RESEARCH ON ADDITION OF MICROENCAPSULATION AND PHENOLIC EXTRACT FROM POMELO PEEL TO YOGHURT PRODUCTS

Abstract

Pomelo peel is often considered a by-product in the pomelo fruit processing. In this study, pomelo peel was utilized as a source of phenolic compounds. The phenolic-rich extract from pomelo peel was encapsulated in a gel matrix and subsequently incorporated into yoghurt product. Two types of gelling agents, agar and carrageenan were employed. The agar/carrageenan 2% ratio and phenolic extract ranged from 1:1 to 1:20 (v/v). The ratio of phenolic encapsulated gel and yoghurt solution varied from 3:70 to 6:70 (w/w). The timing of incorporating the encapsulated gel before and after the fermentation process was also investigated. The results indicated that carrageenan exhibited better structural stability of yoghurt product compared to agar. The optimal ratio observed was 1:5 (v/v) for carrageenan to phenolic extract, and a ratio of 4:70 for phenolic encapsulated gel to yoghurt solution, showing the highest sensory evaluation. During 15 days of product storage at the temperature of 6-8oC, there was a loss of phenolic content from the gel into the yogurt solution, leading to an increase in the phenolic content of the yoghurt. Incorporating the phenolic encapsulated gel after the fermentation process minimized the loss of phenolic compounds from the gel into the yoghurt solution better than incorporating it before fermentation.