Combination Of Nisin Research Articles

Synergy of Nisin Z and Sodium Chloride in the Inhibition of Food-Borne Pathogens and Quality Control of Aquatic Foods

ABSTRACT This study was conducted to investigate the combination of nisin Z and NaCl as a natural food preservative to improve the quality of fish products under refrigerated temperatures. Treatments against Listeria monocytogenes and Staphylococcus aureus included 1000 IU nisin Z (NZ) in 3% (NZ3), 5% (NZ5), or 7% NaCl solution (NZ7). Both NZ5 and NZ7 showed significantly higher antimicrobial activities, and minced Nile tilapia (Oreochromisniloticus) inoculated with L. monocytogenes or S. aureus showed a reduced microbial load compared to the positive control groups. Therefore, the combination of nisin Z and NaCl exhibited potent antibacterial activities, highlighting its usability as a natural alternative to synthetic preservatives.

Effective combination of nisin and sesamol against Listeria monocytogenes

Nisin (NS) has been considered as a food preservative against Listeria monocytogenes, an important foodborne pathogen that causes serious public health problems. However, the effectiveness of NS is also affected due to its instability and resistance of L. monocytogenes to NS. Combining NS with other antimicrobial substances is an excellent strategy to improve the effect. Sesamol (SE) has been reported to have the ability to inhibit the growth of L. monocytogenes. Thus, in this study, based on the determination of the fractional inhibitory concentration indices, the in vitro synergistic antibacterial activity of NS and SE was confirmed using standard L. monocytogenes ATCC19112 and L. monocytogenes isolated from food and clinical sources. The inhibition of NS and SE combination on the growth of L. monocytogenes was higher than that of NS or SE alone in tryptic soy yeast extract broth (TSB-YE) and pasteurized milk. The changes and damages of the cell structure and the cell morphology in the combination group were more significant than those in the single use of NS or SE. These results indicate that the combined application of NS and SE may be a promising alternative to NS for controlling the contamination of L. monocytogenes in food.

Incorporation of nisin and oregano essential oil in cow’s milk to improve the quality of fresh cheese

Firstly, this study aimed to determine the effect of adding nisin (0, 250 and 500 IU mL-1) and oregano essential oil (OEO) (0, 0.025% and 0.05%), alone or in combination, on Staphylococcus aureus load in cow’s milk. Next, it was evaluated the sensory, physicochemical and microbiological quality of fresh cheese (FC) manufactured with milk added of nisin + OEO (C1) or nisin alone (C2) compared to a control cheese (C0, milk without the addition of nisin or OEO). Results showed that adding nisin effectively reduced the S. aureus count in milk in a similar manner to adding way the combination of nisin + OEO compared to the control. FC quality evaluation results revealed that C1 and C2 did not alter the physicochemical quality of FC (pH, fat and total solids content) during storage (0-8 days) compared to the control. Furthermore, C1 and C2 reduced in a similar manner aerobic mesophilic bacteria and Enterobacteriaceae count in FC compared to the control during storage. Sensory evaluation showed that consumers did not value FC added of nisin + OEO (C1) due to its intense aroma of oregano, rating it with the lowest global quality.

The synergistic antibacterial effect and inhibition of biofilm formation of nisin in combination with terpenes against Listeria monocytogenes.

This study was to investigate the synergistic antibacterial effect and inhibition of biofilm formation of nisin in combination with terpenes (carvacrol, cinnamaldehyde, citral and thymol) against Listeria monocytogenes. The bactericidal ranking of terpenes combined with nisin was carvacrol > cinnamaldehyde, citral > thymol. The minimum inhibitory concentration (MIC) of nisin and carvacrol when used together was determined to be 0·1563 mg ml-1 + 0·0195 mg ml-1 (nisin at MIC/2 + carvacrol at MIC/16). The addition of nisin at MIC/2 + carvacrol at MIC/2 caused more decrease in membrane potential than carvacrol or nisin at MIC individually. The decrease rates of hlyA and plcA gene expressions caused by nisin at MIC/2 + carvacrol at MIC/2 were significantly higher than those caused by carvacrol or nisin at MIC individually (P < 0·05). Nisin combined with carvacrol showed the highest inhibition activity to the formation of L. monocytogenes biofilm on stainless steel and lettuce. The inhibition effect of nisin at MIC/2 + carvacrol at MIC/16 was significantly higher than that of nisin at MIC/2 and carvacrol at MIC/16 (P < 0·05).

Integrative Approach of MAP and Active Antimicrobial Packaging for Prolonged Shelf-Life of Composite Bottle Gourd Milk Cake

The current research explored the integrative effect of antimicrobial edible films and modified atmosphere packaging (MAP) on the quality parameters and shelf-life of bottle gourd burfi, which is a heat-desiccated composite Indian confection. The edible antimicrobial films prepared using a combination of nisin and natamycin (NANIF) were evaluated for their antimicrobial activity as the first line of defense against Bacillus cereus and Aspergillus niger. The product was wrapped in developed films, which was followed by flushing of the altered environment employing MAP in a closed PP box and evaluation during refrigerated storage at 4 ± 2 °C, comparing the product with the control counterpart. During this period, the physicochemical, sensory, and microbiological status of the product was assessed. Results indicated a significant (p ≤ 0.05) variance between the two kinds of samples wherein the antimicrobial film produced excellent results in terms of being less supportive toward microbial growth, thereby extending the life of film-treated samples beyond 35 days compared to the control (21 days). In addition, the product conformed to the legal standards of microbiological count well under the permissible limits laid by the FSSAI. Furthermore, the sensory characteristics of the product did not change much, illustrating the significance of the integrative approach.

Combination of Chitosan, Tea Polyphenols, and Nisin on the Bacterial Inhibition and Quality Maintenance of Plant-Based Meat.

Plant-based meat products have gained attention in the food industry and with consumers. Plant-based meat products primarily comprise plant proteins and are rich in nutrients. However, the products are highly susceptible to bacterial contamination during storage. Biological preservatives are easily degradable alternatives to chemical preservatives and can preserve different kinds of food. In order to investigate the preservation properties of chitosan (CS), tea polyphenols (TPs), and nisin treatments on plant-based meats, the sensory evaluation, color difference, pH, TBARS, and the total plate count of E. coli, S. aureus, and Salmonella, indicators of the biological preservative-treated plant-based meat, were determined in this study. The experiment involved blank control- and biological preservative-treated samples. We found that the total microbial count exceeded the national standard provisions in the control samples stored for 14 days. The colors, tissue structures, and flavors of plant-based meat have gradually deteriorated, with the sensory score dropping from 90 to 52. The sample had a loose tissue structure and an obvious sour taste. However, the shelf life of the plant-based meat samples treated with different combinations of the biological preservatives increased compared to the shelf life of the control samples. After 56 d of storage, 1% chitosan, 2.5% tea polyphenols, and 0.04% nisin sensory reduction to 56, the total number of colonies and S. aureus were 4.91 and 2.95 lg CFU/g, approaching the national standard threshold; E. coli was 2 lg CFU/g, reaching the national standard threshold. Thus, the samples treated with 1% chitosan, 2.5% tea polyphenols, and 0.04% nisin had the longest shelf life (56 days) among all experimental groups. Hence, this study reveals that a combination of biological preservatives may be a non-toxic alternative for the efficient preservation of plant-based meat products.

The combined bactericidal effect of nisin and thymoquinone against Listeria monocytogenes in Tryptone Soy Broth and sterilized milk

In this study, the combined bactericidal effect of nisin and thymoquinone (TQ) on Listeria monocytogenes was investigated in Tryptone Soy Broth (TSB) and sterilized milk. The combined treatment resulted in a greater reduction in bacterial number than either nisin or TQ treatment alone. Nisin and TQ respectively caused depolarization and hyperpolarization of the cell membrane of L. monocytogenes , which indicated early injury to the bacteria. Confocal laser scanning microscopy and N -phenyl-l-naphthylamine uptake assay showed disruption of the cell membrane on treatment. Field emission scanning electron microscopy revealed depression and collapse of the cell surface following treatment with nisin and TQ. Growth curves showed that nisin and TQ acted on the bacteria in different growth phases. Fourier-transform infrared spectroscopy demonstrated a reversible hydrogen-bonding interaction between nisin and TQ. Our results suggest that nisin combined with TQ is a more effective antibacterial effect against L. monocytogenes in both TSB and in sterilized milk than either agent alone. Our study sheds light on the inhibitory mechanisms of nisin, TQ, and their combination, and provides a theoretical basis for the synergistic antibacterial application of nisin and TQ in the food industry. • The anti bacterial effect of combined nisin and thymoquinone (TQ) treatment exceeded that of either treatment alone. • Nisin and TQ damaged the bacterial membrane and morphology by different mechanisms. • The inhibitory effects of nisin and TQ on the growth phases of L. monocytogenes were different. • Nisin and TQ interact via intermolecular hydrogen bonding.

Optimisation of the combined treatment of nisin, oregano and ultrasound in decontaminating Listeria monocytogenes and Escherichia coli O157:H7 on cabbage

The effect of combined nisin, oregano and ultrasound treatments on the reduction of Listeria monocytogenes and Escherichia coli O157:H7 on raw cabbage was investigated using Box-Behnken response surface design. The optimised treatment comprising oregano (0.20% v/v), nisin (607.85 IU/g) and ultrasound treatment (14.98 min) showed the highest log reduction of E. coli O157:H7 (3.66 CFU/mL) on cabbage. For L. monocytogenes, an optimal combination of oregano (0.12% v/v), nisin (731.25 IU/g) and ultrasound (13.21 min) resulted in the highest log reduction (8.27 CFU/mL). SEM images showed the effectiveness of the combination treatments against the studied pathogens. The physical properties (colour and texture) of cabbage were analysed after treatment, while the structural damage was determined by electrolyte leakage analysis. There were no colour and textural changes observed between untreated and treated cabbage, while the electrolyte leakage rate increased slightly after application with the combination treatments. The results demonstrate that combined use of oregano, nisin and ultrasound is a promising alternative for E. coli O157:H7 and L. monocytogenes reduction and retaining of the quality characteristics of fresh produce.

Cyclodextrin-Based Nanosponges as Perse Antimicrobial Agents Increase the Activity of Natural Antimicrobial Peptide Nisin.

At present, antibiotic resistance is considered a real problem. Therefore, for decades scientists have been looking for novel strategies to treat bacterial infections. Nisin Z, an antimicrobial peptide (AMP), can be considered an option, but its usage is mainly limited by the poor stability and short duration of its antimicrobial activity. In this context, cyclodextrin (CD)-based nanosponges (NSs), synthesized using carbonyldiimidazole (CDI) and pyromellitic dianhydride (PMDA), were chosen for nisin Z loading. To determine the minimum inhibitory of nisin Z loaded on CD-NS formulations, agar well diffusion plates were used. Then, the bactericide concentrations of nisin Z loaded on CD-NS formulations were determined against Gram-positive (Staphylococcus aureus) and -negative (Escherichia coli) bacteria, using microdilution brain heart infusion (BHI) and tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT). The minimum and bactericide inhibitory values of the nisin complex with NSs were potentially decreased against both bacteria, compared with the nisin-free sample, while the nisin complex with β-CD showed lower antibacterial activity. The antimicrobial effect was also demonstrated by free NSs. Furthermore, the total viable counts (TVCs) antibacterial experiment indicated that the combination of nisin Z in both PMDA and CDI β-CD-based NSs, especially CDI, can provide a better conservative effect on cooked chicken meat. Generally, the present study outcomes suggest that the cross-linked β-CD-based NSs can present their own antimicrobial potency or serve as promising carriers to deliver and enhance the antibacterial action of nisin Z.

Comparative Study of ɛ-Polylysine or Nisin Inhibition Kinetics of Lactococcus lactis and Spoilage Microorganisms in Fresh Flammulina velutipes Fruiting Bodies

Flammulina velutipes is one of the most important edible mushrooms, which quickly decays with a short shelf life. However, little is known about the effect of ɛ-polylysine (ɛ-PL) or nisin on the survival of Lactococcus lactis (L. lactis) during the storage at constant temperatures. The objective of this study was to investigate the effect of ɛ-PL or nisin on the growth of L. lactis and background (BK) microorganisms in fresh Flammulina velutipes fruiting bodies (FVFB) and develop mathematical models to predict their growth behavior. The effect of ɛ-PL (0.15 and 0.30 g/kg) or nisin (0.10 and 0.20 g/kg) on the growth of L. lactis and BK microorganisms in FVFB was analyzed at 4, 16, and 20°C. The lag phase of L. lactis was extended, and the specific growth rate was decreased by increasing concentrations of ɛ-PL or nisin and lowering the temperature. The results showed that ɛ-PL or nisin could control the growth of L. lactis in FVFB. However, the growth of BK microorganisms was not affected by ɛ-PL or nisin. The growth of L. lactis and BK microorganisms could be successfully described by the reparameterized Gompertz and no lag phase models, respectively. Additionally, ɛ-PL or nisin could maintain the quality of FVFB by preventing weight loss, color-changing, and decreasing soluble solid content in FVFB at 4°C. These results suggest that ɛ-PL or nisin in combination with low temperature may inhibit the growth of L. lactis in FVFB and prevent the decrease in the quality of FVFB.

Determination of an effective agent combination using nisin against Salmonella biofilm.

This present study aims to determine the lowest concentration effects of the assayed different antibiotics; antimicrobial agents alone and their combinations with nisin were investigated to prevent the biofilm formation and break down the biofilm structure of Salmonella. While the combination of nisin and EDTA showed a synergistic effect against Salmonella strain, chlorhexidine digluconate and streptomycin with nisin showed a partial synergetic effect; citric acid and sulfonamides with nisin showed an indifferent effect. The use of citric acid and chlorhexidine digluconate alone was very effective in Salmonella inhibition. While the citric acid combined with other agents had not much effect, the use of chlorhexidine digluconate combined with nisin and EDTA inactivated the total initial count within 24h. Significantly, when citric acid and sulfonamides are used alone, they reduce by 64% and 44%, respectively. When they used nisin + EDTA, this ratio increased to 83% and 84%, respectively. For the prevention of biofilm, the most suitable conditions were determined as 97% biofilm inhibition. The results of this study can be used as a guide for the emergence of new approaches to ensure the food safety and quality of the food industry.

Synergistic antibacterial activity and mechanism of action of nisin/carvacrol combination against Staphylococcus aureus and their application in the infecting pasteurized milk

Synergistic antibacterial effect is a promising way to overcome the challenge of microbial contamination in food. In this study, we detected the synergistic interactions of nisin and carvacrol. The MIC of nisin and carvacrol against S. aureus were 60 and 125 μg/mL, respectively. The FICI and FBCI were 0.28125 and 0.09375, which suggested that the nisin/carvacrol combination presented synergistic antibacterial effect against S. aureus. The antibacterial activity of nisin/carvacrol combination was much higher than their individuals and the dose of antibacterials was obviously reduced. The combination could completely kill S. aureus within 8 h, accelerate the destruction of cell membrane, and inhibit formation of biofilm. Under the intervention of nisin, more CAR could enter cell to hunt intracellular targets, leading to an increase in intracellular antibacterial level. Besides, in the storage of pasteurized milk, the combinational treatment successfully inhibited microbial reproduction at 25 °C and 4 °C. Thus, the combination of nisin and carvacrol was a potential synergistic strategy for food preservation.

Bactericidal effect of nisin and reuterin on methicillin-resistant Staphylococcus aureus (MRSA) and S. aureus ATCC 25937

Nisin and reuterin are used in processed foods as preservatives. They are considered to be potential sources of natural antibiotics for the treatment of food contaminated by antibiotic-resistant bacteria, such as methicillin-resistantStaphylococcus aureus. We try to compare the best effect of both nisin and reuterin on the growth of methicillin-resistant S. aureus (MRSA) and S. aureus ATCC 25923. The results indicated that nisin at different concentrations inhibited the growth of methicillin-resistant S. aureus after 4 h, whereas after 12 and 24 h, the bacteria have regrown and reactivated. S. aureus ATCC 25923 was not affected by nisin concentration and has continuously grew at all times. Reuterin at different concentrations gradually inhibited the growth of methicillin-resistant S. aureus and S. aureus ATCC 25923 and declined after 12 h for both. Therefore, it can be deduced that nisin alone exerts a bacteriostatic effect on methicillin-resistant S. aureus but not on S. aureus ATCC 25923. Reuterin is considered as bactericidal effect on both microorganisms. The combination of nisin at a concentration of 25.6 and reuterin at a concentration of 5.2 mg/mL exerted a bactericidal effect on both microorganisms. By mixing nisin with reuterin, it can be more active against both microorganisms.

Impact of Nisin in Combination with Sodium Benzoate and Calcium Carbonate on the Bacterial and Yeast Population of Coconut Neera (Coconut Inflorescence sap)

A natural sap from mature coconut palm known as coconut neera is enriched with essential minerals and vitamins. Rapid microbial fermentation affects neera processing industries because it spoils the physicochemical properties. There are various methods in preservation that extend the shelf life of coconut neera. The addition of nisin is one of the methods which protect neera against fermentation. Therefore, the study is focused to identify the effective combination of nisin (50 ppm) with preservatives like sodium benzoate (500, and 1000 ppm), and calcium carbonate (2500, and 3000 ppm) at two different combinations in neera. At the end of 21 d, 3000 ppm calcium carbonate with 50 ppm nisin in N4 treatment had an effective reduction of 120 × 105 CFU/ml and 143 × 102 CFU/ml for total bacteria and total yeast count. The reduced microbial survival resulted in the pH of 10.45 ± 0.05, total soluble solids of 15.43 ± 0.12 °Brix, and total acidity of 1.11 ± 0.04 mg/ L, at this combination. The treatment of nisin with 3000 ppm calcium carbonate demonstrated the high red fluorescence bacterial cells than the treatment of nisin with 1000 ppm sodium benzoate. Additionally, the microorganisms in N4 treatment precipitated 65.34% Ca2+ from 79.96% in XRF intensity analysis. The synergistic effect of nisin and calcium carbonate explored their antimicrobial activity against the heterogeneous microbial population in coconut neera. The concentration of 3000 ppm calcium carbonate and nisin 50 ppm preserves the physicochemical and sensory qualities, up to 21 d at 4°C, and offer hope for the industrial-scale implementation.

The effect of ultrasound treatment in combination with nisin on the inactivation of Listeria innocua and Escherichia coli

Ultrasound, alone or in combination with natural antimicrobials, is a novel food processing technology of interest to replace traditional food decontamination methods, as it is milder than classical sterilisation (heat treatment) and maintains desirable sensory characteristics. However, ultrasound efficacy can be affected by food structure/composition, as well as the order in which combined treatments are applied. More specifically, treatments which target different cell components could result in enhanced inactivation if applied in the appropriate order. The microbial properties i.e. Gram positive/Gram negative can also impact the treatment efficacy.This work presents a systematic study of the combined effect of ultrasound and nisin on the inactivation of the bacteria Listeria innocua (Gram positive) and Escherichia coli (Gram negative), at a range of cavitation conditions (44, 500, 1000 kHz). The order of treatment application was varied, and the impact of system structure was also investigated by varying the concentration of Xanthan gum used to create the food model systems (0 – 0.5% w/v). Microbial inactivation kinetics were monitored, and advanced microscopy and flow cytometry techniques were utilised to quantify the impact of treatment on a cellular level.Ultrasound was shown to be effective against E. coli at 500 kHz only, with L. innocua demonstrating resistance to all frequencies studied. Enhanced inactivation of E. coli was observed for the combination of nisin and ultrasound at 500 kHz, but only when nisin was applied before ultrasound treatment. The system structure negatively impacted the inactivation efficacy. The combined effect of ultrasound and nisin on E. coli was attributed to short-lived destabilisation of the outer membrane as a result of sonication, allowing nisin to penetrate the cytoplasmic membrane and facilitate cell inactivation.

A Synergistic New Approach Toward Enhanced Antibacterial Efficacy via Antimicrobial Peptide Immobilization on a Nitric Oxide-Releasing Surface.

Despite technological advancement, nosocomial infections are prevalent due to the rise of antibiotic resistance. A combinatorial approach with multimechanistic antibacterial activity is desired for an effective antibacterial medical device surface strategy. In this study, an antimicrobial peptide, nisin, is immobilized onto biomimetic nitric oxide (NO)-releasing medical-grade silicone rubber (SR) via mussel-inspired polydopamine (PDA) as a bonding agent to reduce the risk of infection. Immobilization of nisin on NO-releasing SR (SR-SNAP-Nisin) and the surface characteristics were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy and contact angle measurements. The NO release profile (7 days) and diffusion of SNAP from SR-SNAP-Nisin were quantified using chemiluminescence-based nitric oxide analyzers and UV-vis spectroscopy, respectively. Nisin quantification showed a greater affinity of nisin immobilization toward SNAP-doped SR. Matrix-assisted laser desorption/ionization mass spectrometry analysis on surface nisin leaching for 120 h under physiological conditions demonstrated the stability of nisin immobilization on PDA coatings. SR-SNAP-Nisin shows versatile in vitro anti-infection efficacy against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus in the planktonic and adhered states. Furthermore, the combination of NO and nisin has a superior ability to impair biofilm formation on polymer surfaces. SR-SNAP-Nisin leachates did not elicit cytotoxicity toward mouse fibroblast cells and human umbilical vein endothelial cells, indicating the biocompatibility of the material in vitro. The preventative and therapeutic potential of SR-SNAP-Nisin dictated by two bioactive agents may offer a promising antibacterial surface strategy.

Chemical composition and antibacterial properties of Zataria multiflora Bioss and Mentha longifolia essential oils in combination with nisin and acid acetic

This study was conducted to determine the chemical composition of the Zataria multiflora Bioss and Mentha longifolia essential oils (ZEO and MEO) and evaluate their antibacterial efficiency, alone and in combination with nisin and acid acetic, against Escherichia coli O157: H7 and Staphylococcus aureus. The results of antimicrobial tests showed that plant EOs, nisin, and acetic acid have good bacteriostatic and bactericidal properties. In the checkerboard test, nisin had synergistic interaction with both ZEO and MEO against S. aureus and E. coli (FIC index <0.5). Also, there was a synergistic interaction between ZEO and MEO. Based on the GC-MS analysis, the main constituents of ZEO were carvacrol (49.61%), thymol (14.31%), and p-cymene (5.23%). Besides 1,8-cineole (18.46%), pulegone (14.82%), and piperitone (12.12%) were the most detected substance of MEO. The combination of nisin with the EOs can exert an inhibitory effect on bacterial growth in food. Novelty impact statement In this present study, the synergistic effect of the Zataria multiflora Bioss and Mentha longifolia essential oils (EOs) in combination with nisin and acetic acid was investigated for the first time. The interaction of EOs with nisin and acetic acid against Escherichia coli O157: H7 and Staphylococcus aureus was synergistic and additive, respectively. The two studied EOs also had a synergistic interaction in the combined use.

Control of Listeria monocytogenes and Escherichia coli O157:H7 in enoki mushrooms (Flammulina velutipes) by combined treatments with organic acids, nisin, and ultrasound

This study was undertaken to evaluate the combined effect of organic acids, nisin, and ultrasound (US) on the reduction of Listeria monocytogenes and Escherichia coli O157:H7 in enoki mushrooms stored at 5 °C. Each bacterium was treated with 1–3% organic acids, 0.1% nisin, and 40 kHz US in enoki mushrooms individually or in combination at 25 °C for ≤30 min. Lactic acid (LA) was superior to malic acid, acetic acid, and nisin, decreasing L. monocytogenes and E. coli O157:H7 in enoki mushrooms by more than 3.00 log CFU/g at 25 °C for 30 min. US alone failed to inactivate L. monocytogenes and E. coli O157:H7 in enoki mushrooms. Particularly, L. monocytogenes and E. coli O157:H7 diminished to below the detection limits (<1.55 log CFU/g) in enoki mushrooms after dipping in 3% LA and 0.1% nisin incorporated with 40 kHz US at 25 °C for 30 min and remained constant incapable of growing in samples stored at 5 °C for 120 h. A transmission electron microscopy analysis presented collapse of peripheral cytoplasm layers with formation of local pores and breakage of cell wall structures in L. monocytogenes exposed to combined treatments with 3% LA, 0.1% nisin, and 40 kHz US. A combination of LA, nisin, and US exerted strong synergistic effects for controlling the mushroom carriage of L. monocytogenes and E. coli O157:H7.

The combined effect of coating treatments to nisin, nano-silica, and chitosan on oxidation processes of stored button mushrooms at 4\xa0\xb0C

Agaricus bisporus is an edible fungus with a limited shelf life due to high moisture loss, browning, respiration, self-dissolve, lack of physical protection, rotting, and microbial attack. Mushrooms have been coated with nisin, nano-silica, and chitosan films in order to extend the shelf life, preserve quality and oxidation activities. The results showed that treating the mushrooms with chitosan and nano-silica (CH-AN-SILICA) increased superoxide dismutase activity (SOD—6.53 U kg−1), total phenolic content (TPC—0.39 g kg−1), and malondialdehyde content (MDA—1.63 µmol kg−1). CH-AN-SILICA treatment exhibited the highest scavenging against 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals. While, CH-AN-SILICA with the addition of nisin as an antimicrobial agent preserved almost the reactive oxygen species such as hydroxyl radicals (OH—0.33 µmol g−1), superoxide anion (O2•−—0.271 mmol s−1 kg−1), and hydrogen peroxide (H2O2—21.54 µmol g−1). Besides, both CH-AN-SILICA and CH-AN-SILICA/N enhanced the catalase (CAT) activity and reduced the respiration rate. The results indicated that the combination of nisin, nano-silica, and chitosan coating films was effective in providing a longer storage life with acceptable quality in mushrooms.

Antimicrobial and Preservative Effects of the Combinations of Nisin, Tea Polyphenols, Rosemary Extract, and Chitosan on Pasteurized Chicken Sausage

This study was conducted to evaluate the antimicrobial and preservative effects of the combinations of nisin (NS), tea polyphenols (TP), rosemary extract (RE), and chitosan (CS) on pasteurized chicken sausage. An orthogonal test revealed that the most effective preservative was a mixture of 0.05% NS plus 0.05% TP plus 0.03% RE plus 0.55% CS (weight by sausage weight). This mixture had antimicrobial and antioxidant effects in pasteurized chicken sausage and extended the shelf life to >30 days at 4°C. The inhibitory effects of NS, TP, RE, and CS were also evaluated against Pseudomonas aeruginosa, lactic acid bacteria (LAB), and Staphylococcus aureus, the dominant spoilage and pathogenic bacteria in pasteurized chicken sausage. NS had the greatest inhibitory effect on LAB and S. aureus, with inhibitory zone diameters of 19.7 and 17.8 mm, respectively. TP had the largest inhibitory effect on P. aeruginosa, with a clear zone diameter of 18.2 mm. These results indicate that the combination of NS, TP, RE, and CS could be used as a natural preservative to efficiently inhibit the growth of microorganisms in pasteurized chicken sausage and improve its safety and shelf life.