Effects of pricking, sun-drying and sieving on Ginger (Zingiber officinale Roscoe) colour and powder

Abstract

The effect of pricking, sun drying and sieving on the color retention of Nigerian yellow bark ginger were investigated. The exterior and interior surface of fresh, pricked and sun dried medium sized Nigerian ginger rhizomes (Tafin giwa) were analysed for colour variation. The colour values of the exterior surface of fresh ginger were, L* 59.8±2.6; a*
3.7±0.7; b*16.9±0.75, while the pulp L* 74.0±0.96; a* - 6.2 0.5 b* 32.8±1.28. The interior colour of fresh ginger surface was 24% lighter than the skin surface colour. Drying decreased the external surface colour by 12.5%, pricking darkened the interior surface of ginger by 7.2% and 2.6% respectively for black and gray backgrounds respectively, while sieving was found to lighten the obtained powder up to 3.7% and 2.9% for whole and
pricked dried powdered samples. Drying decreased the “b” values (yellowness) by 32% compared to the “b” values of fresh samples, and a range of 42-87% also decreased “a” values.

Keywords: Ginger, colour, powder, yellow bark, pricking,
drying, sieving

Nigerian Food Journal Vol. 25 (1) 2007: pp. 155-160