Postharvest physiology
M. R. Zandi; A. Aboutalebi Jahromi; B. Behroznam; A. Zakerin
Abstract
Introduction
Strawberry is one of the most important small fruits in the world, which is cultivated as a perennial plant in temperate regions of the world. Ripe strawberry fruit contains compounds such as protein, fiber, sugars such as fructose, glucose, sucrose, organic acids, vitamins, minerals, ...
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Introduction
Strawberry is one of the most important small fruits in the world, which is cultivated as a perennial plant in temperate regions of the world. Ripe strawberry fruit contains compounds such as protein, fiber, sugars such as fructose, glucose, sucrose, organic acids, vitamins, minerals, as well as phenolic compounds and anthocyanins. The aim of this study was to investigate some hormonal treatments and magnetic field on some physiological and biochemical characteristics, shelf life and postharvest life of strawberry cv. Selva under temperature stress.
Materials and Methods
This experiment was performed as a split plot based on a completely randomized design with 3 replications. Physiological and biochemical characteristics were studied on several tissues of Selva strawberry cultivar under several different temperature treatments. The treatments were gibberellic acid at three levels of control, 50 and 100mg/l in the main plots, magnetic field at 3 levels of control, 10 and 20ms, in the subplots and temperature stress in three levels including 2, 8 and 20°C. It was done on strawberries in subplots. Healthy prepared strawberry fruits were subjected to magnetic treatments and then immersed in hormonal solutions for 2min and after drying, stored for 8 days in different refrigerators at temperatures according to research treatments. The samples were then removed from the refrigerator and transferred to a laboratory to measure various characteristics. The studied traits included: fruit weight, fruit diameter, fruit length, fruit moisture content, titratable acidity, fruit juice pH and vitamin C.
Results and Discussion
Results of analysis of variance showed that the simple and triple interactions of treatments on all studied traits were significant. Comparison of the mean triple interaction of gibberellic acid treatment × magnetic field × temperature showed that the highest amount of fruit weight (19.49g), the highest amount of fruit diameter (33.7mm), the highest fruit length (48.62mm), the highest fruit moisture (34.65%) was obtained in the treatment of 50mg/l gibberellic acid, ten Tesla magnetic field and a temperature of eight degrees Celsius. The lowest fruit weight of 10.65 g was obtained in the treatment of non-use of gibberellic acid, non-use of magnetic field and temperature of 20°C. The lowest fruit weight loss of 3.74% was obtained in the treatment of 50 mg/l gibberellic acid, 20 Tesla magnetic field and 2°C. The lowest fruit diameter of 21.52mm was obtained in the treatment of non-consumption of gibberellic acid, absence of magnetic field and temperature of 20°C. The lowest fruit length of 25.63 mm was obtained in the treatment of no gibberellic acid, no magnetic field and a temperature of 20°C. The lowest amount of titratable acidity (0.31%), the lowest pH of fruit juice (4.68) and the highest amount of vitamin C (34.92mg/100 ml) in the treatment of non-use of gibberellic acid, no use of field Magnetic and a temperature of 20°C were obtained. The lowest amount of vitamin C was equal to 20.5mg/100ml in the treatment of no use of gibberellic acid, no use of magnetic field and a temperature of 20°C.High concentrations of gibberellic acid have a beneficial effect on increasing cell division and fruit size. Gibberellic acid increases fruit size and weight due to its effect on increasing cell division in the early stages of fruit development and increasing cell size at late fruit ripening. Magnetic field also affects plant metabolic activity. Fruit volume includes fruit length. It decreases due to the magnetic field. Fruit weight showed a significant positive correlation with fruit diameter, fruit length, fruit moisture and vitamin C. In terms of the triple interaction of the research treatments, the best effective treatment for increasing the storage time of strawberries was the combined treatment of 50 mg/l gibberellic acid and ten Tesla magnetic field and a temperature of 8°C.
Conclusion
Fruit weight showed a significant positive correlation with fruit diameter, fruit height, fruit moisture and vitamin C. In terms of the triple interaction of the research treatments, the best effective treatment for increasing the storage time of strawberries was the combined treatment of 50 mg/l gibberellic acid and ten Tesla magnetic field at a temperature of 8°C.
Ali Hasani; Mohammad Hadi Khosh Taghaza; Mohammadtaghi Ebadi
Abstract
Introduction: Drying of medicinal and aromatic plants (MAPs) is a widely spread method offering physico-chemical stabilization by taking away part of the moisture content, producing different products with different qualitative properties and economical value. The main purpose of MAPs drying is ...
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Introduction: Drying of medicinal and aromatic plants (MAPs) is a widely spread method offering physico-chemical stabilization by taking away part of the moisture content, producing different products with different qualitative properties and economical value. The main purpose of MAPs drying is to extend product shelf life, minimize packaging requirements and reduce shipping weights. Drying is used to stop the growth of microorganisms and preserve the quality of MAPs. There are different drying methods and their suitability can be determined by energy efficiency, drying time, preservation of active substances and other quality properties of the product, depending on market demand. Therefore, determining a suitable drying method to achieve higher active substances in medicinal plants is very important. Advantages of infrared drying include high efficiency of conversion of electrical energy into heat, a suitable alternative source for thermal energy, and uniform heating of the product surface. The aim of this study was to investigate the effect of infrared drying on drying time and the qualitative characteristics of sumac fruit (total color changes, total phenolic content, organic acids, and vitamin C). Material and Methods: Sumac fruits (from the forests of Sardasht city in West Azerbaijan Province, Iran) were used after complete separation from clusters and additional parts for drying and performing the desired treatments. In this research, an infrared dryer was used to dry the sumac sample which was made by the Department of Biosystems Engineering of Tarbiat Modares University. For this study, a factorial experiment was performed based on a completely randomized design. In this experiments, three levels of radiation intensity (0.2, 0.3 and 0.5 watts per square centimeter) and three levels of air velocity (0.5, 1 and 1.5 meters per second) were used. The sample tray inside the dryer was connected by a rod to a digital scale at the bottom of the dryer. The scale had a computer connection port that could measure and record the weight of the fruits continuously during drying. To determine the initial moisture content, 3 samples (50 g) were placed in an oven at 105 °C and after three hours, the samples were taken out of the oven and weighed, and finally the moisture content of the product was calculated on wet basis. The initial moisture content of sumac fruits was approximately 17%. Drying was continued until the product reached a moisture content of 7%. Drying time and quality characteristics of sumac fruit (color changes, total phenolic content, organic acids, and vitamin C) were measured. Colorimeter (Hunterlab, Color Flex model, USA) was used to check the color changes of sumac fruits during drying and the total color changes ( ) compared to the fresh sample were calculated. To measure the total phenolic content, Folin-Ciocalteu phenol reagent was used by a spectrophotometer (Samsung, Smart Spec Flus model, South Korea). Titration method was used to measure vitamin C and organic acids. Finally, based on all the mentioned parameters, the optimization was performed by Design Expert software (version 10) and the best score was obtained based on the utility index. Results and Discussion: The results showed that the intensity of infrared radiation and air velocity had a significant effect on the studied characteristics except total phenolic content. The minimum and maximum drying times were obtained at the highest and lowest infrared intensities and air velocities, respectively. Increasing the infrared intensity and subsequently increasing the temperature had a negative effect on the total color changes, organic acids and vitamin C, so that the least total color changes and the highest amount of organic acids and vitamin C were obtained by reducing the intensity of infrared radiation. The lowest total color change and the highest amount of organic acids were obtained in the treatment of 0.2 W cm-2 × 1.5 m s-1 and the highest amount of vitamin C in 0.2 W cm-2 × 1 m s-1 and 0.3 W cm-2 × 0.5 m s-1 treatments, respectively. The values obtained from the optimization parameters for the studied indicators (drying time, total color changes, organic acids, and vitamin C) showed that the best point for drying of sumac fruit was the infrared radiation intensity of 0.3 W cm-2 and air velocity of 0.5 m s-1. In this treatment, the highest utility index obtained by software was 0.71. Conclusion: Infrared drying reduced the drying time of sumac fruit compared to traditional drying methods (shade and sun drying). In addition to reducing the drying time, infrared drying was a suitable method for preserving the phytochemical properties and color changes of sumac fruits.
Mohsen Mozaffari; Farhang Razavi; Vali Rabiei; Azizollah Kheiry; Akbar Hassani
Abstract
Introduction: Demand for healthy and high-quality fruits has increased in the markets, and compositions such as vitamins, sugars, and anti-oxidant properties of fruits have attracted many consumers. Grapes contain phenols, flavonoids, anthocyanins, tannins and vitamins with high antioxidant properties. ...
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Introduction: Demand for healthy and high-quality fruits has increased in the markets, and compositions such as vitamins, sugars, and anti-oxidant properties of fruits have attracted many consumers. Grapes contain phenols, flavonoids, anthocyanins, tannins and vitamins with high antioxidant properties. Antioxidants support biological systems such as proteins, amino acids, lipids, and DNA against oxidative damage produced by active oxygen species of ROS, resulting in reduction of cell damage and death, cardiovascular disease and cancers in the human body. Selenium is essential for humans and animals and should be fed through a diet, for this reason, FAO recommends entering selenium to agricultural products (especially fruits and vegetables). In recent years, selenium has been recognized as a useful element for plants that have been toxic at high concentrations but at desirable concentrations, it has positive antioxidant effects, increases growth and significantly affects seed germination. Selenium protects plants from several abiotic stresses such as heavy metal and arsenic, ultraviolet radiation, and biotic stress such as pathogens and pests. Selenium neutralizes oxidative stress interfering with lipid peroxidation, and accelerates gluthatione peroxidase (GSH-Px) activity, this phenomenon delay plant senescence and diminish postharvest losses. This element increases the yield and improves the quality of the fruits and vegetables. When Camelia oleifera plants were treated with selenium, cellular content of linoleic acid and sterol were elevated but oleic acid content diminished. Selenium treatment had a significant effect on preserving the sensory and the postharvest quality by decreasing respiration rate and ethylene biosynthesis in broccoli by diminishing phenylalanine ammonia-lyase (PAL) activity and ethylene production in lettuce and chicory. Foliar application of peach and pear trees with selenium, decelerated fruit softening rate and elongated shelf-life. Therefore, treatment of agricultural products with the appropriate amount of selenium can have a positive effect on the increase of the quality and enrichment of selenium in fruits and also play an important role in human health.
Materials and Methods: In order to investigate the effect of selenium as foliar application (0, 1, 2 and 3 mg L-1) on quality traits, antioxidant compounds and enrichment of grape cv. Fakhri, an experiment based on randomized complete block design with three replications in a vineyard (Kurdistan Povince, Ghorveh town) was performed. The 15-year-old vines were sprayed with selenium solution plus 0.1% of Twin 20 as surfactant until the leaves were completely wet (for each vine about 0.5 liter) at three stages of berry growth and development: Berry formation, Lag phase and veraison. A 1000 mg L -1 stock solutions (Made by the Belgian company CHEM-Lab, containing selenium ion Se+6) was used to prepare the desired solutions. At commercial fruit maturity stage (20° Brix), samples of fruits and leaves randomly were collected from treated and control vines and were immediately transferred to the postharvest physiology laboratory. Traits such as total chlorophyll, carotenoid, nitrogen, potassium, selenium content of leaves and fruits, and also, total soluble solids, soluble sugars, titrable acidity, acidity (pH), vitamin C, phenol and flavonoids, antioxidant capacity in fruits and the berry weight were evaluated. Data were analyzed using SAS statistical software (SAS V.9.4), and means were compared by Duncan’s multiple range tests at the 5% of probability level.
Results and Discussion: Results showed positive effects of selenium treatment on evaluated traits. As a result, 2 mg L-1 of selenium increased photosynthetic pigments, nitrogen and leaf potassium, soluble solids, soluble sugars, vitamin C, total phenol, antioxidant capacity of fruits in comparison with untreated vines. The highest amount of titrable acidity, total fruit flavonoid and leaf selenium was recorded in vines treated with 3 mg L-1 selenium, whereas, this treatment had less effect on other traits. The highest amount of berry weight was obtained in 1 mg L-1 of selenium. However, none of the selenium treatments had significant effect on the juice acidity (pH). In general, the results showed a positive effect of selenium on improvement of antioxidant properties, quality and enrichment of grape, and 2 mg L-1 selenium with the highest effect on traits was identified as the best treatment. According to other researchers, foliar application of selenium in "Starking Delicious" apple cultivar was effective in enhancement of fruit selenium content and nutritional properties, postponing the flesh firmness decrease, and delaying fruit ripening resulting from less ethylene production, therefore significantly affecting apple fruit quality and storage life.
