Mohammadreza Asghari; mohammad Tohidian
Abstract
Introduction: Asaclimactericfruit, peach has a highrespiration rateandvery lowshelf life. Nowadays theuse ofappropriatepostharvesttechnologiesto increase fruit postharvest lifeis necessary.Use of nanotechnologyis considered asan effective method to increase fruit postharvest life. Nanotechnology isused ...
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Introduction: Asaclimactericfruit, peach has a highrespiration rateandvery lowshelf life. Nowadays theuse ofappropriatepostharvesttechnologiesto increase fruit postharvest lifeis necessary.Use of nanotechnologyis considered asan effective method to increase fruit postharvest life. Nanotechnology isused extensivelyinallstages of production, processing, storage, packagingand transport ofagriculturalproducts.The objective of this study was to investigate the effect of silver and silica nanocomposites, nanosilver and polypropylene containers on shelf-life and preservation of peach qualitative characteristics (Prunuspersicacv. Elberta) such as titrable acidity, soluble solids, ascorbic acid, total antioxidant and total phenolics content in cold storage after the harvest.
Materials and Methods: To determine the effect of nanopackaging onshelf life andqualitativecharacteristics ofElberta peaches,the experiment was conducted in a factorial based on a completely randomized design with two treatmentsand four replications.The first factor consisted of nanopackagingnanosilver, silver and silica nanocompositesandpolypropylenepackaging, and the second factor was coldstorage periods of15, 30 and 45 daysattemperaturesfrom 0 to0/5 °C and a relative humidityof 85to 95%.In general, the experiment consisted of 36 experimental units, and each includinga container with four Elberta peach fruits.Data were analyzed by using SAS software, and Microsoft Office Excel 2010 software was used to plot the graphs.Duncan's multiple range test was used to compare the means of treatments.
Results and Discussion: At the end of the maintenance period, the highest firmness of peach texture was related to nanosilver containers. The main cause of fruit softening is the destruction of cell wall components, especially pectin, which is caused by certain enzymes such as polygalactronase. Whenstorage timeincreased, polypropylene containers showed a higher weight loss compared to nanocomposite containers, thus the results indicated that nanopackaging had a greater effect on preventing weight loss, which could be attributed to the formation of better barrier against water molecules. Nanoparticles and polypropylene containers up to 30-daystorage period preserved the pH of the product to some extent and prevented it from increasing too much. However, with an increase in storage time from 30 to 45 days, the pH of all dishes showed sharpincrease. In most treatments, fruits grew during the maintenance period, which is due to the reduction of organic acids. The lowest levels of organic acids reduction were recorded in polypropylene and nanosilver treatments. Generally, organic acids decreased as a result of respiration or becoming sugars, whichcan bedirectly related to metabolic activity. Maintaining organic acids in fruits is the result of a slowdown in the processes of ripeningand aging and reduction inrespiration and other metabolic activities. The results showed that in all the three treatments, the amount of soluble solids up to 15-day periodshowed an increasing trend, and after the end of day 30, it stopped in nanosilver and polypropylene treatments, and soluble solids were retained but reduced in nanocomposite treatment showed that this decrease. Nanocomposite containers exhibited the best performance in maintaining ascorbic acid content and preventing its changes, while ascorbic acid content in nanosilver and polypropylene containers varied greatly, thoughthere were no significant differences among thetreatments. Low oxygen environments, such as packaging containers, can inhibit ascorbic acid changes during maintenance by inhibiting oxidation. The results showed that total antioxidant level was almost identical in all treatments at the end of maintenance. Antioxidant activity has a close relationship with phenolic compounds, flavonoids and vitamins. The antioxidant capacity of fruits and vegetables is related to enzymatic and non-enzymatic compounds such as vitamin C, phenolic compounds, and carotenoids. Treatments reducingrespiration and producingethylene can reduce the rate of aging,the rate of free radical production and the consumption of antioxidants. Based on the results, on the day 30 in all treatments, the amount of phenolic compounds initiallyincreased, which is normal in red fruits, but afterwards decreased in all treatments mainly due to the increased activity of the polyphenol oxidase enzyme and the progression of aging. Increasing the amount of phenol on the day 30 can be attributed to decreased activity of the polyphenol oxidase enzyme and the oxidative stress associated with high concentrations of oxygen.
Conclusion: Nanopackaging increased the shelf life and qualitative properties of peach fruit. Nanotechnology has a simple and fast process for industrialization compared to other methods of keeping food products. As a result, the use of modern technologies such as nanopackaging can improve the taste, favor, quality of food and the storage of crops, especially fruits and vegetables.
