Effect of Different Thermal Processing and Addition of Oil on the Physical, Chemical, Anti-Inflammation, Antioxidant and Anti-Diabetic Properties of Onion Extract

Sim, Zhong Jim (2021) Effect of Different Thermal Processing and Addition of Oil on the Physical, Chemical, Anti-Inflammation, Antioxidant and Anti-Diabetic Properties of Onion Extract. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

Text Sim Zhong Jim_Full Text.pdf Restricted to Registered users only Download (1MB)

Abstract

Onion, Allium cepa is a widely known vegetables worldwide. Generally, A. cepa serves as condiment and traditional medicines due to many potential health benefits. Therefore, this study was conducted to investigate the effect of different heating methods (conventional oven and microwave) and addition of oil on the physical (pH, colour), chemical (TPC, TFC), anti-inflammation (FRAP, DPPH), anti-oxidant and anti-diabetic (alpha-amylase) properties of onion extract. The onion was heated in conventional oven and microwave oven separately in the presence or absence of corn oil. The pH and colour change of onion after different treatments were measured. Then, the extract of onion was prepared using methanol at a ratio of 1:20. Results obtained shows that oven-treated onion had higher pH than microwave-treated onion. There was no significant difference in colour of both treated-onion. FRAP and DPPH activity of onion were decreased after conventional oven heating whereas microwave-treated sample showed the trend of increment. After microwave heating, albumin denaturation activity of onion was dropped but no significant change was observed in oven treated extract. All treatments caused significant reduction of alpha-amylase inhibition activity of onion. Survey data showed that although respondents have sufficient knowledge about the effect of cooking methods on the physical, organoleptic, and health value change of onion, they are still lack in knowledge of health benefits of onion. Microwave heating with oil addition was the best treatment in this study to preserve antioxidant and anti-diabetic properties of onion.