxide in honey solutions, indicating its role as an active source of GOX. Raman spectroscopy showed that honey addition altered the molecular structure of gluten by increasing the proportion of random coils at the expense of α-helix structures. This change is likely attributed to the competition between honey sugars and gluten proteins for water molecules in this system. Moreover, honey led to a decrease in the free sulfhydryl content of gluten compared to the control dough, suggesting an increase in disulfide crosslinking points. These enhanced protein-protein interactions were observed in scanning electron microscopy micrographs as a coarse gluten network composed of interconnected strands and fibrils. All LAB strains exhibited optimal acidification (pH < 4.3) in honey-supplemented sourdoughs, promoting the hydrolysis of gluten proteins into smaller fragments. Overall, honey-supplemented sourdoughs showed a gradual increase in the β-sheet content while decreasing the proportion of random coils over time. This trend suggests that the polypeptide fragments interacted through interchain hydrogen bonds, leading to a more ordered structure, which likely contributes to providing dough with good baking aptitude.

Enrichment and Quantitation of Dipeptidyl Peptidase IV Inhibitory Peptides in Quinoa upon Systematic Malting.

Food-derived peptides with an inhibitory effect on dipeptidyl peptidase IV (DPP-IV) can be used as an additive treatment for type 2 diabetes. The inhibitory potential of food depends on technological protein hydrolysis and gastrointestinal digestion, as the peptides only act after intestinal resorption. The effect of malting as a hydrolytic step on the availability of these peptides in grains has yet to be investigated. In this study, quinoa was malted under systematic temperature, moisture, and time variations. In the resulting malts, the DPP-IV inhibition reached a maximum of 45.02 (±10.28) %, whereas the highest overall concentration of literature-known inhibitory peptides was 4.07 μmol/L, depending on the malting parameters. After in vitro gastrointestinal digest, the inhibition of most malts, as well as the overall concentration of inhibitory peptides, could be increased significantly. Additionally, the digested malts showed higher values in both the inhibition and the peptide concentration than the unmalted quinoa. Concerning the malting parameters, germination time had the highest impact on the inhibition and the peptide concentration after digest. An analysis of the protein sizes before and after malting gave first hints toward the origin of these peptides, or their precursors, in quinoa.

From laboratory to industrial use: Understanding process variation during enzymatic protein hydrolysis with dry film fourier-transform infrared spectroscopy

Industries are continuously looking for dedicated sensor solutions for evaluating the chemical composition of products that can provide valuable insights into process control, process optimization, and product quality. A rapid and robust analytical method, Fourier-Transform Infrared (FTIR) spectroscopy, holds significant potential in this regard as it provides detailed compositional values of food nutrients. The main aim of the present study was to use dry film FTIR spectroscopy as an analytical tool to characterize products from an industrial enzymatic protein hydrolysis process and link this to understand industrial process variations. For this purpose, 463 protein hydrolysate samples were obtained from an industrial enzymatic protein hydrolysis plant. In the same period, systematic variations in process parameters such as raw material composition, enzyme type, and water addition, were performed. All samples were analyzed using dry film FTIR spectroscopy. Two subsets containing 200 and 68 hydrolysate samples were chosen for measuring average molecular weight (AMW) and collagen content respectively, providing reference data for constructing calibration models based on partial least squares regression (PLSR). The percentage of low molecular weight constituents was derived from the molecular weight distribution of size exclusion chromatograms of protein hydrolysates and also used in the modeling. Calibration models for the prediction of AMW, low molecular weight constituents, and collagen content were obtained with a good fit and lower estimation errors. Principal component analysis (PCA) of protein hydrolysates' FTIR spectra effectively differentiated process variations (enzyme types and raw materials) without extensive reference analysis. One-factor analysis of variance (ANOVA) tests was used to observe the impact of process variation on product quality. FTIR proved to be a sensitive method for liquid protein analysis and process control with a significant potential in process optimization approaches. To the authors’ knowledge, this is the first time dry film FTIR spectroscopy has been used to evaluate an industrial bioprocess with designed process variations.