Variation of volatile compounds and sensory profile for Protaetia brevitarsis larvae fermented with lactic acid bacteria and yeast.

This study aimed to investigate the correlation between the composition of volatile compounds, consumer acceptance, and drivers of (dis)liking of Protaetia brevitarsis larvae fermented using lactic acid bacteria and yeast. Volatile compounds were analyzed using HS-SPME-Arrow-GC-MS, and a sensory evaluation was conducted with 72 consumers. A total of 113 volatile compounds were detected, and principal component analysis indicated that the samples could be divided into three groups. The calculated relative odor activity values (ROAV) revealed the presence of 27 compounds (ROAV >1). Volatile compounds with high ROAV were predominantly found during yeast fermentation. The sensory evaluation results indicated a strong correlation between low levels of off-odor intensity and high odor liking, emphasizing that odor profile had a more direct association with consumer acceptance than odor intensity. These findings suggest that yeast fermentation using volatile compounds, which positively influences consumer acceptance, is appropriate for Protaetia brevitarsis larvae.

The Effect of Vacuum Films on Physicochemical and Microbiological Characteristics of Hanwoo (Korean Native Cattle).

The objective of this study was to investigate the physicochemical and microbiological characteristics of round of Hanwoo by vacuum packaging film materials, polyvinylidene chloride (PVDC) and ethylene vinyl alcohol (EVOH). The packaged beef samples were stored in refrigerated conditions (2±1°C) for 12 weeks. Physicochemical analysis with pH, surface color, thiobarbituric acid reactive substances (TBARS) values, and volatile basic nitrogen (VBN) values and microbiological analysis with aerobic plate count (APC) and metagenomic analysis of packaged beef samples were performed. The pH and surface color did not change substantially during the 12 weeks and EVOH-packaged beef tended to be lower than those of PVDC-packaged beef. PVDC- and EVOH-packaged samples showed low TBARS and VBN values below standard limits. APC did not exceed 7 Log CFU/g for both samples during storage. In metagenomic analysis, Firmicutes and Lactobacillaceae were dominant phylum and family of the PVDC- and EVOH-packaged beef. In both packaged samples, Dellaglioa algida was the dominant species during storage, with the notable difference being the presence of Lactococcus piscium. Therefore, this study provided the information on the quality of vacuum-packaged beef according to different vacuum films for long-term refrigerated storage.

The Effect of Gelatin Coating and Sonication on the Quality Properties of Wet-Aging Pork Loins.

In this study, we evaluate the effect of gelatin coating and sonication of wet-aged pork loin on quality. The moisture content of wet-aged pork loin with sonication and gelatin coating was the highest in the G5S sample (5% gelatin coating and sonication), while the moisture content of wet-aged pork loin with sonication was higher than that without sonication. The pH of wet-aged pork loin with sonication was lower than that without sonication. The aging loss of 5% gelatin coating with sonication was significantly lower than that of G0 (control), while the cooking loss was the lowest in G0 wet-aged pork loin. The water holding capacity of the wet-aged pork loin was the highest in G1. The thiobarbituric acid reactive substances value of wet-aged pork loin was significantly decreased with coating and not affected by sonication. The gelatin coating and sonication treatment significantly increased the myofibrillar fragmentation index of the samples. Shear force of wet-aged pork loin significantly decreased as the samples were gelatin-coated and sonicated. The myofibrillar and total protein solubilities were not significantly different between samples. In conclusion, the 1% gelatin coating with sonication can enhance the quality of wet-aged pork loin.

Application of Natural Preservatives for Meat and Meat Products against Food-Borne Pathogens and Spoilage Bacteria: A Review.

Meat and meat products are excellent sources of nutrients for humans; however, they also provide a favorable environment for microbial growth. To prevent the microbiological contamination of livestock foods, synthetic preservatives, including nitrites, nitrates, and sorbates, have been widely used in the food industry due to their low cost and strong antibacterial activity. Use of synthetic chemical preservatives is recently being considered by customers due to concerns related to negative health issues. Therefore, the demand for natural substances as food preservatives has increased with the use of plant-derived and animal-derived products, and microbial metabolites. These natural preservatives inhibit the growth of spoilage microorganisms or food-borne pathogens by increasing the permeability of microbial cell membranes, interruption of protein synthesis, and cell metabolism. Natural preservatives can extend the shelf-life and inhibit the growth of microorganisms. However, they can also influence food sensory properties, including the flavor, taste, color, texture, and acceptability of food. To increase the applicability of natural preservatives, a number of strategies, including combinations of different preservatives or food preservation methods, such as active packaging systems and encapsulation, have been explored. This review summarizes the current applications of natural preservatives for meat and meat products.

Antimicrobial and Antibiofilm Effect of ε-Polylysine against Salmonella Enteritidis, Listeria monocytogenes, and Escherichia coli in Tryptic Soy Broth and Chicken Juice.

ε-Polylysine (ε-PL) is a safe food additive that is used in the food industry globally. This study evaluated the antimicrobial and antibiofilm activity of antibacterial peptides (ε-PL) against food poisoning pathogens detected in chicken (Salmonella Enteritidis, Listeria monocytogenes, and Escherichia coli). The results showed that minimum inhibitory concentrations (MICs) ranged between 0.031-1.0 mg/mL, although most bacterial groups (75%) showed MICs of 1.0 mg/mL. The reduction in the cell viability of pathogens due to ε-PL depended on the time and concentration, and 1/2 × MIC of ε-PL killed 99.99% of pathogens after 10 h of incubation. To confirm biofilm inhibition and degradation effects, crystal violet assay and confocal laser scanning microscopy (CLSM) were used. The biofilm formation rates of four bacterial groups (Salmonella, Listeria, E. coli, and multi-species bacteria) were 10.36%, 9.10%, 17.44%, and 21.37% at 1/2 × MIC of ε-PL, respectively. Additionally, when observed under a CLSM, ε-PL was found to induce biofilm destruction and bacterial cytotoxicity. These results demonstrated that ε-PL has the potential to be used as an antibiotic and antibiofilm material for chicken meat processing.

Combinatorial Effects of Protective Agents on Survival Rate of the Yeast Starter, Saccharomyces cerevisiae 88-4, after Freeze-Drying.

A yeast starter is formulated for commercial practices, including storage and distribution. The cell viability of the yeast starter is one of the most important factors for manufacturing alcoholic beverages to ensure their properties during the fermentation and formulation processes. In this study, 64 potential protective agents were evaluated to enhance the survival rate of the brewing yeast Saccharomyces cerevisiae 88-4 after freeze-drying. In addition, the optimized combination of protective agents was assessed for long-term storage. Finally, response surface methodology was applied to investigate the optimal concentration of each protectant. Twenty of the 64 additives led to an increase in the survival rate of freeze-dried S. cerevisiae 88-4. Among the various combinations of protectants, four had a survival rate >95%. The combination of skim milk, maltose, and maltitol exhibited the best survival rate of 61% after 42 weeks in refrigerated storage, and the composition of protectants optimized by response surface methodology was 6.5-10% skim milk, 1.8-4.5% maltose, and 16.5-18.2% maltitol. These results demonstrated that the combination of multiple protectants could alleviate damage to yeasts during freeze-drying and could be applied to the manufacturing starters for fermented foods.

Anti-Biofilm Activity of Cell-Free Supernatant of Saccharomyces cerevisiae against Staphylococcus aureus.

Staphylococcus aureus is one of the most common microorganisms and causes foodborne diseases. In particular, biofilm-forming S. aureus is more resistant to antimicrobial agents and sanitizing treatments than planktonic cells. Therefore, this study aimed to investigate the anti-biofilm effects of cell-free supernatant (CFS) of Saccharomyces cerevisiae isolated from cucumber jangajji compared to grapefruit seed extract (GSE). CFS and GSE inhibited and degraded S. aureus biofilms. The adhesion ability, auto-aggregation, and exopolysaccharide production of CFS-treated S. aureus, compared to those of the control, were significantly decreased. Moreover, biofilm-related gene expression was altered upon CFS treatment. Scanning electron microscopy images confirmed that CFS exerted anti-biofilm effects against S. aureus. Therefore, these results suggest that S. cerevisiae CFS has anti-biofilm potential against S. aureus strains.

Application of mixed natural preservatives to improve the quality of vacuum skin packaged beef during refrigerated storage.

This study aimed to develop an active packaging (AP) system for beef storage using vacuum skin packaging (VSP) applied with mixed natural preservatives (MNPs) consisting of grapefruit seed extract (GSE), cinnamaldehyde (CA), and nisin; and to assess its effect on the physicochemical, microbial, and antibacterial properties against food-borne pathogens in beef compared with using wrapped packaging (WP) and VSP. The pH of the AP was a medium level of WP and VSP. AP was effective in preserving beef surface color including lightness and redness. AP delayed lipid oxidation and protein deterioration of beef by 14 days and 7 days as compared to that in WP and VSP, respectively. It also slowed low microbial counts of psychrotrophic and anaerobic bacteria about 1-2 Log CFU/g and inhibited the growth of experimented food-borne pathogens compared to initial inoculated counts. Our results indicated that MNPs applied to AP could be used to extend the shelf life of beef and prevent related food poisoning.

Predictive model of growth kinetics for Staphylococcus aureus in raw beef under various packaging systems.

This study describes a model of the growth kinetics for S. aureus in raw beef under wrapped packaging (WP), modified atmosphere packaging (MAP), vacuum packaging (VP), and vacuum skin packaging (VSP). Beef samples were inoculated with S. aureus and stored at 10, 15, 20, and 25 °C. VP and VSP showed lower maximum bacteria counts and higher lag time than WP and MAP at all temperatures. At 10 °C, S. aureus in VP and VSP decreased to about 2.5 Log CFU/g. Two primary models (modified Gompertz model and reparameterized Gompertz survival model) were used in the study. The secondary models were described using a polynomial equation and the Davey model. The bias factor (Bf), accuracy factor (Af), and root mean square error (RMSE) of the secondary models were 0.91-1.09, 1.00-1.13, and 0.00-0.68, respectively. The predictive models for kinetics of S. aureus in various packaged raw beef could help to predict the fate of S. aureus more accurately.

Investigating the antimicrobial and antibiofilm effects of cinnamaldehyde against Campylobacter spp. using cell surface characteristics.

Campylobacter species are known as biofilm-forming bacteria in food systems. The aim of this study was to evaluate the antimicrobial and antibiofilm effects of cinnamaldehyde against Campylobacter jejuni and Campylobacter coli isolated from chicken meat. The biofilm-forming C. jejuni and C. coli strains from chicken meat were investigated using minimum inhibitory concentration (MIC) and Campylobacter spp. characteristics. The MIC value was 31.25 µg/mL for the Campylobacter strains tested. Cinnamaldehyde had an inhibition and degradation effect on Campylobacter biofilms at concentrations > 15.63 µg/mL. Campylobacter strains treated with 15.63 µg/mL CA exhibited significantly decreased autoaggregation, motility, exopolysaccharide production, and soluble protein. In addition, Campylobacter biofilms formed on stainless steel were degraded following cinnamaldehyde treatment, as determined by scanning electron microscopy. Taken together, these results suggest that cinnamaldehyde constitutes a potential natural preservative against Campylobacter and a nontoxic biofilm remover that could be applied to control food poisoning in the poultry manufacturing-related food industry. PRACTICAL APPLICATION: Cinnamaldehyde was able to effectively remove the biofilm of Campylobacter in the small crack of stainless steel. Cinnamaldehyde has a potential to replace the synthetic antimicrobial and/or antibiofilm agent as well as has a positive influence on consumer concern for the food safety issues of the poultry industries.

Antibacterial Effect of a Mixed Natural Preservative against Listeria monocytogenes on Lettuce and Raw Pork Loin.

A mixed natural preservative, including grapefruit seed extract (GSE), cinnamaldehyde (CA), and nisin, was investigated for the reduction of Listeria monocytogenes growth on lettuce and raw pork loin. The MIC of each natural preservative was investigated for L. monocytogenes strains tested. Following central composite design, lettuce and pork loin were inoculated with a cocktail of three strains of L. monocytogenes (ATCC 15313, H7962, and NADC 2045 [Scott A]) and treated with the mixed natural preservative that included GSE (0.64 to 7.36 ppm), CA (1.6 to 18.4 ppm), and nisin (0.48 to 5.5 ppm). The MIC of GSE was 31.25 ppm in tested L. monocytogenes strains, and of CA was 500 and 1,000 ppm in L. monocytogenes ATCC 15313 and the other L. monocytogenes strains, respectively. The MIC of nisin was 250 ppm. The R2 value of this model was more than 0.9, and the lack of fit was not significant. The mixed natural preservative showed a synergistic antimicrobial effect and reduced the growth of L. monocytogenes by 4 to 5 log CFU/g on lettuce. In addition, the reduction of L. monocytogenes on pork loin was 3 log CFU/g. The mixed natural preservative, which consisted of GSE (6 to 8 ppm), CA (15 to 20 ppm), and nisin (5 to 6 ppm), increased the antibacterial effect against L. monocytogenes. These results suggest that the use of the mixed natural preservative could reduce the economic cost of food preparation, and response surface methodology is considered effective when measuring synergy among antimicrobials.

Anti-Biofilm Activity of Grapefruit Seed Extract against Staphylococcus aureus and Escherichia coli.

Grapefruit seed extract (GSE) is a safe and effective preservative that is used widely in the food industry. However, there are few studies addressing the anti-biofilm effect of GSE. In this study, the anti-biofilm effect of GSE was investigated against biofilm-forming strains of Staphylococcus aureus and Escherichia coli. The GSE minimum inhibitory concentration (MIC) for S. aureus and E. coli were 25 µg/ml and 250 µg/ml, respectively. To investigate biofilm inhibition and degradation effect, crystal violet assay and stainless steel were used. Biofilm formation rates of four strains (S. aureus 7, S. aureus 8, E. coli ATCC 25922, and E. coli O157:H4 FRIK 125) were 55.8%, 70.2%, 55.4%, and 20.6% at 1/2 × MIC of GSE, respectively. The degradation effect of GSE on biofilms attached to stainless steel coupons was observed (≥ 1 log CFU/coupon) after exposure to concentrations above the MIC for all strains and 1/2 × MIC for S. aureus 7. In addition, the specific mechanisms of this anti-biofilm effect were investigated by evaluating hydrophobicity, auto-aggregation, exopolysaccharide (EPS) production rate, and motility. Significant changes in EPS production rate and motility were observed in both S. aureus and E. coli in the presence of GSE, while changes in hydrophobicity were observed only in E. coli. No relationship was seen between auto-aggregation and biofilm formation. Therefore, our results suggest that GSE might be used as an anti-biofilm agent that is effective against S. aureus and E. coli.

Effect of Various Packaging Methods on Small-Scale Hanwoo (Korean Native Cattle) during Refrigerated Storage.

The objective of this study was to investigate comparison of physicochemical, microbiological, and sensory characteristics of Hanwoo eye of round by various packaging methods [wrapped packaging (WP), modified atmosphere packaging (MAP), vacuum packaging (VP) with three different vacuum films, and vacuum skin packaging (VSP)] at a small scale. Packaged Hanwoo beef samples were stored in refrigerated conditions (4±1°C) for 28 days. Packaged beef was sampled on days 0, 7, 14, 21, and 28. Physicochemical [pH, surface color, thiobarbituric acid reactive substances (TBARS), and volatile basic nitrogen (VBN) values], microbiological, and sensory analysis of packaged beef samples were performed. VP and VSP samples showed low TBARS and VBN values, and pH and surface color did not change substantially during the 28-day period. For VSP, total viable bacteria, psychrotrophic bacteria, lactic acid bacteria, and coliform counts were lower than those for other packaging systems. Salmonella spp. and Escherichia coli O157:H7 were not detected in any packaged beef samples. A sensory analysis showed that the scores for appearance, flavor, color, and overall acceptability did not change significantly until day 7. In total, VSP was effective with respect to significantly higher a* values, physicochemical stability, and microbial safety in Hanwoo packaging (p<0.05).

Comparative analysis of the antioxidant and anticancer activities of chestnut inner shell extracts prepared with various solvents.

BACKGROUND: The chestnut inner shell (CIS) has long been used as a medicinal herb for strengthening the antioxidant in the cosmetic industry. However, little is known about the antioxidant and anticancer effects of the CIS. RESULTS: The antioxidant and anticancer effects of CIS extracts (CISEs) were investigated by the use of various methods and cancer cell lines, respectively. The total polyphenol content of CISEs using ethanol, methanol, butanol, ethyl acetate and water were 53.30, 43.98, 32.16, 26.79 and 11.53 mg gallic acid equivalents g(-1), respectively. The CISEs using ethanol and methanol exhibited high antioxidant activities in the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, ß-carotene bleaching and ferric reducing ability of plasma assays; the effects were equivalent to those of butylated hydroxytoluene. All CISEs at 2.5 mg mL(-1) were shown to have a cytotoxic effect over 50%, and the CISE using ethyl acetate at 0.6 mg mL(-1) was proved to have 90% cytotoxic effect against the tested cancer cells. CONCLUSION: The ethanol and methanol CISEs had potent antioxidant effects, and the ethyl acetate CISE had the highest cytotoxicity. These results suggest that CISEs could be used as functional ingredients for antioxidant and anticancer effects in foods as extraction solvents.