Babak Madani

Effect of calcium chloride treatments on calcium content, anthracnose severity and antioxidant activity in papaya fruit during ambient storage

BACKGROUND There have been no reports on the effects of preharvest calcium application on anthracnose disease severity, antioxidant activity and cellular changes during ambient storage of papaya, and therefore the objective of this study was to investigate these effects. RESULTS Higher calcium concentrations (1.5 and 2% w/v) increased calcium concentration in the peel and pulp tissues, maintained firmness, and reduced anthracnose incidence and severity. While leakage of calcium-treated fruit was lower for 1.5 and 2% calcium treatments compared to the control, microscopic results confirmed that pulp cell wall thickness was higher after 6 days in storage, for the 2% calcium treatment compared to the control. Calcium-treated fruit also had higher total antioxidant activity and total phenolic compounds during storage. CONCLUSION Calcium chloride, especially at higher concentrations, is effective in maintaining papaya fruit quality during ambient storage.

Preharvest calcium applications improve postharvest quality of papaya fruits (Carica papayaL. cv. Eksotika II)

ABSTRACT This research was conducted to evaluate the effects of calcium chloride (CaCl2) and calcium nitrate Ca(NO3)2 on nutrient concentrations and postharvest quality of papaya fruits. In the first experiment, plant stem height increased significantly after Ca(NO3)2 application compared to CaCl2. The calcium content in the peel and pulp for both sources [CaCl2 and Ca(NO3)2] significantly rose with increasing calcium concentrations, but there was a significantly higher content of calcium in fruit peel and pulp in the CaCl2 treatment. Magnesium and potassium in fruits decreased with increasing calcium concentrations. A reduction in anthracnose lesion diameter in the infected fruit with increasing calcium was observed in both CaCl2 and Ca(NO3)2 treatments. Ethylene production in fruits decreased with increasing calcium concentrations. In the second experiment, only CaCl2 was used as the calcium source, and results showed that the calcium content in fruit peel and pulp significantly increased at higher CaCl2 levels, whereas ethylene production, anthracnose lesion diameter, and magnesium content decreased compared to control.

Mitigation of salt-induced oxidative damage in Chinese kale (Brassica alboglabra L.) using ascorbic acid

Salinity could become a threat to hydroponically grown plants due to the differential ion uptake process by the crop itself and/or using low quality irrigation water containing non-essential ions such as sodium and chloride. This study was conducted to determine the interactive effects of salinity and foliar application of ascorbic acid (AsA) on the survival capacity of Chinese kale plants. Three-week-old plants at the 4-leaf stage were exposed to salinity by application of 0, 50 and 100 mM NaCl for 14 days. The activities of antioxidant enzymes, catalase (CAT), peroxidase (POX) and ascorbate peroxidase (APX) along with changes in the accumulation of proline, lipid peroxidation and chlorophyll content in leaves were estimated. Salinity induced obvious changes in the activities of antioxidant enzymes, lipid peroxidation, proline accumulation and chlorophyll content in the leaf tissues. Exogenous application of AsA (5 and 10 mM) to stressed plants resulted in a significant increase (P < 0.05) in APX activity and reduction in the activities of antioxidant enzymes (CAT and POX) as well as a decrease in the contents of stress-induced proline and malondialdehyde (MDA). Higher chlorophyll content was also recorded in stressed plants using AsA. The inherent capability of AsA to scavenge free radicals may have assisted the plant using the lower oxidative damages. The results of this study showed that AsA treatment would reduce the deleterious effects of salt-induced oxidative stress and improve plant tolerance to salt stress.

Suitability of combination of calcium propionate and chitosan for preserving minimally processed banana quality

BACKGROUND The marketability of fresh-cut banana slices is limited by the rapid rate of fruit softening and browning. However, there is no scientific literature available about the role of postharvest calcium propionate and chitosan treatment on the quality attributes of fresh-cut banana. Therefore, the aim of the present study was to investigate these effects. RESULTS The application of calcium propionate plus chitosan (CaP+Chit) retained higher firmness, higher ascorbic acid content, higher total antioxidant activity and higher total phenolic compounds, along with lower browning, lower polyphenol oxidase, lower peroxidase, lower polygalacturonase and lower pectin methyl esterase activities and microbial growth, compared to control banana slices after 5 days of cold storage. CONCLUSION The results of the present study show that CaP+Chit could be used to slow the loss of quality at the same time as maintaining quality and inhibiting microbial loads.