Biopreservation of Fresh Strawberries by Carboxymethyl Cellulose Edible Coatings Enriched with a Bacteriocin from Bacillus methylotrophicus BM47

Bacillus subtilis Edible Films for Strawberry Preservation: Antifungal Efficacy and Quality at Varied Temperatures

Fungal infestations, particularly from Rhizopus stolonifer, pose significant post-harvest challenges for strawberries, compromising their shelf life and quality. Traditional preservation methods, including refrigeration, offer limited protection against such pathogens. This study introduces an innovative approach, utilizing edible films infused with Bacillus subtilis strains GOS 01 B-67748 and HFC 103, known for their antifungal properties. We demonstrate that these bioactive films not only inhibit fungal growth effectively but also enhance the preservation of strawberries at varying temperatures. The inclusion of Bacillus subtilis in edible films represents a significant advancement in extending the viability of strawberries, surpassing the efficacy of conventional methods. Our findings suggest a promising avenue for natural, safe food preservation techniques, aligning with current consumer preferences for additive-free products. This research contributes to the broader understanding of microbial-based food preservation strategies, offering potential applications across a range of perishable commodities.

Probiotic-loaded edible films made from proteins, polysaccharides, and prebiotics as a quality factor for minimally processed fruits and vegetables: A review

Minimally processed fruits and vegetables (MPFVs) are gaining popularity in households because of their freshness, convenience, and rapid consumption, all of which align with today's busy lifestyles. However, their exposure of large surface areas during peeling and slicing can result in contamination by foodborne pathogens and spoilage bacteria, posing potential food safety concerns. In addition, enzymatic browning of MPFVs can significantly reduce their consumer appeal. Therefore, it is necessary to adopt certain methods to protect MPFVs. Recent studies have shown that utilizing biopolymer-based edible films containing probiotics is a promising approach to preserving MPFVs. These active food packaging films exhibit barrier function, antioxidant function, and antimicrobial function while protecting the viability of probiotics, which is essential to maintain the nutritional value and quality of MPFVs. This paper reviews microbial contamination in MPFVs and the preparation of probiotic-loaded edible films with common polysaccharides (alginate, gellan gum, and starch), proteins (zein, gelatin, and whey protein isolate), prebiotics (oligofructose, inulin, and fructooligosaccharides). It also explores the potential application of probiotic-loaded biopolymer films/coatings on MPFVs, and finally examines the practical application requirements from a consumer perspective.

Biopreservative technologies of food: an alternative to chemical preservation and recent developments

Despite centuries of developing strategies to prevent food-associated illnesses, food safety remains a significant concern, even with multiple technological advancements. Consumers increasingly seek less processed and naturally preserved food options. One promising approach is food biopreservation, which uses natural antimicrobials found in food with a long history of safe consumption and can help reduce the reliance on chemically synthesized food preservatives. The hurdle technology method that combines multiple antimicrobial strategies is often used to improve the effectiveness of food biopreservation. This review attempts to provide a research summary on the utilization of lactic acid bacteria, bacteriocins, endolysins, bacteriophages, and biopolymers helps in the improvement of the shelf-life of food and lower the risk of food-borne pathogens throughout the food supply chain. This review also aims to evaluate current technologies that successfully employ the aforementioned preservatives to address obstacles in food biopreservation.

Thymol@Natural Zeolite Nanohybrids for Chitosan/Polyvinyl-Alcohol-Based Hydrogels Applied as Active Pads

Currently, food saving, a circular economy, and zero environmental fingerprints are of major interest. Scientific efforts for enhanced food preservation using "green" methods have been intensified. Even though chemicals could achieve such targets effectively, the global trend against the "greenhouse effect" suggests the use of environmentally friendly biobased materials for this purpose. In this study, the promising biopolymer chitosan is incorporated with the promising biodegradable polymer polyvinyl alcohol to produce an improved biopolymeric matrix. This biodegradable biopolymer was further mixed homogeneously with 15% thymol/nano-zeolite nanohybrid material. The properties of the final developed film were improved compared to the relevant values of chitosan/polyvinyl alcohol film. The mechanical properties were enhanced significantly, i.e., there was a 34% increase in Young's modulus and a 4.5% increase in the ultimate tensile strength, while the antioxidant activity increased by 53.4%. The antibacterial activity increased by 134% for Escherichia coli, 87.5% for Staphylococcus aureus, 32% for Listeria monocytogenes, and 9% for Salmonella enterica. The water vapor diffusion coefficient and the oxygen permeability coefficient decreased to -51% and -74%, respectively, and thus, the water vapor and oxygen barrier increased significantly. The active pads were used in strawberries, and the antimicrobial activity evaluation against the mold of fungi was carried out. The visual evaluation shows that the active pads could extend the shelf life duration of strawberries.

Biodegradable hybrid biopolymer film based on carboxy methyl cellulose and selenium nanoparticles with antifungal properties to enhance grapes shelf life

In the current study, cellulose was extracted from sugarcane bagasse and further converted into carboxy methyl cellulose. The morphological, chemical, and structural characterization of synthesizeed carboxy methyl cellulose was performed. Further, the biopolymer was fabricated with mycogenic selenium nanoparticles and used to develop the biopolymer films. The developed biopolymer films were examined for the fruit shelf life stability, antifungal activity, and biodegradation potential. The results revealed that grapes wrapped with biofilms showed enhanced shelf life of fruit at all storage time intervals. The study also witnesses the antifungal activity of biopolymer films with a remarkable inhibitory action on the spores of Fusarium oxysporum and Sclerospora graminicola phytopathogens. Lastly, the biopolymer films were significantly degradable in the soil within two weeks of incubation. Thus, the developed biopolymer films exhibit multifaceted properties that can be used as an alternative to synthetic plastics for fruit packaging and also helps in protecting against fungal contaminants during storage with naturally degradable potential.

Effectiveness of a Phage Cocktail as a Potential Biocontrol Agent against Saprophytic Bacteria in Ready-To-Eat Plant-Based Food

This study aimed to evaluate the effectiveness of the phage cocktail to improve the microbiological quality of five different mixed-leaf salads: rucola, mixed-leaf salad with carrot, mixed-leaf salad with beetroot, washed and unwashed spinach, during storage in refrigerated conditions. Enterobacterales rods constituted a significant group of bacteria in the tested products. Selected bacteria were tested for antibiotic resistance profiles and then used to search for specific bacteriophages. Forty-three phages targeting bacteria dominant in mixed-leaf salads were isolated from sewage. Their titer was determined, and lytic activity was assessed using the Bioscreen C Pro automated growth analyzer. Two methods of phage cocktail application including spraying, and an absorption pad were effective for rucola, mixed leaf salad with carrot, and mixed leaf salad with beetroot. The maximum reduction level after 48 h of incubation reached 99.9% compared to the control sample. In washed and unwashed spinach, attempts to reduce the number of microorganisms did not bring the desired effect. The decrease in bacteria count in the lettuce mixes depended on the composition of the autochthonous saprophytic bacteria species. Both phage cocktail application methods effectively improved the microbiological quality of minimally processed products. Whole-spectral phage cocktail application may constitute an alternative food microbiological quality improvement method without affecting food properties.

Combinations of Peptide-Protein Extracts from Native Probiotics Suppress the Growth of Multidrug-Resistant Staphylococcus aureus and Citrobacter freundii via Membrane Perturbation and Ultrastructural Changes

The occurrence of multidrug-resistant pathogens in the food chain causes health problems in humans, thus, research for novel antimicrobials to combat their growth is of interest. This study evaluates the antimicrobial potential of several combinations of peptide-protein extracts (PCs) consisting of peptide extracts from three native probiotic strains, Lactiplantibacillus plantarum UTNGt2, Lactococcus lactis UTNGt28, and L. plantarum UTNGt21A, alone or in combination with EDTA (ethylenediaminetetraacetic acid) against multidrug-resistant Staphylococcus aureus ATCC1026 and Citrobacter freundii UTNB3Sm1. Based on the antimicrobial assay, among the 19 tested PCs, two (PC11 and PC17) produced a greater zone of inhibition against both pathogens in vitro. Time-killing assays indicated the rapid death of S. aureus after exposure to PC11 and PC17, while C. freundii was rapidly inhibited by PC11 and PC1 (UTNGt2 only), suggesting that the inhibitory action is pathogen and dose-dependent of a particular molecule present in the extract. A marginal inhibitory effect was observed when the peptides were combined with EDTA. Transmission electron microscopy (TEM) revealed the structural membrane damage of both target strains upon interaction with individual peptide extracts. Different degrees of cell deformation, condensed cytoplasm, membrane blebbing, and ghost cell formation with visibly broken cell walls were observed in S. aureus. Likewise, the separation of the cytoplasmic membrane from the outer membrane, ghost cells, along with ovoid and deformed cells with undulated cell walls were observed for C. freundii. Furthermore, scanning electronic microscopy (SEM) analysis revealed different wrinkled and deformed cells covered by debris. A leakage of aromatic molecules was detected for both pathogens, indicating that PCs disrupted the cell wall integrity, inducing cell death. Given their inhibitory action and capacity to induce damage of the cytoplasmic membrane, the selected PCs may serve to slow bacterial growth in vitro; further research is required to prove their efficiency ex vitro to battle against food poisoning and subsequent human infection.

Comprehensive Review of Polysaccharide-Based Materials in Edible Packaging: A Sustainable Approach

Edible packaging is a sustainable product and technology that uses one kind of "food" (an edible material) to package another kind of food (a packaged product), and organically integrates food with packaging through ingenious material design. Polysaccharides are a reliable source of edible packaging materials with excellent renewable, biodegradable, and biocompatible properties, as well as antioxidant and antimicrobial activities. Using polysaccharide-based materials effectively reduces the dependence on petroleum resources, decreases the carbon footprint of the "product-packaging" system, and provides a "zero-emission" scheme. To date, they have been commercialized and developed rapidly in the food (e.g., fruits and vegetables, meat, nuts, confectioneries, and delicatessens, etc.) packaging industry. However, compared with petroleum-based polymers and plastics, polysaccharides still have limitations in film-forming, mechanical, barrier, and protective properties. Therefore, they need to be improved by reasonable material modifications (chemical or physical modification). This article comprehensively reviews recent research advances, hot issues, and trends of polysaccharide-based materials in edible packaging. Emphasis is given to fundamental compositions and properties, functional modifications, food-packaging applications, and safety risk assessment of polysaccharides (including cellulose, hemicellulose, starch, chitosan, and polysaccharide gums). Therefore, to provide a reference for the development of modern edible packaging.

Antimicrobial Cocktail Combining Specific Peptide Extracts from Native Probiotic Bacteria Hamper Adulteration of Ready-to-Eat Mango Wedges

Consumption of ready-to-eat chopped fruits sold in the streets is a concern, as such activities are outside the regulation and protection in most developing countries. Ready-to-eat mangos are commonly sold as wedges in plastic cups at ambient temperature by mobile vendors in Ecuador, thus they are prone to contamination by bacteria, which poses a safety issue of concern. This work aimed to evaluate the effect of several antimicrobial cocktails consisting of previously designed specific peptide extract combinations from two probiotic bacteria Lactobacillus plantarum UTNCys5-4 and Lactococcus lactis subsp. lactis UTNGt28, along with nisin, a commercial food additive, on mango wedges artificially inoculated with a logarithmic phase culture of a five-strain bacterial mixture (FSBM). Preliminary bacteriological analysis of mango wedges purchased from mobile vendors showed the presence of multiple antibiotic-resistant isolates such E. coli spp., Enterobacter spp., Shigella spp., Salmonella spp., along with yeasts and molds, indicating non-compliance with the food safety standards. The results revealed that two antimicrobial cocktails, T2 and T5, containing cell-free supernatant based (CFS) and precipitated peptides (PP) based cocktails from UTNCys5-4 and UTNGt28 strains applied at dose 1:3 (v/v), were the most efficient combinations that inhibited the colonization of total bacterial counts with 56.03% and 55.61% in mango wedges stored with refrigeration. The reduction of total E. coli counts was 64.93%, while Salmonella and Shigella counts were reduced by 98.09% and 97.93%, respectively, when mango wedges were treated with T5-cocktail. The commercial nisin inhibited total Salmonella spp. counts by 40.13%, while E. coli spp. and Shigella spp. diminished by 28.20% and 37.22%, respectively. Moreover, we showed that T5 but not T7 (nisin) damaged the target cell integrity, thereby eventually inhibiting their growth and reproduction. The selected antimicrobial cocktails exerted a bacteriolytic effect by killing the FSBM simultaneously in a fruit matrix and preventing their accumulation in mango wedges. Furthermore, there is a possibility of using peptide combinatorial treatments to combat drug-resistant bacteria in ready-to-eat fruits.

Edible Coating and Pulsed Light to Increase the Shelf Life of Food Products

The application of edible coatings (EC) in combination with pulsed light (PL) treatments represents an emerging approach for extending the shelf life of highly perishable but high value-added products, such as fresh-cut fruits and vegetables. The surface of these products would benefit from the protective effects of ECs and the PL decontamination capability. This review describes in detail the fundamentals of both EC and PL, focusing on the food engineering principles in the formulation and application of EC and the delivery of efficient PL treatments and the technological aspects related to the food characterization following these treatments and discussing the implementation of the two technologies, individually or in combination. The advantages of the combination of EC and PL are extensively discussed emphasizing the potential benefits that may be derived from their combination when preserving perishable foods. The downsides of combining EC and PL are also presented, with specific reference to the potential EC degradation when exposed to PL treatments and the screening effect of PL transmittance through the coating layer. Finally, the potential applications of the combined treatments to food products are highlighted, comparatively presenting the treatment conditions and the product shelf-life improvement.

Lactic Acid Bacteria as Antibacterial Agents to Extend the Shelf Life of Fresh and Minimally Processed Fruits and Vegetables: Quality and Safety Aspects

Eating fresh fruits and vegetables is, undoubtedly, a healthy habit that should be adopted by everyone (particularly due to the nutrients and functional properties of fruits and vegetables). However, at the same time, due to their production in the external environment, there is an increased risk of their being infected with various pathogenic microorganisms, some of which cause serious foodborne illnesses. In order to preserve and distribute safe, raw, and minimally processed fruits and vegetables, many strategies have been proposed, including bioprotection. The use of lactic acid bacteria in raw and minimally processed fruits and vegetables helps to better maintain their quality by extending their shelf life, causing a significant reduction and inhibition of the action of important foodborne pathogens. The antibacterial effect of lactic acid bacteria is attributed to its ability to produce antimicrobial compounds, including bacteriocins, with strong competitive action against many microorganisms. The use of bacteriocins, both separately and in combination with edible coatings, is considered a very promising approach for microbiological quality, and safety for postharvest storage of raw and minimally processed fruits and vegetables. Therefore, the purpose of the review is to discuss the biopreservation of fresh fruits and vegetables through the use of lactic acid bacteria as a green and safe technique.

Effect of Nano-Edible Coating Based on Beeswax Solid Lipid Nanoparticles on Strawberry’s Preservation

Edible nano-coatings were applied in strawberry with the end goal of preserving quality by 21 days of storage at 4 °C. The beeswax solid lipid nanoparticles (BSLN) were prepared by high-energy homogenization, BSLN had a monomodal dispersion with average particle sizes of 214–227 nm and zeta potential of −30 mV. Four coatings were tested: 0, 10, 20, and 30 g/L of BSLN dispersion, all these edible coatings contained xanthan gum (XG) (3 g/L) and propylene glycol (5 g/L) and contrasted with strawberries without any treatment. The best behavior was achieved with 10 g/L of BSLN showing the lowest weight loss (6.1%), a decay index of (31%), loss of firmness (34%), and ΔE = 11. It was established that a concentration of 30 g/L of BSLN caused physiological damage. Based on the findings found, it can be said that nano-coatings with 10 g/L of BSLN-XG are an excellent alternative in the conservation and to increase of shelf life of strawberry stored in refrigeration. In the present case, it was 10 g/L of BSL. Highlighting the importance to evaluate the best concentration in relation to the fruit characteristics.

Prospect of Polysaccharide-Based Materials as Advanced Food Packaging

The use of polysaccharide-based materials presents an eco-friendly technological solution, by reducing dependence on fossil resources while reducing a product's carbon footprint, when compared to conventional plastic packaging materials. This review discusses the potential of polysaccharides as a raw material to produce multifunctional materials for food packaging applications. The covered areas include the recent innovations and properties of the polysaccharide-based materials. Emphasis is given to hemicelluloses, marine polysaccharides, and bacterial exopolysaccharides and their potential application in the latest trends of food packaging materials, including edible coatings, intelligent films, and thermo-insulated aerogel packaging.