A comparative study on conventional and microwave-assisted extraction for microencapsulation of Garcinia fruit extract

Abstract

(−)-Hydroxycitric acid (HCA) is the principal acid present in the fruit rinds of certain species of Garcinia and is reported to have various health benefits. However, HCA is highly hygroscopic in nature and becomes lactonised during evaporation and drying. To reduce the lactonisation of HCA, Garcinia cowa fruit extract was obtained through two different extraction techniques, autoclave and microwave-assisted extractions, and was then microencapsulated using whey protein isolate (WPI) and denatured whey protein isolate (DWPI) with a 1:1 wall-to-core ratio using a spray drying technique. The microwave-assisted extracts encapsulated with WPI and DWPI had higher free HCA and net HCA recovery than the autoclaved extract encapsulated with similar wall materials. Furthermore, the microwave-assisted extracts and the associated encapsulated samples had higher antioxidant activity than their counterparts. The encapsulation of the microwave-assisted extracts with both wall materials had little variations in their free (55.04 and 54.58% for WPI and DWPI, respectively) and net HCA recovery (84 and 82%) and antioxidant activity (13.3 and 13.6%), which signified a smaller influence of the wall materials. These results indicated that microwave-assisted extraction had a higher extraction efficiency, encapsulation efficiency and antioxidant activity with both wall materials.