Potential In Food Preservation Research Articles

Carboxymethyl chitosan/polyvinyl alcohol hydrogel films by incorporating MSNs as ε-PL carrier with pH-responsive controlled release and antibacterial properties

A hydrogel film with pH-responsive release and excellent antibacterial properties was developed by utilizing mesoporous silica nanoparticles (MSNs) as carriers for ε-PL. Carboxymethyl chitosan (CMCS) is grafted onto aminated-MSNs through amine-bond reaction mediated, which is subsequently bound to polyvinyl alcohol (PVA) by esterification reaction. The addition of MSNs and optimization of CMCS proportion improved the dispersion stability of CMCS/PVA, resulting in a TSI value of 0.6 for 1.6CMCS/0.8PVA@MSNs-ε-PL, which is significantly lower than other groups. The proportion increase of CMCS improved the thermal stability and water oxygen barrier capacities of the 1.6CMCS/0.8PVA@MSNs-ε-PL by enhancing cross-linking with MSNs. The 1.6CMCS/0.8PVA@MSNs-ε-PL exhibited pH-responsive release behavior, with the extent of release increasing proportionally with higher pH levels. The 1.6CMCS/0.8PVA@MSNs-ε-PL exhibited significant antibacterial activity against Pseudomonas azotoformans MN10 in vitro, attributed to the ε-PL's ability to damage the bacterial membrane structure. Hence, the 1.6CMCS/0.8PVA@MSNs-ε-PL exhibits significant potential in food preservation.

Eco-friendly, pH-sensitive curcumin-loaded sodium alginate/hydroxyapatite/quaternary ammonium chitosan microspheres with enhanced antibacterial and antioxidant activities for fruit preservation

The development of intelligent responsive reactive packaging materials with natural polymers shows excellent potential in food preservation. In this study, eco-friendly, pH-sensitive sodium alginate (SA)/hydroxyapatite (HA)/quaternary ammonium chitosan (HACC) composite microspheres loading curcumin (CUR) with excellent antibacterial and antioxidant activities were successfully synthesized. Scanning electron microscopy (SEM) and nitrogen adsorption/desorption tests indicated that the doping of HA substantially increased the specific surface area and pore volume of the microspheres. The loading experiments showed that the efficiency of the microspheres was significantly increased by 49.47 % and 55.10 %, respectively, when HA and HACC were incorporated into the SA network. The release test results suggested that the release rate of SA/HA/HACC microspheres loading CUR (SA/HA/HACC@CUR) increased as the pH decreased, demonstrating notable pH-responsive release characteristics. DPPH free radical scavenging experiments demonstrated that the SA/HA/HACC@CUR had excellent and long-lasting antioxidant capacity. The antibacterial experiments revealed that the SA/HA/HACC@CUR had excellent antibacterial properties, with inhibition rates of 88.73 % and 92.52 % against E. coli and S. aureus, respectively. Making coatings out of microspheres could effectively slow down the rotting and deterioration of cherry tomatoes during storage, suggesting that microspheres with intelligent responses have a broad application prospect in fruit preservation.

Kajian Antibakteri Ekstrak Etanol Kayu Secang (Caesalpinia sappan L.) dan Pemanfaatannya Pada Udang Vannamei (Liptopenaeus vannamei) Segar

Vannamei shrimp (Liptopenaeus vannamei) is a prominent fishery commodity due to its high consumption demand. However, susceptibility to bacterial damage and quality deterioration poses challenges. This study investigates the antibacterial potential of sappan wood extract in preserving shrimp shelf life. The research explores optimal extraction parameters, including solvent type and maceration duration, to assess yield percentage and antibacterial efficacy against Escherichia coli, Salmonella sp., and Vibrio parahaemolyticus. Utilizing a Complete Randomized Block Design (CRBD) in two phases, the study identifies 90% ethanol solvent and 6 hours maceration (P4M6) as the most effective treatment, yielding 7.32%. The extract addition significantly reduces shrimp microbial count, highlighting its potential in food preservation.

Review of Edible Packaging from Durian Seed Starch with Kesum (Polygonum minus Huds) Leaf Extract as Active Food Packaging

Edible packaging, crafted from edible materials like starch, proteins, and fats, ensures safety and consumability. Durian seeds emerge as a promising base material, offering robust protection against environmental factors. Additionally, Kesum leaves harbor antimicrobial compounds, enhancing packaging efficacy. This study utilizes a literature review with content and bibliometric analyses, referencing journals and Google Scholar for secondary data. Findings reveal the potential of incorporating edible coatings from durian seeds and Kesum leaf extract into products stored at freezing temperatures. This application extends shelf life, curbs lipid oxidation, and prevents rancidity despite quality decline. Harnessing the natural properties of durian seeds and Kesum leaves, this research presents an innovative solution to packaging challenges. Edible materials not only enhance safety but also bolster sustainability by reducing waste and environmental impact. The inclusion of antimicrobial compounds ensures product integrity during storage. This study highlights edible packaging's transformative potential in food preservation and sustainability, promising benefits for consumers and the environment alike.

Antibacterial and antibiofilm activities of protocatechualdehyde and its synergy with ampicillin against methicillin-resistant Staphylococcus aureus.

Protocatechualdehyde (PA) is a phenolic acid present in many plants and has many biological activities. Herein, the antagonistic effects and the action mechanism of PA against methicillin-resistant Staphylococcus aureus (MRSA) were studied. The results showed that PA had both significant antibacterial and anti-biofilm activities against MRSA. Additionally, PA had synergy with ampicillin against MRSA. It was elucidated that PA was prominent in destroying cell membranes, increasing cell membrane permeability and intracellular ROS production, thus leading to bacterial cell damage. Transcriptome analysis showed that PA disrupts many physiological pathways, including increasing cell membrane permeability, inhibiting biofilm formation, decreasing resistance to antimicrobial agents, and impairing DNA replication. Finally, the antimicrobial preservation test showed that PA could inhibit the growth of MRSA and prevent the corruption of beef. In summary, PA is an effective natural antibacterial substance and has a good application potential in food preservation, even in tackling antibiotic resistance problems.

Valorizing pomegranate wastes by producing functional silver nanoparticles with antioxidant, anticancer, antiviral, and antimicrobial activities and its potential in food preservation

The food sector generates massive amounts of waste, which are rich in active compounds, especially polyphenols; therefore, valorizing these wastes is a global trend. In this study, we produce silver nanoparticles from pomegranate wastes, characterized by enhanced antioxidant, anticancer, antiviral, and antimicrobial properties and investigated their potential to maintain the fruit quality for sixty days in market. The pomegranate waste-mediated silver nanoparticles (PPAgNPs) were spherical shape (measured by TEM), 20 nm (Zeta sizer), negatively charged −25.98 mV (Zeta potential), and surrounded by active groups (FTIR). The PPAgNPs scavenged 94 % of DPPH radicals and inhibited the growth of pathogens, i.e., Staphylococcus aureus, Listeria monocytogenes, Campylobacter jejuni, Salmonella typhi and Candida with inhibition zones diameters (16–45 mm). They impeded the development of breast and colon cancer cell lines by 80 and 78 %, increased the activity of apoptosis marker caspase 3, and inhibited 82 % of COVID-19. The PPAgNPs were added to the rat diet at 80, 160, and 320 µg/kg levels. PPAgNPs administered at a concentration of 160 µg/kg in the rat diet resulted in the best growth performance, normal liver and kidney parameters (p = 0.029–0.038), lowered lipid profile, malondialdhyde (MDA), and raised glutathion reduced (GSH), total protein (TP). Also, the reduced gene expression of Interleukin 6 (IL-6) and Tumor necrosis factor alpha (TNF-α) in albino rats' serum indicates the anti-inflammatory effect of PPAgNPs. PPAgNPs developed a functional coating to preserve mandarin fruit for 60 days by dipping technique. The active coat containing PPAgNPs can effectively preserve the fruit for 60 days.

Photo- and Sono-Active Food Colorants Inactivating Bacteria.

Food colorants are commonly used as excipients in pharmaceutical and nutraceutical fields, but they have a wide range of other potential applications, for instance, as cytotoxic drugs or mediators of physical antimicrobial treatments. The photodynamic antibacterial activity of several edible food colorants is reported here, including E127, E129, E124, E122, E133, and E150a, alongside Rhein, a natural lipophilic antibacterial and anticancer compound found in medicinal plants. Minimal inhibitory concentration (MIC) values for S. aureus and E. coli showed that E127 and Rhein were effective against both bacteria, while other colorants exhibited low activity against E. coli. In some cases, dark pre-incubation of the colorants with Gram-positive S. aureus increased their photodynamic activity. Adding Rhein to E127 increased the photodynamic activity of the latter in a supportive mode. Optional sensing mechanism pathways of combined E127/Rhein action were suggested. The antibacterial activity of the studied colorants can be ranged as follows: E127/Rhein >> E127 >> E150a > E122 > E124 >> E129 ≈ E133. E127 was also found to exhibit photodynamic properties. Short ultrasonic treatment before illumination caused intensification of E127 photodynamic activity against E. coli when applied alone and especially in combination with Rhein. Food colorants exhibiting photo- and sonodynamic properties may have good potential in food preservation.

Physicochemical, antibacterial and food preservation properties of active packaging films based on chitosan/ε-polylysine-grafted bacterial cellulose

To address the environmental and food contamination issues caused by plastics and microorganisms, antimicrobial films using natural polymers has attracted enormous attention. In this work, we proposed a green, convenient and fast approach to prepare antimicrobial films from chitosan (CS), bacterial cellulose (BC) and ε-polylysine (ε-PL). The effects of different concentrations of ε-PL (0 %, 0.25 %, 0.5 %, 0.75 %, 1 %, w/v) on the physicochemical properties and antibacterial activity of composite films (CS-DABC-x%PL) were systematically investigated. Furthermore, a comprehensive comparison with purely physically mixed CS-BC-x%PL films provides a deeper understanding of the subject matter. Characterization tests of the films were conducted using scanning electron microscope (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results suggested that the incorporation of 0.5 % ε-PL reduced the water solubility of the composite film by 19.82 %, along with improved the tensile strength and thermal stability by 37.31 % and 28.54 %. As ε-PL concentration increased to 1 %, the antibacterial performance of the films gradually enhanced. Additionally, the CS-DABC-0.5%PL film demonstrated effectiveness in delaying the deterioration of tilapia. These findings imply that this novel green packaging material holds significant potential in food preservation due to its promising antibacterial properties.

Evaluation of Antifungal and anti-aflatoxin B1 efficacy of some crude extracts of Chamaerops humilis L. against Aspergillus flavus isolated from peanuts (Arachis hypogea L.)

The present study strengthens the food preservative potential of Chamaerops humilis extracts viz. hexane extract, chloroform extract, ethanol extract, chloroform extract, and methanol extract based on their antifungal, antiaflatoxin, and antioxidant efficacy. The isolation of molds from peanuts were carried out by the suspension-dilution technique and inoculation on agar medium. Antifungal determinations were conducted using the agar plate and liquid dilution methods. The effect of C. humilis L. extracts on the production of AFB1 was determined in a SMKY broth. The molds isolated were of the genera Aspergillus, Penicillium sp., Fusarium sp., and Alternaria sp. with A. flavus (BBH-6) which is identified as the highest AFB1 producer. The minimum inhibitory concentration of extracts against the toxigenic strain of A. flavus ranged between 3.00 mg/ml and 3.50 mg/ml. The extracts were found more efficacious as they inhibited the dry mycelium weight and aflatoxin production of the aflatoxigenic strain A. flavus (BBH-6) at lower concentrations. The extracts showed fungitoxic spectrum against four molds. The IC50 value of C. humilis L. ranged between 140.4 and 189.46 μg/mg, oxidation of linoleic acid was moderately inhibited by the extracts ranges between 53.54 and 69.33%, while their total phenolic content ranged between 47.80 and 115.71 μg/ml. Based on the findings of present investigation, C. humilis L. can be introduced as a proposed solution for formulating plant-based preservative food additives.

Antibacterial properties of peptides from chia (Salvia hispanica L.) applied to pork meat preservation.

Chia-derived peptides might represent a novel alternative to conventional preservatives in food. Despite the antibacterial potential of these molecules, their food application is still limited. This study aimed to evaluate chia-derived peptides' antibacterial and antibiofilm potential in food preservation. The peptides YACLKVK, KLKKNL, KLLKKYL, and KKLLKI were synthesized, and their antibacterial activity against Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Salmonella Enteritidis was evaluated through microdilution tests. A bacterial killing kinetic assay determined bacterial growth over time. The ability to prevent and eradicate S. aureus biofilm was assessed by crystal violet staining. The hemolytic and cytotoxic activities were determined in human red blood cells and fibroblasts using free hemoglobin detection and(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assays, respectively. Finally, a microbial challenge was performed on meat samples inoculated with L. monocytogenes and S. Enteritidis to determine their inhibitory effects on pork meat. Results showed the potential antibacterial activity of these peptides, with minimum inhibitory concentrations ranging from 0.23 to 5.58mg/mL. Biofilm inhibition percentages were above 40%, and eradication percentages were lower than 20%. In vitro assays in human red blood cells and fibroblasts demonstrated that peptides are not hemolytic or cytotoxic agents. In microbiological challenge testing, KKLLKI showed the most promising antibacterial effects against S. Enteritidis on refrigerated pork meat samples. These findings suggest that chia-derived peptides have the potential as natural food preservatives due to their antibacterial and antibiofilm properties. Notably, KKLLKI demonstrated promising antibacterial effects against Salmonella spp. on a complex food matrix, such as pork meat. PRACTICAL APPLICATION: Chia-derived peptides can be a safer alternative to synthetic preservatives in the food industry because the latter may be detrimental to human health. Salmonella spp. growth on chilled pork meat was shown to be inhibited by the peptide KKLLKI, indicating that the use of these peptides may offer a more secure and natural alternative to synthetic preservatives.

Hierarchically Porous Cellulose-Based Radiative Cooler for Zero-Energy Food Preservation

Low temperature preservation is an essential route to extend the food shelf life but remains challenging due to its increasing energy consumption and carbon emission, as well as the need for decentralized food preservation. Passive radiative cooling, which can dissipate an object’s thermal energy through an atmospheric transparency window to ultracold outer space without consuming any energy, provides a sustainable route for food preservation. Here, a hierarchically porous (0.006–10 μm) cellulose acetate/zinc oxide (CA/ZnO) nanocomposite film is constructebased on water-assisted induced phase separation to achieve passive cooling without any energy input. The film with 30 wt % ZnO concentration achieves subambient temperature cooling through high solar reflectivity (97.0%) and high mid-infrared emissivity (94.0%), achieving a daytime temperature drop of 13.8 °C under strong solar illumination. When used in food packaging, the CA/ZnO film can decrease the temperature of enoki mushrooms by up to 18 °C under direct sunlight. The preservation temperature reduction outperforms other commercially available food packaging materials, which can extend strawberries storage time to 9 days. Meanwhile, the film also demonstrates excellent antimicrobial, self-cleaning, and reusable properties. This energy-free cooling film has great potential in food preservation as well as other applications where a controlled environmental temperature is required.

Composite films of sodium alginate and konjac glucomannan incorporated with tea polyphenols for food preservation

At present, food waste has become a serious issue and the use of petroleum-based food packaging films has resulted in a series of potential hazards. Therefore, more attention has been focused on the development of new food packaging materials. The polysaccharide-based composite film loaded with active substances considered to be an excellent preservative material. A novel packaging film based on sodium alginate and konjac glucomannan (SA-KGM) blended with tea polyphenols (TP) was prepared in the present study. The excellent microstructure of films was shown by atomic force microscopy (AFM). It was indicated by FTIR spectra that the components could interact with each other through hydrogen bonds, which was also confirmed by molecular docking simulation. Meanwhile, the mechanical properties, barrier property, oxidation property, antibacterial activity, and stability of the structure of the TP-SA-KGM film were significantly improved. The AFM images and results of molecular docking simulation indicated that TP could affect the cell wall of bacteria by acting with peptidoglycan. Finally, the film showed excellent preservation effects in both beef and apples, which suggested that TP-SA-KGM film could be a novel bioactive packaging material with wide application potential in food preservation.

Multifunctional edible chitin nanofibers/ferulic acid composite coating for fruit preservation

AbstractAbout one‐third of the world's entire food production is lost or wasted every year, in which the perishables such as fruits and vegetables account for the largest proportion due to their short shelf life. Therefore, it has attracted great attention to the development of food preservation. In this paper, a simple strategy for food preservation is developed. Chitin nanofiber aqueous suspension is used as the substrate, and ferulic acid (FA) acts as the physical crosslinker to obtain a multifunctional composite protective coating for fruits. The results of Zeta potential, X‐ray photoelectron spectroscopy (XPS) and X‐ray diffraction (XRD) indicate that there are multiple noncovalent interactions between FA and chitin nanofibers. The chitin/FA coating films show superior mechanical properties, water and oxygen resistance. They could effectively reduce the water loss rate, delay ripening, and resist oxidation and microbial invasion for the fresh strawberries and fresh‐cut apples, indicating the potential in food preservation.

Nanoprecipitates of γ-cyclodextrin/epigallocatechin-3-gallate inclusion complexes as efficient antioxidants for preservation of shrimp surimi products: synthesis, performance and mechanism.

Epigallocatechin-3-gallate (EGCG) is well known for excellent chain-breaking antioxidant capability. However, browning by oxidation and aggregation of EGCG is a non-negligible defect that hinders its applications as an antioxidant in various foodstuffs. Therefore, how to eliminate or mitigate browning efficiently, while retaining functionalities as food additive is a challenge in the food industry. Our results demonstrated that EGCG could be anchored within the internal cavity of γ-cyclodextrin (γ-CD) to form an inclusion structure, where hydrophobic interaction, hydrogen bonding, and π-stacking were identified to be the primary drivers. The interplay between two molecules and the steric hindrance from γ-CD could restrict the motion and aggregation of EGCG efficiently, thus alleviating the browning effect. In addition, the conformational adaption of EGCG within the inclusions would result in general decreases in hydrogen-bond dissociation enthalpies for the pyrogallol-type structure on the b ring, thus enhancing the antioxidant capability. In practical application, the nanoscale γ-CD/EGCG inclusion complexes were validated preliminarily as efficient additives in the preservation of shrimp surimi, presenting significant effects on prolonging the shelf-life of products. Here, nanoscale γ-CD/EGCG inclusion complexes as alternatives to EGCG were tailored as food antioxidants for the preservation of shrimp surimi products, exerting antioxidant effects while mitigating the browning effects of EGCG on products. Through self-assembly, EGCG would be anchored with the cavity of γ-CD, which could regulate the release modes and restrict the aggregation of EGCG. This facile strategy has great potential in food preservation. © 2023 Society of Chemical Industry.

Highly biologically active and pH-sensitive collagen hydrolysate-chitosan film loaded with red cabbage extracts realizing dynamic visualization and preservation of shrimp freshness

Accurate and efficient detection of food freshness is of great significance to guarantee food safety. Herein, pH sensitive colorimetric films with considerable biological activities have been prepared by combining red cabbage anthocyanin extracts (RCE) with collagen hydrolysate-chitosan (CH-CS) matrix film. The formation mechanism of CH-CS-RCE films was discussed by SEM, FT-IR and XRD, which showed that RCE was successfully fixed in CH-CS film through hydrogen bonding and electrostatic interaction. The CH-CS-RCE films exhibited good mechanical properties, high barrier ability, excellent thermal stability, significant antioxidant and antimicrobial activity, and especially sensitive response to pH and ammonia. Fickian diffusion was the main mechanism for the release of RCE from CH-CS-RCE films and such release mechanism facilitated the maintenance of functional features of films. During the storage of shrimps at 4 °C, CH-CS-RCE2% showed a remarkable preservation effect on shrimps, and their shelf life was prolonged from 2 d to 5 d. Furthermore, CH-CS-RCE2% provided a dynamic visual color switching to detect the freshness of shrimp, realizing real-time monitoring of freshness. Color information (RGB) extracted via smartphone APP was used to enhance the accuracy and universality of freshness indication. Thus, this multifunctional film has great potential in food preservation and freshness monitoring.

Antimicrobial Evaluation of Edible and Inedible parts of com-mon Vegetables and their use in increasing shelf life of Milk, Meat and Tomatoes

Background: Bacterial diseases are commonly found all over the world and medicinal plants are vastly used for the cure these diseases. These plants are rich source of valuable antibacterial and food preservative agents. In Pakistan, tons of vegetables are discarded as inedible part during peeling and cutting before cooking as well as due to unavailability of proper preservative techniques. The present study was designed to check antibacterial and food preservative potential of commonly vegetables of Pakistan. Methods: The aqueous and ethanolic extracts of edible and inedible parts of Momordica charantia, Pisum sativum and Abellmoschus esculentus were made and tested against Escherichia coli, Staphylococcus aureus, Salmonella typhimorium, Pasterurella multocida, Lactobacillus bulgaricus and Micrococcus luteus by disc diffusion method. Zones of inhibition were measured. Results: Highest antibacterial activity was observed in ethanolic extracts of inedible parts of Pisum sativum. Moderate activity was observed from edible parts of Momordica charantia. The study has highlighted the use of vegetables as edible vaccines.

A Gas-Permeation Controllable Packaging Membrane with Porous Microspheres as Gas "Switches" for Efficient Preservation of Litchi.

Food wastage represented by the deterioration of perishable food like fruits and vegetables is a serious global problem with tremendous ethical, financial, and environmental costs. The atmosphere (CO2 and O2) has a crucial role in food storage and can regulate physiological food metabolism and microbial growth. Modified atmosphere packaging (MAP) is a promising method used to extend shelf life and preserve the quality of perishable food; yet, its use depends on the specific gas permeability and selectivity of polymer membranes to generate an atmosphere desirable for storage. In this study, we established and validated a new plant leaf-mimetic shellac-based MAP membrane embedded with chitosan porous microspheres loaded with antimicrobial tannic acid (TA-CPM) as gas "switches" for regulating O2 and CO2 permeability and CO2/O2 selectivity. The effects of different amounts of TA-CPM added into the hybrid membranes were examined for litchi preservation at room temperature. Our results showed that this hybrid TA-CPM/shellac packaging membrane could regulate the internal CO2 and O2 concentrations and the CO2/O2 ratio within the packages containing litchis by adjusting the addition amount of TA-CPM. The 0.05% TA-CPM/shellac and 0.10% TA-CPM/shellac packages, especially 0.05% TA-CPM/shellac, generated a more desirable CO2 and O2 atmosphere for litchi preservation compared with controls, which was reflected by the delaying of browning and rotting, maintaining of the natural color of the litchi pericarp, preservation of pulp quality, inhibition of polyphenol oxidase and guaiacol peroxidase activities, and reduction of oxidative cell damage in litchis. The results suggested that 0.05% TA-CPM/shellac and 0.10% TA-CPM/shellac packaging membranes, especially 0.05% TA-CPM/shellac, could generate an ideal atmosphere for litchi storage at room temperature, demonstrating that this permeation-controlled hybrid membrane has great potential in food preservation and other applications requiring a modified atmosphere.

Rosemary (Salvia rosmarinus): Health-Promoting Benefits and Food Preservative Properties

Natural food preservatives in the form of herb extracts and spices are increasing in popularity due to their potential to replace synthetic compounds traditionally used as food preservatives. Rosemary (Salvia rosmarinus) is an herb that has been traditionally used as an anti-inflammatory and analgesic agent, and currently is being studied for anti-cancer and hepatoprotective properties. Rosemary also has been reported to be an effective food preservative due to its high anti-oxidant and anti-microbial activities. These properties allow rosemary prevent microbial growth while decreasing food spoilage through oxidation. Rosemary contains several classes of compounds, including diterpenes, polyphenols, and flavonoids, which can differ between extracts depending on the extraction method. In particular, the diterpenes carnosol and carnosic acid are two of the most abundant phytochemicals found in rosemary, and these compounds contribute up to 90% of the anti-oxidant potential of the herb. Additionally, several in vivo studies have shown that rosemary administration has a positive impact on gastrointestinal (GI) health through decreased oxidative stress and inflammation in the GI tract. The objective of this review is to highlight the food preservative potential of rosemary and detail several studies that investigate rosemary to improve in vivo GI health.

Maltose effective improving production and regulatory biosynthesis of plantaricin EF in Lactobacillus plantarum 163.

Plantaricin EF, a kind of natural antibacterial substance, has shown inhibitory effect on most pathogen and spoilage microorganisms, which possessed great potential in food preservation. However, the lower production of plantaricin EF has limited its large-scale production and application. In this study, the effect of maltose on plantaricin EF production and its regulation mechanism in Lactobacillus plantarum 163 were investigated. Maltose significantly improved the biomass and plantaricin EF production, which increased by 3.35 and 3.99 times comparing to the control without maltose, respectively. The maximum production of plantaricin E and F in fed-batch fermentation were 10.55 mg/L and 22.94 mg/L, respectively. Besides, qPCR results showed that maltose remarkably improved transcription of plnA, plnB, plnD, plnE, plnF, plnG1 and plnH, and heighten transcription of lamR, lamK, hpk6 and rrp6. These results provided an effective method to enhance plantaricin EF production and revealed a possible regulatory mechanism from transcriptome results that hpk6, rrp6, lamK and lamR were relative to plantaricin EF production. Genes, hpk6 and rrp6, promote transcription of plnG1, whereas lamK and lamR enhance transcription of plnA, plnB and plnD, which increased plantaricin EF production. KEYPOINTS: • Maltose was proved to be effective in promoting the biosynthesis of plantaricin EF. • Maltose promoted the transcription of biosynthesis and secretion genes of plantaricin EF. • Up-regulation of genes lamR, lamK, hpk6 and rrp6 heightened the plantaricin EF production.

Antibacterial Activity and Mechanism of Lacidophilin From Lactobacillus pentosus Against Staphylococcus aureus and Escherichia coli.

The main purpose of this study was to explore the antibacterial activity and mechanism of lacidophilin from Lactobacillus pentosus against Staphylococcus aureus and Escherichia coli. The effects of temperature, enzyme, metal ions, and pH on the antibacterial activity of L. pentosus were evaluated. The result showed that lacidophilin had good thermal stability and could be decomposed by trypsin completely. The antibacterial ability was affected by high concentration of metal ions, and the best antibacterial ability was acquired under acidic conditions. The antibacterial mechanism of lacidophilin was explored through studying cytomembrane injury, phosphorus metabolism, protein changes, and oxidative stress response of the indicator bacteria. It was shown that lacidophilin destroyed the cytomembrane of the bacteria and increased the cytomembrane permeability, which resulted in the leak of proteins, nucleic acids, and electrolytes. In addition, it further restrained phosphorus metabolism, caused changes of some protein contents, and increased cytomembrane lipid peroxidation and cell oxidative damage. All these might inhibit the growth of bacteria and even cause their death. This study identified a natural biological preservative with strong antibacterial activity against both Gram-positive and Gram-negative foodborne pathogens. The high antibacterial activity against the two types of bacteria reflected its potential in food preservation used as a natural food preservative.