جستجوی مقالات مرتبط با کلیدواژه "olive leaf" در نشریات گروه "صنایع غذایی"

Oxidation and food pathogens are considered two important and influential factors affecting food quality and health. Recently, due to the increasing demand for natural products, the application of synthetic preservatives to control microbial growth and lipid oxidation have been decreased significantly. Therefore, natural antioxidant and antimicrobial compounds are receiving more attention in food preservation technologies. In the last 2 decades, the use of herbal medicines rich in bioactive molecules (including polyphenols, carotenoids and flavonoids) with medicinal and health effects such as delaying the onset of some diseases such as cardiovascular disorders, diabetes, and cancer have increased. Furthermore, secondary metabolites in plant extracts and essential oils are able to control and inhibit free radical-mediated reactions. The olive tree (Olea europaea) is an evergreen plant that grows in tropical and subtropical regions. Iran is one of the most important olive growers in the world due to its suitable conditions for olive cultivation. The leaves of the olive plant have a high potential for the production of various products such as tea and extracts. Olive leaf extract can be used as a raw material in the production of various products, due to exhibiting various biological activities such as antimicrobial and antiviral activity, lipid stabilizer, blood pressure regulator, antioxidant activity, and free radical scavenger. The leaves of the olive tree also contain various phenolic compounds, mainly Oleuropein and hydroxytyrosol, with antioxidant and antimicrobial activities. Therefore, in this study, the amount of phenolic and flavonoid compounds of olive leaf ethanolic extract and its antioxidant effect and antimicrobial properties on Escherichia coli, Enterobacter aerogenesis, Bacillus cereus and Listeria innocua were investigated. 

The olive leaf ethanolic extract was prepared through maceration method and its total phenolic content (Folin-Ciocalteu method), total flavonoids content (aluminum chloride colorimetric assay), antioxidant activity (ABTS and DPPH free radical scavenging methods), and antimicrobial effect on E. coli, E. aerogenesis, B. cereus and L. innocua (based on disk diffusion agar, well diffusion agar, minimum inhibitory concentration, and minimum bactericidal concentration) were determined according to standard methods. Data were analyzed by SPSS software through one-way ANOVA and Duncan test at p<0.05.  

The ethanolic extract of olive leaves contained 176.58 ± 0.72 mg GAE/g total phenol and 69.85 ± 0.26 mg QE/g total flavonoids. In addition, ethanolic extract of olive leaf was able to inhibit free radicals DPPH (70.62 ± 0.59%) and ABTS (76.15 ± 0.43%). The antimicrobial results showed that the antimicrobial effect of the extract depended on its concentration and type of bacteria. Antimicrobial effect was increased as a function of ethanolic extract, and Gram-positive bacteria (B. cereus and L. innocua) were more sensitive to ethanolic extract of olive leaf than Gram-negative bacteria (E. aerogenesis and E. coli). Generally, B. cereus and E. aerogenesis were the most sensitive and resistant microbial strains to ethanolic extract of olive leaf, respectively.The results of this study showed that the high antioxidant and antimicrobial activity of olive leaf ethanolic extract is mainly due to its phenolic and flavonoid compounds. Olive leaf ethanolic extract was able to neutralize DPPH and ABTS free radicals. Also, Gram-positive bacteria were more sensitive to ethanolic extract of olive leaf than Gram-negative bacteria. In general, the ethanolic extract of olive leaf can be used as a nutraceutical to control or prevent the growth of spoilage/infection-causing microorganisms and free radical reactions in food and the human body. However, more in-depth studies are needed to determine the mechanism of antimicrobial and antioxidant effects of olive ethanolic extract in vitro and in vivo.

Flaxseed oil is sensitive to oxidation due to its high content of polyunsaturated fatty acids. Antioxidant sources such as olive leaves can be used to stabilize it. Olive leaves contain lipase and lipoxygenase enzymes that need to be removed before use. Therefore, the aim of this study was to investigate the extraction of oil by cold pressing of flax seeds with blanched leaves steamed at levels (0 (control sample), 2.5, 5, 7.5 and 10% w / w ) is. Acidity, peroxide, phenolic content, fatty acid composition, chlorophyll content, carotenoid content and oxidative stability of extracted flaxseed oil were investigated during storage. The results showed that by adding different levels of blanched olive leaves, the acidity and peroxide number decreased and the amount of carotenoids, chlorophyll, phenolic compounds content and oxidative stability of oil samples in different levels of blanched olive leaves significantly increased compared to the control sample(P <0.05). On the other hand, during the storage period in the treated samples, the acidity and peroxide number of the samples increased significantly (P <0.05) but this increase was less than the control sample. Also, fatty acid profiles showed that by adding blanched olive leaves, the linolenic acid (18: 3) was preserved during further storage. According to the obtained results, it can be said that with the addition of blanched olive leaves, phenolic compounds in the produced oil increased and also oxidative stability increased and beneficial compounds such as linolenic acid and more carotenoids were preserved and a useful oil can be produced and offered to the consumer market.

Olive leaf extract as a rich source of phenolic compounds has significant anatioxidant and antimicrobial properties, but its direct addition to foods has disadvantages due to bitter taste. Encapsulation by nanoliposomes is one of the useful methods to carry bioactive compounds such as phenols. Therefore, aim of this study was to evaluate addition of nanoliposomes carrying olive leaf extract to butter stability.

First nanoliposomes of olive leaf extract was prepared and at 0 (control sample), 50, 100, 200 and 400 ppm spiked to butter samples, then stored in refrigerator for 80 days, and their physicochemical properties (moisture and fat content, fatty acid profile, acidity and peroxide value), microbial properties (total sycrotroph content) and organoleptic properties (bitter taste, rancidity and general acceptance) evaluated.

Obtained results showed that addition of olive leaf extract nanoliposomes had no effect on butter composition, however, it could prevent from increasing of acidity and peroxides. Microbial analysis also showed that nanoliposomes spiking could prevent from microbial deterioration of butter samples. Organoleptic tests also showed nanoliposomes effect on prevention of olive leaf bitter taste exposure and also rancid taste development of butter samples.

Encapsulation as nanoliposomes is a advanced and useful methods to fortify butter with phenolic compounds of olive leaf and prevention from chemical and microbial spoilage and enhancement of its shelf life.

Olive leaf consumption due to its antioxidant properties and several applications in medicine and pharmaceutical sciences is considered from ancient time. In this research effect of different drying methods including oven drying at 60 °C and 105 °C, microwave drying at 400 W and 700 W and shadow on methanolic extraction of olive leaf were evaluated. Antioxidant properties were assayed using 2,2-diphenyl-1-picrylhydrazyl (DPPH), ABTS, and ferric reducing ability of plasma (FRAP) and also total phenolic and flavonoid content were measured using Folin-Ciocalteu and aluminum chloride respectively. Olive leaf contains 55.17% moisture, 6.12% ash, 3.18% fat, 8.21% protein, 8.58% polysaccharide, 18.48% insoluble carbohydrate, and 27.32% total carbohydrate. Results showed that drying method affect antioxidant properties and phenolic and flavonoid extraction significantly. By increasing the concentrations of extracts, their anti-radical activity increased and the radical scavenging ability of extracts depended on their concentration. Highest antioxidant property were seen in 400 W microwave and the lowest results were in oven drying at 60 °C.

Medicinal herbs contain large secondary compounds that often have important biological activity, and since extracts of plants are widely used in the pharmaceutical, food, and health industries, various extraction methods are very important. One of these herbs is the olive leaf, which has more beneficial properties than other parts due to its phenolic compounds, its antioxidant and antimicrobial effects. The purpose of this study was to determine the optimal conditions for extraction of bioactive compounds in the olive leaf of Minoodasht area of Golestan province, using by subcritical water method and its antibacterial effect on Staphylococcus aureus and Escherichia coli bacteria by the methods of Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) and Disc Distribution. Optimum extraction conditions were carried out at temperatures 120-180 ° C, under a pressure corresponding to the extraction temperature and mixing ratio of 1:20, with physicochemical properties (efficiency, turbidity, and brix). Antimicrobial properties (MIC and MBC) of extracts extracted by each and every one (soaking and subcritical water) against Staphylococcus aureus and Escherichia coli bacteria in concentrations of 25-5130 ppm with three replications, the results showed that the effect of high concentrations of bioactive compounds in extracts obtained by the subcritical water method on gram-positive bacteria of Staphylococcus aureus. Also, in the disk diffusion method, resistant gram-negative bacteria of Escherichia coli and Staphylococcus aureus was the most sensitive bacteria.

Different intrinsic and extrinsic factors may initiate the oxidation of lipids. The initial products of oxidation are tasteless and odorless and after degradation and production of secondary products, the off-flavors and off-odors will appeare in edible oils. This is a great concern in food industry, because it decreases the shelflife of food products. Free radicals are produced during chain reactions in lipid oxidation process. To avoid this, synthetic antioxidants are usually used which are sensible to heat and are hazardous to human health and may cause cancer. Polyphenols have antioxidant activity and absorb free radicals. Thus, the vegetable oils rich in polyphenols can affect human health. In this research, we aimed to investigate the application of natural extract of olive leaves as a natural antioxidant to avoid soy oil oxidation and to compare it with synthetic antioxidants. Matherials and In this project, methanol and acetone solvents in an ultrasonic apparatus were used to extract the phenolic compounds of the leaves of Mary and Yellow varieties of olive. The amount of phenolics, as well as their antioxidant effect on the oxidation of crude soybean oil, was investigated. The phenolic contents were measured by Folin–Ciocalteu method and the antioxidant activities of the extracts were determined by two controlling methods of DPPH radical-scavenging activity and Ferric reducing power, and then the results were compared with antioxidant activities of synthetic antioxidants.The antioxidant effects of different concentrations of the extracts on delaying the oxidation of crude oil were studied by determining their peroxide and thiobarbitoric acid values. The leaves of Mary variety showed the highest amount of phenolics (101.382mg/g), as determined by measureing the phenolic contents. The results suggested that the methanolic extract of Mary variety had a better antioxidant activity than the other natural antioxidants, compared to synthetic antioxidants BHT and TBHQ. In addition, it was shown that the radical scavenging activity was directly correlated with the increase of the extract concentration. Then the methanolic extract of Mary variety at three levels 100, 200 and 500 ppm and BHT and TBHQ antioxidants at 100 and 200 ppm were added to antioxidant-free soy oil. The control oil, which lacked antioxidants, showed the highest peroxide and thiobarbitoric acid values. The methanolic extract of the Mary variety showed the highest extraction efficiency as well as the most antioxidant activety. In addition, it was shown that the radical scavenging activity was increased by the increase of extract concentration. The methanolic extract of Mary variety at the concentration of 500 ppm was comparable with the synthetic antioxidants at the levels of 100 and 200ppm.

The aim of this study was to compare the effects of olive leaf extracts and synthetic antioxidant BHT at Concentration of 1% at increase the shelf life of rainbow trout fillets in light salted and packed at 4±1 °C that Index of peroxide (PV), free fatty acids (FFA), Thiobarbituric acid (TBA), Humidity, pH and sensory evaluation of fillets of rainbow trout kept in the refrigerator at the time of Zero, 3, 6, 9, 12 and 15 were measured. Based on the statistical results, PV was in all treatments significantly over time decline (P<0.05), Also TBA and FFA values over time in all treatments significantly increased (P<0.05) but TBA, PV and FFA of antioxidant samples compared with control samples was significantly at all times to lower (P<0.05). Also Methanol extracts olive leaves at 1% as good as control the peroxide value and thiobarbituric acid and replace synthetic antioxidants is such as Butylated hydroxytoluene at level 100 ppm. According to the results of organoleptic test and no significant difference between both antioxidants can advised be use types of antioxidants to keep the fish. According to the results the research olive leaf extract had more efficiency on increasing of shelf life, smell, texture of the fish fillets.