Dielectric barrier discharge cold plasma treatment of pork loin: Effects on muscle physicochemical properties and emulsifying properties of pork myofibrillar protein

Effect of different pretreatment methods on the stability of pumpkin seed milk and potential mechanism

Pumpkin seeds represent a valuable source of plant protein and can be utilized in the production of plant-based milks. This study aims to investigate the effects of different pretreatment techniques on the stability of Pumpkin Seed Milk (PSM) and explore potential mechanisms. Raw pumpkin seeds underwent pretreatment through roasting, microwaving, and steaming to prepare PSM. Physiochemical attributes such as composition, storage stability, and particle size of PSM were evaluated. Results indicate that stability significantly improved at roasting temperatures of 160 °C, with the smallest particle size (305 ± 40 nm) and highest stability coefficient (0.710 ± 0.002) observed. Nutrient content in PSM remained largely unaffected at 160 °C. Protein oxidation levels, infrared, and fluorescence spectra analysis revealed that higher temperatures exacerbated the oxidation of pumpkin seed emulsion. Overall, roasting raw pumpkin seeds at 160 °C is suggested to enhance PSM quality while preserving nutrient content.

Effects of oxidative stress and protein S-nitrosylation interactions on mitochondrial pathway apoptosis and tenderness of yak meat during postmortem aging

To reveal the interaction of oxidative stress and protein S-nitrosylation on mitochondrial pathway apoptosis and tenderness development in postmortem yak meat. Herein, we selected yak longissimus dorsi muscle as the research object and treated hydrogen peroxide (H2O2) with S-nitrosoglutathione agent (GSNO) as well as Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) in mixed injections with 0.9 % saline as a control group, followed by incubation at 4 °C for 12, 24, 72, 120 and 168 h. Results showed that this interaction significantly increased mitochondrial ROS and NO content (P < 0.05) while weakening the antioxidant capacity of GSH and TRX redox response systems or accelerating the Ca2+ release process, leading to mitochondrial functional impairment and increased apoptosis rate. Notably, the H2O2 + L-NAME group showed more pronounced apoptosis. Hence, we suggest that the interaction between oxidative stress and protein S-nitrosylation could positively regulate yak meat tenderization.

Modification of soy protein isolate and pea protein isolate by high voltage dielectric barrier discharge (DBD) atmospheric cold plasma: Comparative study on structural, rheological and techno-functional characteristics

The modification in structural, rheological, and techno-functional characteristics of soy and pea protein isolates (SPI and PPI) due to dielectric barrier discharge cold plasma (DBD-CP) were assessed. The increased carbonyl groups in both samples with cold plasma (CP) treatment led to a reduction in free sulfhydryl groups. Moreover, protein solubility of treated proteins exhibited significant improvements, reaching up to 59.07 % and 41.4 % for SPI and PPI, respectively, at 30 kV for 8 min. Rheological analyses indicated that storage modulus (G') was greater than loss modulus (G″) for CP-treated protein gels. Furthermore, in vitro protein digestibility of SPI exhibited a remarkable improvement (4.78 %) at 30 kV for 6 min compared to PPI (3.23 %). Spectroscopic analyses, including circular dichroism and Fourier Transform-Raman, indicated partial breakdown and loss of α-helix structure in both samples, leading to the aggregation of proteins. Thus, DBD-CP induces reactive oxygen species-mediated oxidation, modifying the secondary and tertiary structures of samples.

Chemical and physical changes induced by cold plasma treatment of foods: A critical review

Cold plasma treatment is an innovative technology in the food processing and preservation sectors. It is primarily employed to deactivate microorganisms and enzymes without heat and chemical additives; hence, it is often termed a "clean and green" technology. However, food quality and safety challenges may arise during cold plasma processing due to potential chemical interactions between the plasma reactive species and food components. This review aims to consolidate and discuss data on the impact of cold plasma on the chemical constituents and physical and functional properties of major food products, including dairy, meat, nuts, fruits, vegetables, and grains. We emphasize how cold plasma induces chemical modification of key food components, such as water, proteins, lipids, carbohydrates, vitamins, polyphenols, and volatile organic compounds. Additionally, we discuss changes in color, pH, and organoleptic properties induced by cold plasma treatment and their correlation with chemical modification. Current studies demonstrate that reactive oxygen and nitrogen species in cold plasma oxidize proteins, lipids, and bioactive compounds upon direct contact with the food matrix. Reductions in nutrients and bioactive compounds, including polyunsaturated fatty acids, sugars, polyphenols, and vitamins, have been observed in dairy products, vegetables, fruits, and beverages following cold plasma treatment. Furthermore, structural alterations and the generation of volatile and non-volatile oxidation products were observed, impacting the color, flavor, and texture of food products. However, the effects on dry foods, such as seeds and nuts, are comparatively less pronounced. Overall, this review highlights the drawbacks, challenges, and opportunities associated with cold plasma treatment in food processing.

Effects of plasma-activated slightly acidic electrolyzed water on salmon myofibrillar protein: Insights from structure and molecular docking

The present study investigated the impact of plasma-activated water (PAW), slightly acidic electrolytic water (SAEW) and plasma-activated slightly acidic electrolytic water (PASW) treatment on myofibrillar protein (MP) in salmon fillets. Additionally, the interaction mechanism between myosin and reactive oxygen species was explored by molecular docking. Compared with the control group (719.26 nm), PASW treatment group exhibited the smallest particle size (408.97 nm). The PASW treatment exhibited efficacy in reducing MP aggregation and inhibiting protein oxidation. In comparison with other treatments, PASW treatment demonstrated a greater ability to mitigate damage to the secondary and tertiary structures of MP. O3 and H2O2 interact with myosin through hydrogen bonding. Specifically, O3 interacts with Lys676, Gly677, and Met678 of myosin while H2O2 binds to Thr681, Asp626, Arg680, and Met678. This study offers novel insights into the impact of PASW on MP, and provides a theoretical foundation for its application in aquatic product processing.

Unlocking the molecular modifications of plasma-activated water-induced oxidation through redox proteomics: In the case of duck myofibrillar protein (Anas platyrhynchos)

Plasma-activated water (PAW) contains multiple active species that alter the structure of myofibrillar protein (MP) to enhance their gel properties. This work investigated the impact of PAW on the oxidation of cysteine in MP by label-free quantitative proteomics. PAW treatment caused the oxidation of 8241 cysteine sites on 2815 proteins, and structural proteins such as nebulin, myosin XVIIIB, myosin XVIIIA, and myosin heavy chain were susceptible to oxidation by PAW. Bioinformatics analysis, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, subcellular localization, and STRING analysis, indicated that these proteins with differential oxidation sites were mainly derived from the cytoplasm and membrane, and were involved in multiple GO terms and KEGG pathways. This is one of the first reports of the redox proteomic changes induced by PAW treatment, and the results are useful for understanding the possible mechanism of PAW-induced oxidation of MP.

Assessing the Effects of Cold Atmospheric Plasma on the Natural Microbiota and Quality of Pork during Storage

Cold atmospheric plasma (CAP) is a novel non-thermal technology with significant potential for use in meat processing to prolong shelf life. The objective of the study was to evaluate the efficiency of CAP treatment on the natural microbiota and quality traits of pork stored for 8 days at 4 °C. CAP treatment was applied by employing piezoelectric direct discharge technology to treat pork samples for 0, 3, 6, and 9 min. Reductions of approximately 0.8-1.7 log CFU/g were observed in total viable counts (TVC) and Pseudomonas spp. levels for CAP treatments longer than 3 min, immediately after treatment. A storage study revealed that CAP-treated pork (>6 min) had significantly lower levels of TVC, Pseudomonas spp., and Enterobacteriaceae throughout storage. Regarding quality traits, CAP application for longer than 3 min significantly increased water retention and yellowness and decreased meat redness compared to untreated pork. However, other parameters such as pH, tenderness, and lightness exhibited no statistically significant differences between untreated and CAP-treated pork. Lipid oxidation levels were higher only for the 9-min treatment compared to untreated pork. Our results revealed that CAP is a promising technology that can extend the microbiological shelf life of pork during refrigeration storage.

Changes in Flavor and Volatile Composition of Meat and Meat Products Observed after Exposure to Atmospheric Pressure Cold Plasma (ACP)

Studies on the atmospheric pressure cold plasma (ACP) exposure of meat and meat products mainly determine microbial inactivation, lipid oxidation, and meat color. Some studies include sensory evaluation, but only a few determine the changes in volatile composition due to ACP treatment. The results of sensory evaluation are inconclusive and range from "improvement" to "off-odor". This could be due to differences in the food matrix, especially in processed foods, or different experimental settings, including inadvertent effects such as sample heating. The few studies analyzing volatile composition report changes in alcohols, esters, aldehydes, and other compounds, but not necessarily changes that are novel for meat and meat products. Most studies do not actually measure the formation of reactive species, although this is needed to determine the exact reactions taking place in the meat during ACP treatment. This is a prerequisite for an adjustment of the plasma conditions to achieve antimicrobial effects without compromising sensory quality. Likewise, such knowledge is necessary to clarify if ACP-exposed meat and products thereof require regulatory approval.

Whey Protein Hydrolysate Improved the Structure and Function of Myofibrillar Protein in Ground Pork during Repeated Freeze-Thaw Cycles

Whey protein hydrolysate (WPH) has made a breakthrough in inhibiting oxidative deterioration and improving the quality of meat products during storage. Based on our previous study of extracting the most antioxidant active fraction I (FI, the molecular weight < 1 kDa) from whey protein hydrolysates of different molecular weights, the present study continued to delve into the effects of WPH with fraction I on the structure and function of myofibrillar proteins (MP) in ground pork during the freeze-thaw (F-T) cycles. With the number of F-T cycles raised, the total sulfhydryl content, the relative contents of α-helix, Ca2+-ATPase activity, K+-ATPase activity, solubility, emulsion activity index (EAI), and emulsion stability index (ESI) of MP gradually decreased. Conversely, the carbonyl content and the relative content of random curl showed an increasing trend. In particular, the damage to the structure and the function of MP became more pronounced after three F-T cycles. But, during F-T cycles, FI stabilized the structure of MP. Compared to the control group, the 10% FI group showed a remarkable improvement (p < 0.05) in the total sulfhydryl content, Ca2+-ATPase activity, K+-ATPase activity, solubility, EAI and ESI after multiple F-T cycles, suggesting that 10% FI could effectively inhibit protein oxidation and had the influence of preserving MP function properties. In conclusion, WPH with fraction I can be used as a potential natural antioxidant peptide for maintaining the quality of frozen processed meat products.

Effects of Cold Plasma Treatment Conditions on the Lipid Oxidation Kinetics of Tilapia Fillets

This study investigated the effects of different cold plasma treatment conditions on the lipid oxidation kinetics of tilapia fillets. The results indicated that increasing the voltage and prolonging the treatment time of cold plasma could cause an increase in the peroxide value and thiobarbituric acid-reactive substance values of the fillets. The changes in the primary and secondary oxidation rates of the lipids in the fillets under different treatment conditions were consistent with zero-order reaction kinetics. The analysis of the fitting of the Arrhenius equation showed that the effect of treatment voltage on the activation energy of lipid oxidation was higher than that of treatment time. When the voltage was higher than 64.71 kV, the activation energy of the primary oxidation of lipids was greater than that of secondary oxidation. Within 0-5 min, the activation energy of primary oxidation first increased then decreased, and was always greater than that of secondary oxidation. Therefore, the primary lipid oxidation of tilapia was more sensitive to the treatment conditions of cold plasma.

The mechanism of Leuconostoc mesenteroides subsp. IMAU:80679 in improving meat color: Myoglobin oxidation inhibition and myoglobin derivatives formation based on multi enzyme-like activities

The Leuconostoc mesenteroides subsp. IMAU:80679 (LM) was chosen for its superior capability in enhancing redness, and was incubated in a broth system containing metmyoglobin (MetMb) to investigate its mechanisms for color improvement. The a* value of LM group reached its highest level of 52.75 ± 1.04 at 24 h, significantly higher than control of 19.75 ± 0.6 (p < 0.05). The addition of LM could inhibit myoglobin oxidation to some extent. Meanwhile, higher content of nitrosylmyoglobin (NOMb) and Zn-protoporphyrin (Znpp) were observed in LM samples during the whole incubation period. Furthermore, enzymatic activity and encoded genes related to MetMb reduction and pigment formation were determined to explain its possible mechanism on color enhancement. Finally, by extracting crude enzymes and adding them to meat batters, the redness of crude enzyme group was comparable to that achieved with 20 ppm nitrite, providing a potential method on compensating for nitrite/nitrate substitution in meat products.

Enhanced Gel Properties of Duck Myofibrillar Protein by Plasma-Activated Water: Through Mild Structure Modifications

This study assessed the gel properties and conformational changes of duck myofibrillar protein (DMP) affected by plasma-activated water (PAW) generated at various discharge times (0 s, 10 s, 20 s, 30 s, and 40 s). With the treatment of PAW-20 s, the gel strength and water-holding capacity (WHC) of DMP gels were significantly increased when compared to the control group. Throughout the heating process, dynamic rheology revealed that the PAW-treated DMP had a higher storage modulus than the control. The hydrophobic interactions between protein molecules were significantly improved by PAW, resulting in a more ordered and homogeneous gel microstructure. The increased sulfhydryl and carbonyl content in DMP indicated a higher degree of protein oxidation with PAW treatment. Additionally, the circular dichroism spectroscopy demonstrated that PAW induced α-helix and β-turn transformed to β-sheet in DMP. Surface hydrophobicity, fluorescence spectroscopy, and UV absorption spectroscopy suggested that PAW altered DMP's tertiary structure, although the electrophoretic pattern indicated that the primary structure of DMP was mostly unaffected. These results suggest that PAW can improve the gel properties of DMP through mild alteration in its conformation.

Effect of Cold-Plasma-Treated Phosphate Solution to Substitute Partial Nitrite on the Color, Texture, and Flavor of Smoked Sausage

There are several alternative technologies to nitrite use in meat products, including cold plasma. In this study, a cold-plasma-treated phosphate solution was added to smoked sausage, as a new ingredient. Subsequently, the color, texture, and flavor of the samples were analyzed. The results showed that, compared with nitrite (0.075 g/kg nitrite added to sausage), the addition of 30~90% nitrite and cold-plasma-treated phosphate solution had no significant effect on the a* value or the relative content of oxygenated myoglobin (p > 0.05). The amount of residual nitrite in the smoked sausage prepared with the addition of 30~70% nitrite and cold-plasma-treated phosphate solution was significantly lower than that of the nitrite-treated group. The addition of nitrite combined with cold-plasma-treated phosphate solution had no significant effects on the texture (hardness, springiness, cohesiveness, and resilience) or the sensory evaluation of the smoked sausage. A total of 69 volatile compounds were detected, and 20 of them had VIP (Variable Importance Plot) scores higher than one. In conclusion, cold plasma treatment represents a potential technology to partially substitute nitrite. This study provides new methods for the application of this nitrite substitute.