جستجوی مقالات مرتبط با کلیدواژه "پوسیدگی میوه" در نشریات گروه "زراعت"

Postharvest fungal diseases can limit the storage period and shelf life, and thus market life of fruit and vegetables, which results in serious economic losses worldwide. Despite the efficacy of synthetic fungicides in the control of postharvest decay, public concerns about chemical and toxic residues in food and the increase in drug-resistant strains of many pathogens indicate the need for development of new strategies. Coatings and packaging materials have been considered as another method for increasing the postharvest storage time of fruits and vegetables. Chitosan-based nano composites are proper alternatives to mitigate the negative impacts of conventional coatings and films on human and environmental health. Additionally, natural chitosan coatings and packaging incorporated with functional compounds decrease the postharvest losses of fruits and vegetables without changing their nutritive and sensorial properties. Therefore, the current research work was performed to investigate the effectiveness of chitosan and chitosan nanofiber on the quality and storability of strawberry fruit cv. Paros. 

This study was conducted in the form of a factorial experiment based on a completely randomized design with two factors and three replications. The first factor was treatments in 5 levels including dry control, distilled water, chitosan 0.5%, chitosan nanofibers 0.2% and chitosan nanofibers 0.5% and the second factor was storage time in 5 levels including: Zero, 5, 10, 15 and 20 days. The treatments were applied as a 2-minute immersion of the fruits in the prepared solution at ambient temperature (25 ° C), and the samples were stored after drying in plastic disposable containers at 4°C and relative humidity of 85 to 90%. At the end of the storage periods, the values of weight loss, pH of fruit juice, total soluble solids, titratable acidity, and firmness of fruit tissue, color indexes, total anthocyanin, total phenol content, vitamin C content, antioxidant activity and percentage of decay of the aforementioned treatments were evaluated. 

The results showed that at the end of the storage period, the 0.5% chitosan nanofiber treatment was able to maintain the TA value 77% higher than the control at same-day. Also, the TSS of 0.5% and 0.2% chitosan nanofiber treatments was lower than the control, which indicates a delay in the tissue softening of coated fruits due to a lower breakdown of sugars. On the 20th day of storage, the pH, TSS/TA, and the percentage of weight loss in the treatment of 0.5% chitosan nanofiber were lower than the control; the explanation for the rise in pH of control fruits is due to the decrease in organic acids and potential sugar conversion. The highest value of firmness between treatments was found in the 0.5% chitosan nanofiber treatment (3.11 Newton) after 20 days of storage. The semi-permeable surface of coated fruits may have contributed to fruit firmness persistence by limiting metabolic gaseous exchange (oxygen and carbon dioxide) across the coating barrier, followed by a decrease in metabolic activity and oxidizing enzyme effectiveness. The highest content of vitamin C, total phenol, and total anthocyanin were in the 0.5% chitosan nanofiber treatment, which showed a significant difference from other treatments. At the end of storage, the percentage of antioxidant activity of fruits in coating treatments including 0.5% chitosan nanofiber, 0.2% chitosan nanofiber, and 0.5% chitosan, 25%, 14%, and 5%, respectively, was higher than the dry control. Higher contents of color indexes including Lightness (L*), Redness (a*), yellowness (b*) and Chroma, and lower values of Hugh angle were observed in fruit coated with chitosan nanofiber. The percentage of decay in chitosan nanofiber-treated fruits (0.5% and 0.2%) and chitosan (0.5%) decreased by 61%, 55%, and 43% more than the control, respectively.

The present study found that using a 0.5% chitosan nanofiber coating was the most effective way to maintain the quality of strawberries during storage for up to 20 days. It allowed good preservation quality such as weight loss, decay, antioxidant activity, firmness, color, Vitamin C, anthocyanin content, and total phenolic compounds. However, 20 days is a sensitive period for the commercialization of strawberries, considering the normal time of 7–14 days is generally accepted. Consequently, various storage strategies can be applied to suit the market needs.

The occurrence of the micro-dusts phenomenon as a result of environmental changes as well as reduction of rainfall and drying of wetlands in the country have begun since two decades ago and are increasing every year. At the same time, as the micro-dusts phenomenon occurs, the probability of transmission of the pathogenic agents on various crop products, such as dates will cause significant damage, quality degradation and marketability of this fruit. This issue has a particular importance in the commercialization and export of dates specially for Medjool variety. During the years 2013-2015, sampling was done from infected fruit tissues of different growth stages of Medjool variety consist of Khalal, Kharak, Rotab and date which were exposed to dust and samples were cultured in potato dextrose agar (PAD) culture medium. After examining the samples, the relative frequency of the most prevalent fungi causing rotting was determined in the date fruit. The fungi Alternaria alternata, Aspergillus niger, A. phoenicis, Helminthosporium sp., Fusarium sp., and Rhizopus stolonifer were isolated and identified as agents of the fungal rot from fruits infected with dust. Results showed that under relatively humid conditions, exposure of palm fruit by micro-dusts will increase the severity of rotting damage by 8.53% and the fruit falling by 13.43%. Results also indicated that amount of fruit rotting affected by this phenomenon was higher during the Rotab stage and early stage of ripening compared to the late stages of fruit ripening. Therefore, it is recommended that the covering of fruit clusters should be carried out before the time that Kharak turns into Rotab, so that the palm fruit can be protected from damages caused by fungal agents of rotting and dust contamination.

This experiment was carried out based on a completely randomized design with three replications. Essential oils of Salvia macrosiphon, Hypericum perforatum and Zhumeria majdae at two levels: 250 and 500 ml/l and calcium chloride (2% and 4%) were applied on fruits that had been immersed in Botrytis cinerea spores, stored at a temperature of 4±1℃ and then kept for 16 days. Fruit decay (%), pH, fruit weight loss (%), TTS (%), total acid (mg/100 ml), tissue firmness ,color and changes in vitamin C were measured. Result showed that essential oils and calcium chloride had significant effect on fruit decay. Decay completely controled in all treated fruit expect Salvia macrosiphon (500 ml/l). The lowest and highest water loss was observed in calsium chloride (4%) and Salvia macrosiphon essential oil (500 ml/L) treatments, respectively. Tissue firmness was significantly higher in treated fruits than in control. Generally, calcium chloride (2% and 4%) and Salvia macrosiphon at 250 and 500 ml/l level showed the highest firmness. The lowest TSS (%) was shown in control fruits. Fruits treatment with calcium cheloride (2% and 4%) and essential oils of Zhumeria majdae at 250 and 500 ml/l level showed significantly higher vitamin C content. In general, all calcium chloride and essential oil treatments (except Zhumeria majdae at 250 ml/l) showed better color than the control. This research revealed that calcium chloride and Essential oils of the above three plants were effective in decay control and maintaining strawbery fruit quality during 16 days storage.