Use of Edible Coatings to Preserve Date Fruits (Phoenix Dactylofera L.)

Abstract

Here, the physical and chemical properties of date fruits were improved using three types of edible coating: pectin (P), methyl cellulose (MC) and olive oil. Dry and semi-dry date fruits were heated at 50 °C for 3 h and then treated with various coating formulations. The date fruits were drained, dried and stored for 3 and 6 months at room temperature in zip-lock plastic bags and brown paper bags. The experiments led to the measurement of fruit moisture percentage, total soluble solids (TSS), firmness, total tannin content and total phenolic content (TPC). According to the results, the coated date fruits generally contained higher percentages of moisture than the untreated fruits. The pectin-based coating provided the best potential among other coatings for extending the shelf life of date fruits. Also, zip-lock plastic bags considerably extended the shelf life of date fruits. The edible coatings substantially benefited several cultivars of date fruits, i.e. ‘Khadrawy’, ‘Estamaran’, ‘Hallawy’, ‘Piarom’ and ‘Zahidi’. The TSS contents of fruits were not significantly affected by the coating treatments, but using paper bags for the storage of date fruits led to a better maintenance of TSS percentage in fruits, as compared to the use of plastic bags. Date fruits became firmer as a result of using olive oil as the coating material, whereas the use of pectin reduced the fruits firmness. The lowest tannin content was recorded in fruits coated with MC, whereas the highest content was measured in those coated with pectin and olive oil. The ‘Estamaran’ and ‘Zahidi’ cultivars showed the highest and the lowest TPC, respectively. A better maintenance of TPC was observed when storing the date fruits in plastic bags, as compared to the use of paper bags. Therefore, edible coatings and plastic bags can extend the shelf life of dry and semi-dry date fruits effectively when storing them at room temperature for 3 months.