The widespread usage of petroleum-based polymers as single-use packaging has had harmful effects on the environment. Herein, we developed sustainable chitin nanofiber (ChNF) coatings that prolong ...the shelf life of fresh cucumbers and delay the growth of pathogenic bacteria on their surfaces. ChNFs with varying degrees of acetylation were successfully prepared via deacetylation using NaOH with treatment times of 0-480 min and defibrillated using mechanical blending. With longer deacetylation reaction times, more acetamido groups (-NHCOCH
) in chitin molecules were converted to amino groups (-NH
), which imparted antibacterial properties to the ChNFs. The ChNF morphologies were affected by deacetylation reaction time. ChNFs deacetylated for 240 min had an average width of 9.0 nm and lengths of up to several μm, whereas rod-like structured ChNFs with a mean width of 7.3 nm and an average length of 222.3 nm were obtained with the reaction time of 480 min. Furthermore, we demonstrated a standalone ChNF coating to extend the shelf life of cucumbers. In comparison to the rod-like structured ChNFs, the 120 and 240-min deacetylated ChNFs exhibited a fibril-like structure, which considerably retarded the moisture loss of cucumbers and the growth rate of bacteria on their outer surfaces during storage. Cucumbers coated with these 120 and 240-min deacetylated ChNFs demonstrated a lower weight loss rate of ⁓ 3.9% day
compared to the uncoated cucumbers, which exhibited a weight loss rate of 4.6% day
. This protective effect provided by these renewable ChNFs holds promising potential to reduce food waste and the use of petroleum-based packaging materials.
This study focused on preparation of microfibers from bamboo culms using steam explosion with and without chemical treatments, and utilization of the isolated fibers in formation of bamboo paper ...fabricated with nanofibrillated cellulose (NFC). Compared with those obtained from the steam explosion alone (S), the bamboo microfibers isolated using the steam explosion followed by bleaching process (S/A) exhibited a significantly reduced fiber width of 7.5μm and a markedly increased cellulose content of 97.85%. The S/A fiber showed an increased decomposition temperature, corresponding with lower contents of hemicellulose and lignin than those of the S fiber. The S/A microfibers were subsequently proceeded to paper formation. Physical and mechanical properties of the paper with an introduction of different NFC concentrations (0–50wt%) were investigated. The linear relationship between the density, porosity and mechanical properties of the paper and NFC contents was observed. The more the NFC content, the greater the density and the lower the porosity the paper exhibited. At 50wt% NFC, the paper density increased to 0.64gcm−3, and the paper porosity decreased to 57.0% whereas the paper without NFC showed a density of 0.39gcm−3 and porosity of 73.6%. Tensile strength and strain of the paper composed with 50wt% NFC were 10-fold and 3-fold, respectively, greater than those of the paper without NFC. The addition of NFC could manifest paper mechanical properties and porosity within the paper structure, which would be useful for scaffold and membrane applications.
Helicobacter pylori, linked to gastric diseases, is targeted for probiotic treatment through bacteriocin production. Bacteriocins have gained recognition for their non-toxic effects on host cells and ...their ability to combat a wide range of pathogens. This study aimed to taxonomically characterize and evaluate the safety and probiotic properties of the novel species of Lactococcus sp. NH2-7C isolated from fermented pork, as well as its bacteriocin NH2-7C, both in vitro and in silico. Comparative genotypic analysis revealed an average nucleotide identity of 94.96%, an average amino acid identity of 94.29%, and a digital DNA-DNA hybridization value of 63.80% when compared to Lactococcus lactis subsp. lactis JCM 5805
. These findings suggest that strain NH2-7C represents a novel species within the genus Lactococcus. In silico assessments confirmed the non-pathogenic nature of strain NH2-7C and the absence of genes associated with virulence and biogenic amine formation. Whole-genome analysis revealed the presence of the nisA gene responsible for nisin A production, indicating its potential as a beneficial compound with anti-Helicobacter pylori activity and non-toxic characteristics. Probiotic assessments indicated bile salt hydrolase and cholesterol assimilation activities, along with the modulation of interleukin-6 and tumour necrosis factor-α secretion. Strain NH2-7C demonstrated gastrointestinal tolerance and the ability to adhere to Caco-2 cells, affirming its safety and probiotic potential. Additionally, its ability to produce bacteriocins supports its suitability as a functional probiotic strain with therapeutic potential. However, further in vitro and in vivo investigations are crucial to ensure its safety and explore potential applications for Lactococcus sp. NH2-7C as a probiotic agent.
Weissella hellenica BCC 7239, isolated from Thai fermented pork sausage called Nham, produced two putatively novel bacteriocins, 7293A and 7293B. Both bacteriocins had broad antimicrobial spectra and ...exceptionally inhibited several important Gram-negative food-borne pathogens (Pseudomonas aeruginosa, Aeromonas hydrophila, Salmonella Typhimurium and Escherichia coli). The highest amount of bacteriocin was produced in MRS and APT media at 30 °C without agitation. Bacteriocin 7293A showed relatively higher antimicrobial activity than bacteriocin 7293B. However, pH and thermal stability of bacteriocin 7293A was lower. These bacteriocins were of proteinaceous nature, in which the complete inactivation of their antimicrobial activity after treatment by proteolytic enzymes, including trypsin, α-chymotrypsin, pepsin and protease K was observed, whilst lipase and α-amylase exhibited no effect. Antimicrobial activity of both peptides was also not inactivated by organic solvents (ethanol, isopropanol, acetone, acetonitrile) and surfactants (Tween 20, Tween 80 and Triton X-100). Bacteriocin 7293A and B exhibited bactericidal effect against both Gram-positive and Gram-negative indicators without cell-lysis. According to ESI/MS analysis, the molecular masses of bacteriocin 7293A and B were determined to be 6249.302 and 6489.716 Da, respectively. Because their molecular masses were not similar to those of other known bacteriocins, both bacteriocin 7293A and B could be novel bacteriocins. Thus, both novel bacteriocins hold promise for applications in the prevention or treatment of pathogenic infections as food and feed additives to replace antibiotics for enhancing the productivity and sustainability of food animals.
•Weissella hellenica BCC 7293 produced two putatively novel bacteriocins.•Purified bacteriocins inhibit several Gram-negative food borne pathogens.•Bacteriocins 7293A and B exhibited bactericidal effect without cell-lysis.
The suitability of Lactiplantibacillus plantarum (L. plantarum) as a functional starter culture in Nham fermentation was investigated, with a focus on evaluating both its probiotic attributes and ...fermentation capability. L. plantarum BCC 4352 (LpbBCC4352) exhibited colony-associated antimicrobial activity against Kocuria rhizophila, L. plantarum, Latilactobacillus sakei ssp. sakei, and Pediococcus pentosaceus, as well as the zoonotic Streptococcus suis. LpbBCC4352 exhibited impressive acid (pH 2.5) and bile resistance, coupled with notable survival rates in a simulated human digestive model. In addition, the strain is able to utilize fructo-oligosaccharides in simulated human colon conditions. It also displayed robust adhesion to human colon cell monolayers (Caco-2) and gastric mucin. Furthermore, it showed a promising cholesterol reduction ability in the fermentation medium. The safety of LpbBCC4352 for human consumption was confirmed through a hemolytic activity assay and antibiotic susceptibility testing. Moreover, using LpbBCC4352 as a starter culture not only enhanced the firmness of Nham but also ensured consumer satisfaction. The overall findings emphasize the potential use of LpbBCC4352 as a safe and effective functional starter culture, particularly in the production of Nham.
Cellulose-based paper is an alternative substitution for petroleum-based polymers for packaging applications, but its mechanical performance is poor when in contact with water. Herein, chitosan was ...applied on cellulose-based paper via a coating approach. The effects of chitosan coatings between none and five layers on the color properties, wettability, thermal properties, mechanical performance, and overall migration in food simulants of the paper were evaluated. After the application of chitosan, chitosan first filled cavities between cellulose fibers within a network, and the chitosan film was formed on the paper surface later. This resulted in a pronounced increase in wettability and mechanical properties associated with a loss of whiteness and an increase in yellowness of the coated paper. The chitosan-coated paper became hydrophobic with a water contact angle of 94.7 ± 2.8°, and a robust improvement of 156.4% for tensile strength and 114.8% for strain at break was observed for the paper coated with three layers of chitosan in wet conditions in comparison to the uncoated paper. A reduction in the migration of the low molecular residuals from the paper could be hindered by the chitosan coating. These enhanced features revealed that chitosan-coated paper could be used as a food-contact material.
•Chitosan was applied on cellulose-based paper by a coating method.•Greater mechanical properties of chitosan coated paper were observed in wet conditions.•The hydrophilicity of the paper was transformed into the hydrophobic feature with incorporation of chitosan.•A reduction in the migration of the low molecular residuals from the paper could be hindered by the chitosan coating.•The chitosan-coated paper prepared could possibly be used for direct-contact packaging.
Meat and meat products have always been an important part of human diet, and contain valuable nutrients for growth and health. Nevertheless, they are perishable and susceptible to microbial ...contamination, leading to an increased health risk for consumers as well as to the economic loss in meat industry. The utilization of bacteriocins produced by lactic acid bacteria (LAB) as a natural preservative has received a considerable attention. Inoculation of bacteriocin-producing LAB cell as starter or protective cultures is suitable for fermented meats, whilst the direct addition of bacteriocin as food additive is more preferable when live cells of LAB could not produce bacteriocin in the real meat system. The incorporation of bacteriocins in packaging is another way to improve meat safety to avoid direct addition of bacteriocin to meat. Utilization of bacteriocins can effectively contribute to food safety, especially when integrated into hurdle concepts. In this review, LAB bacteriocins and their applications in meat and meat products are revisited. The molecular structure and characteristics of bacteriocins recently discovered, as well as exemplary properties are also discussed.
•LAB bacteriocins could be used as an effective natural preservative for meat.•GarQ and Bac7293A are novel Class IId bacteriocins.•Incorporation of bacteriocins in packaging is another means to improve meat safety.•Hurdle technology enhances the antimicrobial effectiveness of bacteriocins.
Chitosan with low (25 kDa) and high molecular weight (2100 kDa) were used to enhance performances of paper made from steam-exploded bamboo fibers and nanofibrillated cellulose. Chitosan solutions ...with concentrations of 0–1.0 wt% were manually applied on paper surface using a facile coating approach with a wire bar. Effects of chitosan coatings on morphology, thermal stability, wettability, mechanical performances and antibacterial properties of the paper were investigated. The larger improvement in the mechanical properties and wettability of the chitosan coated paper was observed with increasing concentrations of chitosan due to the disappearance of empty pores between fibers within a cellulose network by the formed chitosan matrix. These improvements were significantly higher when high molecular weight chitosan was applied. Yet, the addition of chitosan slightly decreased the thermal stability of the coated paper, and the chitosan coating did not improve the antimicrobial properties of the paper. The antimicrobial activity of chitosan against Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli) was found to be diminished when a chitosan solution was entrapped within paper. Together with the overall migration of the paper in food simulants, the results suggested that the chitosan coated paper could be applied for non-food-direct-contact packaging materials.
This study aimed to develop an antimicrobial biodegradable food packaging for control of pathogens in pangasius fish fillets, one of the world's most consumed freshwater fish. Bacteriocin 7293 ...(Bac7293), a novel bacteriocin from Weissella hellenica BCC 7293, was diffusion coated onto poly (lactic acid)/sawdust particle biocomposite film (PLA/SP) with the maximum amount of 19.54 ± 2.87 μg/cm2. According to the JIS Z 2801:2000 standard testing method, the produced PLA/SP film impregnated with Bac7293 (PLA/SP + Bac7293) effectively inhibited both Gram-positive (Listeria monocytogenes and Staphylococcus aureus) and Gram-negative bacteria (Pseudomonas aeruginosa, Aeromonas hydrophila, Escherichia coli and Salmonella Typhimurium) which have been considered as a reason for the rejection of pangasius fish fillets. This antimicrobial film inhibited the growth of target microorganisms by about 2–5 log CFU/cm2, depended on bacterial strains, compared with control, both in vitro and in pangasius fish fillets by means of challenge test. The overall migration of PLA/SP + Bac7293 film to food simulants was maximized in isooctane (3.67 ± 0.47 mg/dm2) which was much lower than the overall migration limit regulated by the commission of the European communities. This suggested high potential application of PLA/SP + Bac7293 as a good antimicrobial packaging for pangasius fish fillets.
•PLA/SP film enriched with Bac7293, a novel bacteriocin, was developed.•PLA/SP film played the role to maintain the antimicrobial activity of Bac7293.•The film inhibited both Gram-positive and Gram-negative food borne pathogens.•The overall migration of PLA/SP + Bac7293 was in compliance with regulation of EU.
White feces syndrome (WFS) is one of the major constrains for shrimp cultivation. Although the pathogen causing WFS remains largely unknown, WFS has been associated with an increase in vibrio ...abundances in shrimp haemolymph and intestine. We demonstrated that hen egg white lysozyme (HEWL) inhibited in vitro growth of Vibrio spp. including V. alginolyticus, V. harveyi, and V. parahaemolyticus. To alleviate shrimp losses from WFS, HEWL was supplemented into feed at 0.005, 0.025, 0.125, and 0.625 g/kg diet. Supplementation at 0.125 (HEWL0.125) and 0.625 (HEWL0.625) g/kg diet retained the antimicrobial activity under the cultivation water. Both of the supplemental levels also showed a significant antimicrobial activity and reduction in vibrio richness in shrimp gastrointestinal tract. We further analyzed the effect of HEWL supplementation on the expression of immune and antioxidant related genes in hepatopancreas. HEWL0.125 substantially upregulated the expression of prophenoloxidase, serine proteinase, superoxide dismutase, thioredoxin, and ferritin. Growth performance analysis of weight gain, average daily gain (ADG), feed conversion ratio, and survival rate was also determined, but there were no differences in those parameters. When shrimp were challenged with a pathogenic strain of V. harveyi, we observed the greater survival rate in HEWL0.125 than that of the control group (66.67% vs. 16.67%). Importantly, the effect of HEWL0.125 on WFS was evaluated in a shrimp farm. The incidence of WFS was disappeared without recurrence in shrimp fed HEWL0.125. As a result, the survival and ADG were improved significantly. In conclusion, dietary supplementation of HEWL0.125 could inhibit vibrio growth and stimulate immune- and antioxidant-related gene expression leading to resistance against WFS in shrimp.
•Hen egg white lysozyme (HEWL) exhibited the in vitro and in vivo anti-vibrio activity.•Dietary supplementation of HEWL activated immune- and antioxidant-related genes expression in Pacific white shrimp.•Dietary supplementation of HEWL promoted disease resistance against vibriosis and white feces syndrome.
PDF
