Characterization and application of the nanocompiste packaging films containing clay and TiO2 on preservation of tomato fruit under cold storage.

BACKGROUND: Tomato (Lycopersicon esculentum), a valuable economic crop worldwide, often goes to waste due to improper packaging and handling. In the present study, three types of low-density polyethylene nanocomposite films containing 3% clay (Closite 20A), 3% TiO2 nanoparticles, and their combination were synthesized using melt blending method, and evaluated on the quality parameters of tomato fruit during 42 days of storage at 4 °C. RESULTS: Transmission electron microscopy confirmed the degree of dispersion and exfoliation of the nanoparticles. The TiO2/clay-nanocomposite films exhibited notable enhancements in Young's modulus and tensile strength compared to conventional films. The addition of clay and TiO2 nanoparticles resulted in reduced permeability to CO2, O2, and water vapor. Fruits packed with clay/TiO2 nanocomposite films showed decreased ethylene production, mitigated weight loss, and maintained pH, titratable acidity, total soluble solids, and firmness. Furthermore, clay/TiO2 nanocomposite films enhanced membrane stability, decreased membrane lipid peroxidation, and enhanced catalase and ascorbate peroxidase enzyme activity in fruits. CONCLUSIONS: The relatively good exfoliation of clay nanoparticles and the proper dispersion of TiO2 nanoparticles, which were confirmed by TEM, led to an increase in mechanical and physical properties in the Clay/TiO2 nanocomposite. This film displayed more potential in maintaining the quality properties of tomato fruit during cold storage. Therefore, this film can be considered a practical solution for minimizing pathogen risks and contamination, and enhancing the overall quality of tomato fruit.

Morphological diversity of indigenous wild pomegranate (Punica granatum L. var. spinosa) accessions from northeast of Iran.

Wild pomegranate is a valuable edible species in the plant ecosystem of the Hyrcanian forests and the northern plains of the Caspian coast in Iran. The genetic diversity of these wild pomegranates can be effective in pomegranate breeding programs and germplasm conservation. In the present study, morphological diversity in 103 wild pomegranates (Punica granatum L. var. spinosa) in the northeastern area of Iran was studied using 46 traits related to trees, flowers, and fruits. The results showed that the fruit weight ranged from 17.93 to 99.9 g with an average of 48.92 g, the total aril weight ranged from 0.54 g to 64.78 g with an average of 24.25 g, and the weight of 100 arils was between 4.89 and 46.21 with an average of 13.79. The fruit cracking percent, crown shape, aril juiciness, calyx, and corolla colors show a high coefficient of variation (CV > 70%). Based on PCA results, fruit weight and total aril weight, peel weight, and fruit length and diameter were important on determining differences among accessions. In biplot analysis, genotype distribution was determined by two main factors. In cluster analysis, the studied accessions were divided into two different major clusters and two subclusters in each one. The results showed a high diversity of important pomological traits in wild pomegranates such as fruit weight, fruit cracking percent, crown shape, total aril weight, aril juiciness corolla, and calyx color that can be used in breeding programs to improve pomegranate juice quality and marketability.

Alleviation of postharvest chilling injury in sweet pepper using Salicylic acid foliar spraying incorporated with caraway oil coating under cold storage.

The decrease in the postharvest quality of sweet peppers in terms of the physiological disorders resulting from cold storage (<7-10°C) results in the significant economic losses. The ability of pre-harvest foliar spraying of Salicylic acid (SA) (1.5 and 3 mM) and the postharvest caraway (Carum carvi) oil coating (0.3% and 0.6%) on chilling injury (CI) and the quality of stored sweet pepper at 4 ± 2°C for 60 d followed by an additional 2 d at 20°C were investigated. The antifungal activity of caraway oil (0.15%, 0.3%, and 0.6%) on Botrytis cinerea mycelia in in vitro showed that the maximum percentage of inhibition was equal to 95% in the medium with 0.6% of this oil. The CI of sweet pepper was significantly reduced by increasing SA, and caraway oil concentrations compared to the control, especially the lowest CI (14.36%), were obtained at 3 mM SA and 0.6% caraway oil treatment. The results showed a significant delay in the changes of weight loss (79.43%), firmness (30%), pH (6%), total soluble solids (TSS) (17%), titratable acidity (TA) (32%), and color surface characteristics and capsaicin content (5%) compared to control fruits at 3 mM SA and 0.6% caraway oil concentrations. Results indicated that the decrease in CI was related to a decrease in electrolyte leakage, malondialdehyde (MDA) content, total phenolic production, decay incidence, and an increase in the activity of antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD). Thus, the incorporation of SA (3 mM) and caraway oil (0.6%) to reduce the CI of stored sweet pepper at low temperature can be considered a practical solution to improve the quality and marketability of this product.