Characterization and bioactive potential of epicuticular wax from date fruits

Abstract

Date fruits (DFs) are lucrative fruits with both nutritional and medicinal benefits. Although DF byproducts have gained interest as potential functional food ingredients, the functional role of DF waxes remains unexplored. Most plant fruits, including DFs,had a lipophilic cuticular layer; and constitutes of epicuticular wax (EPW), which has an important role in respiration losses, mechanical support, fruit softening, and pathogen resistance. In this study, the compositional and antioxidant properties of EPW from Majdool, Khalas, and Fard DFs were investigated. Moreover, thermal transitions of EPW were examined. Results revealed the highest EPW yield in Majdool (16.62 ± 1.68 mg wax/cm2) and the lowest in Khalas (0.075 ± 0.008 mg wax/cm2). Ultraviolet–visible spectroscopy showed maximum absorptivity at 250 and 290 nm across all varieties, corresponding to conjugated dienes and trienes, respectively. Fourier transform infrared peaks confirmed the presence of hydroxyl, methylene, and carbonyl groups, including specific domains of phenolic compounds. Khalas and Fard EPWs reported more total phenolic content and scavenging activity than Majdool EPW. The variations were observed in the melting temperatures of EPW, ranging from 60 °C to 85 °C. These findings establish a theoretical foundation for the potential application of DF EPW in food and pharmaceutical industries.