Effect of processing on bioactive compounds in oyster nuts (Telfairia Pedata)

Abstract

This study aimed at determining the nutrient content of oyster nut, the bioactive compounds in oyster nut and the effect of processing on bioactive compounds in oyster nut. Dry oyster nut samples were collected for Namutumba district and transported to Makerere University School of Food Technology, Nutrition and Bio-engineering; Food chemistry laboratory for analysis. The fibrous outer shell was removed and then the inner shell split to get the cotyledons. The de-shelled nuts were divided into two portions; one was milled raw and the other roasted at a temperature of 120˚C in an oven for 40minutes.The raw sample was further divided into two; one boiled in an oven at 180˚C for 10minutes and the other left untreated. The results showed that oyster nuts were rich in fat (58.87±0.83%) and moderate in proteins (34.82±0.8%). However, the results also demonstrated that oyster nuts had low contents of flavonoids (0.25±0.04mg/ml), vitamin A (0.28±0.01mg/100g) and E (17.04µ/L) and processing further reduced their values. Boiling reduced flavonoids from 0.25 to 0.19mg/100g, vitamin A from 0.28mg/100g in raw to 0.15mg/100g in boiled and vitamin E from 17.04µg/L to 13.63µg/L in boiled. Roasting reduced flavonoids from 0.25mg/ml to 0.07mg/ml, vitamin A from 0.28mg/100g to 0.22mg/100g while vitamin E reduced from 17.04 to 14.94µg/L. Therefore, due to the high content of fat, oyster nut can be used to enhance energy intake in severely ill patients and also as a food vehicle for fortification with fat-soluble vitamins. However, I recommend roasting as method of thermal processing to minimize loss of vitamins A and E during preparation of oyster nut and further research is needed to determine appropriate temperature and time for preserving the bioactive compounds in oyster nut.