Honey is a naturally sweet substance that the bee collects from the nectar of flowers and sap of plants, after adding various enzymes, processing and evaporating excess moisture, it stores it in the hive. The aim of this study is investigating the changes in the antioxidant activity of the 10 honey samples under different storage conditions [The samples were heated in water bath (48 Degree Celsius for 1 day and 80 Degree Celsius for 4 minutes), or kept at room temperature (25 Degree Celsius) for 3 and 6 months. Then they were re- evaluated for antioxidant activity]. Antioxidant activity by three methods: DPPH, beta-carotene-linoleic acid and reduction power method in honey samples evaluated. Measurements for all methods used in this research were done in three replications for each sample. Data were analyzed by SPSS software. Kolmogorov-Smirnov test was used to check the normality of the distribution of variables. The one-way ANOVA was used to compare the mean between groups. According to the results, antioxidant activity of honeys were increased under thermal condition and were decreased during storage. Storage and processing condition (thermal treatment) can cause changes in antioxidant activity as well as the quality of honey.
Various natural oils/extracts and their constituents incorporated into biopolymer-based edible films as a promising technology with the knowledge that these compounds have been able to reduce microbial growth and chemical changes of packed foodstuffs. The objective of this study was to evaluate the effect of incorporation of Ziziphora clinopodioides essential oil (ZEO; 0, 0.25 and 0.5%) and sesame oil (SO; 0, 0.5 and 0.75%) into chitosan-flaxseed mucilage (CH-FM) film against Listeria monocytogenes, Salmonella typhimurium, Staphylococcus aureus and Escherichia coli O157:H7 in vitro condition and raw minced trout fillets during refrigerated condition. The in vitro antibacterial and antioxidant properties of CH-FM films were evaluated using agar disk diffusion method and free radical scavenging activity assay, respectively. The most important constituents of ZEO were found to be carvacrol (65.22%), thymol (19.51%), ɣ-terpinene (4.63%) and p-cymene (4.86%). The lowest and highest antimicrobial effect against S. aureus, L. monocytogenes, E. coli O157:H7 and S. typhimurium were found for CH-FM films enriched with SO 0.5% (0.98-1.24 mm) and ZEO 0.5% + SO 0.75% (5.01-6.25 mm), respectively. The antioxidant property of CH-FM based films were found to be ranged 5.45% ± 0.04-37% ± 0.45. In treated trout fillets, the counts of L. monocytogenes, S. aureus, E. coli O157:H7 and S. typhimurium were 1.54-4.18, 0.34-3.35, 0.29-1.45 and 0.19-1.27 log CFU/g significantly lower than control groups after two weeks of refrigerated storage, respectively. The designated films had good antibacterial effect against some food borne pathogenic bacteria including L. monocytogenes, S. aureus, S. typhimurium and E. coli O157:H7 in raw rainbow trout fillets.
Background: Honey, a naturally sweet food product, exhibits several health beneficial effects. The quality of honey differs by its microbiological, physicochemical, and antioxidant properties, which can significantly vary from brand to brand and country to country. Objectives: This study aimed to assess the physicochemical properties and antioxidant activity of honey brands distributed in Tehran City, Iran, and compare these parameters with national and international standards. Methods: Five brands (Shakelli, Khansar, Golagin, Shafi, and Kral) of honey in Tehran were selected, and 5 samples of each brand were collected from supermarkets and analyzed by standard methods for physicochemical properties and antioxidant activity. The collected data were analyzed using SPSS software, version 20. Results: The results depicted significant differences among studied honey brands in all physicochemical properties (except for ash, total reducing sugars, and sucrose content) and antioxidant activity (P<0.05). The moisture, ash, pH, free acidity, total reducing sugars, sucrose, diastase, and 5-hydroxymethylfurfural (HMF) contents of honey brands ranged within 16.30%-15.34%, 0.24%-0.40%, 4.27-4.39 units, 9.15-10.68 meq/kg, 77.84%-79.74%, 3.66%-4.57%, 2.28-3.28 DN (diastase number), and 6.67-11.84 mg/kg, respectively. Thus, the physicochemical properties of studied honey brands, except for diastase activity, were within national and international legal ranges. Moreover, total phenolic contents (TPC) and radical scavenging activity (RSA) of 1,1-diphenyl-2-picrylhydrazyl (DPPH) of honey brands ranged within 28.72-39.36 mg GAE/100 g and 63.83%-73.91%, respectively. In addition, a highly significant positive correlation was observed between TPC and RSA of DPPH of honey samples (r=0.798, P<0.01). Conclusion: The studied honey brands were of good quality and met national and international standards.
The aim of the present study was to evaluate antioxidative effects of water and ether extracts of Iranian Urtica dioica , during its pre and post flowering on vegetable oil during storage. Different concentration of water and ether extracts (0, 200, 400, 600, 800 and 1000 ppm) and β-Hydroxy toluene (BHT; 200 ppm) were added to sunflower oil emulsion in the presence of cupric ions and incubated for 7 days at 60°C. Peroxide values (PVs) and thiobarbituric acid reacting substances (TBARS) levels were measured each day up to day seven. Furthermore, antioxidant capacity of the extracts was determined using DPPH and β-Carotene linoleic acid methods. Values were compared among groups in each incubation time points using 1-way ANOVA. Results showed that DPPH and β-Carotene-linoleic acid assay findings on the U. dioica extracts were comparable to those found for BHT. Furthermore, in all incubation time points, U. dioica extracts lowered PVs and TBARS levels significantly when compared with the control (p<0.001). In this respect, the water extract was more potent than the ether extract. In addition, antioxidant properties of the water extracts in post flowering stage were similar to those of BHT in the same concentration (200 ppm). It seems that water extract of the post flowering U. dioica is a potent antioxidant for oil and oily products.
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