Food Chemistry
Mahbobe Mohammadi; Soheila Aghaei Dargiri; Somayeh Rastegar
Abstract
The use of edible coatings has been considered as an effective solution to improve the shelf life and quality of fruits. In this research, increase in the shelf life of citrus fruits (Citrus aurantifolia cv. Mexican lime) coated with Persian gum and pomegranate seed oil was investigated. Different treatments ...
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The use of edible coatings has been considered as an effective solution to improve the shelf life and quality of fruits. In this research, increase in the shelf life of citrus fruits (Citrus aurantifolia cv. Mexican lime) coated with Persian gum and pomegranate seed oil was investigated. Different treatments of lemon fruit coated with Persian gum and pomegranate seed oil with concentrations (zero (control), 0.5% and 1% gum, combination of 0.5% and 1% gum and pomegranate seed oil, 0.05% and pomegranate seed oil 0.05 percent) were prepared and after 24 days of storage at ambient temperature (20 ± 2 °C and relative humidity of 50-60 percent) were statistically evaluated in the form of a completely random design with three replications. The results of this research showed that the treatments used had an effective role in controlling the weight loss of fruit during storage. Thus, the lowest percentage of weight loss was observed in the pomegranate seed oil treatment. Except pomegranate seed oil treatment, other treatments showed less TSS than the control. In most of the treatments, the content of phenol, flavonoid and antioxidant was at a higher level than the control. The average comparison results showed that the fruits coated with 1% gum (85.36 units/ml) showed significantly more peroxidase activity than the control (60.35 U/ml). Persian gum edible coating 1% and 0.5% as well as Persian gum 1% in combination with pomegranate seed oil significantly controlled the activity of polyphenol oxidase enzyme. The treated samples showed less yellowness (b*) than the control. In general, the best marketability was observed in fruits coated with 1% gum. Therefore, it is recommended to use this coating to preserve the freshness and quality of the Mexican lime fruit during storage in the environment.
Somayeh Rastegar; Azam Shojaee; Behjat Tajeddin
Abstract
Introduction: Persian walnut (Juglans regia) from Juglandaceae family is one of the most important fruits in the world that has an important role in human health. It contains a notable list of plant nutrients that has been found to have disease preventing and health promoting properties. Walnut is a ...
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Introduction: Persian walnut (Juglans regia) from Juglandaceae family is one of the most important fruits in the world that has an important role in human health. It contains a notable list of plant nutrients that has been found to have disease preventing and health promoting properties. Walnut is a source of bioactive compounds such as phenolic and flavonoid complexes where they act as antioxidants and free radical scavengers. It also contains pleasant flavor and high concentration of minerals and fatty acids. Extending shelf-life of this perishable fruit has been accomplished due to its high oil level and oxidation of oil (Tajeddin, 2004). Rate of loss in walnut kernel quality and quantity between harvest and consumption affects its productivity. Control of temperature is the most effective tool for extending the shelf life of fresh horticultural products. However, to reduce high losses and keeping product’s quality, packaging method is very important as well as low temperature. Therefore, in this study, the effect of temperature (4 and 25 oC) and packaging methods (vacuum and air packaging) on the changes of walnut kernel compounds was evaluated to improve quality of its storability during six month cold storage.
Materials and methods: Walnut harvested from a commercial garden at the mountain regional of Raber, Kerman province. All chemical materials for different tests obtained from Merck Company, Germany. Immediately after walnuts harvesting, they were dehulled and dried in expose of sun shade with the circulation of natural air. The walnuts were then transferred to the laboratory and their wooden shells were removed. Subsequently, about 25 g of walnut kernel was packaged in the polyethylene films with 87μm (0.087 mm) thickness, under a vacuum machine and stored at 4°C and 25°C to be later assessed for further analyses intended for six months. Phenol, flavonoid, carbohydrate, protein, water percent, color parameters (C, h, WI), organoleptic characteristics, and peroxide value of kernels were measured every month during storage time. The control samples of packaged walnuts under environmental conditions were also stored. The current study carried out as a factorial assay on the basis of a completely randomized design with three replications at Hormozgan University. Data were subjected to ANOVA using SAS software version 9.4. Verification of significant differences was done using Duncan's Test at 1% probability level.
Results and discussion: Results showed that carbohydrate and proteins decreased during storage time. Both of vacuum package and low temperature contorted the reduction of different characteristics of kernel such as bioactive compounds during storage significantly. Sensory properties were also reduced during storage, especially at the end of period, in all conditions except for treatment at 4°C and vacuum packing. Control samples (temperature 25°C and air-containing packags) during the experiment showed a lower quality for all factors. Samples that stored in low temperature and vacuum package had better brightness (higher chroma, Hugh, lightness (L) and white index values (Wi)) than other treatments. The treatments had a significant role in the preventing of increasing peroxide value. The peroxide value in treated samples was increased from 0.023 to 0.68 meq/g, while in vacuum packages it was changed from 0.023 to 0.37 meq/g. Increasing of peroxide value was observed from 0.023 to 0.68 and from 0.023 to 0.25 meq/g in room temperature and cold temperature, respectively. After six months, the average peroxide value in all samples was less than one milliequivalent per oil kilogram. Decreasing of phenolic compounds (30%) and flavonoids (35%) and increasing the peroxide index simultaneously led to the reduction of the appearance and organoleptic properties of the control samples. Generally, vacuum package and low temperature condition that using in this study showed the best effect on the nutritional compounds quality of walnut kernel such as bioactive components during six months storage. Shelf life enhancement of walnut by vacuum packaging in the different polymers has been already reported by Tajeddin, 2004.
Saeedeh Zarbakhsh; Somayeh Rastegar
Abstract
Introduction: The date palm (Phoenix dactylifera L.) plays an important social, environmental, and economic role for many people living in arid and semiarid regions of the world. Fruits of the date palm are very commonly consumed in many parts of the world and considered as a vital component of the diet ...
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Introduction: The date palm (Phoenix dactylifera L.) plays an important social, environmental, and economic role for many people living in arid and semiarid regions of the world. Fruits of the date palm are very commonly consumed in many parts of the world and considered as a vital component of the diet and a staple food in most Arab countries. Nearly 2000 cultivars of date palm are known in the world, but only some have been evaluated for their performance and fruit quality. Dates are rich in certain nutrients and provide a good source of rapid energy, due to their high carbohydrate content (70–80%). Moreover, date fruits contain fat (0.20–0.50%), protein (2.30–5.60%), dietary fiber (6.40–11.50%), minerals (0.10–916 mg/100 g dry weight), and vitamins (C, B1, B2, B3, and A) with very little or no starch. The aim of the present work was to investigate the chemical composition, carbohydrate, and antioxidant capacity of two date palm varieties grown in Hormozgan and Farce province.
Materials and methods: After collection, all date samples were washed with tap water, and the seeds were removed, dried at room temperature under shadow. Moisture content was determined by drying samples in oven at 60 °C until constant weight was attained. The determination of proteins was done by Bradford method. Color measurement of fruit made using a portable CR-400 colorimeter (Minolta Chroma Meter CR-400 Osaka japan).Total polyphenols were determined as described by Waterhouse, 2002.The results were expressed as milligram gallic acid equivalents per 100 g of dry weight (mg GAE/100 g DW). Total flavonoids content (TFC) of the date extracts were measured according to the colorimetric assay of Chang et al., 2002. The hydrogen peroxide (H2O2) scavenging ability of palm dates was carried out using 2, 2-diphenyl- 1-picryl hydrazyl (DPPH) spectrophotometric method described by Choi with some modification.
Results and Discussion: Based on the results, The highest fruit length (43.6 mm), weight of pulp (9.3 g) and antioxidant activity (57 mgFW) were found in Piarom date of Hajiabad and the highest phenol (20.7 mg/gFW), TSS (77.3%) and titratable acid (0.023%) were recognized in Zahedi date of Hajiabad. Although date varieties from Jahrom showed better color index and tannin content than Hajiabad date. In comparison between two varieties, Piarom date was better in fruit weight (28.3 g), moisture content and protein content (7%) and flavonoids (22.2 mg CEQ/gFW) than the Zahedi date. However, the carbohydrate of Zahedi date (85%) was higher than the Piarom date. Therefore, in addition to the variety, location and climate condition also have the important role in determining the nutritional value of date palm fruit.
