Application of antisolvent precipitation method for encapsulation of date seed extracts of Rabbi variety in zein ptotein biopolymer

The aim of this study was to investigate the antioxidant properties of date seed methanolic extracts of Rabbi variety and evaluating the physicochemical properties of zein nanoparticles loaded with these extracts. Ultrasonic treatment was used to extract methanolic extract from date seed powder and antisolvent precipitation method was used to encapsulate date seed methanolic extracts in amounts of 0.05, 0.1, 0.15 and 0.2 g in zein biopolymer carrier. In this study, the total phenolic content (TPC) and half maximal inhibitory concentration (IC50) value of date seed extracts of Rabbi variety in 45 min, the temperature of 500C of ultrasonic bath and 70% methanol solvent concentration were obtained respectively 369.47 mg gallic acid equivalents (GAE)/g dry weight and 5.08 µg/m1. By increasing the ratio of encapsulated extract in zein carrier from 0.1 to 0.4, the encapsulation efficiency from 85.90 to 95.19% and the size of zein particles loaded with methanolic extracts from 129.95 to 183.30 nm increased and the zeta potential of nanoparticles decreased from +19.15 to +14.48 mV. The size and zeta potential of extract-free zein particles were determined 109.30 nm and +21.96 mV, respectively. The results of ATR-FTIR analysis indicated that with increase the ratio of methanolic extract encapsulated in the zein carrier, the stretching peak of O‒H⋯O bond changed and increased from 3292.85 to 3294.85 cm-1. In Investigating the FE-SEM images, extract-free zein nanoparticles and zein nanoparticles loaded with date seed extracts had semi-spherical morphology. Overall, the hydrophobic nature of zein carrier caused it to bind with the phenolics of Rabbi date seed extract through non-covalent, van der Waals, hydrogen, and hydrophobic interactions. Therefore, it can be used as a strong carrier for the encapsulation of date seed extracts.