Structural, material and antibacterial properties of quercetin incorporated soy protein isolate films and its binding behavior through molecular docking

This study aimed to investigate the three different methods for the fabrication of quercetin (1%-3% w/w of protein) incorporated soy protein isolate (SPI) films and their effect on material properties. The quercetin incorporated SPI films prepared by these methods were characterized by Fourier transform infrared (FTIR) spectroscopy, UV-Vis spectrophotometer, tensile properties, and water uptake and leaching properties. The cross-linking pattern was revealed by the FTIR spectrum that showed formation of an ester group because of interaction between the quercetin hydroxyl group and the carboxyl side chain of SPI amino acids. The tensile strength of SPI films were enhanced with the addition of quercetin as it increased to a maximum of 6.17 MPa while neat SPI film had tensile strength 4.13 MPa. The prepared films exhibit significant antibacterial activity against Listeria monocytogenes and Escherichia coli. The In-silico docking analysis demonstrates that covalent and non-covalent forces play crucial roles in binding interaction. It shows the formation of four hydrogen bonds, two salt bridges along with one pi-alkyl interaction. The simulation studies reflect the crucial amino acid residues involved in SPI-quercetin binding. The effect of quercetin binding with SPI on its stability and compactness is revealed by Root mean square deviation (RMSD) and radius of gyration studies.

Effect of tea polyphenols on chitosan packaging for food preservation: Physicochemical properties, bioactivity, and nutrition

Chitosan packaging has been widely studied for food preservation, the application of which is expanded by the incorporation of tea polyphenols. This paper reviews the influence of tea polyphenols incorporation on chitosan-based packaging from the perspectives of physicochemical properties, bioactivity used for food preservation, and nutritional value. The physicochemical properties included optical properties, mechanical properties, water solubility, moisture content, and water vapor barrier property, concluding that the addition of tea polyphenols improved the opacity, water solubility, and water vapor barrier property of chitosan packaging, and the mechanical properties and water content were decreased. The bioactivity used for food preservation, that is antioxidant and antimicrobial properties, is enhanced by tea polyphenols, improving the preservation of food like meat, fruits, and vegetables. In the future, efforts will be needed to improve the mechanical properties of composite film and adjust the formula of tea polyphenols/chitosan composite film to apply to different foods. Besides, the identification and development of high nutritional value tea polyphenol/chitosan composite film is a valuable but challenging task. This review is expected to scientifically guide the application of tea polyphenols in chitosan packaging.

Factors affecting production and effectiveness, performance improvement and mechanisms of action of bacteriocins as food preservative

Modern society is increasingly attracted with safe, natural, and additive-free food products, that gives preference to bacteriocins produced by General Recognized as Safe bacteria as a food preservative. Bacteriocins have been reported to be effective in extending shelf life of diverse foods such as meats, dairy products, wine, juice, and fruits and vegetables, whereas commercialized bacteriocins remain only nisin, pediocin, and Micocin. It is important that commercialized preservatives undergo an easy-to-handle manufacturing while maintaining high efficacy. Limited application of bacteriocins is most often caused by the absence of legislatives for use, low production, high cost and complicated purification process, reduced efficiency in the complex food matrix and insufficiently defined mechanism of action. Accordingly, this review provides an overview of bacteriocins, in relation to production stimulation, general purification scheme, impact of food matrix on bacteriocin effectiveness, and collaborative technology to improve bacteriocin performances. It is worth to note that purification and performance improvement technology remain the two challenging tasks in promoting bacteriocins as a widely used bio-preservative. Furthermore, this review for the first time divides bacteriocin receptors into specific classes (class I, II, III) and nonspecific class, to provide a basis for an in-depth understanding of the mechanism of action.

Disinfection of Clostridioides difficile on spinach with epigallocatechin-based antimicrobial solutions and sodium hypochlorite

The removal of C. difficile inoculated on fresh spinach leaves washed with antimicrobial solutions was investigated. In addition, the effect of washing solutions on the total aerobic mesophilic bacteria (TAMB) and Enterobacteriaceae in the fresh spinach was examined. The fresh spinach was washed through immersion in different concentrations (MIC, 2xMIC, and 4xMIC) of the natural disinfectant solution (NDS) consisting of EDTA, borax, and epigallocatechin gallate (EGCG) content developed in our laboratory and green tea extract-acetic acid (GTE-AA) for varying contact times (5 and 15 min). Different concentrations (50, 100, and 200 ppm) of sodium hypochlorite (NaOCl) and tap water as the control group were used to compare the effectiveness of the NDS. In addition, the effects of washing on the color, texture, and total phenol content of the spinach were determined. No statistical difference was observed in the washing of the spinach leaves with NDS prepared at 2xMIC and 4xMIC concentrations, while inhibition of C. difficile ranged between 2.11 and 2.32 logs. The highest inhibition was observed in the application of 50 ppm NaOCl for 15 min with a decrease of 2.88 logs in C. difficile spores. The GTE-AA and NDS decreased the number of TAMB by 2.27-3.08 log and, 3.21-3.66 log, respectively. Washing spinach leaves with natural disinfectant for 5 min caused a decrease of 2.58 logs in Enterobacteriaceae load, while washing with 50 ppm NaOCl for 15 min reduced Enterobacteriaceae load by 4 logs. Tap water was ineffective in reducing any microbial load. No difference was detected in the color parameters of the spinach through all washes. Although all antimicrobial washes made a difference in the texture of the spinach, the greatest loss in firmness was observed in the spinach washed with NaOCl. Washing spinach with epigallocatechin-based wash solutions can remove C. difficile in possible C. difficile contamination, thereby reducing the environmental load of C. difficile. Epigallocatechin-based disinfectants can be an alternative to chlorine-based disinfectants in improving the microbial quality of vegetables.

The use of essential oils in chitosan or cellulose-based materials for the production of active food packaging solutions: a review

In recent decades, interest in sustainable food packaging systems with additional functionality, able to increase the shelf life of products, has grown steadily. Following this trend, the present review analyzes the state of the art of this active renewable packaging. The focus is on antimicrobial systems containing nanocellulose and chitosan, as support for the incorporation of essential oils. These are the most sustainable and readily available options to produce completely natural active packaging materials. After a brief overview of the different active packaging technologies, the main features of nanocellulose, chitosan, and of the different essential oils used in the field of active packaging are introduced and described. The latest findings about the nanocellulose- and chitosan-based active packaging are then presented. The antimicrobial effectiveness of the different solutions is discussed, focusing on their effect on other material properties. The effect of the different inclusion strategies is also reviewed considering both in vivo and in vitro studies, in an attempt to understand more promising solutions and possible pathways for further development. In general, essential oils are very successful in exerting antimicrobial effects against the most diffused gram-positive and gram-negative bacteria, and affecting other material properties (tensile strength, water vapor transmission rate) positively. Due to the wide variety of biopolymer matrices and essential oils available, it is difficult to create general guidelines for the development of active packaging systems. However, more attention should be dedicated to sensory analysis, release kinetics, and synergetic action of different essential oils to optimize the active packaging on different food products. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Antimicrobial Compounds in Food Packaging

This review presents current knowledge on antimicrobial agents that are already used in the food packaging industry. At the beginning, innovative ways of food packaging were discussed, including how smart packaging differs from active packaging, and what functions they perform. Next, the focus was on one of the groups of bioactive components that are used in these packaging, namely antimicrobial agents. Among the antimicrobial agents, we selected those that have already been used in packaging and that promise to be used elsewhere, e.g., in the production of antimicrobial biomaterials. Main groups of antimicrobial agents (i.e., metals and metal oxides, organic acids, antimicrobial peptides and bacteriocins, antimicrobial agents of plant origin, enzymes, lactoferrin, chitosan, allyl isothiocyanate, the reuterin system and bacteriophages) that are incorporated or combined with various types of packaging materials to extend the shelf life of food are described. The further development of perspectives and setting of new research directions were also presented.

Investigation of Potential Use of Soybean Protein Isolate–Chinese Bayberry Tannin Extract Cross-Linked Films in Packaging Applications

The possibility of using commercial bayberry tannin (BT) from a Chinese source as a cross-linker and functional additive to develop soybean protein isolate (SPI)-based films was explored in this study by using the solvent casting method. In particular, the impacts of BT loading on the tensile strength, microstructure, thermal stability, water resistance and antioxidant capacity were fully investigated. The results reveal that SPI incorporated with BT yielded a phenolic–protein hybrid whose relevant films exhibited an improvement in tensile strength of around two times greater compared with native SPI as a result of the formed interactions and covalent cross-links, which could be proven using FTIR spectroscopy. The introduction of BT also led to the compact microstructure of SPI–BT films and enhanced the thermal stability, while the water vapor permeability was reduced compared with the control SPI film, especially at high loading content of tannin. Additionally, the use of BT significantly promoted the antioxidant capacity of the SPI-based films according to DPPH radical scavenging assay results. On this basis, Chinese bayberry tannin is considered a promising natural cross-linker and multifunctional additive that can be dedicated to developing protein-derived films with antioxidant activity for food packaging applications.

Chitosan Film Functionalized with Grape Seed Oil—Preliminary Evaluation of Antimicrobial Activity

Although the fishing and wine industries undoubtedly contribute significantly to the economy, they also generate large waste streams with considerable repercussions on both economic and environmental levels. Scientific literature has shown products can be extracted from these streams which have properties of interest to the cosmetics, pharmaceutical and food industries. Antimicrobial activity is undoubtedly among the most interesting of these properties, and particularly useful in the production of food packaging to increase the shelf life of food products. In this study, film for food packaging was produced for the first time using chitosan extracted from the exoskeletons of red shrimp (Aristomorpha foliacea) and oil obtained from red grape seeds (Vitis vinifera). The antimicrobial activity of two films was analyzed: chitosan-only film and chitosan film with the addition of red grape seed oil at two different concentrations (0.5 mL and 1 mL). Our results showed noteworthy antimicrobial activity resulting from functionalized chitosan films; no activity was observed against pathogen and spoilage Gram-positive and Gram-negative bacteria, although the antimicrobial effects observed were species-dependent. The preliminary results of this study could contribute to developing the circular economy, helping to promote the reuse of waste to produce innovative films for food packaging.

Efficacy of Biopolymer/Starch Based Antimicrobial Packaging for Chicken Breast Fillets

Food contamination leading to the spoilage and growth of undesirable bacteria, which can occur at any stage along the food chain, is a significant problem in the food industry. In the present work, biopolymer polybutylene succinate (PBS) and polybutylene succinate/tapioca starch (PBS/TPS) films incorporating Biomaster-silver (BM) and SANAFOR^® (SAN) were prepared and tested as food packaging to improve the lifespan of fresh chicken breast fillets when kept in a chiller for seven days. The incorporation of BM and SAN into both films demonstrated antimicrobial activity and could prolong the storability of chicken breast fillets until day 7. However, PBS + SAN 2%, PBS/TPS + SAN 1%, and PBS/TPS + SAN 2% films showed the lowest microbial log growth. In quality assessment, incorporation of BM and SAN into both film types enhanced the quality of the chicken breast fillets. However, PBS + SAN 1% film showed the most notable enhancement of chicken breast fillet quality, as it minimized color variation, slowed pH increment, decreased weight loss, and decelerated the hardening process of the chicken breast fillets. Therefore, we suggest that the PBS + SAN and PBS/TPS + SAN films produced in this work have potential use as antimicrobial packaging in the future.

Natural Anti-Microbials for Enhanced Microbial Safety and Shelf-Life of Processed Packaged Meat

Microbial food contamination is a major concern for consumers and food industries. Consumers desire nutritious, safe and “clean label” products, free of synthetic preservatives and food industries and food scientists try to meet their demands by finding natural effective alternatives for food preservation. One of the alternatives to synthetic preservatives is the use of natural anti-microbial agents in the food products and/or in the packaging materials. Meat and processed meat products are characteristic examples of products that are highly perishable; hence natural anti-microbials can be used for extending their shelf-life and enhancing their safety. Despite several examples of the successful application of natural anti-microbial agents in meat products reported in research studies, their commercial use remains limited. This review objective is to present an extensive overview of recent research in the field of natural anti-microbials, covering essential oils, plant extracts, flavonoids, animal-derived compounds, organic acids, bacteriocins and nanoparticles. The anti-microbial mode of action of the agents, in situ studies involving meat products, regulations and, limitations for usage and future perspectives are described. The review concludes that naturally derived anti-microbials can potentially support the meat industry to provide “clean label”, nutritious and safe meat products for consumers.

Development of antiviral and bacteriostatic chitosan-based food packaging material with grape seed extract for murine norovirus, Escherichia coli and Listeria innocua control

Edible coatings and films based on chitosan, and containing grape seed extract (GSE), were developed and their activities tested against murine norovirus (MNV-1), Listeria innocua and Escherichia coli K12. Grape seed extract concentrations of 1%, 1.5%, and 2.5% dissolved in deionized water resulted in MNV-1 plaque reductions (p < .05) of 1.75, 2.60, and 3.58 log PFU/ml, respectively after 3 hr. Two percent (w/w) chitosan solutions incorporated with 2.5% and 5% GSE also significantly (p < .05) reduced MNV-1 titers by 2.68 and 4.00 log PFU/ml, respectively after 3 hr. Additionally, incorporation of the GSE into the chitosan films also showed antimicrobial efficacy against MNV-1, L. innocua, and E. coli K12. Chitosan films containing 5%, 10%, and 15% GSE caused MNV-1 reductions of 0.92, 1.89, and 2.27 log PFU/ml, respectively, after 4 hr of incubation. Also, after 24 hr, the 5% and 10% GSE films reduced MNV-1 titers by 1.90 and 3.26 log PFU/ml, respectively, while the 15% GSE film reduced MNV-1 to undetectable levels. For E. coli K12, there were reductions of 2.28, 5.18, and 7.14 log CFU/ml after 24 hr exposure by the 5%, 10%, and 15% GSE films, respectively. Also, L. innocua counts were reduced by 3.06, 6.15, and 6.91 log CFU/ml by the 5%, 10%, and 15% GSE films, respectively. This study demonstrated that GSE in edible films and coatings is effective against the organisms tested, and this shows that they are effective against foodborne microbes of public health concerns.

Antimicrobial Activity of Chitosan-Based Films Enriched with Green Tea Extracts on Murine Norovirus, Escherichia coli, and Listeria innocua

Edible films can be designed to serve as carriers of antimicrobial agents and be used to control pathogenic foodborne viruses and bacteria. This research tested this concept by dissolving green tea extract (GTE) in chitosan film-forming solutions (FFS) and using it to prepare dried chitosan edible films. As a control, the GTE was also dissolved in deionized water (DW). The FFS and the dried chitosan films with the GTE and the DW without chitosan were all evaluated against murine norovirus (MNV-1), Escherichia coli K12, and Listeria innocua. Both the FFS and the DW with GTE were incubated with ~10⁷ PFU/ml of the virus suspensions for 3 h. The chitosan films with GTE were incubated for 4 and 24 h at 23 ± 1°C. The results showed that the DW containing 1, 1.5, and 2.5% aqueous GTE, significantly (p < 0.05) reduced MNV-1 plaques by 1.7, 2.5, and 3.3 logs after 3 h exposure, respectively. Similarly, FFS containing 2.5 and 5.0% GTE reduced MNV-1 counts by 2.5 and 4.0 logs, respectively, after 3 h exposure. The dried chitosan films with 5, 10, and 15% GTE were also effective against MNV-1 infectivity. After 24 h incubation, the 5 and 10% chitosan GTE films produced significant (p < 0.05) titer reductions of 1.6 and 4.5 logs, respectively. Chitosan films containing 15% GTE reduced MNV-1 plaques to undetectable levels in 24 h. All chitosan GTE films reduced E. coli K12 and L. innocua populations to undetectable levels in tryptic soy broth after 24 h exposure. The results of this study showed that edible films enriched with GTE have potential to reduce both foodborne viruses and bacteria.

A chitosan-based edible film with clove essential oil and nisin for improving the quality and shelf life of pork patties in cold storage

This study assessed chitosan (CS)-based edible films with clove essential oil (CO) and nisin (NI) singly or in combination, for improving quality and shelf life of pork patties stored in cold conditions. The treatments were control (without chitosan film coating), CS, CS-CO, CS-NI, and CS-CO-NI, and these were tested for physicochemical, microbiological and sensory qualities for 15 days (3 days per interval) on samples in cold storage (4 ± 2 °C). Overall, the results showed that the lightness (L* value) (53.47 to 67.58), yellowness (b* value) (1.32 to 2.88), pH (5.31 to 7.98), metmyoglobin (MetMb) content (54.10 to 63.36%), free fatty acid (FFA) (0.67 to 3.17%), peroxide value (PV) (0.80 to 3.67 milliequivalent/100 g), thiobarbituric acid reactive substances (TBARS) (0.69 to 3.27 mg MDA per kg), total viable count (TVC) (2.97 to 7.63 log CFU g-1), psychotrophic bacteria count (psychrotrophs) (2.94 to 6.59 log CFU g-1), Enterobacteriaceae (2.59 to 6.57 log CFU g-1), lactic acid bacteria (LAB) (2.53 to 6.81 log CFU g-1) and sensory scores (red non-discolored part (1 to 4.70), discoloration (1 to 4.40) and off-odor (1 to 5.00)) were gradually increased during storage and whereas redness (a* value) (16.43 to 8.62) and redness index (12.54 to 3.01) were decreased. However, the quality changes were minimal in the pork patties treated with CS-CO-NI. Based on sensory and microbiological evaluations, the shelf life of treated pork patties was 6 days for control, 9 days for CS and CS-NI, and 12 days for CS-CO and CS-CO-NI.

Sublethal Injury Caused to Listeria monocytogenes by Natural Plant Extracts: Case Study on Grape Seed Extract and Garlic Extract

Natural antimicrobials, such as grape seed extract (GSE) and garlic extract (GE), are often used as (a part of) novel food preservation technologies, especially due to their antilisterial effect. However, little is known on the extent of sublethal injury (SI) these extracts cause to Listeria monocytogenes, possibly leading to overestimated efficacies for such novel technologies. The influence of both extracts on the sublethal injury of L. monocytogenes strain LMG23775 was investigated, also using propidium iodide staining to investigate the nature of the injury. Minimum inhibitory concentrations were 500 mg gallic acid equivalents (GAE)/L and 7.5 μg allicin/mL for GSE and GE, respectively. These concentrations slowed down the growth of L. monocytogenes, while only causing a significant amount of SI for GSE. Pure extracts caused inactivation of the cells, with GSE being the most effective. Sublethal injury from pure GSE was mainly caused by membrane damage. In pure GE, a significant amount of SI, not caused by membrane damage, was also present, albeit less pronounced than in pure GSE. In conclusion, both extracts cause a significant amount of sublethal injury to L. monocytogenes, which is not taken into account in relevant studies investigating novel food preservation applications involving natural plant extracts.

Development of Hydrogels to Improve the Safety of Yukhoe (Korean Beef Tartare) by Reducing Psychrotrophic Listeria monocytogenes Cell Counts on Raw Beef Surface

This study developed an antimicrobial hydrogel to control Listeria monocytogenes in Yukhoe (Korean beef tartare). Four hydrogels (hydrogel 1: 5% alginate+1% chitosan+0.2% CaCl₂, hydrogel 2: 1% κ-carrageenan+1% chitosan, hydrogel 3: 2% κ-carrageenan+1% CaCl₂, and hydrogel 4: 2% κ-carrageenan+3% CaCl₂) were prepared. The hydrogels then absorbed 0.1% grapefruit seed extract (GSE) and 0.1% citrus extract (CE) for 30, 60, 120, and 240 min to be antimicrobial hydrogels. To select the most effective antimicrobial hydrogel, their swelling ratio (SR) and antilisterial activities were determined. The selected hydrogel (2×2 cm) was then placed on surface of beef (round; 3×3 cm), where L. monocytogenes (ca. 10⁶ CFU/g) were inoculated, and the cell counts were enumerated on PALCAM agar. Among the hydrogels, the SR of hydrogel 1 increased with absorbing time, but other hydrogels showed no significant changes. Antimicrobial hydrogel 1 showed higher (p<0.05) antilisterial activity than other antimicrobial hydrogels, especially for the one absorbed the antimicrobial for 120 min. Thus, the antimicrobial hydrogel 1 absorbed antimicrobials for 120 min was applied on raw beef at 4℃, and reduced (p<0.05) more than 90% of L. monocytogenes on raw beef. These results indicate that antimicrobial hydrogel 1 formulated with 0.1% GSE or 0.1% CE is appropriate to improve the safety of Yukhoe by reducing psychrotrophic L. monocytogenes cell counts on raw beef.

Natural antimicrobials for beet leaves preservation: in vitro and in vivo determination of effectiveness

Nisin (Ni), natamycin (Na), green tea extract (GTE) and their combinations were evaluated for controlling beet leaves' native microbiota as well as Listeria innocua and Escherichia coli external contaminations. Antimicrobial effectiveness was evaluated through in vitro and in vivo studies. In the in vitro studies, GTE treatment (0.85%) completely eliminated growth of native microbiota, reduced L. innocua from values of 8.5-3.5 log from 24 h onwards and reduced E. coli below detection limit (DL) after 72 h. Ni (500 IU/mL) was the most effective against L. innocua (7 log CFU/mL reduction) and its combination with GTE presented significant interactions for mesophilic aerobic bacteria (MAB) and L. innocua control. Na (200 ppm) alone or in combination with GTE did not show antimicrobial activity against microorganisms under study. Additionally in vivo evaluation showed that 2.5-5% GTE concentrations are needed to achieve significant inhibitory effects on MAB, L. innocua and E. coli. Furthermore, the best results for MAB and L. innocua control were obtained with the GTE5 + Ni treatment. This study revealed that GTE, either alone or combined with nisin, is a highly promising option with potential for reducing or preventing the growth of pathogenic and spoilage microorganisms present in leafy vegetables, specifically in beet leaves.

Effects of Acidification and Preservatives on Microbial Growth during Storage of Orange Fleshed Sweet Potato Puree

Orange Fleshed Sweet Potato (OFSP) puree, a versatile food ingredient, is highly perishable limiting its use in resource constrained environments. It is therefore important to develop shelf-stable puree. A challenge test study was carried out to determine the effect of combinations of chemical preservatives and acidification on microbial growth in stored puree. Puree was prepared and treated as follows: control (A); 0.05% potassium sorbate+0.05% sodium benzoate+1% citric acid (B); 0.1% potassium sorbate+0.1% sodium benzoate+1% citric acid (C); 0.2% potassium sorbate+0.2% sodium benzoate+1% citric acid (D); 1% citric acid (E). Samples were inoculated with Escherichia coli and Staphylococcus aureus at levels of 5.2 x 109 cfu/100g and 1.5 x 109 cfu/100g, respectively, before being evaluated during storage for 10 weeks at prevailing ambient temperature (15-25°C) and refrigeration temperature (4°C). Total aerobic counts, yeasts, and molds were also evaluated. E. coli and S. aureus counts declined significantly (p<0.05) by 4 log cycles in all puree treatments except for control and puree with only citric acid. Total viable count, yeasts, and molds were completely inhibited except for puree with only citric acid. Combination of chemical preservatives and acidification is effective in inhibiting pathogens and spoilage microorganisms in sweet potato puree.

Evaluation of peanut skin and grape seed extracts to inhibit growth of foodborne pathogens

Peanut skin extract (PSE) and grape seed extract (GSE) are derived from waste products in the wine and peanut industries, respectively. Both have high concentrations of polyphenols, known to possess antioxidant and antimicrobial properties. PSE primarily contains "A-type" procyanidins, while GSE primarily contains "B-type" procyanidins. These differ structurally, but are both isomers of epicatechin dimers. The objective of this study was to evaluate the antimicrobial effects of PSE containing A-type procyanidins and GSE containing B-type procyanidins against select foodborne pathogens (Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Typhimurium). The minimum inhibitory concentration (MIC) of the two extracts on L. monocytogenes, E. coli O157:H7, and S. Typhimurium was determined using the pour plate method. GSE had a significantly lower MIC (p ≤ .05) than PSE for L. monocytogenes (GSE = 60.6 ppm, PSE > 68.2 ppm) and S. Typhimurium (GSE = 45.7 ppm, PSE = 60.6 ppm), but no difference in inhibition of E. coli O157:H7. Since GSE contributed to greater inhibition, GSE extract was fractionated into monomer-rich (consisting primarily of catechins, epicatechins, and epicatechin gallates) and oligomer-rich (consisting of dimers, trimers, tetramers, up to decamers) components. Growth curves of all three pathogens in the presence of full extract, monomer and oligomer fractions were compared separately. None of the extracts inhibited S. Typhimurium growth. Generally, the extract containing greater oligomer components inhibited growth of L. monocytogenes and E. coli O157:H7 when compared to the control. Results indicate that an extract with type B procyanidins higher in oligomers may have greater antimicrobial properties.

Antibacterial and Antiadhesive Activities of Extracts from Edible Plants against Soft Drink Spoilage by Asaia spp

This study was conducted to investigate the antibacterial and antiadhesive activities of ethanol extracts from five edible plant parts: cinnamon bark ( Cinnamomum zeylanicum ), licorice root ( Glycyrrhiza radix ), nettle leaves ( Urtica dioica ), green tea leaves ( Camellia sinensis ), and elderberry flowers ( Sambucus nigra ). The chemical constituents of the extracts were identified using high-performance liquid chromatography and liquid chromatography plus mass spectrometry. Six strains of Asaia lannensis and Asaia bogorensis bacteria isolated from spoiled commercial fruit-flavored noncarbonated mineral water were used. Bacterial adhesion to polystyrene as an attachment substrate in culture media supplemented with 10% plant extract was evaluated using luminometric measurement of the ATP extracted from adhered cells. The viability of the adhered and planktonic cells was assessed using the plate count method, and the relative adhesion coefficient was calculated. All tested crude extracts contained flavonols (kaempferol, quercetin, and their derivatives), flavanols (catechin and derivatives), flavanones (glabrol, licorice glycoside A, and liquiritin), and phenolic acids (gallic, quinic, chlorogenic, neochlorogenic, caffeic, coumaric, and ferulic). The culture medium with 10% elderberry extract provided the least favorable environment for all tested bacterial strains. Extracts from green tea, cinnamon, and licorice also had significant inhibitory effects on the adhesion of the tested bacterial strains. This research suggests that the addition of selected edible plant extracts could improve the microbial stability of noncarbonated soft drinks.

Effect of the combination of natural antioxidants and packaging methods on quality of pork patties during storage

The effect of combination of phyto-extracts (sea buckthorn extract (SBTE), grape seed extract (GSE)) on different physico-chemical, oxidative stability, instrumental colour and texture, sensory and microbiological properties of pork patties were investigated under aerobic and MAP (50 % CO2: 50 % N2) packaging conditions. Treatments viz. T-1 (aerobic packaged control), T-2 (aerobic packaged containing 0.3 % SBTE+ 0.1 % GSE), T-3 (MAP packaged control) and T-4 (MAP packaged containing 0.3 % SBTE+ 0.1 % GSE) at 4 ± 1 °C for 35 days and samples were drawn at 7 days interval. The pH decreased initially up to 21 days and thereafter increased on further storage whereas water activity followed a decreasing trend throughout the storage period, irrespective of the treatment and packaging conditions. Results of oxidative stability parameters revealed that peroxide value, TBARS and FFA followed an increasing trend in both the packaging groups during storage however, the rate of increase was significantly lower (P < 0.05) in MAP packaged products than aerobic packaged products and phyto extracts incorporated products than their respective control. Instrumental colour and texture profiles were best maintained in MAP packaged treated products (T-4) which has higher redness (a*) value whereas lightness (L*) and yellowness (b*) showed lower (P < 0.05) value. MAP packaging resulted in superior sensory properties of pork patties as compared to aerobic packaged products. Standard plate count, psychrophiles and Coliforms were significantly (P < 0.05) lower in treated products than control and microbial count was better maintained in MAP than aerobic condition. Results concluded that the combined use of antioxidants and MAP packaging would be a useful method to control the oxidative and microbial quality changes of pork patties and it can be successfully stored for 35 days.

Novel food packaging systems with natural antimicrobial agents

A new type of packaging that combines food packaging materials with antimicrobial substances to control microbial surface contamination of foods to enhance product microbial safety and to extend shelf-life is attracting interest in the packaging industry. Several antimicrobial compounds can be combined with different types of packaging materials. But in recent years, since consumer demand for natural food ingredients has increased because of safety and availability, these natural compounds are beginning to replace the chemical additives in foods and are perceived to be safer and claimed to alleviate safety concerns. Recent research studies are mainly focused on the application of natural antimicrobials in food packaging system. Biologically derived compounds like bacteriocins, phytochemicals, enzymes can be used in antimicrobial food packaging. The aim of this review is to give an overview of most important knowledge about application of natural antimicrobial packagings with model food systems and their antimicrobial effects on food products.

Evaluation of Chitosan-Starch-Based Edible Coating To Improve the Shelf Life of Bod Ljong Cheese

The objective of this work was to evaluate the effectiveness of antimicrobial edible coatings to improve the quality of Bod ljong cheese throughout 25 days of storage. Coatings were prepared using chitosan, water chestnut starch, and glycerol as a base matrix, together with several combinations of antimicrobial substances: Cornus officinalis fruit extract (COFE), pine needle essential oil (PNEO), and nisin. Application of coating on cheese decreased water loss, lipid oxidation, changes in headspace gas composition, and color. Moreover, the edible coatings with COFE or PNEO had increased antimicrobial activity and did not permit growth of microorganisms. COFE and PNEO are manufactured from food-grade materials so they can be consumed as an integral part of the cheese, which represents a competitive advantage over nonedible coatings.

Antibacterial, antiviral, and antifungal properties of wines and winery byproducts in relation to their flavonoid content

Grapes produce organic compounds that may be involved in the defense of the plants against invading phytopathogens. These metabolites include numerous phenolic compounds that are also active against human pathogens. Grapes are used to produce a variety of wines, grape juices, and raisins. Grape pomace, seeds, and skins, the remains of the grapes that are a byproduct of winemaking, also contain numerous bioactive compounds that differ from those found in grapes and wines. This overview surveys and interprets our present knowledge of the activities of wines and winery byproducts and some of their bioactive components against foodborne (Bacillus cereus, Campylobacter jejuni, Escherichia coli, Listeria monocytogenes, Salmonella enterica, Staphylococcus aureus, Yersinia enterocolitica, Vibrio cholerae, Vibrio vulnificus), medical (Helicobacter pylori, Klebsiella pneumoniae), and oral pathogenic bacteria, viruses (adeno, cytomegalo, hepatitis, noro, rota), fungi (Candida albicans, Botrytis cinerea), parasites (Eimeria tenella, Trichomonas vaginalis), and microbial toxins (ochratoxin A, Shiga toxin) in culture, in vivo, and in/on food (beef, chicken, frankfurters, hot dogs, lettuce, oysters, peppers, pork, sausages, soup, spinach) in relation to composition and sensory properties. Also covered are antimicrobial wine marinades, antioxidative and immunostimulating aspects, and adverse effects associated with wine consumption. The collated information and suggested research needs might facilitate and guide further studies needed to optimize the use of wines and byproducts to help improve microbial food safety and prevent or treat animal and human infections.

Identifying ingredients that delay outgrowth of Listeria monocytogenes in natural, organic, and clean-label ready-to-eat meat and poultry products

The objective of this study was to identify ingredients that inhibit Listeria monocytogenes in natural, organic, or clean-label ready-to-eat meat and poultry products. Fourteen ingredients were screened in uncured (no-nitrate-or-nitrite-added), traditional-cured (156 ppm of purified sodium nitrite), cultured (alternative cured, natural nitrate source, and Staphylococcus carnosus), or preconverted (alternative cured, natural nitrite source) turkey slurries. Slurries were cooked, cooled, inoculated to yield 3 log CFU/ml L. monocytogenes, stored at 4°C, and tested weekly for 4 weeks. Three antimicrobial ingredients, 1.5 % vinegar-lemon-cherry powder blend, 2.5 % buffered vinegar, and 3.0 % cultured sugar-vinegar blend, were incorporated into alternative-cured ham and uncured roast beef and deli-style turkey breast. Controls included all three meat products without antimicrobial ingredients and a traditional-cured ham with 2.8 % sodium lactate-diacetate. Cooked, sliced products were inoculated with 3 log CFU/g L. monocytogenes, vacuum packed, and stored at 4 or 7°C, for up to 12 weeks. For control products without antimicrobial agents stored at 4°C, a 2-log L. monocytogenes increase was observed at 2 weeks for ham and turkey and at 4 weeks for roast beef. Growth (>1-log increase) in the sodium lactate-diacetate was delayed until week 6. Compared with the control, the addition of either vinegar-lemon-cherry powder blend or buffered vinegar delayed L. monocytogenes growth for an additional 2 weeks, while the addition of cultured sugar-vinegar blend delayed growth for an additional 4 weeks for both ham and turkey. The greatest L. monocytogenes delay was observed in roast beef containing any of the three antimicrobial ingredients, with no growth detected through 12 weeks at 4°C for all the treatments. As expected, L. monocytogenes grew substantially faster in products stored at 7°C than at 4°C. These data suggest that antimicrobial ingredients from a natural source can enhance the safety of ready-to-eat meat and poultry products, but their efficacy is improved in products containing nitrite and with lower moisture and pH.

Efficacy of cold-pressed terpeneless Valencia oil and its primary components on inhibition of Listeria species by direct contact and exposure to vapors

This study used disk diffusion assays to evaluate the effectiveness of cold-pressed terpeneless Valencia oil (CPTVO) and its primary components (linalool, citral, and decanal) at inhibiting Listeria via direct contact or exposure to vapors. In general, all Listeria strains tested responded similarly to CPTVO and its components. Direct contact with linalool produced zones of inhibition that were significantly smaller (P < 0.0001) than those associated with all other antimicrobials tested. Zones of inhibition for sealed plates were significantly larger (P < 0.0001) than those observed for unsealed plates, although the method for sealing the plates was insignificant. Exposure to CPTVO vapors resulted in zones of inhibition that were significantly smaller than those resulting from decanal vapors (P < 0.0001). The difference observed between the zones of inhibition produced by antimicrobial exposure via vapors or direct contact was only slightly significant (P = 0.02). Antimicrobial essential oil (EO) vapors may be an effective alternative to direct contact EOs to safely and effectively inhibit microorganisms while minimizing undesired organoleptic changes sometimes associated with EO contact. CPTVO and its primary components, decanal and citral, may have potential in the food industry as all natural, generally recognized as safe antimicrobials used in modified atmosphere packaging designed to inhibit Listeria without requiring direct contact with food products.

Electrostatic spraying of food-grade organic and inorganic acids and plant extracts to decontaminate Escherichia coli O157:H7 on spinach and iceberg lettuce

The prevalence of foodborne illnesses is continually on rise. In the U.S.A., Escherichia coli O157:H7 (E. coli) has been associated with several outbreaks in minimally processed foods. Spinach and lettuce pose higher food safety risks and recurring food recalls suggest the insufficiency of current disinfection strategies. We aimed at offering a natural antimicrobial alternative using organic acids (malic, tartaric, and lactic acids [MA, TA, and LA, respectively]) and grape seed extract (GSE) and a novel application method using electrostatic spraying to evenly distribute the antimicrobials onto produce. Spinach and lettuce samples were washed, sanitized with sodium hypochlorite solution (6.25 mL/L), dip inoculated in water containing E. coli (7.0 log CFU/mL) for 24 h, and rewashed with sterile water to remove nonadhered pathogens. The samples were sprayed electrostatically with MA, LA, and GSE alone and in combinations and for comparison, with phosphoric acid (PA) and pH controls with deionized water adjusted to 1.5/2.3/3.6 and stored at 4 °C. When combined with LA (3%), MA (3%) showed 2.1 to 4.0 log CFU/g reduction of E. coli between the days 1 and 14 on spinach and 1.1 to 2.5 log CFU/g reduction on lettuce. Treatment with PA (1.5%) and PA (1.5%)-GSE (2%) exhibited 1.1 to 2.1 log CFU/g inhibition of E. coli on spinach during the 14-d storage. Our findings demonstrated the efficacy of electrostatic spraying of MA, LA, and GSE on fresh produce to improve the safety and lower the public health burden linked to produce contamination.

PRACTICAL APPLICATION

Electrostatic spraying is an emerging technique that can be adopted to improve the distribution and application of antimicrobials during fresh produce sanitation. Relatively simple and quick, the process can access most/all parts of produce surface and offer protection from food pathogens. The use of malic and lactic acids with or without grape seed extract can serve as effective antimicrobials when sprayed electrostatically, lowering the risk from postcontamination issues with spinach and iceberg lettuce. This application technology can be extended to improve the commercial food safety of other produce, fruits, poultry, and meat.

Effectiveness of Zataria multiflora Boiss essential oil and grape seed extract impregnated chitosan film on ready-to-eat mortadella-type sausages during refrigerated storage

BACKGROUND

The effectiveness of chitosan films containing Zataria multiflora Boiss essential oil (ZEO) (5 and 10 g kg(-1) ) and grape seed extract (GSE) (10 g kg(-1) ) on lipid oxidation and microbial (lactic acid bacteria, aerobic mesophiles and inoculated Listeria monocytogenes) characteristics of mortadella sausage at 4 °C for 21 days was evaluated. The release of total phenolics (TPs) into sausage was also assessed.

RESULTS

All films exhibited antibacterial activity against L. monocytogenes on agar culture media. Chitosan films containing ZEO were the most effective on the growth of bacteria. The growth of L. monocytogenes was significantly inhibited by ZEO-GSE containing films especially during storage of the sausages for 6 days. Aerobic mesophiles and lactic acid bacteria were the most sensitive and resistant groups to films by 0.1-1.1 and 0.1-0.7 log cycles reduction, respectively. Sausages wrapped by 10 g kg(-1) GSE + 10 g kg(-1) ZEO films had the lowest degrees of lipid oxidation, which was 23% lower than the control. The TPs of ZEO films decreased to zero after 6 days, whereas TPs of GSE films followed a slight decrease during the storage.

CONCLUSION

Antimicrobial/antioxidant chitosan film could be developed by incorporating GSE and ZEO for extending the shelf life of mortadella sausage.