Modification of techno-functional and health-promoting properties of orange by-products through ultrasonication

Abstract

The orange juice extraction process generates significant amounts of by-products which currently lack practical applications leading to economic losses and potentially posing environmental threats. To enable their utilization, an orange pulp–peel powder mixture was subjected to different ultrasonication (US) input powers (200, 300, 400 W) and treatment times (15, 30, 45 min). Particle size was reduced with increasing treatment power and time which led to a maximum increase of 25.8% of water holding capacity (WHC), 12.9% of oil holding capacity (OHC) and 7.6% of bile acid adsorption capacity (BAC). Therefore, the highest treatment power and time (400 W, 45 min) were selected to be applied on mixtures comprised of different proportions of orange pulp and peel. PU80 contained 80% pulp and 20% peel, PU50 equal proportions and PU20 20% pulp and 80% peel. Solubility and content of crude fiber did not significantly change in the mixtures after US. However, WHC increased in all mixtures while OHC significantly improved in PU50 (8.16 g g⁻¹). Inhibition of α-amylase (AAIR) and pancreatic lipase (PLIR) were enhanced in US treated PU80 and PU50. PU20 showed the highest increase of BAC from 3.28 mg g⁻¹ to 4.13 mg g⁻¹ after US which was related to an increase of the total phenolic content (TPC) in this treated mixture. This study could demonstrate that the efficacy of US in enhancing different properties of orange by-products highly depends on the ratio of orange pulp and peel in the by-product mixture, thus polysaccharide composition.