EFFECT OF BLANCHING ON AMYGDALIN CONTENT AND PHYSICOCHEMICAL PROPERTIES OF LESSER YAM (Dioscorea esculenta L) FLOUR

Abstract

Lesser yam (Dioscorea esculenta L) helps effectively lower blood glucose levels and exhibits anti-inflammatory, anti-diabetic and antibacterial properties. However, it also contains the toxin amygdalin, which imparts bitterness and can cause dizziness. The purpose of this study is to evaluate the effect of blanching temperature (70, 80, 90^oC) and duration (60, 80, 90 seconds) of the lesser yam slices (2 ÷ 3 mm thickness) on changes in amygdalin content, color values, swelling power, RVA viscosity properties, and gel hardness of lesser yam flour. The results show that blanching temperature plays a dominant role (accounting for 50 - 80%) in reducing amygdalin content, as well as altering RVA parameters and gel hardness. Blanching time also significantly contributes (10 - 30%) to changes in color, swelling power, and other properties. Specifically, increasing the blanching temperatures from 70 to 90^oC, the lesser yam flour had lower values for some properties such as 10% for the amygdalin content, 21% for swelling power, 41% for the final viscosity, 12% for the pasting temperature decrease 12%, and 81% for the gel hardness but not much for the color values (L) and whiteness index (WI). The gel hardness of the flour was positively correlated with its viscosity and swelling capacity. The findings indicated that blanching at 80°C for 90 seconds was optimal for the lesser yam flour with the lowest amygdalin (68.38 mg/100g dried weight), but with the highest value of the light color L (93.53), the whileness index WI (85.15) and gel hardness (0.47N/cm²) and not significant change of swelling power (11,14 g/g dried weight) and pasting temperature (92.08^oC) and final viscosity (3438.5 cP).