Abstract
Minimally processed pomegranate aril sacs are highly sensitive due to their increased respiration and transpiration rate. Although whole pomegranate fruit can be stored for up to two months at 4–5°C, this extended storage can negatively impact the shelf-life of aril sacs. Given the health benefits of pomegranate fruit and the rising global demand for minimally processed fruits, there is a critical need to understand and enhance the postharvest quality of these arils. This study aimed to formulate and assess the performance of methyl cellulose-based edible coatings enriched with nanomaterials to extend the storability of minimally processed pomegranate aril sacs during and after withdrawal from cold storage (shelf-life).
Two distinct studies were conducted to achieve this aim. In the first study, a methyl cellulose-based edible coating was functionalised with zinc oxide nanoparticles (ZnONPs) at concentrations of 0, 0.1, 0.25, 0.5, and 1%. Fresh pomegranates were minimally processed into aril sacs, coated for 5 minutes, packed in punnets, and stored at 4°C for 24 days. Quality attributes such as firmness, weight loss, respiration rate, total soluble solids (TSS), titratable acidity (TA), and total phenolic content were measured. Coated samples showed significant improvements (p<0.05), in reduced weight loss, retained firmness, and lower respiration rates when compared with uncoated controls.
In the second study, methyl cellulose-ZnONP composite coatings were reinforced with cellulose nanofibers (CNF) at 0, 0.5, 1, 3, and 5% to enhance barrier properties. Pomegranate were stored at 5°C for two months, thereafter, sanitized, minimally processed into aril sacs, and coated for 5 minutes. After treatment, the aril sacs were stored at 5°C for 15 days, with quality assessments conducted every three days. CNF-reinforced coatings outperformed ZnONP-only, maintaining firmness, reducing weight loss, and reducing respiration rate more effectively.
On overall, these findings demonstrated that ZnONPs incorporated into methyl cellulose-based coatings can preserve the shelf-life of minimally processed pomegranate aril sacs. Additionally, CNF reinforced coatings showed superior performance in maintaining fruit quality after prolonged storage, suggesting significant potential for reducing postharvest losses in imported fruits.