Natural Biopreservatives Research Articles

Purification, characterization, and antimicrobial mechanism of a novel broad-spectrum bacteriocin produced by Lactiplantibacillus plantarum SCA12 from Traditional Chinese Fermented Mustard greens

In this study, Lactiplantibacillus plantarum SCA12, a producer of bacteriocins, derived from traditional Chinese fermented mustard greens was isolated. A novel L. plantarum SCA12-derived bacteriocin, LPsca12, was purified through a multi-step protocol involving macroporous adsorption resin, cation exchange, Sephadex G-25 column chromatography, and reverse-phase high-performance liquid chromatography (RP-HPLC). The molecular mass of LPsca12 was determined to be 1197.0 Da through matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. The amino acid sequence of LPsca12 was characterized as GLFPSLVRGPR via liquid chromatography-tandem mass spectrometry (LC-MS/MS). Antimicrobial assessment was then carried out, identifying LPsca12 as a broad-spectrum bacteriocin active against both Gram-negative and Gram-positive bacteria, particularly Salmonella paratyphi A. It demonstrates excellent thermal stability (121 °C, 15 min) and maintains its antibacterial activity under acidic conditions (pH 2.0–6.5). Additionally, LPsca12 is sensitive to digestion by pepsin and trypsin. The antimicrobial action of LPsca12 involves compromising the cell membrane integrity, forming pores, and promoting leakage of intracellular contents, which dissipates both the membrane potential (ΔΨ) and cytoplasmic transmembrane pH gradient (ΔpH) of the target cells. These findings suggest that LPsca12 holds promise as a natural biopreservative in food processing.

Raffinocyclicin is a novel plasmid-encoded circular bacteriocin produced by Lactococcus raffinolactis with broad-spectrum activity against many gram-positive food pathogens.

This study describes the discovery and characterization of raffinocyclicin, a novel plasmid-encoded circular bacteriocin, produced by the raw milk isolate Lactococcus raffinolactis APC 3967. This bacteriocin has a molecular mass of 6,092 Da and contains 61 amino acids with a three-amino acid leader peptide. It shows the highest identity to the circular bacteriocins bacicyclicin XIN-1 (42.62%), aureocyclicin 4185 (42.62%), and garvicin ML (41.53%). A broad inhibitory spectrum includes strains from Staphylococcus, Enterococcus, Streptococcus, Micrococcus, Lactobacillus, Leuconostoc, and Listeria, in addition to a pronounced inhibitory effect against Lactococcus and Clostridium. It displays low sensitivity to trypsin, most likely as a result of its circular nature. The raffinocyclicin gene cluster is composed of 10 genes: 6 core genes, genes encoding an accessory three-component ABC transporter (rafCDE), and a putative transcriptional regulator related to the MutR family. A lack of inhibitory activity in the cell-free supernatant combined with the pronounced activity of cell extracts suggests that the majority of raffinocyclicin is associated with the cell rather than being released to the extracellular environment. This is the first report of a bacteriocin produced by the L. raffinolactis species.IMPORTANCEThe present study aimed to characterize raffinocyclicin, a novel circular bacteriocin produced by the lactic acid bacteria Lactococcus raffinolactis APC 3967. Bacteriocins are generally cationic and hydrophobic peptides with antimicrobial activity, which present diverse biotechnological properties of interest for the food industry. Raffinocyclicin inhibits a wide range of bacteria, including foodborne pathogens, and is stable against different treatments which suggest its potential as a natural biopreservative. Whole-genome sequencing and the genetic analysis of the raffinocyclicin gene cluster showed that it is encoded by plasmid that could be used in the future to transfer the ability to produce the bacteriocin to other lactic acid bacteria for industrial applications. These results together highlight the potential of this novel antimicrobial as a biopreservative to be used by the food industry.

Lactobacillus plantarum derived nanoparticles deliver class IIa bacteriocin as a potential natural food preservatives

In recent years, the growing concern over human health risks associated with chemical preservatives in food has sparked increased interest in utilizing natural biopreservatives derived from probiotics. Bacteriocins, which are antibacterial peptides that have been deemed safe for human consumption and have been applied to food preservation. Several studies have emphasized that nanoparticles derived from edible plants can modulate microbes’ metabolic processes. In this study, we discovered that Lactobacillus plantarum LPL-1 can produce extracellular nanoparticles (LPL-NPs) containing a specific class IIa bacteriocin known as plantaricin LPL-1. LPL-NPs effectively suppressed the growth of Listeria monocytogenes 54002 by gradually disrupting their cell membranes. Intriguingly, we have also demonstrated that the ginger derived exosome-like NPs (GELNPs) enhance the antibacterial activity of LPL-NPs by enriching plantaricin LPL-1 within them through activation of a quorum sensing system component. Furthermore, GELNPs-treated LPL-NPs (GLPL-NPs) can effectively extend the storage period of sturgeon at 4 °C by mitigating pathogenic bacterial growth, preserving sensory quality, and reducing the levels of total volatile basic nitrogen (TVB-N), K value, trichloroacetic acid (TCA)-soluble peptides, and thiobarbituric acid reactive substances (TBARS). This study provides insight into a strategy for application of LPL-NPs as a natural biopreservative for food preservation.

Marine Pediococcus pentosaceus E3 Probiotic Properties, Whole-Genome Sequence Analysis, and Safety Assessment.

Probiotics play a significant role in enhancing health, and they are well known for bacteriocins production. Evaluating probiotics' whole-genome sequence provides insights into their consumption outcomes. Thus, genomic studies have a significant role in assessing the safety of probiotics more in-depth and offer valuable information regarding probiotics' functional diversity, metabolic pathways, and health-promoting mechanisms. Marine Pediococcus pentosaceus E3, isolated from shrimp gut, exhibited beneficial properties, indicating its potential as a probiotic candidate. Phenotypically, E3 strain was susceptible to most antibiotics assessed, tolerant to low pH and high bile salt conditions, and revealed no hemolysin activity. Interestingly, E3-neutralized CFS revealed significant antibacterial activity against pathogens under investigation. Therefore, the concentrated CFS was prepared and evaluated as a natural biopreservative and showed outstanding antimicrobial activity. Furthermore, integrated-based genome assessment has provided insight into probiotic characteristics at the genomic level. Whole-genome sequencing analysis revealed that the E3 genome possesses 1805 protein-coding genes, and the genome size was about 1.8Mb with a G + C content of 37.28%. Moreover, the genome revealed the absence of virulence factors and clinically related antibiotic genes. Moreover, several genes consistent with probiotic microorganisms' features were estimated in the genome, including stress response, carbohydrate metabolism, and vitamin biosynthesis. In addition, several genes associated with survival and colonization within the gastrointestinal tract were also detected across the E3 genome. Therefore, the findings suggest that insights into the genetic characteristics of E3 guarantee the safety of the strain and facilitate future development of E3 isolate as a health-promoting probiotic and source of biopreservative.

Purification and structural characterization of APTs, a novel antifungal peptide produced by Lactobacillus paracasei ALAC-4, and its inhibitory effect on Candida albicans

Fungal contamination poses significant food safety risks. Lactobacillus paracasei ALAC-4, originally isolated from traditional fermented foods in Inner Mongolia, exhibits antifungal properties. Here, we isolated and purified the active fraction from ALAC-4 to derive the antifungal peptide, demonstrating its antifungal efficacy against Candida albicans. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed severe deformation of C. albicans cell surfaces upon exposure to the antifungal peptide, resulting in membrane rupture and pore formation. Simultaneously, a decrease in Zeta potential and K+ ion leakage occurred on the C. albicans cell surface. Treatment with antifungal peptides reduced the hydrophobicity of the cell surface, indicating decreased adsorption rates of C. albicans cells. Additionally, LC-MS/MS analysis identified the antifungal peptide APTs with a molecular mass of 423.18 Da and an amino acid sequence of S-G-G-G-F, representing a novel and previously unreported antifungal peptide. Circular dichroism analysis indicated that the secondary structure of APTs primarily comprised α-helices. This study underscores the potential of APTs as a natural biopreservative for food preservation.

Biopreservation of Fresh Sardines (Sardina pilchardus) Using Lactiplantibacillus plantarum OV50 Isolated from Traditional Algerian Green Olives Preparations

Lactiplantibacillus plantarum OV50 is a novel strain that was isolated from Algerian olives. Prior to its use as a natural biopreservative, OV50 underwent characterization for various functions. OV50 shows no proteolytic, lipolytic, or hemolytic activity. In addition, it is non-cytotoxic to eukaryotic cells and does not exhibit acquired antibiotic resistance. OV50 was tested with Pseudomonas aeruginosa ATCC 27835, Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739, and Vibrio cholerae ATCC 14035 in a sardine based-medium at 37 °C and 7 °C. At 37 °C, OV50 completely inhibited the growth of these foodborne pathogens for a maximum of 6 h. At 7 °C, it suppressed their growth for a maximum of 8 days, except for S. aureus ATCC 6538, whose growth was reduced from 4 to 2 log CFU/mL. Microbiological counts, total volatile basic nitrogen (TVB-N), and peroxide values (PV) concentrations were determined in fresh sardines inoculated with OV50 and kept at 7 °C for 12 days. The inoculated sardines showed a significant reduction in TVB-N levels at D8 (34.9 mg/100 g) compared to the control (59.73 mg/100 g) and in PV concentrations at D4 (6.67 meq/kg) compared to the control (11.44 meq/kg), as well as a significant reduction in the numbers of Enterobacterales, Coliforms, Pseudomonas spp., Vibrio spp., and S. aureus At D8 and D12 compared to the control. Taken together, these results indicate that OV50 can improve the microbiological safety, freshness, and quality of sardines.

Biopreservative Efficacy of Some Common Spices Sold in Dakingari Market on Hot-Break Locally Processed Tomato Paste

The research investigated the biopreservative efficacy of some common spices sold in dakingari market as substitutes for chemical preservatives on hot-break locally processed tomato paste (Platinum 7 F1 variety). After concentration, the paste was divided into thirty one (31) portions labeled A–O2. The spices were added to tomato paste in the following proportion of ginger; garlic; onion; pepper; ginger and garlic; ginger and onion; ginger and pepper; garlic and onion; garlic and pepper; onion and pepper; ginger, garlic and onion; ginger, garlic and pepper; garlic, onion and pepper; onion, pepper and ginger; ginger, garlic, onion and pepper 3 and 5 percent. Each mixture (450g) was evenly homogenized, filled up into air-tight Mayonnaise jars and stored at room temperature over a period of 9 weeks. Pure cultures were obtained from distinct colonies by repeating streaking on fresh agar plates and subjected to microscopic examination and biochemical tests such as Gram staining. Microbial examination and yeast counts of the samples were enumerated on a weekly basis while the pure microbial isolates were identified. Results showed that those without fungi growth are; Sample G (ginger and onion), Sample O (onion, pepper and ginger), Sample D (onion), Sample E (pepper), Sample M (ginger, garlic and pepper) and Sample L (ginger, garlic and onion), Sample I (garlic and onion) (3 and 5%). The microorganisms were identified as organism: Rhizopus orazae, Penicillium citrinum, Aspergillus micronesiensis, Aspergillus flavus, Aspergillus niger , Phoma multristrata, Lactobacillus plantarum, Lactobacillus brevis, Leuconostoc mensenteroides, Lactobacillus acidophilus, Lactobacillus fermentum. The study concluded only Sample D (onion) and Sample N (garlic, onion and pepper) that has no bacteria growth (3 and 5%).The study concluded that combined samples with combination of garlic or ginger (3 and 5%) suitably preserved tomato paste for 9 weeks without deterioration. The use of natural products such as ginger, onion and garlic as natural preservatives could significantly improve tomato utilization in household production in Dakingari and Nigeria at large where refrigeration is greatly hampered by erratic power supply. Further investigation for other biopreservatives is recommended to ascertain the safety consumption of tomato paste of the people in the study area and the need to look into more new natural bio-preservatives which can promote human health besides acting as food preservative.

Exploring the Potential of Pomegranate Peel Extract as a Natural Food Additive: A Review.

Pomegranate is one of the super fruit and a storehouse of several antioxidants and health-promoting compounds which can act as a natural food additive. The pomegranate processing industry generates huge quantities of by-products, particularly peels (50% of fresh fruit weight), that cause environmental pollution due to improper disposal. In this perspective, the present review article focuses on the chemical composition of pomegranate peel and its application as a natural food additive in different food products such as bakery, dairy, meat/meat products, fish/fish products, edible oils, and packaging materials. There is a continuous demand for processed foods exhibiting natural food additives over foods containing synthetic additives/colorants, which can cause serious health implications such as cancer with regular consumption. The food industry is looking for an alternative to synthetic/artificial food additives. To overcome these problems, pomegranate peel or its extract can be used as a natural biopreservative in food products that are prone to fat oxidation and microbial growth. Pomegranate peel contains bioactive compounds, especially tannins, phenolic acids, and flavonoids, which have nutraceutical value and possess higher antioxidant activity and antimicrobial properties. Due to these properties, pomegranate peel prevents lipid oxidation in fatty foods and can also retard the microbial growth.

Nano-Conjugated Food-Derived Antimicrobial Peptides As Natural Biopreservatives: A Review of Technology and Applications.

In recent years, microbial food safety has garnered a lot of attention due to worldwide expansion of the food industry and processed food products. This has driven the development of novel preservation methods over traditional ones. Food-derived antimicrobial peptides (F-AMPs), produced by the proteolytic degradation of food proteins, are emerging as pragmatic alternatives for extension of the shelf-life of food products. The main benefits of F-AMPs are their wide spectrum antimicrobial efficacy and low propensity for the development of antibiotic resistance. However, direct application of F-AMPs in food limits its efficacy during storage. Therefore, the development of nanocarriers for the conjugation and distribution of potential AMPs may hold great potential to increase their bioactivity. This review highlights the significance of F-AMPs as a feasible and sustainable alternative to conventional food preservatives. The most recent developments in production, characterization, and mode of action of these AMPs against planktonic and biofilm forming pathogens are thoroughly discussed in this work. Moreover, nano-conjugation of F-AMPs with different nano-carriers and potential future application in food packaging are emphasized. This review may aid in comprehending the nano-conjugation of F-AMPs and offer insightful recommendations for further exploration and potential uses in the food processing industry.

Characterization of yoghurt supplemented with Lacticaseibacillus rhamnosus as a bioprotective antifungal culture

Lactic acid bacteria (LAB) play a very important role as natural bio-preservatives in foods. Accordingly, the inhibitory effect of Lactobacillus rhamnosus (L. rhamnosus) on 4 fungi species of Yarrowia, Penicillium expansum (P. expansum), Saccharomyces cerevisiae (S. cerevisiae), Aspergillus niger (A. niger), Kluyveromyces lactis (K. lactis) was investigated. Then P. expansum was selected as the most important contaminant mould in yoghurt to study the use of L. rhamnosus to reduce selective spoilage of P. expansum in yoghurt. Also, the effect of this bioprotective culture on the count of starter bacteria and some characteristics of yoghurt was determined. L. rhamnosus (106 cfu /mL) was inoculated into the milk along with yoghurt starter bacteria, so that four samples were produced T0 (L. rhamnosus = 0, P. expansum = 0), T1 (L. rhamnosus = 106 cfu/mL, P. expansum = 0), T2 (L. rhamnosus = 0, P. expansum = 105cfu/mL); T3 (L. rhamnosus = 106 cfu/mL, P. expansum = 105cfu/mL). All samples were analysed for pH, acidity, viscosity, syneresis, microbial (survival of Streptococcus thermophilus and Lactobacillus bulgaricus and P. expansum) and overall acceptability. L. rhamnosus had an inhibitory effect on the survival of P. expansum (p<0.05) but was not able to completely control it. L. rhamnosus in T3 sample had an inhibitory effect from the first day to the end of storage. Furthermore, during the storage, the survival of yoghurt starter bacteria in probiotic yoghurt samples was higher than the control (p<0.05). T3 had lower pH, viscosity and overall acceptability score compared to the control and its syneresis was higher (p<0.05). In general, the addition of 106 cfu/mL of L. rhamnosus did not have a complete inhibitory effect on P. expansum (105 CFU/mL) until the end of storage time.

Insights into factors affecting lactoperoxidase conformation stability and enzymatic activity

Lactoperoxidase is a glycoprotein from the superfamily of mammalian haeme-containing peroxidases and has a great potential as a natural biopreservative in food and medicine due to its antimicrobial activity. For lactoperoxidase to be effectively utilised, its structural stability and consequently enzymatic activity must be maintained. Our measurements showed that two-state denaturation curve was observed at pH 3.5 and 4.0 in 100 mm buffers, whereas aggregation occurred at pH 5.0–7.0. Lactoperoxidase conformation stability was also affected by buffer type and buffer molar concentration and in presence of various ions (Ca2+, Mg2+, Na+). Furthermore, when lactoperoxidase was partially depleted of iron and calcium ions (de-LPO), thermal stability was lower in comparison with that of native lactoperoxidase and decreases in enzymatic activity were also observed. The enzymatic activity of lactoperoxidase was affected by the choice of buffer, pH, molar concentration of buffer, and temperature, but not by the presence of different ions.

Three novel leaderless bacteriocins have antimicrobial activity against gram-positive bacteria to serve as promising food biopreservative

BackgroundDue to the detrimental effects of chemical preservatives, there has been an increasing demand for safer, healthier and natural bio-preservatives. Bacteriocins have attracted increasing interest because of their potential as natural bio-preservatives.ResultsWe screened a large number of Bacillus thuringiensis strains and isolated one strain (B. thuringiensis P86) with antimicrobial activity against several foodborne pathogens. Three novel leaderless bacteriocins, including thucin A1, thucin A2 and thucin A3, were purified and identified from the culture supernatant of B. thuringiensis P86, whose molecular masses were 5552.02, 5578.07 and 5609.06 Da, respectively. Thucin A1 was then selected as a representative to be tested, and it exhibited potent inhibitory activity against all tested gram-positive bacteria. More importantly, thucin A1 showed stronger antimicrobial activity than nisin A against two important foodborne pathogens Bacillus cereus and Listeria monocytogenes. In addition, thucin A1 exhibited strong acid–base adaptability (pH 2–11), high endurance to heat, good stability to trypsin and pepsin, no hemolysis activity and cytotoxicity, and could effectively inhibit or eliminate Bacillus cereus and Listeria monocytogenes in skim milk.ConclusionsOur findings indicate that these novel leaderless bacteriocins are potentially promising food biopreservatives.

Antimicrobial compound produced by human gut lactic acid bacteria having antifungal activity against aflatoxigenic Aspergillus flavus MTCC 2798

Lactic acid bacteria (LAB) are a group of distinguished bacteria that have reserved their place in the food industry, with their probiotic properties as well as their ability to produce many antimicrobial compounds. The antagonistic microorganisms and their bioactive compounds have a potential application as natural bio preservatives as they not only inactivate but also inhibit the growth of undesired microorganisms in food. Hence, the use of LAB and their antimicrobial compounds like organic acids, hydrogen peroxide, diacetyl, bacteriocins, etc. attract considerable interest during the past years. Among the 173 human gut LAB studied 17 isolates showed antifungal activity against aflatoxigenic Aspergillus flavus MTCC 2798. All the seventeen isolates produced antimicrobial compounds such as lactic acid, hydrogen peroxide, diacetyl. GC–MS based metabolic profiling of the methanolic extracts of 17 isolates identified 40 metabolites. Thirteen metabolites were identified and reported to have potent antimicrobial activity. The results suggest the antagonistic potential of antimicrobial compounds produced by human gut LAB having significant application in the pharmaceutical and food industry. Novelty impact statement Antimocrobial compounds were produced by seventeen antifungal human gut Lactic acid bacteria have promising application as food preservative. GC–MS based metabolic profiling of the methanolic extracts of 17 isolates identified thirteen metabolites reported to have potent antimicrobial activity. Bioactive metabolite Cyclo(leucyl prolyl), was present in the methonolic extract of all the seventeen LAB isolates reported to have anti-aflatoxin activity, thus confirms the anti-aflatoxigenic property of the isolates.

Bioactivities of Calocybe indica protein combined with cell-free supernatant of Lactobacilli from a fermented cereal against free radicals and microorganisms

Edible fungi and lactic acid bacteria (LAB) are emerging as reservoirs of diverse bio-functional products. This study investigated antioxidant and antimicrobial activities of a mushroom; Calocybe indica protein (CIP) and cell-free supernatant (CFS) of Lactococcus lactis, Lactobacillus fermentum, and Lactobacillus brevis isolated from a fermented cereal food-Kati against free radicals and microorganisms associated with fruits spoilage. Protein extract from C. indica was subjected to ammonium sulfate precipitation (55% saturation). Synergistic radical scavenging activities of CIP and CFSs of LAB against 2,2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS˙+), 1,1-diphenyl-2-picrylhydrazyl (DPPH˙), hydroxyl radicals (OH˙) and their Fe2+ ion chelation activity were within 70.39-84.77%, 62.51-87.63%, 70.58-88.56%%, and 62.83-78.76%, respectively. Combinatory effects of CIP and CFSs showed pronounced zones of inhibition of 6.5 mm to 12.1 mm against tested microorganisms. The study established that, bioactivities of C. indica and Lactobacilli can be attributed to their inherent bioactive proteins, suggesting their potential exploitation as natural bio-preservatives.

Retrospecting the concept and industrial significance of LAB bacteriocins

Ever increasing demand for natural products with minimum chemical additives has necessitated the search for innovative green, potent, environment friendly, natural substitutes for prolonging the shelf life of food products. The lactic acid bacteria (LAB) are a group of Gram-positive microorganisms with great biotechnological potential in the food industry. To reduce pathogen invasion, they can produce inhibitory compounds (bacteriocins, organic acids, hydrogen peroxide, diacetyl, and carbon dioxide). LAB-bacteriocin are proteinaceous antimicrobial molecules with a diverse genetic origin, post-translationally modified or not, that can help the producer organism to outcompete other bacterial species. In addition, they are emerging as a novel wave of potential antibiotics with potent in vitro and in vivo activities. Moreover, LAB-bacteriocin serves as an effective method of natural bio preservation in the food industry and enables the reduction of other costly or user-unfriendly treatments while increasing the product self-life. Therefore, this article provides a recapitulation of classification of bacteriocins, potential of LAB to produce different bacteriocins, their biology, and purification methods. Additionally, it will give a critical snapshot of industrial applications of LAB-bacteriocin as a starter culture, preservative, antibiotic, and probiotics, etc.

Beyond biopreservatives, bacteriocins biotechnological applications: History, current status, and promising potentials

Bacteriocins are those ribosomally synthesized peptides secreted by bacteria that were first known in 1925. From this date till now, bacteriocins keep attracting scientists' attention for their potency and their ability to be employed in various human and animal health-improving biotechnological applications. Bacteriocins have started as a safe, natural biopreservatives, then as alternatives and/or support for some currently used antibiotics, promising anti-multidrug-resistant bacteria, antileishmanial, antifungal, and antiviral agents. Currently, some bacteriocins have been successfully acting as a treatment for certain types of tumors, ulcers, and cancers. Moreover, some potent bacteriocins are involved in other clinical and therapeutical applications In this review, we are highlighting the history and characteristics of bacteriocins, describing their biosynthesis, and comparing their modes of action with those of other antimicrobial peptides. Also, showing suitable bacteriocins delivery systems, and some current and potential bacteriocins contributions in oral health care, human body protection, treatment of systemic infections and peptic ulcers, controlling upper respiratory tract infection, urogenital tract infections. Additionally, potential applications of bacteriocins as an antitumor, anticancer, and spermicidal agents and in women's health care were clarified. Finally, future perspectives related to bacteriocins applications in medical fields were discussed.

Antioxidant and Antibacterial Activities of Four Underutilized Fruits of Bangladesh

Antioxidant and antibacterial activities of four underutilized fruits namely Jujube (Ziziphus mauritiana Lam.), Olive (Elaeocarpus serratus L.), Roselle (Hibiscus sabdariffa L.), and Taikor (Garcinia pedunculata Roxb.) commonly found in Bangladesh were evaluated. The highest total phenolic content (685.08 ± 27.65 mg GAE/100 ml) and total flavonoid content (148.18 ± 0.40 mg QE/100 ml) were found in Taikor extract, which compliance with its highest DPPH scavenging activity and antibacterial properties. It exerted a significantly higher (p ≤ 0.05) zone of inhibition against Escerichia coli, Staphylococcus spp. and Pseudomonas spp. than the other experimented fruit extracts. The antioxidant activity was found as Taikor (43.15 ± 1.61%)> Roselle (33.07 ± 1.61%) > Olive (28.68 ± 0.78%) > Jujube (24.81 ± 1.34%). Bacillus spp. are found to be more susceptible to the experimented sample extracts. Fruit samples studied may be utilized as potential sources of natural antioxidants and antibacterial compounds, and their extracts may be used as natural biopreservatives to extend the shelf life of foodstuffs. Bangladesh J. Bot. 50(4): 1035-1039, 2021 (December)

Utilization of Industrial Rosa damascena Mill. By-products and Cocoa Pod Husks as Natural Preservatives in Muffins

Cocoa Pod Husks (CPH) and by-product from supercritical CO2 extracted Rosa damascena Mill. (RDCO2) were used as biopreservatives in muffins. Both by-products were rich source of polyphenols: 28.3 ± 0.6 mg/g Dry Weight (DW) and 17.9 ± 0.7 mg/g DW RDCO2 and CPH, respectively, and exhibited potent antioxidant capacity: 449.1 ± 8.5 µmol Trolox Equivalents (TE)/g DW (by ORAC method) and 58.9 ± 2.1 µmol Gallic Acid Equivalents (GAE)/g DW (by HORAC method) for the RDCO2, and 373.8 ± 9.0 µmol TE/g DW (by ORAC) and 36.8 ± 3.8 µmol GAE/g DW (by HORAC) for the CPH. RDCO2 extracts successfully inhibited development of several important pathogenic and saprophytic microorganisms causing microbial spoilage of food systems. The control muffins were good for consumption up to the 17th day, while the products supplemented with RDCO2 and CPH: until 20th day of storage at 22 ± 0.5 °C. The amount of dietary fibers in muffins supplemented with both by-products increased 3 times (8.57 ± 0.12 %) compared to control (2.91 ± 0.12 %) and the polyphenolic compounds increased 2.5 times (from 50.0 ± 0.3 for the control to 185.9 ± 0.6 mg/g DW). For the first time by-product of supercritical CO2 extraction of Rosa damascena Mill. was characterized and used as natural and cheap biopreservative.

Production of cationic antifungal peptides from kenaf seed protein as natural bio preservatives to prolong the shelf-life of tomato puree

This study determined the favourable fermentation conditions for the production of antifungal peptides from kenaf seeds and their effectiveness in extending the shelf-life of tomato puree. The optimum fermentation conditions for the maximum activity of the antifungal peptides were 8.4% (w/v), 7 days and 3.7% for substrate/water ratio, fermentation time and glucose concentration, respectively. Eight cationic peptides of low molecular weight ranging from 840 to 1876 Da were identified in kenaf seed peptides mixture (KSPM). The minimum inhibitory concentration and minimum fungicidal concentration of KSPM against Fusarium sp. were 0.18 mg/mL and 0.70 mg/mL, respectively, while those for Aspergillus niger were 1.41 mg/mL and 2.81 mg/mL respectively. KSPM exhibited a fungicidal effect and a prolonged lag phase, with increased fungal membrane permeability as the concentration of KSPM increased, as evidenced by the release of intracellular constituents. The treatment of tomato puree with 1000 mg/kg KSPM delayed fungal growth for up to 14 and 23 days at 25 °C and 4 °C respectively, significantly reducing Aspergillus niger and Fusarium sp. counts. In conclusion, kenaf seed peptides prepared by lacto-fermentation possess antifungal activity, hence can be applied as natural bio preservatives to extend the shelf-life of food products such as tomato puree.

Pediocin PA-1 production by Pediococcus pentosaceus ET34 using non-detoxified hemicellulose hydrolysate obtained from hydrothermal pretreatment of sugarcane bagasse

Listeria monocytogenes is one of the foodborne pathogens of most concern for food safety. To limit its presence in foods, bacteriocins have been proposed as natural bio-preservatives. Herein, a bacteriocin was produced on hemicellulose hydrolysate of sugarcane bagasse by Pediococcus pentosaceous ET34, whose genome sequencing revealed an operon with 100% similarity to that of pediocin PA-1. ET34 grown on hydrolysate-containing medium led to an increase in the expression of PA-1 genes and a non-optimized purification step sequence resulted in a yield of 0.8 mg·L-1 of pure pediocin (purity > 95%). Culture conditions were optimized according to a central composite design using temperature and hydrolysate % as independent variables and validated in 3-L Erlenmeyers. Finally, a process for scaled-up implementation by sugar-ethanol industry was proposed, considering green chemistry and biorefinery concepts. This work stands up as an approach addressing a future proper sugarcane bagasse valorisation for pediocin production.