Chemometric evaluation of functional components and anti-quorum sensing activity of mulberry leaves from Indian cultivars: a potential contribution to the food industry.

BACKGROUND: Potential use of many native, easily available vegetal materials for human consumption and value addition is not well recognized. Mulberry, being a traditional industrial crop rich in nutrients and nutraceuticals can be of great importance for the food industry. However, mulberry leaves are mainly being utilized in sericulture and are not exploited for their functional components. Thus, the selection of promising mulberry cultivars, rich in bioactive compounds, like resveratrol and 1-deoxynojirimycin, increase their potential use in functional foods. RESULTS: Chlorogenic acid, myricetin and kaempferol were the major polyphenols present in the nine selected cultivars, in the range 0.001-0.086, 0.003-0.079 and 0.003-0.163 g kg-1 fresh weight (FW), respectively. Protocatechuic acid, epicatechin and rutin were predominantly present in cultivars V-1, G-2 and ML (0.103, 0.080 and 0.121 g kg-1 FW, respectively). Similarly, resveratrol and 1-deoxynojirimycin were highest in cultivars ML and K-2 (0.078 and 0.079 g kg-1 FW, respectively). Leaf extracts of cultivars G-2 and ML were able to effectively inhibit the violacein production with 64.08% and 70.04%, respectively at the concentration of 6 mg mL-1 presumably due to a higher content of polyphenols. Chemometric evaluation of chromatographic data showed the intraspecific variability and secondary metabolite co-existence in different cultivars. CONCLUSIONS: Considering phytoconstituents, cultivars G-2, ML, K-2 and V-1 could contribute efficiently to the rational utilization of mulberry in agro-food industries. Furthermore, cultivars G-2 and ML leaves can be a new source of quorum sensing inhibitory agents. © 2021 Society of Chemical Industry.

Applications of Fruit Polyphenols and Their Functionalized Nanoparticles Against Foodborne Bacteria: A Mini Review.

The ingestion of contaminated water and food is known to cause food illness. Moreover, on assessing the patients suffering from foodborne disease has revealed the role of microbes in such diseases. Concerning which different methods have been developed for protecting food from microbes, the treatment of food with chemicals has been reported to exhibit an unwanted organoleptic effect while also affecting the nutritional value of food. Owing to these challenges, the demand for natural food preservatives has substantially increased. Therefore, the interest of researchers and food industries has shifted towards fruit polyphenols as potent inhibitors of foodborne bacteria. Recently, numerous fruit polyphenols have been acclaimed for their ability to avert toxin production and biofilm formation. Furthermore, various studies have recommended using fruit polyphenols solely or in combination with chemical disinfectants and food preservatives. Currently, different nanoparticles have been synthesized using fruit polyphenols to curb the growth of pathogenic microbes. Hence, this review intends to summarize the current knowledge about fruit polyphenols as antibacterial agents against foodborne pathogens. Additionally, the application of different fruit extracts in synthesizing functionalized nanoparticles has also been discussed.

Effect of Cedrus deodara extract on the physiochemical and sensory properties of salted meat and its action mechanism.

The effect of pine needle extract from Cedrus deodara (PNE) on the quality of salted meat was reported, and its action mechanism was further investigated. With the treatment of PNE, the physicochemical properties of salted meat were improved. The peroxide value decreased from 16.18 to 6.78 mmol O2 /kg, while the thiobarbituric acid value decreased from 0.79 to 0.40 mg MDA/kg. Moreover, the salted meat with PNE also had the better texture, color, and volatile compositions. The 0.2% PNE group showed the highest ΔE value (63.16 ± 0.56), hardness (813.5 ± 48.7 g), and volatility (45.86 ± 0.39), while the control group showed the lowest ΔE value (43.92 ± 2.13), hardness (515.8 ± 17.3 g) and volatility (29.97 ± 0.56). In addition, with the analysis of fluorescence and circular dichroism spectroscopy, the spatial structures of myofibrillar protein (MP) in salted meat were obviously changed by PNE. Meanwhile, methylconiferin, 1-O-feruloyl-ß-D-glucose, nortrachelogenin, secoxyloganin, 1-O-(4-coumaroyl)-ß-D-glucose and pelargonidin-3-O-glucoside were identified from PNE. Furthermore, according to the analysis of molecular docking, hydrogen bond, hydrophobic force, and electrostatic force were obtained as the main molecular forces between MP and the phenolic compounds of PNE, while arginine, glutamic acid, and glycine residues were the main binding sites. All results suggested that PNE might be a potential candidate to improve the quality of salted meat in the food industry. PRACTICAL APPLICATION: The quality deterioration of meat may not only affect its further processing and consumption but also may lead to some food safety problems. In present study, PNE exhibited the fine capability to inhibit the oxidation of meat, while it could ameliorate the texture, color, and physicochemical properties of meat due to its tightly interaction with myofibrillar protein. All result suggested that PNE could be potentially utilized to improve the quality of meat in food industry.

Prevalence of fungi in fresh tomatoes and their control by chitosan and sweet orange (Citrus sinensis) peel essential oil coating.

BACKGROUND: Fungal contamination is a major cause of food spoilage. There is an urgent need to find and characterize natural preservatives. This study evaluates the prevalence of fungi in tomatoes and their control by using essential oil (EO) from sweet orange peel. Essential oils were extracted from dried and fresh sweet orange peels by using n-hexane and ethanol as extraction solvents. Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS) analyses were performed to identify the chemical composition of the EO. A combination of chitosan (CS) and EO was used to control the fungal decay of tomatoes inoculated with Aspergillus niger and Penicillium citrinum. RESULTS: Tomatoes obtained from local markets and supermarkets showed a high prevalence of Aspergillus and Penicillium spp. Essential oils extracted by ethanol from dried peels showed complete inhibition of A. niger and P. citrinum and hyphal degradation at a minimum inhibitory concentration (MIC) of 100 µL mL-1 . The combination of EO with chitosan (2%) as a coating, effectively controlled the fungal decay of tomatoes until the eighth day of storage at 25 °C. CONCLUSION: Due to their edible nature, and their antifungal and preservative potential, EO- and CS-based coatings can be used to extend the shelf life of tomatoes and other agriculture commodities. Essential oil- and CS-based coating can be used as alternative to synthetic preservatives, which are associated with various health hazards. © 2021 Society of Chemical Industry.

Pomegranate By-Products as Natural Preservative to Prolong the Shelf Life of Breaded Cod Stick.

This work evaluated the efficacy of pomegranate byproducts, specifically peel powder, as valid preservatives for food quality. Ready-to-cook cod sticks breaded with pomegranate peel powder were prepared. Shelf-life tests were conducted on breaded cod sticks during refrigerated storage (17 days) at 4 °C, monitoring the pH, microbiological and sensory quality. In addition, the nutritional quality of both the breaded and control samples was assessed. The results highlighted that active samples showed higher phenol and flavonoid content and higher antioxidant activity compared to the control fish, suggesting that pomegranate peel powder was responsible for a significant increase in cod stick nutritional quality. Furthermore, the cod stick active breading led to a delay in microbial growth without affecting the sensory properties; rather, it helped slow down the sensory attribute decline during the refrigerated storage. The data suggest that using pomegranate byproducts in breaded cod stick was effective in prolonging its shelf life, as well as improving its nutritional quality. Therefore, pomegranate peel powder can be considered as a potential resource as natural food preservative.

Effects of high-molecular-weight chitosan coating prepared in different solvents on quality of catfish fillets during 6-month frozen storage.

Effects of high-molecular-weight (800 kDa) chitosan coating on quality of catfish fillets were examined during 6-month frozen (-20 °C) storage. Coating solutions, included distilled water (Control), 800AC1% (1% w/v chitosan in 1% v/v acetic acid), AS3% (3% w/v aspartic acid), and 800AS3% (3% w/v chitosan in 3% w/v aspartic acid). Changes in physicochemical, microbial, and consumer perception of chitosan-coated catfish fillets during frozen storage were examined. The 800AS3% coating was found to be effective in inhibiting microbial growth, controlling lipid oxidation, reducing drip loss and cooking loss, and retaining color and texture of catfish fillet during frozen storage. After 6-month frozen storage, the aroma of thawed fillets coated with 800AS3% was accepted by 77.92% of consumers with 66% positive purchase intent. This study demonstrated that a nonpungent aspartic acid, instead of commonly used pungent acetic acid, can be used in preparation of preservative high-molecular-weight chitosan coating. PRACTICAL APPLICATION: The findings of this study indicated that high-molecular-weight chitosan coating showed preservative effects on quality of frozen raw catfish fillets. In our previous study, chitosan (800 kDa) at 1% and 3% concentrations showed antibacterial activity in vitro. The nonpungent aspartic acid can be used as a solvent to dissolve high-molecular-weight chitosan instead of the commonly used pungent acetic acid. The most effective coating treatment was 3% w/v chitosan in 3% w/v aspartic acid. This finding would be applicable to other seafood and fish products.

Chemical composition, extraction sources and action mechanisms of essential oils: Natural preservative and limitations of use in meat products.

The antimicrobial activity of essential oils (EO) is associated with the presence of secondary metabolites synthesized by plants. Its mechanism of action involves the interaction of its hydrophobic components with the lipids present in the cell membrane of microorganism, resulting in metabolic damages and cell death. Spoilage and pathogenic microorganisms are contaminants in meat and meat products with considerable impacts on food quality and safety. Research shows the potential of applying essential oils in the preservation of meat food systems as compounds of low toxicity, extracted from a natural source, and as an alternative to consumer demand for healthy foods with a more natural appeal. In addition, there is a great diversity of plants from which essential oils can be extracted, whose antimicrobial activity in vitro and in meat and meat products has been proven.

Method for the safe storage of sugar beets using an ion-ozone mixture.

BACKGROUND: Sugar refineries cannot modernize the current processing technology and increase their capacity in proportion to the increasing harvest of raw beets. This entails an increase in the processing time. Sugar beets are not subject to long-term storage, and when they are stored in inappropriate conditions, root crops rot, resulting in sugar loss. The aim of this study is to increase the safety of beets during long-term storage before processing and to develop a device for its implementation which will lead to an improvement in the biological value of sugar beet root crops and an increase in the efficiency of technological processes. METHODS: The experiment used sugar beets from the Koksu sugar plant and was carried out by treating sugar beets with an ion-ozone mixture to increase their shelf life. The treatment was carried out in an ion-ozone installation. Physicochemical and microbiological analyses were carried out using several methods: chemical extraction, potentiometry and photocolorimetry. RESULTS: The results of the study showed that when sugar beets were treated with ozone at a concentration of 0.5 g/m3 and 2 g/m3, the acidity decreased to 0.6 degrees, and the sugar content increased by 2.3% and 3.3%, respectively. When sugar beets were processed with an ozone concentration of 2 g/m3 and a molecular ion concentration of 1,000,000 units/cm3, a decrease in moisture was observed to 69%, the acidity decreased 2 times and the sugar content increased by 3%. When the beets were processed with an ozone concentration of 2 g/m3 and a molecular ion concentration of 1,000,000 units/cm3, a decrease in acidity was observed to 0.65-0.67 degrees, and the sugar content increased by 2-2.5%. Also, in all the above optimal processing conditions, a decrease in yeast growth was observed. CONCLUSIONS: As a result of the study, the following three optimal conditions were established for the processing of sugar beet root crops before storage: an ozone concentration of 0.5 g/m3 and 2 g/m3; an ozone concentration of 5 mg/m3 and molecular ions of 500,000 units/cm3; an ozone concentration of 2 g/m3 and molecular ions of 1,000,000 units/cm3.

Bio-preservation of chocolate mousse with free and immobilized cells of Lactobacillus plantarum D2 and lemon (Citrus lemon L.) or grapefruit (Citrus paradisi L.) zest essential oils.

BACKGROUND: The bio-preservation of food products using various natural ingredients and metabolites from various types of beneficial microorganisms released during targeted fermentation is a method that simultaneously has a preservative effect on the food product and provides a model of its composition in order to ensure its functional and health properties. This double effect can be achieved by incorporating ingredients with proven preservative and functional effects into the food product, such as essential oils from various plant species and probiotic bacteria. The aim of the present research was to study the synergistic effect of selected probiotic lactic acid bacteria (LAB) and essential oils with high antimicrobial activity against pathogenic and spoilage microorganisms for the bio-preservation of chocolate mousse food emulsion. METHODS: The susceptibility of the selected probiotic strain Lactobacillus plantarum D2 to different concentrations of the selected lemon or grapefruit essential oil was examined using the disc-diffusion method. Nine chocolate mousse variants were prepared with the inclusion of free or immobilized cells of the probiotic strain L. plantarum D2 and/or lemon or grapefruit zest essential oils. The chocolate mousse variants were stored for 20 days in refrigerated conditions, and changes in the concentration of viable lactobacilli cells, the pH and the microbiological purity were monitored in accordance with standard requirements by taking samples on the 0th, 5th, 10th, 15th, and 20th days of storage. An organoleptic evaluation of the chocolate variants was performed on the 0th day. RESULTS: Concentrations of up to 1% lemon or grapefruit essential oil did not affect the growth of the probiotic strain L. plantarum D2, which revealed opportunities for their joint application for the bio-preservation of food emulsions. The obtained chocolate mousse variants were characterized by preserved organoleptic characteristics and microbiological safety. Free or immobilized probiotic L. plantarum D2 cells applied alone or in combination with lemon or grapefruit essential oils provided bio-preservation of the food emulsions, maintaining a high concentration of viable cells (106-107 cfu/g) during storage under refrigerated conditions for 20 days. CONCLUSIONS: The combined application of free or immobilized probiotic LAB and lemon or grapefruit essential oils resulted in better bio-preservation results than in the use of probiotic LAB or essential oils alone, thus suggesting a synergistic effect between the two bio-preservative agents. Moreover, the obtained chocolate mousse emulsions can be classified as functional foods and the chocolate mousse food matrix can successfully be used as a vehicle for delivery of probiotic LAB to a wide range of food consumers. The obtained results and the developed successful bio-preservation strategy for the production of chocolate mousse food emulsions would provide grounds for the future selection of other probiotic lactobacilli strains, essential oils and synergistic combinations of them for the development of successful bio-preservation strategies for other types of food and beverage products.

Application of Pomegranate by-Products in Muscle Foods: Oxidative Indices, Colour Stability, Shelf Life and Health Benefits.

In recent years, considerable importance is given to the use of agrifood wastes as they contain several groups of substances that are useful for development of functional foods. As muscle foods are prone to lipid and protein oxidation and perishable in nature, the industry is in constant search of synthetic free additives that help in retarding the oxidation process, leading to the development of healthier and shelf stable products. The by-products or residues of pomegranate fruit (seeds, pomace, and peel) are reported to contain bioactive compounds, including phenolic and polyphenolic compounds, dietary fibre, complex polysaccharides, minerals, vitamins, etc. Such compounds extracted from the by-products of pomegranate can be used as functional ingredients or food additives to harness the antioxidant, antimicrobial potential, or as substitutes for fat, and protein in various muscle food products. Besides, these natural additives are reported to improve the quality, safety, and extend the shelf life of different types of food products, including meat and fish. Although studies on application of pomegranate by-products on various foods are available, their effect on the physicochemical, oxidative changes, microbial, colour stabilizing, sensory acceptability, and shelf life of muscle foods are not comprehensively discussed previously. In this review, we vividly discuss these issues, and highlight the benefits of pomegranate by-products and their phenolic composition on human health.

Control of postharvest diseases caused by Penicillium spp. with myrtle leaf phenolic extracts: in vitro and in vivo study on mandarin fruit during storage.

BACKGROUND: In the postharvest handling of horticultural commodities, plant extracts with fungicidal activity are a valid alternative to synthetic fungicides. The fungicidal activity of myrtle leaf extracts from eight cultivars was studied in vitro against Penicillium digitatum, Penicillium italicum, and Penicillium expansum and on artificially inoculated mandarins with green and blue molds during storage for 12 days at 20 °C and 90% RH. RESULTS: Hydroxybenzoic acids, hydrolysable tannins, and flavonols were identified by high-performance liquid chromatography (HPLC). Despite sharing the same phenolic profile, extracts of eight myrtle cultivars significantly differed in the concentration of phenolics. Hydrolysable tannins are the principal subclass representing nearly 44.9% of the total polyphenols, whereas myricitrin was the most abundant flavonol in all cultivars. Myrtle extracts strongly inhibited conidial germination of the pathogens tested, although the greatest efficacy was observed against P. digitatum. At a concentration of 20 g L-1 , all the extracts completely inhibited fungi growth; only 'Angela', 'Tonina' and 'Grazia' extracts were effective at lower concentrations (15 g L-1 ). On inoculated fruit, myrtle extracts significantly controlled rot development. As a preventive treatment, 'Ilaria' and 'Maria Rita' extracts significantly reduced the rate of fruit with green mold decay lesions. When applied as a curative treatment, all the exacts decreased the incidence of decay. Against P. italicum, all the extracts applied as preventive treatments controlled decay effectively, while as curative treatment some of the extracts were not effective. All the extracts reduced the size of the infected areas. CONCLUSION: The results propose myrtle extracts as a possible natural alternative to synthetic fungicides. © 2021 Society of Chemical Industry.

Saccharomyces cerevisiae as a delivery system of Zataria multiflora Boiss. essential oil as a natural preservative for food applications: Encapsulation of Iranian Zataria multiflora Boiss. essential oil.

BACKGROUND: The following study is an evaluation of the encapsulation, stability and release profile of Iranian Zateria multiflora boiss essential oil (ZEO) in Saccharomyces cerevisiae yeast cells. Encapsulation was performed with different essential oil / yeast weight ratios at different temperatures. The encapsulation efficiency and stability of the loaded yeasts and the release profiles of carvacrol and thymol (as the main active ingredients of ZEO) were also investigated. RESULT: The encapsulation efficiencies of carvacrol and thymol at a ZEO / yeast weight ratio of 1.25 were 30.9% ± 0.01% and 44.5% ± 0.02%, respectively. Loaded yeast cells were stable during the 4-week storage period. Both carvacrol and thymol showed substantial releases of around 60% during the first hour and around 70% during the second hour at two different water temperatures, followed by steady release. CONCLUSION: Zateria multiflora boiss essential oil can be encapsulated effectively in S. cerevisiae yeast cells, refrigerated without degradation, and released efficiently. Zateria multiflora boiss essential oil encapsulated into S. cerevisiae yeast may be used as a potential preservative for the food and drug industry. © 2020 Society of Chemical Industry.

Application of essential oils as antimicrobial agents against spoilage and pathogenic microorganisms in meat products.

Meat and meat products are perishable products that require the use additives to prevent the spoilage by foodborne microorganisms and pathogenic bacteria. Current trends for products without synthetic preservatives have led to the search for new sources of antimicrobial compounds. Essential oils (EOs), which has been used since ancient times, meet these goals since their effectiveness as antimicrobial agents in meat and meat products have been demonstrated. Cinnamon, clove, coriander, oregano, rosemary, sage, thyme, among others, have shown a greater potential to control and inhibit the growth of microorganisms. Although EOs are natural products, their quality must be evaluated before being used, allowing to grant the Generally Recognized as Safe (GRAS) classification. The bioactive compounds (BAC) present in their composition are linked to their activity, being the concentration and the quality of these compounds very important characteristics. Therefore, a single mechanism of action cannot be attributed to them. Extraction technique plays an important role, which has led to improve conventional techniques in favour of green emerging technologies that allow to preserve better target bioactive components, operating at lower temperatures and avoiding as much as possible the use of solvents, with more sustainable processing and reduced energy use and environmental pollution. Once extracted, these compounds display greater inhibition of gram-positive than gram-negative bacteria. Membrane disruption is the main mechanism of action involved. Their intense characteristics and the possible interaction with meat components make that their application combined with other EOs, encapsulated and being part of active film, increase their bioactivity without modifying the quality of the final product.

Beetroot and radish powders as natural nitrite source for fermented dry sausages.

The aim of this study was to investigate the use of radish and beetroot powders as potential substitutes of nitrite in fermented dry sausages due to their high nitrate content (around 16,000 and 14,000 mg/kg, respectively). Six treatments were prepared and evaluated during the ripening process and storage time: C1 (control with 150 mg/kg sodium nitrite and 150 mg/kg sodium nitrate), C2 (control without sodium nitrite/nitrate), R05 (0.5% radish powder), R1 (1% radish powder), B05 (0.5% beetroot powder) and B1 (1% beetroot powder). The addition of vegetable powders influenced moisture content, weight loss and water activity of sausages. Nitrite was formed from radish and beetroot powders during the ripening process, especially in R1 and B1 treatments. Beetroot powder affected colour, pigments and lactic acid bacteria counts. The results of pH, colour, lipid oxidation, nitrite and nitrate analysis suggest R1 treatment as a potential nitrite replacer obtained from a simple and feasible drying process.

Chemistry, safety, and regulatory considerations in the use of nitrite and nitrate from natural origin in meat products - Invited review.

Nitrite and nitrate have been traditionally used for the preservation of meat products because of the effective antimicrobial action of nitrite against Clostridium botulinum, the outgrowth of its spores as well as other bacteria. However, the use of nitrite and nitrate has been questioned in last half century due to the possible generation of N-nitrosamines through reaction of nitrite with secondary amines. Nitrite replacement strategies began in the 70s addressing these issues and instigated searches for natural alternatives to nitrate and nitrite, or for natural sources of nitrite and nitrate such as vegetable extracts. These alternatives have been considered by producers and consumers as an attractive practice even though they may also have some risks. This manuscript reviews and discusses the chemistry, safety, and regulatory considerations in the use of nitrite and nitrate from natural origin for the preservation of meat products.

A water-soluble polysaccharide from Anethum graveolens seeds: Structural characterization, antioxidant activity and potential use as meat preservative.

A novel water-soluble polysaccharide named AGP1 was successfully isolated from seeds of Anethum graveolens by hot water extraction and further purified by DEAE-Sepharose chromatography. AGP1 has a relative molecular weight of 2.1 104 Da determined by Ultra-high-performance liquid chromatography (UHPLC). The AGP1 characterization was investigated by chemical and instrumental analysis including gas chromatography mass spectrometry (GC-MS), Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction. Results showed that AGP1 was mainly composed of glucose, galactose, mannose and arabinose in a molar percent of 54.3, 23.8, 14.7 and 7.2, respectively. The thermogravimetry analysis (TGA) and the differential scanning calorimetry (DSC) were used and showed that AGP1 has good thermal stability until 275 °C. Moreover, the purified polysaccharide demonstrated an appreciable in vitro antioxidant potential. The addition of the AGP1, particularly at 0.3% (w/w), in turkey sausages instead of ascorbic acid, as preservative, reduced the lipid peroxidation, preserved the pH and color and improved the bacterial stability during cold storage at 4 °C for 12 days. Overall, the results showed that the AGP1 deserves to be developed as functional and bioactive components for the food and nutraceutical industries.

Shelf-life extension of pomegranate arils using chitosan nanoparticles loaded with Satureja hortensis essential oil.

BACKGROUND: This study was conducted in two parts to improve the antimicrobial activity and stability of Satureja hortensis essential oil (SEO) and its impacts on the quality of pomegranate arils. In the first part, SEO was encapsulated by an ionic gelation technique into 142.2-267.7 nm chitosan nanoparticles (CSNPs). In the second part of the experiment, the CSNPs and CSNPs-SEO were applied to improve storability of pomegranate arils. Arils were dipped in water (control), CSNPs and CSNPs-SEO for 5 min. After superficial water removal, arils were packed into polystyrene boxes and stored at 5 °C for 18 days. RESULTS: Based on spectrophotometry analysis, the encapsulation efficiency (EE) of SEO-loaded CSNPs (CSNPs-SEO) decreased from 26.57% to 7.41% and their loading capacity (LC) increased from 4.72% to 6.17%, respectively, upon increasing the initial SEO content from 0.125 to 0.5 g g-1 of chitosan. Phytochemicals and water content were maintained, and microbial counts were reduced in the coated arils during storage. Total phenol and antioxidant activity decreased during storage. At the end of storage, the highest total phenol content (2980.0 mg gallic acid equivalents L-1 ) was found in arils treated with CSNPs-SEO, whereas ascorbic acid content was maximal (6.32 mg L-1 ) in arils treated with CSNPs. The encapsulation of savory essential oil in chitosan nanoparticles did not have undesirable effects in pomegranate arils. CONCLUSION: Pre-storage treatment of pomegranate arils with CSNPs-SEO could be considered a beneficial treatment to better maintain the biochemical and sensorial quality during storage. © 2020 Society of Chemical Industry.

Leptospermum petersonii as a Potential Natural Food Preservative.

Leptospermum petersonii (family Myrtaceae) is often cultivated for ornamental purposes but also serves as a rich source of bioactive essential oils. While several studies focused on the activities of the essential oils, this study analysed the potential of spent L. petersonii leaves as a natural food preservative. METHOD: We investigated the in vitro antioxidant and antimicrobial activities of crude L. petersonii extracts against activities of the purified isolated flavonoid, 6-methyltectochrysin, which was characterized using spectroscopic methods. The antioxidant assays followed ORAC, FRAP and TEAC tests. The antimicrobial activities of the extract and purified flavonoid were analysed against six multi-drug resistant microbial strains in broth dilution assays. RESULT: The results revealed that both the crude extracts and isolated 6-methyltectochrysin exhibited positive radical ion scavenging antioxidant potential, however the crude extract was about 6-fold more potent antioxidant than the purified 6-methyltectochrysin. The crude extract also showed strong antimicrobial activities against Bacillus cereus, and even more potent antimicrobial agent than the reference ampicillin antibiotic against Klebsiella pneumoniae subsp. pneumoniae. A higher resistance was observed for the tested Gram-negative strains than for the Gram-positive ones. 6-methyltectochrysin was generally inactive in the antimicrobial assays. CONCLUSION: The crude methanolic extract showed significant bioactivity which validates the medicinal relevance of the plant. The observed biological activities, especially against a notorious strain of B. cereus, suggest that L. petersonii could be a promising natural source of food preservatives.

Modulation of volatile release and antimicrobial properties of pink pepper essential oil by microencapsulation in single- and double-layer structured matrices.

The bioactivity of essential oils applied in foods to act as natural preservatives can be reduced due to interactions with other components of the food matrix. Microencapsulation can help to increase the functionality of these compounds. In addition, the electrostatic interaction between proteins and polysaccharides can result in double-layered encapsulating structures, ensuring greater protection to essential oils than using only protein as surface active agent. In this work, pink pepper essential oil was microencapsulated by spray drying of single-layer emulsions, stabilized by soy protein isolate (SPI), and of double-layer emulsions, stabilized by soy protein isolate/high methoxyl pectin (SPI/HMP). Pink pepper essential oil showed predominance of α-pinene, ß-pinene, ß-mircene, δ-3-carene, d-limonene, and germacrene D. Compared to SPI microcapsules, SPI/HMP microcapsules better preserved the total volatile content identified in pure oil, showed less water adsorption during storage at relative humidity ≥75% and improved antimicrobial properties. When stored for 20 days (25 °C/RH = 52.8%), both microcapsules allowed more gradual release of volatiles compared with non-encapsulated oil. Microencapsulation by spray drying did not have negative effects on the antioxidant activity of the encapsulated oil, as the microcapsules showed similar results to the non-encapsulated oil, around 11 µg Trolox/mg of oil. After storage, however, the non-encapsulated oil showed greater losses of its antioxidant activity due to higher rates of volatile release. In the in vitro antimicrobial activity assay, both microcapsules inhibited growth of Staphylococcus aureus, Bacillus subtilis, Listeria monocytogenes and Listeria innocua, although no inhibition was observed against Gram-negative bacteria. When added in milk, both microcapsules reduced bacterial growth, whereas non-encapsulated oil showed no satisfactory inhibition. Faster reduction of microbial growth in milk was observed for SPI/HMP microcapsules. Inhibition results were better for skim milk than for whole milk, suggesting that the interaction of essential oil with other lipids present in milk decreased its bioactivity. Microencapsulation positively affected the functionality of pink pepper essential oil, highlighting its potential for application as a natural preservative in food products.

Improvement of in vitro and in situ antifungal, AFB1 inhibitory and antioxidant activity of Origanum majorana L. essential oil through nanoemulsion and recommending as novel food preservative.

Origanum majorana essential oil (OmEO) encapsulated into chitosan nanoemulsion is being reported as a novel preservative of stored food items against fungi, aflatoxin B1 (AFB1) contamination and lipid peroxidation. The major component of OmEO identified through GC-MS was terpinen-4-ol (28.92%). HR-SEM, FTIR and XRD analyses confirmed successful encapsulation of OmEO into chitosan nanoemulsion (OmEO-CsNe). The results showed remarkable improvement in efficacy after nanoencapsulation, since OmEO-CsNe completely inhibited the growth and AFB1 production by Aspergillus flavus at 1.0 µL/mL, which was 2.5 and 1.5 µL/mL, respectively for OmEO. The inhibition of ergosterol followed by release of cellular ions and 260 and 280 nm absorbing materials demonstrated plasma membrane as possible antifungal target. Inhibition of methylglyoxal confirmed antiaflatoxigenic mode of action. OmEO-CsNe showed enhanced antioxidant activity (IC50 = 14.94 and 5.53 µL/mL for DPPH and ABTS, respectively) and caused in situ inhibition of lipid peroxidation and AFB1 production in maize (third most important staple crop after wheat and rice) without altering their sensory attributes and presented safety profile (LD50 = 11,889 µL/kg) when tested on mice. The findings indicate that the encapsulation considerably enhances the performance of OmEO, therefore can be recommended as a promising antifungal agent to extend the shelf-life of food items.