Evaluation of meat-quality and myofibrillar protein of chicken drumsticks treated with plasma-activated lactic acid as a novel sanitizer

The challenges and prospects of using cold plasma to prevent bacterial contamination and biofilm formation in the meat industry

The risk of foodborne disease outbreaks increases when the pathogenic bacteria are able to form biofilms, and this presents a major threat to public health. An emerging non-thermal cold plasma (CP) technology has proven a highly effective method for decontaminating meats and their products and extended their shelf life. CP treatments have ability to reduce microbial load and, biofilm formation with minimal change of color, pH value, and lipid oxidation of various meat and meat products. The CP technique offers many advantages over conventional processing techniques due to its layout flexibility, nonthermal behavior, affordability, and ecological sustainability. The technology is still in its infancy, and continuous research efforts are needed to realize its full potential in the meat industry. This review addresses the basic principles and the impact of CP technology on biofilm formation, meat quality (including microbiological, color, pH value, texture, and lipid oxidation), and microbial inactivation pathways and also the prospects of this technology.

Current Status of Non-Thermal Sterilization by Pet Food Raw Ingredients

Recently, as the concept of pet food that satisfies both nutritional needs and the five senses has evolved, so too has the demand for effective pet food non-thermal sterilization methods. Prominent non-thermal technologies include high-pressure processing, plasma, and radiation, which are favored for their ability to preserve nutrients, avoid residues, and minimize compositional changes, thereby maintaining quality and sensory properties. However, to assess their effectiveness on pet food, it is essential to optimize operational parameters such as pressure levels, plasma intensity, radiation dosage, and temperature. Further studies are needed to evaluate microbial sterilization efficacy and sensory attributes. This exploration is expected to lay the groundwork for preventing zoonotic diseases and improving the production of high-quality pet food.

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.

Effects of nano freezing-thawing on myofibrillar protein of Atlantic salmon fillets: Protein structure and label-free proteomics

This study investigated the impact of magnetic nanoparticles (MNPs) -assisted cryogenic freezing integrated with MNPs combined microwave thawing (NNMT) on the structural integrity of myofibrillar proteins and alterations in protein profiles in salmon fillets. The NNMT showed the lowest myofibrillar fragmentation index (MFI) value (2.73 ± 0.31) among the four freezing-thawing groups. The myofibrillar structure exhibited the highest level of integrity, while the myofibrillar proteins demonstrated minimal aggregation and displayed the most stable secondary and tertiary structures in response to NNMT treatment. Compared with the other three treatments, NNMT exhibited a high abundance of ionic and hydrogen bonds, resulting in stronger interactions between the proteins and water molecules. The label-free proteomics analysis revealed that different freezing-thawing methods primarily affected the cytoskeletal proteins, with collagen and myosin being down-regulated due to degradation caused by cold stress and recrystallization. Additionally, NNMT demonstrated a superior capability in stabilizing salmon cytoskeletal proteins.

Effect of plasma-activated lactic acid on microbiota composition and quality of puffer fish (Takifugu obscurus) fillets during chilled storage

Fresh puffer fish (Takifugu obscurus) are susceptible to microbial contamination and have a very short shelf-life of chilled storage. Hence, this study aimed to evaluate the effects of plasma-activated lactic acid (PALA) on microbiota composition and quality attributes of puffer fish fillets during chilled storage. The results showed that PALA treatment effectively reduced the growth of bacteria and attenuated changes in physicochemical indicators (total volatile basic nitrogen, pH value, K value, and biogenic amines) of puffer fish fillets. Additionally, insignificant changes were observed in lipid oxidation during the first 8 days (p > 0.05). Illumina-MiSeq high-throughput sequencing revealed that PALA effectively inhibited the growth of Pseudomonas in puffer fish fillets and maintained the diverse characteristics of the microbial community. In combination with sensory analysis, PALA extended the shelf life of puffer fish fillets for 4 days, suggesting that PALA could be considered a potential fish fillet preservation method.

Deciphering the thick filaments assembly behavior of myosin as affected by enzymatic deamidation

Enzymatic deamidation is a promising approach in enhancing the solubility of myofibrillar proteins (MPs) in water paving the way of tailor manufacturing muscle protein-based beverages. This work aimed to clarify the solubilization mechanism by deciphering myosin thick filaments assembly as affected by protein-glutaminase deamidation. With the extension of deamidation, filamentous structures in MPs shortened continuously. Dynamic monitoring of quartz crystal microbalance-dissipated showed the adsorption capacity of the deaminated MPs was reduced from 3.66 ng/cm2 to 2.03 ng/cm2, indicating that the ability to assemble myosin thick filaments was significantly weakened. By simulating the surface charge, it was found that deamidation may neutralize the positive charged clusters distanced at 14-29 nm from rod C-terminus. Since this region confers myosin electrostatic property to initiate staggered dimerization, deamidation in this region, which severely affected the electrostatic balance between residues, impaired ordered thick filament growing and elongating, thus promoting the solubilization of MPs in water.

Effect of plasma-activated organic acids on different chicken cuts inoculated with Salmonella Typhimurium and Campylobacter jejuni and their antioxidant activity

Lactic acid, gallic acid, and their mixture (1% each) were prepared (LA, GA, and LGA) and plasma-activated organic acids (PAOA) were produced through exposure to plasma for 1 h (PAL, PAG, and PLGA). Chicken breast and drumstick were immersed in the prepared solutions for 10 min and analyzed their antibacterial effect against Salmonella Typhimurium and Campylobacter jejuni and antioxidant activity during 12 d of storage. As a result, PAOA inactivated approximately 6.37 log CFU/mL against S. Typhimurium and 2.76, 1.86, and 3.04 log CFU/mL against C. jejuni (PAL, PAG, and PLGA, respectively). Moreover, PAOA had bactericidal effect in both chicken parts inoculated with pathogens, with PAL and PLGA displaying higher antibacterial activity compared to PAG. Meanwhile, PAOA inhibited lipid oxidation in chicken meats, and PAG and PLGA had higher oxidative stability during storage compared to PAL. This can be attributed to the superior antioxidant properties of GA and LGA, including higher total phenolic contents, ABTS+ reducing activity, and DPPH radical scavenging activity, when compared to LA. In particular, when combined with plasma treatment, LGA showed the greatest improvement in antioxidant activity compared to other organic acids. In summary, PLGA not only had a synergistic bactericidal effect against pathogens on chicken, but also improved oxidative stability during storage. Therefore, PLGA can be an effective method for controlling microorganisms without adverse effect on lipid oxidation for different chicken cuts.

A review on plasma-activated water and its application in the meat industry

Meat is a nutritious food with a short shelf life, making it challenging to ensure safety, quality, and nutritional value. Foodborne pathogens and oxidation are the main concerns that lead to health risks and economic losses. Conventional approaches like hot water, steam pasteurization, and chemical washes for meat decontamination improve safety but cause nutritional and quality issues. Plasma-activated water (PAW) is a potential alternative to thermal treatment that can reduce oxidation and microbial growth, an essential factor in ensuring safety, quality, and nutritional value. This review explores the different types of PAW and their physiochemical properties. It also outlines the reaction pathways involved in the generation of short-lived and long-lived reactive nitrogen and oxygen species (RONS) in PAW, which contribute to its antimicrobial abilities. The review also highlights current studies on PAW inactivation against various planktonic bacteria, as well as critical processing parameters that can improve PAW inactivation efficacy. Promising applications of PAW for meat curing, thawing, and decontamination are discussed, with emphasis on the need to understand how RONS in PAW affect meat quality. Recent reports on combining PAW with ultrasound, mild heating, and non-thermal plasma to improve inactivation efficacy are also presented. Finally, the need to develop energy-efficient systems for the production and scalability of PAW is discussed for its use as a potential meat disinfectant without compromising meat quality.

Novel strategies for controlling nitrite content in prepared dishes: Current status, potential benefits, limitations and future challenges

Sodium nitrite is commonly used as a multifunctional curing ingredient in the processing of prepared dishes, especially meat products, to impart unique color, flavor and to prolong the shelf life of such products. However, the use of sodium nitrite in the meat industry has been controversial due to potential health risks. Finding suitable substitutes for sodium nitrite and controlling nitrite residue have been a major challenge faced by the meat processing industry. This paper summarizes possible factors affecting the variation of nitrite content in the processing of prepared dishes. New strategies for controlling nitrite residues in meat dishes, including natural pre-converted nitrite, plant extracts, irradiation, non-thermal plasma and high hydrostatic pressure (HHP), are discussed in detail. The advantages and limitations of these strategies are also summarized. Raw materials, cooking techniques, packaging methods, and storage conditions all affect the content of nitrite in the prepared dishes. The use of vegetable pre-conversion nitrite and the addition of plant extracts can help reduce nitrite residues in meat products and meet the consumer demand for clean labeled meat products. Atmospheric pressure plasma, as a non-thermal pasteurization and curing process, is a promising meat processing technology. HHP has good bactericidal effect and is suitable for hurdle technology to limit the amount of sodium nitrite added. This review is intended to provide insights for the control of nitrite in the modern production of prepared dishes.

Insight into the microorganisms, quality, and protein structure of golden pompano (Trachinotus ovatus) treated with cold plasma at different voltages

Cold plasma (CP) is a non-thermal novel technology for the processing of heat-sensitive food products, but there is concern regarding its impact on food quality. Voltage is one of the most direct factors affecting the bacteriostatic effect of CP. Golden pompano (Trachinotus ovatus) was treated with CP at different voltages (10, 20, and 30 kV). The total viable count decreased as the CP voltage increased, reaching a maximum reduction of 1.54 lg CFU/g on golden pompano treated at 30 kV. No effects on water-holding capacity, pH, total volatile base nitrogen, and T_2b relaxation time were observed, indicating that all CP treatments retained the freshness and bound water of the samples. However, as the CP voltage increased, peroxide value and thiobarbituric acid-reactive substances of golden pompano gradually increased, the protein tertiary structure unfolded, and α-helices converted to β-sheets, indicating inevitable lipid and protein oxidation caused by excessive CP voltage. Therefore, a suitable voltage of CP should be selected to inhibits the growth of microorganisms, which avoids deterioration of sea-foods quality.

Using TRIS-Buffered Plasma-Activated Water to Reduce Pathogenic Microorganisms on Poultry Carcasses with Evaluation of Physicochemical and Sensory Parameters

Foodborne diseases are mainly caused by the contamination of meat or meat products with pathogenic microorganisms. In this study, we first investigated the in vitro application of TRIS-buffered plasma-activated water (Tb-PAW) on Campylobacter (C.) jejuni and Escherichia (E.) coli, with a reduction of approx. 4.20 ± 0.68 and 5.12 ± 0.46 log₁₀ CFU/mL. Furthermore, chicken and duck thighs (inoculated with C. jejuni or E. coli) and breasts (with natural microflora) with skin were sprayed with Tb-PAW. Samples were packed under a modified atmosphere and stored at 4 °C for 0, 7, and 14 days. The Tb-PAW could reduce C. jejuni on days 7 and 14 (chicken) and E. coli on day 14 (duck) significantly. In chicken, there were no significant differences in sensory, pH-value, color, and antioxidant activity, but %OxyMb levels decreased, whereas %MetMb and %DeoMb increased. In duck, we observed slight differences in pH-value, color, and myoglobin redox forms for the Tb-PAW, which were not perceived by the sensory test persons. With only slight differences in product quality, its application as a spray treatment may be a useful method to reduce C. jejuni and E. coli on chicken and duck carcasses.

Inactivation of Listeria monocytogenes through the synergistic interaction between plasma-activated water and organic acid

This study observed that when plasma-activated water (PAW) was combined with organic acid, it showed a synergistic inactivation effect on Listeria monocytogenes, which is highly resistant to PAW. When comparing various organic acids, lactic acid (LA) showed the greatest synergistic effect, followed by malic acid (MA), citric acid (CA), and acetic acid (AA), whereas propionic acid (PA) did not show a synergistic effect. Organic acid lowered the activity of ROS defense enzymes (catalase, superoxide dismutase) by reducing intracellular pH (pH_i), which induced the increase in the accumulation of ROS of PAW within the cell. In the end, the synergistic inactivation effect appeared as the increased occurrence of oxidative damage when organic acid was combined as a series of preceding causes. In this case, LA with the greatest ability to lower the pH induced the greatest synergistic effect, suggesting that LA is the best candidate to be combined with PAW. As a result of observing changes in inactivation activity for L. monocytogenes of PAW combined with 1.0% LA while storing at - 80, -20, 4, 25, & 37 °C for 30 days, respectively, it was confirmed that the lower the temperature, the lower the activity loss during the storage period, and that it had an activity of 3.72 log reduction based on 10 min treatment when stored at - 80 °C for 30 days. Application of PAW combined with 1.0% LA stored at - 80 °C for 30 days to mackerel inoculated with L. monocytogenes in ice form resulted in a decrease of 4.53 log after 120 min treatment, without changing the quality of mackerel. These results suggest that combining LA with PAW can be an effective control strategy for L. monocytogenes with high resistance to PAW, and can be effectively utilized, even in ice form.

Non-Destructive Detection of Meat Quality Based on Multiple Spectral Dimension Reduction Methods by Near-Infrared Spectroscopy

The potential of four dimension reduction methods for near-infrared spectroscopy was investigated, in terms of predicting the protein, fat, and moisture contents in lamb meat. With visible/near-infrared spectroscopy at 400-1050 nm and 900-1700 nm, respectively, calibration models using partial least squares regression (PLSR) or multiple linear regression (MLR) between spectra and quality parameters were established and compared. The MLR prediction models for all three quality parameters based on the wavelengths selected by stepwise regression achieved the best results in the spectral region of 400-1050 nm. As for the spectral region of 900-1700 nm, the PLSR prediction model based on the raw spectra or high-correlation spectra achieved better results. The results of this study indicate that sampling interval shortening and of peak-to-trough jump features are worthy of further study, due to their great potential in explaining the quality parameters.

Evaluating the influence of cold plasma bubbling on protein structure and allergenicity in sesame milk

BACKGROUND

Sesame is a traditional oilseed comprising essential amino acids. However, the presence of allergens in sesame is a significant problem in its consumption; thus, this study attempted to reduce these allergens in sesame oilseeds.

OBJECTIVE

The present study aimed to evaluate the effect of cold plasma processing on structural changes in proteins, and thereby the alteration of allergenicity in sesame milk. Method: Sesame milk (300 mL) was processed using atmospheric pressure plasma bubbling unit (dielectric barrier discharge, power: 200 V, and airflow rate: 16.6 mL/min) at different exposure times (10, 20, and 30 min).

RESULTS

The efficiency of plasma-bubbling unit as measured by electron paramagnetic resonance in terms of producing reactive hydroxyl (OH) radicals proved that generation of reactive species increased with exposure time. Further, the plasma-processed sesame milk subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and differential scanning calorimetery analysis revealed that plasma bubbling increased the oxidation of proteins with respect to bubbling time. The structural analysis by Fourier transform infrared spectroscopy and circular dichroism revealed that the secondary structure of proteins was altered after plasma application. This change in the protein structure helped in changing the immunoglobulin E (IgE)-binding epitopes of the protein, which in turn reduced the allergen-binding capacity by 23% at 20-min plasma bubbling as determined by the sandwich-type enzyme-linked immunosorbent assay. However, 30-min plasma bubbling intended to increase allergenicity, possibly because of increase in IgE binding due to the generation of neo epitopes.

CONCLUSION

These changes proved that plasma bubbling is a promising technology in oxidizing protein structure, and thereby reducing the allergenicity of sesame milk. However, increase in binding at 30-min bubbling is to be studied to facilitate further reduction of the binding capacity of IgE antibodies.

Hybridising plasma functionalized water and ultrasound pretreatment for enzymatic protein hydrolysis of Larimichthys polyactis: Parametric screening and optimization

Hybridising plasma functionalized water and ultrasound pretreatment for the enzymatic hydrolysis (HPUEH) of Larimichthys polyactis was evaluated by adopting Plackett-Burman design for parametric screening of six key variables, and Box-Behnken design for optimizing three most significant variables including plasma generating voltage (P_V), ultrasound treatment time (U_T), and enzyme concentration (E_C). The models developed for predicting the degree of hydrolysis (DoH), protein recovery (PVY), and soluble protein content (SPC) were sufficiently fitted to the experimental data (R² ≥ 0.966) with non-significant lack of fit and used for determining the optimum conditions as P_V of 70 V, U_T of 15 min, and E_C of 1.787%, with predictive values of 27.74%, 85.62%, and 3.28 mg/mL for DoH, PVY, and SPC, respectively. HPUEH presented hydrolysates with smaller peptide sizes and molecular weights, enhanced DoH, PVY, SPC, amino acids and antioxidant activity, but reduced emulsifying and foaming properties when compared with conventional enzymatic hydrolysis.

Modelling of inactivation kinetics of Escherichia coli and Listeria monocytogenes on grass carp treated by combining ultrasound with plasma functionalized buffer

Linear (first-order) and non-linear (Weibull, biphasic, and log-logistic) models were evaluated for predicting the inactivation kinetics of Escherichia coli and Listeria monocytogenes on grass carp treated by a novel technique (UPFB) combining ultrasound (US) with plasma functionalized buffer (PFB). Results showed that UPFB was more effective for inactivating bacteria when compared with individual applications of US or PFB with reductions of 3.92 and 3.70 log CFU/g for Escherichia coli and Listeria monocytogenes, respectively. Compared with the linear model, the three non-linear models presented comparable performances and were more suitable for describing the inactivation kinetics with superior adj-R² (0.962-0.999), accuracies (0.970-1.006) and bias factors (0.995-1.031), and by assessing the strengths of evidence, weights of evidence and evidence ratios for the models, the biphasic model was identified as the best fit model. The current study provided new insights into the effective evaluation of decontamination methods.

Plasma-Activated Water for Food Safety and Quality: A Review of Recent Developments

Plasma-activated water (PAW) has received a lot of attention lately because of its antibacterial efficacy and eco-friendly nature. Compared to traditional disinfectants, this novel and intriguing option has a high disinfectant capacity while causing little to no modifications to the foodstuffs. Until now, PAW has successfully demonstrated its effectiveness against a broad range of microorganisms on a wide variety of food items. Though the efficacy of PAW in microbial reduction has been extensively reviewed, a relatively significant issue of food quality has been largely overlooked. This review aims to summarize the current studies on the physicochemical characteristics and antimicrobial potential of PAW, with an in-depth focus on food quality and safety. According to recent studies, PAW can be a potential microbial disinfectant that extends the shelf life of various food products, such as meat and fish products, fruits and vegetables, cereal products, etc. However, the efficacy varies with treatment conditions and the food ingredients applied. There is a mixed opinion about the effect of PAW on food quality. Based on the available literature, it can be concluded that there has been no substantial change in the biochemical properties of most of the tested food products. However, some fruits and vegetables had a higher value for the enzyme superoxide dismutase (SOD) after PAW treatment, while only a few demonstrated a decrease in the Thiobarbituric acid reactive substances (TBARS) value. Sensory properties also showed no significant difference, with some exceptions in meat and fish products.

Tailoring protein intrinsic charge by enzymatic deamidation for solubilizing chicken breast myofibrillar protein in water

Inspired by the salt-in effect, the potential use of protein-glutaminase (PG) to increase the intrinsic charges of chicken breast myofibrillar proteins (CMPs) for enhanced water solubility was tested. The degree of deamidation (DD) and solubility of CMPs increased with PG reaction time. Over 60% of CMPs were soluble in water under a DD of 6.5% due to specific conversion of glutamine to glutamic acid. PG deamidation could remarkably increase the net charge of CMPs with a merit in maintaining most of the amino acid and protein subunit compositions. Such a high electrostatic repulsion exerted a transformation of β-sheet into α-helix, unfolded the structure to expose hydrophobic residues, and allowed the dissociation of myofibril and release of subunits (myosin, actin or their oligomers), leading to a stable colloidal state. This work may foster the engineering advances of protein micro-modification in the tailor manufacture of muscle protein-based beverages.

Plasma-activated water: A novel frozen meat thawing media for reducing microbial contamination on chicken and improving the characteristics of protein

To solve the problems of microbial contamination and protein loss caused by the conventional thawing method, plasma-activated water (PAW) and ultrasound were applied. Changes in microorganisms, protein loss, oxidation, degradation, digestion, and lipid oxidation were measured to evaluate the practicability of novel thawing treatments. Compared with the conventional thawing treatment, PAW thawing and ultrasound in combination with PAW thawing resulted in the reduction of the bacterium for 0.62-1.17 log CFU/g. Due to the presence of PAW in the thawing medium, the protein loss was reduced by 17.1-23.1%. NO radicals in the PAW retarded the lipid oxidation rate of chickens during thawing processing. These novel thawing treatments also had no significant effect on the apparent quality and protein compositions of chicken meat, and even improved protein digestion. PAW thawing treatment plays the role of sterilization while minimizing the protein loss, can be further applied to the thawing of poultry meat.