Cryoprotective effect of soluble soybean polysaccharides and enzymatic hydrolysates on the myofibrillar protein of Nemipterus virgatus surimi.

Cryoprotective effect and potential mechanism of soluble soybean polysaccharides (SSPS) and enzymatic hydrolysates on surimi was investigated. After hydrolysis, the molecular weight of SSPS significantly decreased, and the hydrolysates prepared by endo-polygalacturonase (EPG-SSPS) was the lowest (154 kDa). Infrared spectrum analysis revealed that enzymatic hydrolysis didn't alter the functional groups of SSPS, but it did augment the exposure to hydroxyl groups. Surimi containing 5 % EPG-SSPS had the lowest freezable water after 20 days of frozen storage. Furthermore, the 5 % EPG-SSPS group manifested the highest metrics in total sulfhydryl (8.0 × 10-5 mol/g), active sulfhydryl content (6.7 × 10-5 mol/g), Ca2+-ATPase activity, and exhibited the lowest level in carbonyl content, surface hydrophobicity (153 µg). Notably, the 5 % EPG-SSPS maintained the stability of protein structure. Conclusively, SSPS enzymatic hydrolysate using endo-polygalacturonase imparted superior cryoprotective effect on the myofibrillar protein of surimi, and the mechanism might be a decrease in molecular weight and exposure of hydroxyl groups.

Inhibitory effects of glutathione peroxidase on microbial spoilage of crayfish (Procambarus clarkii) during refrigerated storage.

The variety of enzyme-based biological preservatives is limited. This study evaluated the effects of glutathione peroxidase (GSH-Px) on the quality of crayfish during refrigerated storage by measuring the pH, total volatile basic nitrogen, trimethylamine, and microbial contamination in crayfish muscle simulation system. The results revealed that 0.3% GSH-Px (CK3) not only suppressed the degradation of nitrogenous substances but also decreased the contamination levels of total viable, Enterobacteriaceae, and Pseudomonas counts (P < 0.05). Furthermore, the populations of Lactococcus, Aeromonas, and Massilia differed in the CK3 group compared to the other groups (P < 0.05) at the end of the storage (day 15). Moreover, the principal coordinate analysis showed that the colony composition of CK3 stored for 15 days was similar to that of the control group stored for 10 days. Therefore, GSH-Px exhibits antibacterial activity against Gram-negative bacteria and has good application potential in freshwater aquatic product preservation.

Arginine as a regulator of antioxidant and gel formation in yak Myofibrillar proteins: Efficacy and mechanistic insights.

Arginine (Arg), a safe basic amino acid, modulates interprotein interactions and impacts the processing characteristics of myofibrillar proteins (MP) in meat products, as numerous studies have demonstrated. This study aimed to explore the effects of varying concentrations of Arg (0.025, 0.050, 0.100, 0.200 %) on the physicochemical properties and gel behavior of yak MP. Utilizing yak MP as the substrate, we assessed and analyzed the physicochemical attributes and gel performance of the MP-Arg composite system. The findings revealed that Arg facilitates MP unfolding and internal group exposure, effectively mitigating oxidative tertiary structure alterations. Arg exerts potent antioxidant activity on MP, augmenting their water-holding capacity, which ameliorates gel properties. In this experiment, 0.05 % Arg maximally inhibited oxidative damage to MP, with protection being concentration-dependent. Collectively, these findings suggest that Arg effectively inhibits the oxidative degradation of MP structure and promotes the formation of enhanced gel characteristics.

Effects of melatonin on inhibiting quality deterioration of postharvest water bamboo shoots.

Water bamboo shoots (Zizania latifolia) is prone to quality deterioration during cold storage after harvest, which causes the decline of commodity value. Chlorophyll synthesis and lignin deposition are the major reasons for quality degradation. This paper studied the influence of exogenous melatonin (MT) on the cold storage quality of water bamboo shoots. MT treatment could delay the increase in skin browning, hardness and weight loss rate, inhibit chlorophyll synthesis and color change of water bamboo shoots, while maintain the content of total phenols and flavonoids, and inhibit lignin deposition by inhibiting the activity and gene expression of phenylpropanoid metabolism related enzymes as PAL, C4H, 4CL, CAD, and POD. The results indicate that exogenous MT treatment can effectively inhibit the quality degradation of cold stored water bamboo shoots.

The influence of γ-PGA on the quality of cooked frozen crayfish during temperature fluctuations.

The purpose of this study was to compare the influences of gamma-poly glutamic acid (γ-PGA) (1, 2, 3, and 4 %) to see which could outperform conventional cryoprotectant mixture (4 % sorbitol + 4 % sucrose) on cooked crayfish properties, such as physicochemical, textural qualities, oxidation reaction, water distributions, and microstructure integrity, during different freeze-thaw cycles. Crayfish quality characteristics improved significantly as γ-PGA concentration increased compared to control samples.Adding γ-PGA 4 % reduced the carbonyl content from 4.20 to 3.00 nmol/ mg protein during fluctuation-1 (F1), and from 4.15 to 2.80 nmol/ mg protein during fluctuation-2 (F2) compared to control samples. Furthermore, it increased the total sulfhydryl content from 4.15 and 4.76 to 6.19 and 6.47 mol/105 g protein during F1 and F2 and after five freeze-thaw cycles (FTC). This suggests that this concentration was more effective at controlling protein changes than other concentrations. γ-PGA generally enhanced the water-holding capacity by preventing protein denaturation and limiting ice crystal recrystallization. As a result, microstructure stability was evident, texture degradation was avoided, and the crayfish's color was preserved.

Effects of cold atmospheric plasma pre-treatment on maintaining the quality of ready-to-eat drunken red shrimp (Solenocera crassicornis) stored at chilled conditions.

This present study investigated the effect of cold atmospheric plasma (CAP) pre-treatment on the quality of ready-to-eat drunken red shrimp (Solenocera crassicornis) during chilled storage. The shrimp were pre-treated with the CAP at 40 kV and 36 kH for 100 s in a plasma generating equipment before the drunken treatment and compared with an untreated control sample. The results showed that the CAP pre-treatment significantly inhibited the total viable count (TVC) values, total volatile basic nitrogen (TVB-N) content, and polyphenol oxidase (PPO) activity of the drunken shrimp compared to the control treatment. Furthermore, the CAP pre-treatment also significantly maintained the myofibrillar protein (MP) content, texture properties, and a more stable histological structure of muscle fibers compared to the control. High-throughput sequencing results confirmed that the CAP pre-treatment significantly reduced the diversity and abundance of several bacteria in the shrimp. Gas chromatography-ion mobility spectrometry (GC-IMS) analysis detected that the CAP pre-treatment effectively maintained the stability of volatile organic compounds (VOCs). These findings provide valuable theoretical support for the processing and storage of drunken shrimp.

Investigating the migration hypothesis: Effects of trypsin-like protease on the quality of muscle proteins of red shrimp (Solenocera crassicornis) during cold storage.

This study aimed to investigate the effect of trypsin-like protease (TLP) on the quality of muscle proteins in red shrimp (Solenocera crassicornis) during cold storage. The results indicated that the activity of TLP decreased significantly in the head of shrimp but increased significantly in the muscle tissues during the cold storage. The myofibril fragmentation index (MFI) value of intact shrimp was significantly higher than that of beheaded shrimp, while the Ca2+-ATPase activity of intact shrimp was significantly lower than that of beheaded shrimp. SDS-PAGE analysis showed that the molecular weight of purified TLP from the shrimp head was about 24 kDa, and the TLP showed high activity at 50 °C and pH 8, indicating that the TLP belongs to the trypsin family. Results from in vitro simulation experiments indicated that the process of TLP incubation significantly reduced the particle size and enlarged the distribution of myofibrillar proteins (MPs) in shrimp muscle tissues. The comparisons were made with respect to the control samples. It can be inferred that TLP migrated from the shrimp head to the muscle tissues during storage and thus promoted the degradation of MPs in red shrimp. The beheading treatment could be an effective mean to maintain better quality and extend the commercialization of shrimp products.

Effects of tetrasodium pyrophosphate coupled with soy protein isolate on the emulsion gel properties of oxidative myofibrillar protein.

The effects of protein oxidation on the emulsion gel properties of myofibrillar protein (MP) in the presence of tetrasodium pyrophosphate (TSPP) and soybean protein isolate (SPI) were investigated from the perspective of interfacial protein interactions. The results showed that the emulsifying activity and emulsion stability of MP increased by 35.2 %-181.6 % with elevated H2O2 concentrations (1-20 mM), while the gel strength and water holding capacity of MP emulsions first increased to a maximum at 5 mM H2O2 and then decreased. TSPP and SPI further reinforced the effects caused by oxidation. The emulsifying properties of MP and its emulsion gel properties were closely related to surface hydrophobicity/hydrogen bonds/hydrophobic interactions and disulfide bonds among interfacial proteins, respectively. However, these correlations became difficult to define when TSPP and SPI were introduced. The study provides a theoretical basis for the strategy development to reduce protein oxidation damage on meat product quality.

Tetrasodium pyrophosphate promotes light meromyosin crosslinking by microbial transglutaminase.

Phosphates are commonly included in meat processing, where oxidation is inevitable, to improve water binding. This present study attempted to reveal the interactive roles of protein oxidation and tetrasodium pyrophosphate (TSPP) on the crosslinking pattern of myosin mediated by transglutaminase (TGase). Mild oxidation at 1 mM H2O2 facilitated the TGase-initiated crosslinking, with the dominate crosslinking site shifted from S1 (in nonoxidized myosin) to Rod. The introduction of TSPP alleviated the oxidation stress on proteins, and was conductive to the crosslinking reaction notably at the LMM domain. The crosslinking sites in untreated myosin were identified as Gln-613 (S1) and Gln-1498 (LMM) by amino-acid sequence analysis, while strongly oxidation resulted in the loss of Gln-1498. Contrastively, four new reactive crosslinking sites were generated by TSPP, one (Gln-558/Gln-567) located on S1 and three (Gln-1362, Gln-1374, and Gln-1423/Gln-1426) on LMM. Yet, Gln-1362 was eliminated under strong oxidation at 50 mM H2O2.

Development and properties of bacterial cellulose, curcumin, and chitosan composite biodegradable films for active packaging materials.

To deal with serious environmental damage resulting from plastic packaging materials, biodegradable films using natural products have gained considerable attention. Here, we provide a simple, fast, and environmentally-friendly route to construct a biodegradable film using chitosan (CS), bacterial cellulose (BC), and curcumin (Cur). Composite films (CSn-BC-Cur) using CS with different molecular weights were investigated, and their water moisture content (MC), water solubility (WS), contact angle (CA), mechanical properties, barrier properties, and antioxidant properties were compared. The obtained films were characterized by SEM, XRD, and TGA. The results showed that chitosan with a higher molecular weight presented higher contact angles and mechanical properties, along with a lower moisture content, water vapor transmission rate, and oxygen transmission rate. Furthermore, when the composite film was placed in 95 % ethanol, it released active substances. The results suggest that these composite films can be used as promising materials for food packaging.

Tomato pomace extract and organic peppermint essential oil as effective sodium nitrite replacement in cooked pork sausages.

The effect of supercritical fluid extract of tomato pomace (TP) and essential oil of organic peppermint (PM) on pH, color, residual nitrite content, lipid oxidation (TBARS value) and total plate count (TPC) of cooked pork sausages produced with 50 mg/kg of sodium nitrite was investigated. Five batches were produced: T1: 100 mg/kg of sodium nitrite; T2: 50 mg of sodium nitrite; T3: 50 mg of sodium nitrite and 0.150 µL/g TP; T4: 50 mg of sodium nitrite, 0.075 µL/g TP and 0.075 µL/g PM; T5: 50 mg of sodium nitrite and 0.150 µL/g PM. The lowest residual nitrite content and TBARS value were observed in treatment T4. The inclusion of TP increased redness of cooked pork sausages. TPC was the lowest in treatment T5. The results of this study showed that the addition of TP and PM enhanced quality of cooked sausages produced with reduced level of sodium nitrite.

Prediction of skin permeation and concentration of rhododendrol applied as finite dose from complex cosmetic vehicles.

Finite dose experiments represent clinical use wherein depletion of dose, evaporation of excipients, and gradual change in vehicle composition may occur. In the present study, we attempted a mathematical approach for predicting skin permeation and concentration of a cosmetic active, rhododendrol (RD), from complex vehicle-based formulations applied in finite dose. In vitro skin permeation and concentration studies of RD were conducted from formulations containing water and polyols with concentrations ranging from 10 to 100% under infinite and finite dose conditions using vertical Franz diffusion cells. Observed data for skin permeation and the viable epidermis and dermis (VED) concentration of RD were estimated by the differential equations under Fick's second law of diffusion together with water evaporation kinetics and changes in the partition coefficient from vehicles to the stratum corneum. As a result, a goodness-of-fit was observed allowing accurate estimation of skin permeation and VED concentration of RD. This mathematical approach could become a useful tool to estimate the skin permeation and concentration of actives from topical formulation applied in finite dose conditions likened in actual use.

Influence of temperature fluctuations on growth and recrystallization of ice crystals in frozen peeled shrimp (Litopenaeus vannamei) pre-soaked with carrageenan oligosaccharide and xylooligosaccharide.

Temperature fluctuation is a common problem in the frozen storage of shrimp products. This study investigated the influence of carrageenan oligosaccharide (CO) and xylooligosaccharide (XO) on the growth and recrystallization of ice crystals in frozen peeled shrimp exposed to temperature fluctuations. Shrimp soaked with water and 3.0% (w/v) Na4P2O7 solution were designated as the negative and positive controls, respectively. Our data revealed that both CO- and XO-soaked shrimp had significant improvements in thawing and cooking loss, myofibrillar protein content, Ca2+-ATPase activity, and textural variables when exposed to temperature fluctuations compared to control samples. Microstructural imaging indicated that soaking the shrimp in CO and XO slowed the progression of damage caused to tissue myofibrils by large ice crystals, as well as inhibited the growth and recrystallization of ice crystals in muscle tissues. SDS-PAGE analysis confirmed that treatment with the oligosaccharides exhibited marked effects on the stability of muscle proteins and inhibited the degradation of muscle proteins affected by the temperature fluctuations. Based on these data, we hypothesize that the incorporated CO and XO may bind to muscle proteins and capture water molecules in the myofibrillar network through hydrogen bonding, thereby suppressing the myofibrillar denaturation and tissue structure destruction induced by the growth and recrystallization of ice crystals.

Astaxanthin encapsulation in multilayer emulsions stabilized by complex coacervates of whey protein isolate and Persian gum and its use as a natural colorant in a model beverage.

Crustacean byproducts are valuable sources of astaxanthin. In this study, an astaxanthin-rich lipid phase was extracted from shrimp waste and encapsulated in multilayer emulsions. Stabilized by electrostatic complexes of whey protein isolate (WPI) and Persian gum (PG), the multilayer emulsions were created by different WPI:PG mixing ratios (1:2-1:4). The resultant emulsions were then exposed to lyophilization. The encapsulation efficiency of astaxanthin in lyophilized powders was 42.9-49.8 (g astaxanthin/100 g astaxanthin). The moisture content and water activity of the powders decreased significantly (p < 0.05), but their solubility and hygroscopicity increased significantly (p < 0.05) in response to an increase in the PG content of the mixture (or by reducing the WPI:PG ratio). Morphological characterizations revealed the formation of smaller and more uniform microcapsules when higher amounts of PG were used. Water dispersibility was higher than 94 (g powder/100 g powder). The results of an accelerated stability test showed an improvement in astaxanthin chemical stability in the multilayer emulsions, particularly when the WPI:PG ratio was 1:4. A model beverage consisting of water (89 g/100 g), sugar (10 g/100 g) and citric acid (1 g/100 g) was prepared and the potential application of astaxanthin microcapsules as a natural colorant was studied and compared with a synthetic colorant (E110) under the effect of light/darkness, temperature (4 and 25 °C) and time (0-60 d). The encapsulated lipid extract imparted a highly stable color to the product which was comparable to the effect of the synthetic colorant. However, the astaxanthin concentration was highly affected by time and partially affected by light and temperature.

The mechanistic effect of bromelain and papain on tenderization in jumbo squid (Dosidicus gigas) muscle.

Jumbo squid (Dosidicus gigas) muscle is rather hard and tough, which directly affects consumer acceptance. In this study, the tenderization effect of bromelain and papain on squid muscle during enzymolysis is examined and compared with an untreated control and water-treated sample. Squid mantle were incubated with different solutions (water, bromelain, and papain solution) for 40 min in a 30 °C water bath. Then, the mantle samples were subjected to water holding capacity (WHC) analysis, texture evaluation, biochemical determination, and histological observations. The results revealed that bromelain and papain disadvantageously decrease the water holding capacity when compared to the control and water-treated samples. Furthermore, following tenderization with bromelain or papain, muscle hardness, shear force, myofibrillar protein content, and Ca2+ ATPase activity were all significantly decreased. Additionally, some essential amino acids were released following tenderization. When examining the myofibrillar fragmentation index (MFI), bromelain and papain were shown to cause high levels of hydrolysis in myofibrillar and sarcoplasmic proteins. Moreover, microstructural imaging indicated that the tenderization treatments disrupted myofibrils and generated a larger number of small fragments in the muscle tissues, subsequently decreasing microstructure stability and integrity. SDS-PAGE analysis confirmed that bromelain and papain have a high proteolytic activity, with some small peptides and/or short fragments detected post-tenderization. The results presented herein demonstrated that bromelain and papain improved squid muscle tenderness and can be utilized to ensure a more desirable squid product.

Coriander essential oil as natural food additive improves quality and safety of cooked pork sausages with different nitrite levels.

The effect of coriander essential oil (CEO) at concentrations of 0.075-0.150 µL/g on pH, color, lipid oxidation (TBARS), residual nitrite concentration and microbial growth of cooked pork sausages produced with different levels of sodium nitrite (0, 50 and 100 mg/kg) was investigated. Artificial neural networks modeling and the multi-response optimization were used to determine the optimal combinations of process parameters and storage time. Reduced concentration of sodium nitrite (60 mg/kg) in combination with 0.12 µL/g of CEO resulted in satisfying redness (a* approx. 11.1) and improved oxidative (TBARS approx. 0.12 mg MDA/kg) and microbial stability (total plate count - TPC approx. 2.50 Log CFU/g) of cooked pork sausages during refrigerated storage. Therefore, the results of this paper revealed significant antioxidative and antimicrobial activity of CEO, and consequently its high potential of utilization in processing of cooked pork sausages with enhanced quality and shelf-life.

Investigating proteome and transcriptome response of Cryptococcus podzolicus Y3 to citrinin and the mechanisms involved in its degradation.

Citrinin (CIT) contamination has been reported in agricultural foods and is known to be nephrotoxic to human and animals. In the present study, the proteomes and transcriptomes of C. podzolicus Y3 treated with or without 10 µg/mL CIT were compared by two-dimensional electrophoresis (2-DE) and RNA sequencing, respectively. The proteomics results showed that there were 23 differentially expressed proteins (DEPs), 8 DEPs were up-regulated and 15 DEPs were significantly down-regulated. Transcriptomic analysis showed that 1208 genes were differentially expressed, 551 (43.05%) DEGs were up regulated and 657 (56.95%) were down-regulated. These results showed that the CIT treatment caused DNA damage, oxidative stress and cell apoptosis in C. podzolicus Y3. CIT treatment also activated the defense response (DNA repair and drug resistance biological process, antioxidative activity and TCA cycle) as well as drug metabolism (synthesize the CIT-degrading enzymes) in yeast cells to respond to CIT stress and degrade CIT.

Essential oil versus supercritical fluid extracts of winter savory (Satureja montana L.) - Assessment of the oxidative, microbiological and sensory quality of fresh pork sausages.

The effect of winter savory (Satureja montana L.) essential oil (SEO) and supercritical extracts (SE1; SE2) at concentrations of 0.075 and 0.150 µL/g on pH, lipid oxidation (TBARS), microbial growth and sensory quality of fresh pork sausages during storage were investigated. SEO, SE1 and SE2 improved oxidative and microbial stability of fresh pork sausages. The addition of SEO and SE1 at concentration of 0.150 µL/g affected the reduction of total Enterobacteriaeceae count to under 3 log cfu/g. Sausages produced with SE1 and SE2 had a higher scores for odor, flavor and overall acceptance compared to sausages treated with SEO and control sample. Therefore, the results of this paper revealed significant antioxidative and antimicrobial activity of SE1 and SE2, and consequently its high potential of utilization in processing of fresh pork sausages.

Phenolics composition, antioxidant properties and toxicological assessment of Prosopis alba exudate gum.

The objective of this work was to deepen on the study of functional properties of the phytochemicals present in Prosopis alba exudate gum (G), as well as to rule out possible adverse effects of some of its components. Commonly employed purification methods were compared. Filtration prevents further loss of potentially bioactive compounds. The filtrated gum showed a higher concentration of phenolics, flavonoids and tannins than arabic gum, which was correlated with better in vitro antioxidant properties. Particularly, tannins, commonly considered as toxic compounds in exudate gums, were found in lower concentration than in others gums obtained from genus Prosopis and Acacia. The toxicological evaluation performed on rats did not show symptoms of intoxication associated with the administration of the gum. These results provide useful evidence to support the potential use of G as a safe functional food additive with the added benefit of taking advantage of a non-exploited natural resource.

Preparation process optimization of pig bone collagen peptide-calcium chelate using response surface methodology and its structural characterization and stability analysis.

In this study, alcalase and neutrase were used in combination to prepare collagen peptides with high calcium binding ability. The optimal conditions for the preparation of peptide-calcium chelate (mass ratio of peptide/calcium of 4.5:1 for 40 min at 50 °C and pH 9) were determined by response surface methodology (RSM), under which a calcium chelating rate of 78.38% was obtained. The results of Ultraviolet-Visible (UV-Vis), fluorescence and Fourier transform infrared (FT-IR) spectra synthetically indicated that calcium could be chelated by carboxyl oxygen and amino nitrogen atoms of collagen peptides, thus forming peptide-calcium chelate. The chelate was stable at various temperatures and pH values, and exhibited excellent stability in the gastrointestinal environment, which could promote calcium absorption in human gastrointestinal tract. Moreover, Caco-2 cell monolayer model was used to investigate the effect of peptide-calcium chelate on promoting calcium absorption. Results showed that peptide-calcium chelate could significantly improve calcium transport in Caco-2 cell monolayer and reverse the inhibition of calcium absorption by phosphate and phytate. The findings provide a scientific basis for developing new calcium supplements and the high-value utilization of pig bone.