Total Sulfhydryl Research Articles

Ultrasonic treatment increased functional properties and in vitro digestion of actomyosin complex during meat storage

We investigated the effects of ultrasonic treatment (400 W, 20 kHz, 45.52 W/L) and storage time (0 d, 3 d, 7 d and 10 d) on functional properties, structural changes and in vitro digestion of actomyosin complex isolated from vacuum-packed pork. As storage time increased, turbidity, surface hydrophobicity, active sulfhydryl and total sulfhydryl of actomyosin complex increased, while protein solubility decreased. Ultrasonic treatment increased surface hydrophobicity, protein solubility and active sulfhydryl content but decreased turbidity and total sulfhydryl content compared with the control. Ultrasonic treatment caused a reduction in α-helix content on 0 day and the fluorescence intensity of tryptophan and tyrosine residues. It increased pancreatin digestibility of actomyosin complex and the number of peptides of smaller than 1 kDa. However, it decreased the number of peptides. The findings provide a new insight into the application of appropriate ultrasonic treatment to promote meat digestibility.

Effects of soy protein isolate on gel properties and water holding capacity of low-salt pork myofibrillar protein under high pressure processing

This paper studies the effects of soy protein isolate (SPI; 0, 2% and 4%; Weight/Weight) on texture, rheological property, sulfhydryl groups, and the water distribution state of low-salt (1% NaCl) pork myofibrillar protein systems under high pressure processing (HPP, 200 MPa, 10 min). The L⁎ value, cooking yield, hardness, total and reactive sulfhydryl, surface hydrophobicity, and the G' value at 80 °C of pork myofibrillar protein increased significantly (P < 0.05) when SPI was added; however, the springiness, cohesiveness, and chewiness of gels with 4% SPI were lower than of gels with 2% SPI. The rheological findings indicated that the thermal stability of the myofibrillar protein increased when SPI was added. The initial relaxation time of T2b, T21, and T22 decreased when SPI increased; meanwhile, the peak ratio of P21 increased significantly (P < 0.05), implying that water had lower mobility. Overall, the 2% SPI could enhance gel characteristics and water-holding capacity of pork myofibrillar protein under 200 MPa.

Carboxymethylcellulose-induced changes in rheological properties and microstructure of wheat gluten proteins under different pH conditions.

The interaction between gluten and hydrocolloid additive, as well as the pH condition during dough formation is very important in making flour products. In this study, the influence of different pH conditions on the interactions between gluten proteins (including glutenin and gliadin) and carboxymethylcellulose (CMC), and on the rheological and microstructure changes of gluten proteins was investigated. The dynamic frequency sweep indicated CMC-gluten displayed more solid-like behavior under alkaline conditions than that under acidic conditions. The creep-recovery experiment suggested acidic conditions were not conducive to maintain the elasticity of CMC-gluten. Microstructural changes of various glutens with CMC showed that a higher ratio of β-sheets was observed in the CMC-gluten and CMC-glutenin under alkaline conditions. Total free sulfhydryl contents and changes in tryptophan microenvironment showed glutenin played a key role in the G polymerization with the addition of CMC. Lower surface hydrophobicity of CMC-gluten was displayed under acidic conditions. Scanning electron microscopy images showed that neutral and alkaline conditions were conducive to the network structure formation of CMC-gluten and CMC-glutenin. This study investigated the interaction of CMC with gluten, gluten, and gliadin under different pH conditions, providing a basis for expanding dough quality improvement, and extending the in-depth application of CMC in the food industry.

High-intensity ultrasound improves threadfin bream surimi gelation at low NaCl contents.

Effects of high-intensity ultrasound (HIU) treatments on gelation of threadfin bream (Nemipterus spp.) surimi at various NaCl contents (0.5, 1, and 2% NaCl) were investigated. Protein extractability at 0.5% NaCl was increased with the ultrasonic intensity (p <0.05). At all tested NaCl contents, reactive sulfhydryl group (SH) content and surface hydrophobicity of the surimi pastes were increased after HIU treatments and were accompanied by a decrease in the Ca2+ -ATPase activity and total SH content, indicating a greater extent of unfolding and conformational changes induced by HIU at higher NaCl contents. Textural properties and color of the surimi gels at 0.5% NaCl were improved concomitant to an increase in ultrasonic intensity (p <0.05), whereas HIU treatments resulted in inferior gels at 1 and 2% NaCl. Scanning electron microscopy (SEM) revealed that HIU resulted in a more orderly gel network at 0.5% NaCl. Fourier transform infrared (FT-IR) spectroscopy indicated that the α-helix content of the surimi gels was decreased as the ultrasonic intensity and NaCl content increased, confirming that structural changes induced by HIU were more profound at higher NaCl contents. The results suggested that HIU technology can be applied to improve only the 0.5% NaCl surimi gel. PRACTICAL APPLICATION: High-intensity ultrasound (HIU) improved surimi gel containing 0.5% NaCl due to an increase in protein extractability and protein conformational changes. It is likely to lay a theoretical foundation for utilization of HIU technology in production of surimi-based products at low/reduced salt levels.

Protective effect of resveratrol on citrullinemia type I-induced brain oxidative damage in male rats.

Citrullinemia Type I is an inborn error, which leads to accumulation of citrulline and ammonia in blood and body tissues. We evaluated the in vitro effects of citrulline, ammonia and the influence of resveratrol on oxidative stress parameters in the cerebrum of 30- and 60-day-old male Wistar rats. Citrulline (0.1, 2.5, 5.0mM), ammonia (0.01, 0.1, 1.0mM) and resveratrol (0.01, 0.1, 0.5mM) were added to the assays to measure thiobarbituric acid reactive substances (TBA-RS), total sulfhydryl content and the activity of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Citrulline (2.5 and 5.0mM) increased TBA-RS in the cerebellum of 30-day-old and in the cerebral cortex and cerebellum of 60-day-old. Citrulline (5.0mM) increased SOD and reduced GSH-Px in the hippocampus of 30-day-old, whereas in the cerebellum it increased GSH-Px. In the cerebral cortex, 2.5 and 5.0mM citrulline reduced GSH-Px. In 60-day-old, 2.5 and 5.0mM citrulline increased SOD in the cerebellum, increased GSH-Px in the cerebral cortex and 5.0mM citrulline reduced CAT and increased SOD in the cerebral cortex. Ammonia (0.1 and 1.0mM) reduced the sulfhydryl content in the cerebral cortex of 30- and 60-day-old, 1.0mM ammonia increased SOD and reduced GSH-Px in the cerebellum of 30-day-old and increased SOD in the hippocampus and cerebellum of 60-day-old. Resveratrol was able to prevent the majority of these alterations. Thus, citrulline and ammonia induce oxidative stress in the cerebrum of rats; however, resveratrol was able to exert antioxidant effects against these substances.

Freezing-then-aging treatment improved the protein digestibility of beef in an in vitro infant digestion model

In vitro protein digestibility of freezing-then-aged beef was investigated in an infant digestion model. The treatments were divided into freezing-then-aging (FA) and aging-only (AO) groups. Carbonyl and total free sulfhydryl contents were the same between both groups for 14-day aging. Freezing had no effect on beef myofibrillar protein tertiary structure. Although caspase-3 activity did not differ, the FA group showed higher cathepsin B activity than the AO group (p < 0.05). The 10% trichloroacetic acid-soluble α-amino content was higher in FA than AO group, on aging day 14 (p < 0.05). Post in vitro digestion of beef aged for 14 days, the FA group had a higher content, than the AO group, of α-amino groups and proteins digested under 3 kDa (p < 0.05). An electrophoretogram of the digesta showed improved digestion of actin in the FA group. Collectively, the freezing-then-aging process enhanced the protein digestibility of beef in this in vitro infant digestion model.

Effect of High Voltage Cold Plasma on Oxidation, Physiochemical, and Gelling Properties of Myofibrillar Protein Isolate from Asian Sea Bass (Lates calcarifer).

The effects of in-bag dielectric barrier discharge high voltage cold plasma (IB-DBD-HVCP) on myofibrillar protein isolate (MPI) from Asian sea bass (ASB) and its impact on the physiochemical and gelling properties of MPI gels were elucidated. A mixture of argon (90%) and oxygen (10%) was used for generating IB-DBD-HVCP. MPI was subjected to IB-DBD-HVCP for varying times (5–15 min). Total carbonyl content was increased, while total sulfhydryl content was decreased in MPI, especially with augmenting treatment time (TT) (p < 0.05). Surface hydrophobicity initially increased when IB-DBD-HVCP TT of 5 min (DBD-HVCP5) was implemented, followed by subsequent decrease with increasing TT. Based on gel electrophoresis, lower actin and myosin heavy chain (MHC) band intensities were found for MPI subjected to IB-DBD-HVCP, particularly when a TT longer than 10 min was used, compared to those of the control. Gel made from DBD-HVCP5 had higher breaking force, deformation, and highest G′ value compared to others. A more ordered and fibrous network was found in DBD-HVCP5 treated gel. Therefore, IB-DBD-HVCP treatment, particularly for 5 min, enhanced cross-linking of proteins in ASB myofibrillar proteins, which resulted in the improved gel elasticity and strength.

Changes in the biochemical properties of yeast during oxygen saturation of semi-finished bakery products

Microbiological and biochemical processes caused by yeast are the main factors affecting the quality of bread. The ability to manage the vital activity of yeast allows you to regulate these processes and contribute to the intensification of technological processes in baking. An important factor that affects the activity of yeast is oxygen. In bread-making technology, oxygen is mainly considered as a factor that affects oxidative processes. The effect of aeration of bakery semi-finished products on the properties of yeast has not been studied enough. In this work, we studied the enzymatic activity (zimase, maltase), morphological characteristics, viability and quantity of water-soluble sulfhydryl compounds released by yeast when the yeast suspension and liquid sourdough were saturated with oxygen in the range of 4-16 mg / l. The lifting force of yeast when the suspension was saturated with oxygen improved by 23 %. Similarly, the lifting force of liquid sourdough changed when it was saturated with oxygen. Increasing the oxygen content 3 times increased the lift of the liquid sponge by 20 %. It was found that the accumulation of total sulfhydryl compounds in the control was more intense than that in semi-finished products saturated with oxygen. In general, the oxygen content in the yeast suspension and in the liquid sponge significantly activates the vital activity of yeast and, accordingly, intensifies the process of their preparation.

The comparison of pro- and antioxidative parameters in plasma and placental tissues during early phase of placental development in cows

Physiological balance between pro- and antioxidative processes is crucial for placentation and further development of fetus and placenta. Parameters of pro- and antioxidative profile may serve as markers of proper course of pregnancy. The aim of study was to assess whether the balance between pro- and antioxidative parameters during placentation phase in bovine placenta is maintained. Placental and blood samples were collected from healthy, HF, pregnant (2nd-3rd month) cows (n = 8) in slaughterhouse and in farm, respectively. Formylokinurenine and bityrosine content were measured spectrofluorimetrically in blood plasma and tissue homogenates while metabolites of lipid peroxidation, total antioxidant capacity, SH groups and activity of antioxidative enzymes (glutathione peroxidase and superoxide dismutase) were determined in examined tissues by spectrophotometry. Western blotting was used to confirm the presence of enzymatic proteins in placenta. Results: Local profile in tissues was more pronounced than general profile in blood plasma. Activities of antioxidative enzymes were significantly (p < 0.05) higher in 2nd compared to 3rd month of pregnancy in maternal part of placenta while prooxidant parameters showed opposite relationship. Obtained results showed significant differences when compared to data from non-pregnant animals or time of parturition. Further studies are necessary for elucidation of placentation phase in cows.

Fluctuated low temperature combined with high-humidity thawing to retain the physicochemical properties and structure of myofibrillar proteins from porcine longissimus dorsi

The physicochemical and structural changes in myofibrillar proteins (MPs) from porcine longissimus dorsi under low temperature combined with high-humidity thawing (4 °C, 90% RH, LHT) and fluctuated low temperature combined with high-humidity thawing (2 → 6 → 2 °C, 90% RH, FLHT) treatments were compared with those under refrigerator thawing (RT). The changes in the thermal stability and viscoelasticity of the MPs after FLHT treatment was insignificant (P < 0.05) compared with the corresponding properties of the fresh samples. In addition, FLHT resulted in a desirable water distribution, the highest total sulfhydryl content, and the lowest carbonyl content compared to the other treatments, suggesting that it effectively decreases protein oxidation. FLHT also led to slight changes in the aggregation and integrity of the MPs. Furthermore, a stable tertiary structure was obtained through FLHT. In contrast, the largest variations in all indicators of the MPs were observed following RT. These results confirmed that FLHT reduced the physicochemical deterioration of MPs from porcine muscle, thereby indicating the potential of FLHT for application in the thawing of meat.

L-Arginine and l-Lysine Alleviate Myosin from Oxidation: Their Role in Maintaining Myosin's Emulsifying Properties.

This study investigated the alleviative effects of l-arginine and l-lysine on the emulsifying properties and structural changes of myosin under hydroxyl radical (·OH) stress. The results showed that ·OH decreased the emulsifying activity index and emulsifying stability index but increased the creaming index and droplet size of a soybean oil-myosin emulsion (SOME). Confocal laser scanning microscopy demonstrated that ·OH caused larger and more inhomogeneous SOME droplets. l-Arginine and l-lysine effectively alleviated ·OH-induced destructive effects on the emulsifying properties of myosin. In addition, ·OH increased the extent of protein carbonylation and dityrosine formation, surface hydrophobicity, and β-sheet content, but decreased the tryptophan fluorescence intensity, solubility, total sulfhydryl, and α-helix content of myosin. Although l-lysine increased dityrosine fluorescence intensity, l-arginine and l-lysine effectively alleviated the aforementioned structural changes of myosin. Therefore, l-arginine and l-lysine could mitigate ·OH-induced structural changes of myosin, which enabled myosin to maintain its emulsifying capacity under oxidative stress.

Effects of Nasturtium officinale Extract on Antioxidant and Biochemical Parameters in Hemodialysis Patients: A Randomized Double-Blind Clinical Trial.

Background Increased oxidative stress play an important role in the risk of cardiovascular disease, mortality, and mortality patients undergoing dialysis. Nasturtium officinale (watercress) contains numerous phytochemical compounds that act as an antioxidant by preventing oxidative damage to biomolecules. Therefore, this research aimed to explore the effect of the ethanolic extract of Nasturtium officinale (EENO) on antioxidant and biochemical markers of hemodialysis patients. Methods In this double-blind, placebo-controlled trial, 46 hemodialysis patients were randomly recruited to consume either 500 mg/day EENO (n = 23) or placebo capsule (n = 23) for 4 weeks, at Shahid Beheshti Hospital, Yasuj, Iran, in 2019. Biomarkers of oxidative stress including glutathione peroxidase (GPX), superoxide dismutase (SOD), malondialdehyde (MDA), total oxidant status (TOS), total antioxidant capacity (TAC), and total sulfhydryl protein (T-SH) and biochemical parameters such as BUN, Hb, WBC, PLT, Ca, Ph, K, ALB, TChol, TG, LDL, and HDL were evaluated on days 0 and 28. Results The serum levels of MDA and BUN significantly decreased after taking EENO supplementation (P < 0.001); however, SOD activity increased during the same period (P < 0.001). The serum levels of TAC remained constant in the intervention group, while it significantly declined in the placebo group (P < 0.09). The extract also prevented elevation in the serum levels of LDL and TG compared to the placebo group, although it was not statistically significant. Conclusions The data indicated that the consumption of EENO improved some of the antioxidant parameters and minimizes the change in TG and LDL in hemodialysis patients. Therefore, due to the role of these factors in mortality and morbidity of dialysis patients, EENO can improve the condition of dialysis patients. However, more studies with longer intervention times and different doses of EENO are recommended.

The protective effect of roflumilast and ibuprofen on testicular ischemia reperfusion injury: An experimental study.

The aim of the present study is to investigate the efficiency of roflumilast and ibuprofen in an experimental rat testicular ischemia reperfusion injury model in the light of histological and biochemical data. A total of 32 prepubertal male rats were randomly divided into four groups as G1: Control Group (testicular torsion/detorsion + saline (0.9% of 2 ml) was applied). G2: Sham Group only right scrotal incision was performed; G3: Ibuprofen Group (tes-ticular torsion/detorsion + ibuprofen administration); and G4 Roflumilast Group (testicular torsion/detorsion + roflumilast adminis-tration). Oxidative markers such as malondialdehyde (MDA), myeloperoxidase (MPO), total sulfhydryl (TSH), and nitrite (NO) levels as well as histopathological changes were analyzed. Tissue MPO, MDA, and NO levels were significantly higher and TSH levels significantly lower in control group compared to sham group (p<0.001). The histopathologic scores of drug groups (Groups 3 and 4) were significantly lower than group 1 (p<0.001). In comparison of Group 3 and Group 4 with each other, the mean values of MPO and MDA were statistically significantly lower in Group 4 (p<0.001). A higher mean value of TSH was found in Group 3 without statistically significance (p=0.32). There was also an insignificant decrease in mean NO values of Group 3 compared to Group 4 (p=0.44). In comparison of drug groups, Group 4 had statistically insignificant better scores. Our results indicate that administrating ibuprofen and roflumilast reduced testicular ischemia reperfusion injury in rat testis torsion model. In comparison, roflumilast is found to be more beneficial.

Physico-chemical and gel properties of heat-induced pasteurized liquid egg white gel: effect of alkyl chain length of alcohol

ABSTRACT The influence of alcohols with different alkyl chain length (methanol, ethanol and propanol) on the physicochemical properties (turbidity, surface hydrophobicity, exposed and total free sulfhydryl groups, denaturation temperature; Tm ) of pasteurized liquid egg white (PLEW), including gel properties (gel hardness and expressible liquid) and microstructure of heat-induced PLEW gel prepared at 75°C were studied. The results showed that alkyl chain length of alcohol and alcohol concentration had no impact on the total free sulfhydryl groups, but significantly increased the turbidity, surface hydrophobicity, exposed free sulfhydryl groups, gel hardness and expressible water. Increase the alkyl chain length of alcohol also significantly decreased the Tm and the total enthalpy change during heat-induced gelation of PLEW. Addition of 5% alcohol altered the microstructure of the PLEW gels in an alkyl chain length dependent manner.

Nutritional Composition and Antioxidant, Antimicrobial, and Cytotoxic Activities of the Scaly Tooth Wild Mushroom, Sarcodon squamosus (Agaricomycetes), from Turkey.

Among natural products, mushrooms are well known for their nutritional value and health-improving features. In this study, the total phenolic content, total oxidant status, total antioxidant capacity, lipid hydroperoxides, and total free sulfhydryl levels of wild edible mushroom Sarcodon squamosus were investigated. The agar disc diffusion method was applied to test the antimicrobial effect of S. squamosus methanolic extract against Gram-positive bacteria (Micrococcus luteus NCIBM, Staphylococcus aureus ATCC 25923, and Bacillus subtilis ATCC 6633), Gram-negative bacteria (Proteus vulgaris RSKK 96026, Escherichia coli ATCC 35218, and Yersinia enterocolitica RSKK 1501), and yeast (Candida albicans ATCC 10231). According to the obtained results, S. squamosus methanolic extract had strong antioxidant and antimicrobial activity. Antiproliferative effects of the time and dose of S. squamosus extract on human hepatocellular carcinoma HepG2 cells were determined with the XTT assay. The anti-invasive and apoptotic potential of the extract was evaluated with the Matrigel invasion chamber and TUNEL assays, respectively. S. squamosus extract also showed antiproliferative and anti-invasive activity and induced apoptosis in HepG2 hepato-cellular carcinoma cells in vitro. In conclusion, S. squamosus can be considered as both a functional food and a source of nutraceuticals.

Evaluation of Total Antioxidant Activity and Oxidative Stress in Seminal Plasma from Dogs Supplemented with Fish Oil and Vitamin E.

BackgroundWe evaluated the effect of fish oil (FO) and FO in addition to vitamin E (VE) supplementation on total antioxidant activity of dog seminal plasma, and further assessed oxidative stress. Additionally, we measured the effect of this supplementation on hematological parameters and serum biochemistry.Materials and MethodsIn this experimental study, six male dogs were assigned to one of the following three groups for a period of 60 days using a replicated 3×3 Latin square design: control (CG), FO (FOG) and FO in addition to VE (FOEG). On days 0 and 60 of the trial, semen and blood samples were obtained. 2,2V-azino-bis (3-ethylbenzo- thiazoline-6-sulfonate) (ABTS) and ferric reducing antioxidant power (FRAP) assays were used to determine total antioxidant activity. Oxidative stress was determined by measuring total sulfhydryl group (T-SH).ResultsDogs supplemented with FO alone had a lower total antioxidant activity in seminal plasma (ABTS: -59.86% vs. CG and -57.3% vs. FOEG; and FRAP: -37.3% vs. CG and -40.5% vs. FOEG), and higher oxidative stress (T-SH: +53.0% vs. CG and+60.2% vs. FOEG) compared with the other two groups (P<0.05). Serum triglyceride (TG) concentration de- creased in FOG and FOEG compared with CG, on day 60 (P<0.01).ConclusionWe concluded that total antioxidant activitydecreased and oxidative stress increased in seminal plasma of dogs after FO supplementation for 60 days.

New Markers of Platelet Activation and Reactivity and Oxidative Stress Parameters in Patients Undergoing Coronary Artery Bypass Grafting.

Objective Recent studies have shown that the red cell distribution width- (RDW-) to-platelet (PLT) count ratio (i.e., RPR) and the mean platelet volume (MPV)/PLT ratio (i.e. MPR) are more sensitive markers of atherosclerosis-connected risk than RDW and PLT alone. The present study is aimed at investigating the oxidative stress status and these two new markers of platelet activation in two different heart surgery modalities: cardiopulmonary bypass (CPB) and off-pump coronary artery bypass (OPCAB). We also aimed to test the possible relationship between RPR and MPR, respectively, and the severity and complexity of atherosclerotic plaque, measured as Syntax Score. Patients and Methods. A total of 107 patients encompassed this prospective study (i.e., 60 patients in CPB group and 47 patients in OPCAB). Blood samples were drawn at several time intervals: before skin incision (t1), immediately after intervention (t2), 6 h (t3), 24 h (t4), 48 h (t5), and 96 h after cessation of the operation (t6). Results The values of RPR and MPR were similar in CPB and OPCAB before surgery and started to rise in t2 (i.e., immediately after the intervention). This increase lasted to t5 (i.e., 48 hours after the intervention), when it became the highest. After that, both markers started to regress about the 96th hour after the beginning of surgery. Nominal values of both indices were higher in CPB than in OPCAB in all study points after the surgery. Furthermore, a significantly higher level of antioxidative parameters (i.e., total sulfhydryl groups and paraoxonase 1) in the OPCAB group compared to the CPB group was noted at t5 study point (i.e., 48 hours after the surgery), whereas no significant difference was noted in prooxidant levels (i.e., lipid hydroperoxides and advanced oxidation protein products) between these groups at this study point. MPR and RPR correlated positively with Syntax Score at several study points after the surgery completion. Syntax Score, MPR, and RPR showed good clinical accuracy in surgery-related complication prediction ((AUC = 0.736), 95th CI (0.616-0.856), P = 0.003)). Conclusion When combined, MPV, RDW, and platelet count, such as MPR and RPR, could be good predictors of coronary artery disease status, regarding the aspect of joint inflammation, oxidative stress, and thrombosis.

Low-temperature combined with high-humidity thawing improves the water-holding capacity and biochemical properties of Portunus trituberculatus protein

Abstract This study compared the effects of conventional thawing methods (water immersion thawing (WIT, (25±1) °C), natural air thawing (AT, (25±1) °C, relative humidity (RH) (65±2) per cent), refrigerator thawing (RT, 4 °C, RH (80±2) per cent) and low-temperature (LT) combined with high-humidity thawing (LT, –1 °C to 1 °C (LT–1–1), 2–4 °C (LT2–4), 5–7 °C (LT5–7) and 8–10 °C (LT8–10), RH≥95 per cent) on the water-holding capacity, lipid oxidation and biochemical properties of Portunus trituberculatus (P. trituberculatus) myofibrillar protein. The results showed that WIT and AT significantly decreased the water-holding capacity while dramatically increasing lipid oxidation, protein oxidation and degeneration, resulting in serious P. trituberculatus quality deterioration. High humidity was beneficial for P. trituberculatus thawing. The thawing time of P. trituberculatus under the conditions of LT2–4 was only 39.39 per cent of that of conventional air thawing at 4 °C (RT), and the LT2–4 samples not only maintained better water-holding capacity but also had an obviously reduced degree of lipid oxidation, protein oxidation and denaturation. Thawed samples LT2–4 and LT5–7 provided better maintenance of P. trituberculatus quality than the LT–1–1 and LT8–10 samples. The best quality was exhibited after thawing at 2–4 °C. The levels of thiobarbituric acid reacting substances, carbonyl content and surface hydrophobicity observably decreased in these samples, while the total sulfhydryl contents dramatically increased compared to those of conventionally thawed samples, indicating lower lipid oxidation and protein oxidation. Moreover, the Ca2+-ATPase activity of the sample thawed at 2–4 °C (2.06 μmol Pi/mg prot/h) was markedly higher than that of samples subjected to WIT and AT. The product qualities observed after thawing at –1 °C to 1 °C, 5–7 °C and 8–10 °C under LT were comparable to that observed by RT. Considering its thawing efficiency and product quality, LT is a suitable method for the thawing of P. trituberculatus, and the ideal thawing conditions were LT at 2–4 °C.

Effects of Gallic Acid by Ultrasound on Physicochemical Properties of Lateolabrax Japonicas Myofibrillar Protein

The effects of different concentrations of gallic acid (0 mg/g, 1 mg/g, 2 mg/g, 4 mg/g, and 6 mg/g) on the physicochemical properties of Lateolabrax japonicas myofibrillar protein were studied with 400 W ultrasound. The results showed that gallic acid decreased the particle size, total sulfhydryl group, carbonyl and dimer tyrosine content and Ca2+-ATPase activity (P&lt;0.05) of myofibrillar protein, however, increased the zeta potential. Ultrasonic wave could cooperate with gallic acid to slow down protein oxidation and make the protein solution system more stable. When the concentration of gallic acid was 2 mg/g, the indicators of protein solution were most favorable, which improved the properties of protein.

Effect of ice-temperature storage on some properties of salt-soluble proteins and gel from chicken breast muscles

ABSTRACT The changes in physicochemical properties of salt-soluble proteins and gel prepared with chicken breast muscles during −1.5oC (ice-temperature) and 4oC (refrigerated temperature) storage were investigated. Compared with the samples of 4oC stored group, the decrease in solubility, the content of total sulfhydryl and available sulfhydryl groups of SSP from chicken breast muscles at −1.5oC storage was effectively delayed, and the increase of both surface hydrophobicity and content of disulfide bond was obviously inhibited. The gel prepared with −1.5oC stored samples had much higher holding capacity of water, lower cooking loss, better springiness, and more uniform three-dimensional network structures with smaller-sized pores than those from 4°C stored-samples. Additionally, great changes in the proportions of non-flowing water and free water ratio were observed during 4oC storage. In short, the ice-temperature storage used for chicken meat preservation was better than refrigerated storage.