Comparative Study of Total Phenolic Content and Total Flavonoid Content Extraction from Guava Juices by Progressive Freeze Concentration and Evaporation

Abstract

The guava fruit is rich with high valuable nutrients that have health-promoting features. It has been used over the centuries across various cultures in the world. Nowadays, people enjoy a simpler way to ensure a healthy diet by consuming supplements and juices. Guava juice was concentrated through progressive freeze concentration (PFC) or evaporation techniques. Total phenolic (TPC) content and total flavonoid content (TFC) were determined after these processes. TPC was analysed by folin-ciocalteu test and TFC was determined through Dowd method. Temperature and stirring rate were manipulated during the process. It was observed that TPC and TFC were higher for PFC than evaporation techniques, with TPC value of 8.1050 mg gallic acid equivalent (GAE)/g guava and TFC value of 0.8296 mg Quercetin/g guava, respectively. It was observed that the increase of temperature will enhance the TPC extraction due to higher mass transfer for extraction but reduce the TFC extraction due to the conversion of flavonoids into monomers.