Cassava bagasse starch and oregano essential oil as a potential active food packaging material: A physicochemical, thermal, mechanical, antioxidant, and antimicrobial study.

This research evaluates the use of cassava bagasse starch and oregano essential oil (OEO) in an active film. For comparison, films of cassava starch (CS) and cassava bagasse starch (BS) were prepared with OEO at 1, 2, and 3 %. Physical, thermal, mechanical, antioxidant, and antimicrobial properties were determined. BS films presented higher thickness, WVP, ΔE, modulus of elasticity, and maximum stress, but lower strain at break compared to CS films. Adding OEO into the films increased their thickness, moisture, solubility, WVP and strain at break. However, maximum stress, modulus of elasticity, and T dmax decreased. The CS films added with 3 % of OEO showed higher WVP (6.32 × 10-14 kg m/m2.s.Pa), intermediate solubility of 39 % and low maximum stress (0.19 MPa) while the BS film with 3 % of OEO presented 5.73 × 10-14 kg m/m2.s.Pa, 30 % and 0.39 MPa, respectively. The increase from 1 % to 3 % of OEO increased the total phenolic compound content and antioxidant activity of the films by 1.3-fold and 3.7-fold, respectively. The incorporation of 3 % OEO in the films inhibited the growth of S. aureus and E. coli. Therefore, BS and OEO films offer a promising solution as biodegradable active food packaging, providing a more sustainable alternative to traditional non-biodegradable plastic packaging.

The force of Zein self-assembled nanoparticles and the application of functional materials in food preservation.

Zein self-assembled nanoparticles (Z-NPs) are an excellent delivery carrier for bioactive components. However, the poor stability of its application in the food industry is the main problem. This paper focused on the self-assembly force of Z-NPs and the factors affecting the stability of Z-NPs. Meanwhile, the modification methods of zein and its interaction with food additives were analyzed. Additionally, its application in the field of food preservation was reviewed. The main interactions between zein and polyphenols encompass hydrogen bonding, non-covalent interactions, and hydrophobic interactions. Besides, the interactions with polysaccharides involve both covalent and non-covalent interactions. Furthermore, the protein interactions entail hydrophobic interactions, electrostatic interactions, hydrogen bonds, and π-π stacking. The primary driving forces governing zein self-assembly encompass electrostatic interactions, hydrogen bonding, van der Waals forces, hydrophobic interactions, and π-π stacking. Meanwhile, functionalized Z-NPs can be used in the food preservation industry to prolong the shelf life of food.

Poly(vinyl chloride) Films Incorporated with Antioxidant ZnO-Flavonoid Nanoparticles: A Strategy for Food Preservation.

Antioxidant films were prepared using poly(vinyl chloride) (PVC) incorporated with 0.5% or 1.0% zinc oxide (ZnO)-flavonoid (quercetin or morin) nanoparticles (NPZnO-Q% or NPZnO-M%) via the casting method. NP incorporation within the polymer matrix influenced the structural, morphological, optical, and thermal properties of the PVC-based films, as well as their antioxidant activity as assessed using the DPPH radical scavenging method. Our results indicated that increasing ZnO-flavonoid NP concentration increased films thickness, while reducing ultraviolet light (UV) transmittance but conserving transparency. The presence of NPZnO-Q% or NPZnO-M% improved the surface uniformity and thermal stability of the active films. In terms of antioxidant activity, there was an enhancement in the DPPH radical scavenging capacity (PVC/ZnO-Q1.0% > PVC/ZnO-Q0.5% > PVC/ZnO-M0.5% > PVC/ZnO-M1.0% > PVC), suggesting that the packaging can help protect food from oxidative processes. Therefore, these antioxidant films represent an innovative strategy for using as active food packaging material, especially intended for aiding in quality preservation and extending the shelf life of fatty foods.

New insights into essential oil nano emulsions loaded natural biopolymers recent development, formulation, characterization and packaging applications: A comprehensive review.

Customer demand for wholesome diets has spurred researchers to explore preservative-free methods for maintaining food product quality. Nano emulsion-based coatings and films are seen as sustainable solutions for extending the shelf life of fresh produce. These innovations are driving progress in various industries. Nano emulsion techniques offer effective encapsulation of bioactive compounds due to their small droplet size, stability, and enhanced activity. This review highlights the preparation and manufacturing methods of biopolymer-based nano emulsions containing essential oils, which are used as edible coatings and films over the past decade, representing the first comprehensive review paper on this topic to encompass research from the past ten years. The characterization and application of these coatings and films are also discussed. It has been revealed that essential oils can be successfully incorporated into nano emulsion delivery system with different biopolymers. These edible coatings and films help delay or prevent oxidation in various food products, enhancing their quality and safety during storage. They present a green, sustainable, and biodegradable solution for protecting fresh foods in the industry. Essential oil biopolymer nano emulsions not only extend shelf life but also offer protection against hazards, contributing to consumer trust in food safety and quality. This technology holds promise for delivering healthier food options in the marketplace. The current review thus provides an updated overview of the latest literature on EO nano emulsions as active agents in the advancement of edible coatings and films.

Modified Chitosan-Based Coating/Packaging Composites with Enhanced Antibacterial, Antioxidant, and UV-Resistant Properties for Fresh Food Preservation.

Chitosan-based biomass packaging materials are a promising material for food preservation, but their limited solubility, antioxidant capacity, UV resistance, and mechanical properties severely restrict their application. In this study, we developed a novel chitosan-based coating/packaging composite (QCTO) using quaternary ammonium salt and tannic acid (TA)-modified chitosan (QCS-TA) and oxidized chitosan (OCS). The introduction of quaternary ammonium salt and TA effectively improves the water solubility and antibacterial, antioxidant, and UV-resistant properties of chitosan. The Schiff-base bond formed between OCS and QCS-TA, along with the TA-mediated multiple interactions, conferred the prepared composite film with good mechanical properties (69.9 MPa tensile strength) and gas barrier performance to water (14.3 g·h-1·m-2) and oxygen (3.5 g·mm·m-2·h-1). Meanwhile, the prepared QCTO composites demonstrate excellent biocompatibility and safety and are applied as coatings for strawberries and bananas as well as packaging films for mushrooms. These preservation experiments demonstrated that the prepared composites are able to effectively reduce weight loss, prevent microbial growth, maintain color, and significantly prolong the shelf life of fresh products (bananas, strawberries, and mushrooms extended shelf life by 6, 5, and 6 days, respectively). Therefore, the developed QCTO coating/packaging film shows great potential for applications in the field of food preservation and packaging.

Chitosan-ginger essential oil nanoemulsions loaded gelatin films: A biodegradable material for food preservation.

The alarming issue of food waste, coupled with the potential risks posed by petroleum-based plastic preservation materials to both the environment and human health necessitate innovative solutions. In this study, we prepared nanoemulsions (NEs) of chitosan (CS) and ginger essential oil (GEO) and systematically evaluated the effects of varying NEs concentrations (0, 10 %, 30 %, 50 %) on the physicochemical properties and biological activities of gelatin films. These films were subsequently applied to blueberry preservation. The scanning electron microscopy confirmed that the NEs were well-integrated with the Gel matrix, significantly enhancing the performance of the Gel films, including improvements of mechanical properties (tensile strength from 7.71 to 19.92 MPa; elongation at break from 38.55 to 113.65 %), thermal, and barrier properties (water vapor permeability from 1.52 × 10-9 to 6.54 × 10-10 g·m/Pa·s·m2). The films exhibited notable antibacterial and antioxidant activities due to the gradual release of GEO, thereby extending the storage life of blueberries. Moreover, the prepared composite films demonstrated excellent biodegradability and environmental friendliness, with the majority of the material decomposing within 30 days under soil microbial action. In conclusion, the active films loaded with NEs exhibit superior performance and hold significant potential for developing biodegradable materials for food preservation.

Impact of Antioxidant-Enriched Edible Gel Coatings and Bio-Based Packaging on Cherry Tomato Preservation.

This research investigates the effects of using edible gel coatings and bio-based packaging materials on extending the shelf life of cherry tomatoes. Two edible gel coatings (guar gum and guar gum +5% of a lemon (Citrus limon (L.) Osbeck pomace extract obtained in the research laboratory) were applied on cherry tomatoes, then they were packaged in bio-based materials (cellulose tray + PLA lid). Guar gum, glycerol, sorbitol, extra virgin olive oil, and tween 20 were used in coating formulation. Uncoated tomatoes packed in bio-based materials and conventional plastic (PET trays + lid) were tested as a control. Samples were stored for 45 days at 20 °C and their quality parameters were evaluated. Coated tomatoes maintained firmness and weight, and the enriched coated samples showed a significant increase in phenol content, derived from the antioxidant extract. Samples packed in PET showed a sensory unacceptability (<4.5) after 45 days correlated with a greater decline in firmness (from 10.51 to 5.96 N) and weight loss (from 7.06 to 11.02%). Therefore, edible gel coating and bio-based packaging proved to be effective in maintaining the overall quality of cherry tomatoes for 45 days, offering a promising approach to reduce plastic polymer use and food waste.

Nanocomposite films based on chia (Salvia hispanica L.) flour seeds incorporating antioxidant chitosan nanoparticles.

Chia (Salvia hispanica L.) flour seeds produce films with good barrier properties against water vapor and could be used as food packaging; however, their mechanical properties are poor, which limits their application. The incorporation of nanoparticles into natural polymers is a strategy used to improve the properties of films to increase their applications. Furthermore, nanoparticles can encapsulate antioxidant agents and generate active films. The objective of this study was to evaluate the influence of chia flour (4%-7%), glycerol (15%-25%), and chia extract-loaded chitosan nanoparticles (ChCNp) (0%-0.75%) on the physical, mechanical, barrier, structural and antioxidant properties of chia flour nanocomposite films. Chitosan nanoparticles loaded with antioxidant chia extract were synthesized by ionic gelation and incorporated into the films. The thickness, water vapor permeability, tensile strength, and antioxidant properties of the films were evaluated using a Box-Behnken experimental design. Structural analysis was conducted using the FTIR technique. The results of the ANOVA of the responses were adjusted to second and third order polynomial models obtaining determination coefficients of 0.96-0.99. The water vapor permeability of the films was 3.89 × 10-8-1.68 × 10-7 g mm/Pa s m2, tensile strength was 0.67-3.59 MPa and antioxidant activity was 57.12%-67.84%. The variables presented different effects on the films. Increasing the chia seed flour concentration negatively affected the water vapor permeability but improved the tensile strength and the antioxidant capacity of the films. The increase in glycerol concentration caused the films to become brittle. The nanoparticles had a significant effect on the thickness of the films and improved their mechanical and antioxidant properties. However, they did not show an effect on barrier properties. The results demonstrate that it is possible to obtain nanocomposite films with antioxidant capacity from chia seed flour and with the incorporation of chitosan nanoparticles loaded with antioxidants.

Triple synergistic sterilization of Prussian blue nanoparticle-doped chitosan/gelatin packaging film for enhanced food preservation.

To mitigate food spoilage caused by microbial contamination and extend the shelf life of food, antibacterial and eco-friendly biological packaging materials as an alternative to petroleum-based plastics is encouraged. Herein, an innovative and green composite film with triple antibacterial activity has been fabricated by introducing prussian blue nanoparticles (PBNPs) into chitosan (CS)-based films blended with gelatin (Gel) for the preservation of food, named CS/Gel/PB film. Due to the incorporation of PBNPs, CS/Gel/PB film exhibits enhanced mechanical, barrier and water resistance, and thermal abilities. The inherent bacterial trapping and killing capabilities of CS (contact killing), photothermal/photodynamic killing based on the excellent photothermal property of PBNPs under NIR irradiation synergistically facilitate the sterilization against Escherichia coli and Staphylococcus aureus (antibacterial ratio = 99.99 %). The film exhibits outstanding preservation capability in product storage, significantly extending the shelf life of strawberry and pork to 15 and 7 days, respectively. Meanwhile, the cytotoxicity assessment of CS/Gel/PB against HepG2 cells ascertains a cell viability exceeding 96 %, indicating a negligible toxicity level. Additionally, this film also exhibits superior biodegradability (preliminary degradation on the 10th day and completion on the 40th day) compared with PE film. Overall, these properties demonstrate great potential of CS/Gel/PB film as a novel packaging material.

Formulation of a Three-Component Essential Oil Mixture from Lavandula dentata, Rosmarinus officinalis, and Myrtus communis for Improved Antioxidant Activity.

The optimization of existing natural antioxidants that are highly effective is crucial for advancements in medicine and the food industry. Due to growing concerns regarding the safety of synthetic antioxidants, researchers are increasingly focusing on natural sources, particularly essential oils (EOs). Combining EOs might enhance antioxidant activity due to increased chemical diversity. This study investigates, for the first time, the antioxidant properties of EOs from Lavandula dentata, Rosmarinus officinalis, and Myrtus communis, both individually and in combination, using the augmented-simplex design methodology. The in vitro evaluation of the antioxidant activity was performed using DPPH and ABTS radical scavenging assays. Chromatography gas-mass spectrometry (CG-MS) revealed that 1,8-cineol (37.27%) and pinocarveol (12.67%) are the primary components of L. dentata; verbenone (16.90%), camphor (15.00%), and camphene (11.03%) are predominant in R. officinalis; while cineol (43.32%) is the main component of M. communis. The EOs showed varying scavenging activities against ABTS and DPPH radicals, with DPPH assay values ranging from 194.10 ± 3.01 to 541.19 ± 3.72 µg/mL and ABTS assay values ranging from 134.07 ± 1.70 to 663.42 ± 2.99 µg/mL. These activities were enhanced when the EOs were combined. The optimal antioxidant blend for DPPHIC50 consisted of 20% L. dentata, 50% R. officinalis, and 30% M. communis. For the highest ABTS radical scavenging activity, the best combination was 18% L. dentata, 43% R. officinalis, and 40% M. communis. These results highlight the potential of EO combinations as new natural formulations for use in cosmeceutical, food, and pharmaceutical sectors.

Research on Food Preservation Based on Antibacterial Technology: Progress and Future Prospects.

The nutrients present in food are not only prone to a series of physicochemical reactions but also provide conditions for the growth and reproduction of foodborne microorganisms. In recent years, many innovative methods from different fields have been introduced into food preservation, which extends the shelf life while maximizing the preservation of the original ingredients and properties of food. In this field, there is a lack of a systematic summary of new technologies emerging. In view of this, we overview the innovative methods applied to the field of food preservation in recent 3 years, focusing on a variety of technological approaches such as antimicrobial photodynamic therapy based on nanotechnology, electromagnetic radiation sterilization based on radiation technology, and antimicrobial peptides based on biomolecules. We also discuss the preservation mechanism and the application of the different methods to specific categories of products. We evaluated their advantages and limitations in the food industry, describing their development prospects. In addition, as microorganisms are the main causes of food spoilage, our review also has reference significance for clinical antibacterial treatment.

Converting fruit peels into biodegradable, recyclable and antimicrobial eco-friendly bioplastics for perishable fruit preservation.

The development of biodegradable antimicrobial bioplastics for food packaging holds great promise for solving the pollution and safety problems caused by petrochemical plastics and spoiled food. Herein, a natural active-bioplastic synthesized from citrus peel biomass is presented for perishable fruit preservation. These plastics are characterized by the nanoscale entanglement and recombinant hydrogen bonding between the endogenous pectin, polyphenols and cellulose micro/nanofibrils. They have attractive flexibility, tensile strength, gas barrier properties and antimicrobial activities, and can effectively extend the shelf life of perishable fruits such as banana and mango when used as food packaging. Cytotoxicity, degradability tests and life-cycle assessment show that these plastics had excellent nontoxicity and can be safely degraded or easily recycled. This work demonstrates a sustainable strategy for converting peel waste into eco-friendly bioplastics, providing a unique and novel insight into radically reducing the pollution and life-health threats posed by petrochemical plastics and spoiled food.

Fortification of cassava starch edible films with Litsea cubeba essential oil for chicken meat preservation.

Chicken meat is highly perishable and mainly preserved by plastic packaging materials, whereas their widely used have increased environmental burden and threatened human health. Bioactive packaging materials fabricated by biopolymers are promising alternatives for meat preservation. Herein, cassava starch (CS)/sodium carboxymethyl cellulose (CMC) edible films fortified with Litsea cubeba essential oil (LC-EO) were fabricated and characterized. Results showed the textural, mechanical and barrier properties of the CS/CMC edible films were significantly improved after incorporating with LC-EO. Moreover, the composite edible films exhibited potent antibacterial properties, biodegradability, hydrophobicity, and thermal stability. Whereas the water solubility and moisture content was reduced up to 29.68 % and 24.37 %, respectively. The release behavior of LC-EO suggested the suitability of the composite edible films for acidic foods. Comparing with the control group, the pH values of the meat samples packaged with CS/CMC/LCEO-4 mg/mL edible films maintained at around 6.7, and weight loss rate was 15 %. The color and texture changes, and the lipid oxidation of the meat samples with CS/CMC/LCEO-4 mg/mL packaging were also markedly delayed. The microbial growth was retarded at 6.35 log CFU/g after storage for 10 days. These findings suggested the CS/CMC/LCEO-4 mg/mL edible films had great potential for chicken meat preservation.

Organic nanoparticles incorporated starch/carboxymethylcellulose multifunctional coating film for efficient preservation of perishable products.

Most of postharvest agricultural produces are perishable due to microorganisms infections and physiological change. Herein, one kind of multifunctional coating film of SC-ECCNPs was developed by incorporating organic nanoparticles of ECCNPs into starch/carboxymethylcellulose (SC) to prolong shelf life of food with excellent performances. The SC-ECCNPs coating was prepared with starch and sodium carboxymethylcellulose as film substrate (SC) to incorporate with organic nanoparticles of ECCNPs formed by integrating epigallocatechin-3-gallate (EGCG), cysteine (Cys), and cinnamaldehyde (CA). The incorporation of ECCNPs improves the UV-resistance and physical properties of SC-ECCNPs coating and also endows it with excellent antioxidative and broad-spectrum antibacterial activity. The application possibilities of SC-ECCNPs coating were explored with strawberries and oranges as samples, validating that the SC-ECCNPs coating can prolong the shelf life of fruits at room temperature. The biosafety of the coating was further confirmed with hemolysis and MTT experiments. The SC-ECCNPs coating film was prepared with natural substrates via a simple and green method. The investigation provides an instructive way for developing advanced packaging materials with high performances.

Ratanjot (Alkanna tinctoria L.) Root Extract, Rich in Antioxidants, Exhibits Strong Antimicrobial Activity against Foodborne Pathogens and Is a Potential Food Preservative.

Natural and sustainable plant-based antioxidants and antimicrobials are highly desirable for improving food quality and safety. The present investigation assessed the antimicrobial and antioxidant properties of active components from Alkanna tinctoria L. (herb) roots, also known as Ratanjot root. Two methods were used to extract active components: microwave-assisted hot water (MAHW) and ethanolic extraction. MAHW extract yielded 6.29%, while the ethanol extract yielded 18.27%, suggesting superior Ratanjot root extract powder (RRP) solubility in ethanol over water. The ethanol extract showed significantly higher antioxidant activity than the MAHW extract. Gas Chromatography-Mass Spectrometry analysis revealed three major phenolic compounds: butanoic acid, 3-hydroxy-3-methyl-; arnebin 7, and diisooctyl pthalate. The color attributes (L*, a*, b*, H°ab, C*ab) for the ethanolic and MAHW extracts revealed significant differences (p < 0.05) in all the above parameters for both types of extracts, except for yellowness (b*) and chroma (C*ab) values. The ethanol extract exhibited antimicrobial activity against 14 foodborne bacteria, with a significantly higher inhibitory effect against Gram-positive bacteria (Listeria monocytogenes and Staphylococcus aureus) than the Gram-negative bacteria (Salmonella enterica serovar Typhimurium and Escherichia coli). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were both 25 mg/mL for the Gram-negative bacteria, while the MIC and MBC concentrations varied for Gram-positive bacteria (0.049-0.098 mg/mL and 0.098-0.195 mg/mL) and the antimicrobial effect was bactericidal. The antimicrobial activities of RRP extract remained stable under broad temperature (37-100 °C) and pH (2-6) conditions, as well as during refrigerated storage for 30 days. Application of RRP at 1% (10 mg/g) and 2.5% (25 mg/g) levels in a cooked chicken meatball model system prevented lipid oxidation and improved sensory attributes and retarded microbial growth during refrigerated (4 °C) storage for 20 days. Furthermore, the RRP extract was non-toxic when tested with sheep erythrocytes and did not inhibit the growth of probiotics, Lacticaseibacillus casei, and Lactiplantibacillus plantarum. In conclusion, the study suggests that RRP possesses excellent antimicrobial and antioxidant activities, thus making it suitable for food preservation.

Essential Oil Nanoemulsions-A New Strategy to Extend the Shelf Life of Smoothies.

Over the years, consumer awareness of proper, healthy eating has increased significantly, but the consumption of fruits and vegetables remains too low. Smoothie drinks offer a convenient way to supplement daily diets with servings of fruits and vegetables. These ready-to-eat beverages retain the nutritional benefits of the raw ingredients from which they are made. Furthermore, they cater to the growing demand for quick and nutritious meal options. To meet consumer expectations, current trends in the food market are shifting towards natural, high-quality products with minimal processing and extended shelf life. Food manufacturers are increasingly aiming to reduce or eliminate synthetic preservatives, replacing them with plant-based alternatives. Plant-based preservatives are particularly appealing to consumers, who often view them as natural and organic substitutes for conventional preservatives. Essential oils, known for their antibacterial and antifungal properties, are effective against the microorganisms and fungi present in fruit and vegetable smoothies. However, the strong taste and aroma of essential oils can be a significant drawback, as the concentrations needed for microbiological stability are often unpalatable to consumers. Encapsulation of essential oils in nanoemulsions offers a promising and effective solution to these challenges, allowing for their use in food production without compromising sensory qualities.

Self-assembled thymol-betaine co-crystals with controlled release and hygroscopic properties as green preservatives for aflatoxin prevention.

Mycotoxins are representative contaminants causing food losses and food safety problems worldwide. Thymol can effectively inhibit pathogen infestation and aflatoxin accumulation during grain storage, but high volatility limits its application. Here, a thymol-betaine co-crystal system was synthesized through grinding-induced self-assembly. The THY-TMG co-crystal exhibited excellent thermal stability with melting point of 91.2 °C owing to abundant intermolecular interactions. Remarkably, after 15 days at 30 °C, the release rate of thymol from co-crystal was only 55%, far surpassing that of pure thymol. Notably, the co-crystal demonstrated the ability to bind H2O in the environment while controlling the release of thymol, essentially acting as a desiccant. Moreover, the co-crystals effectively inhibited the growth of Aspergillus flavus and the biosynthesis of aflatoxin B1. In practical terms, the THY-TMG co-crystal was successful in preventing AFB1 contamination and nutrients loss in peanuts, thereby prolonging their shelf-life under conditions of 28 °C and 70% RH.

A review of advancements in chitosan-essential oil composite films: Better and sustainable food preservation with biodegradable packaging.

In response to the environmental pollution caused by non-degradable and non-recyclable plastic packaging films (PPFs) and the resulting health concerns due to the migration of microplastics into food, the development of biodegradable food packaging films has gained great attention. Chitosan has been extensively utilized in the food industry owing to its abundant availability, exceptional biocompatibility, degradability, and antimicrobial properties. Chitosan-essential oil composite films (CEOs) represent a promising avenue to replace conventional PPFs. This review provides an overview of the advancements in CEOs over the past decade, focusing on the effects of essential oils (EOs) on CEOs in terms of antimicrobial activity, antioxidant effect, gas barrier, light barrier, and mechanical properties. It also offers insights into the controlled release of EOs in CEOs and summarizes the application of CEOs in fresh food preservation.

Acid-hydrolyzed phenolic extract of parsley (Petroselinum crispum L.) leaves inhibits lipid oxidation in soybean oil-in-water emulsions.

The antioxidant activity of the natural phenolic extracts is limited in particular food systems due to the existence of phenolic compounds in glycoside form. Acid hydrolysis post-treatment could be a tool to convert the glycosidic polyphenols in the extracts to aglycones. Therefore, this research investigated the effects of an acid hydrolysis post-treatment on the composition and antioxidant activity of parsley extracts obtained by an ultrasound-assisted extraction method to delay lipid oxidation in a real food system (i.e., soybean oil-in-water emulsion). Acid hydrolysis conditions were varied to maximize total phenolic content (TPC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. When extracts were exposed to 0.6 M HCl for 2 h at 80 ℃, TPC was 716.92 ± 24.43 µmol gallic acid equivalent (GAE)/L, and DPPH radical scavenging activity was 66.89 ± 1.63 %. Not only did acid hydrolysis increase the concentrations of individual polyphenols, but it also resulted in the release of new phenolics such as myricetin and gallic acid. The extract's metal chelating and ferric-reducing activity increased significantly after acid hydrolysis. In soybean oil-in-water emulsion containing a TPC of 400 µmol GAE/L, the acid-hydrolyzed extract had an 11-day lag phase for headspace hexanal compared to the 6-day lag phase of unhydrolyzed extract. The findings indicated that the conversion of glycosidic polyphenols to aglycones in phenolic extracts can help extend the shelf-life of emulsion-based foods.

Heterologous expression of pediocin PA-1 in Pichia pastoris: cloning, expression, characterization, and application in pork bologna preservation.

OBJECTIVE: Pediocin PA-1, an antimicrobial peptide derived from Pediococcus acidilactici PAC1.0, has a potential application as a food preservative thanks to its strong inhibitory activity against the foodborne pathogen L. monocytogenes. This study aimed to produce Pediocin PA-1 from the yeast P. pastoris and evaluate its characteristics. METHODS: Gene encoding Pediocin PA-1 was integrated into P. pastoris X33 genome to establish the strain X33::ped, which could produce and secrete this peptide into culture medium. The antimicrobial activity of Pediocin PA-1 was examined using agar diffusion assay. The stability of pediocin PA-1 was determined based on its remaining antibacterial activity after exposure to proteases and extreme pH and temperatures. The potential use of this bacteriocin in food preservation was demonstrated using the L. monocytogenes infected pork bologna. The anticancer activity of Pediocin PA-1 was also investigated on some cancer cells using MTT assay. RESULTS: We established the yeast P. pastoris X33::ped capable of producing pediocin PA-1 with antimicrobial activity against L. monocytogenes and some other harmful bacteria. Pediocin PA-1 was stable at 100˚C and resistant against pH 1-12 for 1 h, but susceptible to trypsin, α-chymotrypsin, and proteinase K. This peptide could reduce the number of L. monocytogenes in pork bologna by 3.59 log CFU/g after 7 days of storage at 4˚C. Finally, Pediocin PA-1 (25 µg/ml) inhibited the proliferation of A549 and Hela cancer cells. CONCLUSION: We succeeded in producing active Pediocin PA-1 from P. pastoris and demonstrated its potential use in food preservation and pharmaceutical industry.