Effects of Functional Edible Coatings and Storage on Bioactive Compounds, Antioxidant Properties and Sugars in Barhi Dates

Barhi dates at the Khalal stage were preserved using functional coatings developed using chitosan (CH) and olive-cake (OCE) and orange-peel (OPE) extracts in different ratios. The amounts of total flavonoids, total tannins, and total carotenoids, and antioxidant properties were evaluated. The coated and uncoated samples were also quantified for individual bioactive constituents including flavonoids and phenolic acids using liquid chromatography-mass spectrometry (LCMS). Significant (p ≤ 0.05) improvements in the functional properties and phytochemical content were observed in coated fruits after the application of coatings (OCE+CH and OPE+CH) and during storage at 4 °C. The major phytochemicals detected were vanillic, syringic, ferulic, cinnamic, p-coumaric and protocatechuic acids, and quercetin-3-glucoside and rutin. The highest vanillic acid (536.78 mg/kg), syringic acid (157.39 mg/kg) and ferulic acid (96.42 mg/kg) were detected in 2% OPE+CH-coated dates. Application of functional CH coatings containing OCE and OPE was also found effective in preventing the conversion of sucrose to glucose and fructose through slowing down invertase activity. The application of OPE+CH and OCE+CH coatings can be potentially used to enhance the functional properties and slow down the ripening process in Barhi dates at an early stage (Khalal) of maturity.