Antioxidants are diverse groups of biological compounds, including phenolic compounds, flavonoids, alkaloids, and terpenoids, which act as free radical scavenging. Fruits are the natural antioxidant resources that constitute principal dietary components. Therefore, identifying the type and amount of antioxidant compounds in different fruits and the factors affecting them is crucial to achieving a diet rich in antioxidants. The quality and quantity of antioxidant compounds in fruits are influenced by various factors such as climate, species and cultivars, fruit developmental stage, processing methods, and storage conditions. In horticulture, fruits are divided into three categories based on climatic origin, including temperate fruits (rich in anthocyanins and phenolic acids) such as apples, grapes, and berries, subtropical fruits (rich in flavonoids and phenolic acids) such as pomegranate and olives, and tropical fruits (rich in flavonoids and carotenoids) such as bananas and mangoes. Also, there is a significant variation in the quantity and quality of antioxidant compounds in a specimen of fruits, which can be the basis for selecting parents by breeders to achieve antioxidant-rich cultivars. The amount of phenolic compounds in fruits is related to the degree of fruit maturity or ripening, and usually, with increasing age, the amount of phenolic compounds increases. From a processing point of view, recently, the use of wine and olive industry waste products has been considered as a potential source of dietary or food preserving antioxidants. In this review, various antioxidant compounds in different fruits have been considered, and the factors affecting their quality and quantity are discussed.

Introduction: Food-borne pathogens are causes of poisoning and gastrointestinal infections. In recent years, it is recommended to use natural materials like plant extracts and essences instead of chemical preservatives in food industry. Therefore, the aim of this study was to identify the phenolic compounds of ethanolic walnut kernel and its antimicrobial effect on some food-borne pathogens.Methods: In this experimental study, after collection of walnut kernel, its ethanolic extract was prepared. Then its antimicrobial activity on salmonella typhimurium, shigella disentriae, listeria monocytogenes was examined as Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) using microdilution method.Chloramphenicol (30mg) was used as the reference antimicrobial agent. Total phenols, flavonoids and flavonols were also determined by colorimetric method.Results: The results showed that MIC was between 0.625 and 1.25 mg/ml and MBC was between 1.25 and 2.5mg/ml for ethanolic extract. Total phenols were 365 ± 14.71mg/g gallic acid equivalent, and total flavonoids and flavonols were 285±12.25 and 132 ± 1.63mg/g rutin equivalent, respectively.Conclusion: These findings showed that walnut kernel has antibacterial effects on three aforementioned bacteria and can substitute for chemical preservatives. More studies, such as examinations in food models are needed to unravel the antimicrobial effects of this plant.

Quantitative and qualitative study of phenolic compounds (phenolic acids, flavanols and anthocyanins) in peel of Gala apple were implemented using analytical HPLC, fluorescence microscopy and epi-illumination light microscopy at  three different growing stages [1- fruit early growing stage 2- mid-stage of fruit development (80 days after full bloom) 3- during commercial harvest time]. The results showed qualitative and quantitative differences between diverse growing stages regarding the content and accumulation of phenolic compounds. HPLC and microscopic studies showed that anthocyanin content of peel increased progressively during season. Microscopic data revealed that the highest anthocyanin accumulation occurred at the commercial harvest time. Our results showed that phenolic acids content decreased till mid-season but then, after their content had increasing pattern until commercial harvest time. Microscopic pictures verified this claim as well. Simultaneous comparison of HPLC and microscopy of derived data showed that flavanol content of peel increased towards mid season. In contrast, a drastic decline was recorded for flavanols during commercial harvest time. Comparative survey of microscopic and chromatographic data indicated that the great potential of fluorescence microscopy for study of phenolic compounds in apple peels. In brief, integrated study of phenolic compounds by means microscopic and chromatographic techniques is fast and easy methods for identification and quantification of phenolic compounds leading to accurate conclusion regarding elevation of apple fruit quality criteria.

Many industries generate phenolic pollutants during their manufacturing processes. Most of these compounds are toxic and have been classified as hazardous pollutants. Soybean peroxidase (SBP) catalyzes the oxidation and polymerization of phenolic compounds in the presence of hydrogen peroxide. The polymerized products can easily precipitate and be filtered from the solution. In this study phenolic solutions such as synthetic wastewater containing phenol, o-cresol and m-cresol, were treated with soybean peroxidase (SBP). The effect of some parameters was investigated on the removal process. The results showed that, an increase in hydrogen peroxide up to the optimum amount leads to an elevated removal of phenolic compounds. Higher concentrations of H2O2 inhibited the reaction. Treatment in the presence of PEG (polyethylene glycol) as an additive increased the effect of enzymatic removal. Application of different concentrations of the enzyme in the reaction mixture showed positive regression between enzyme concentration and removal of phenols. Studies to determine the optimum pH for enzyme activity revealed that elimination of phenols was improved in neutral pH. In addition, this study revealed that intact soybean seed-hulls were effective on the elimination of phenolic compounds in synthetic wastewater; treatment time significantly affected the concentration of seed-hulls needed for removal of phenols.

To evaluate antioxidant activity of some natural phenolics, tallow olein was employed as a lipid system. Since animal fats are weak in natural antioxidants, studying antioxidant activity will provide a desirable behavior profile for them. Edible sheep tail fat was effectively fractionated by acetone crystallization at constant temperatures of 25, 15 and 5°C. In order to stabilize mutton tallow olein, antioxidant activities of some phenolic compounds including gallic acid, caffeic acid, catechin,quercetin, tannic acid, ellagic acid and salicylic acid were studied in tallow olein as a lipid system, at 150°C at 40, 60, 80, 100, 200 and 400 mg/L concentrations, by measuring induction time. Rancimat apparatus was employed as a mean to evaluate the antioxidant activity. The results indicated that gallic acid had the highest stabilizing effect on tallow olein while ellagic acid had the least effect as primary antioxidants. Among phenolic compounds investigated, only salicylic acid showed no antioxidant activity which is in contrast to all other antioxidant compounds. The results showed that, in tallow olein, the antioxidant activities of the ellagic and tannic acid are comparable to a-tocopherol whereas quercetin, catechin, gallic acid and caffeic acid are much more potent than a-tocopherol.

Background: Trigonella L. is a well-known worldwide growing genus of the Fabaceae family. In addition to food, the plants have various medicinal properties, including reducing fat and blood sugar, antibacterial, anti-ulcer, and analgesic. Objective: Variability in agro-morphological traits, phenolic compounds, and proximate composition of the aerial parts of some Iranian Trigonella and its relative e. g. Medicago L. species was studied to introduce the superior species for further use in breeding and exploitation programs. Methods: The seed samples of T. astroides, T. elliptica, T. filipes, T. foenum-graecum, T. spruneriana, M. crassipes (syn: T. crassipes), M. monantha (syn: T. monantha), M. monspeliaca (syn: T. monspeliaca), M. orthoceras (syn: T. orthoceras), and M. phrygia (syn: T. aurantiaca) were collected from different regions of Iran, and then were cultivated at the same agronomic conditions. Morphological traits were measured by a ruler, digital caliper and scales. Proximate composition (moisture, ash, fibre, protein, fat, and carbohydrates) and phenolic acids of the aerial parts were determined by the AOAC method and HPLC, respectively. Results: Significant morphological differences among the studied species were observed. The highest protein content was measured in M. orthoceras (13. 4 ± 0. 4 %), followed by T. filipes (11. 5 ± 0. 8 %), and T. spruneriana (11. 1 ± 0. 4 %). Fibre content was ranged from 0. 7 ± 0. 04 % to 4. 9 ± 0. 4 %. In the extracts of the studied species, catechin, chlorogenic acid, and pcoumaric acid were found in abundance (0. 01 ± 0. 05-69. 32 ± 0. 7 mg/g DW). Conclusion: Trigonella filipes and T. spruneriana could be selected as suitable species for further exploitation in food and pharmaceutical industries.