Chemical stabilization of colour of ginger paste and its antioxidant and proteolytic activities

Ginger (Zingiber officinale) is a popular spice and ginger paste offers convenience in use. But ginger paste turns pink during storage which adversely affects its acceptability. To prepare ginger paste green rhizomes were washed, peeled, blended, and the pH of paste was adjusted to 4.2 using 30% citric acid. Xanthan gum was added @ 0.12%. To control pink discoloration CaCl2, CaHPO4, CaNO3, MgSO4, EDTA, ascorbic acid, EDTA + ascorbic acid and SO2 (as potassium meta bisulphite) were added to ginger paste. Samples were packed and pasteurized in glass jars. CaCl2 (0.3 M) and SO2 (350 ppm) were found to be the best in checking pink discoloration. The antioxidant (as TBA-value) and proteolytic activities (as tyrosine value) in ginger paste were 0.072 and 301.25 mu g, respectively when it was used @ 5 ml/100 g chicken meat as compared to the corresponding values of 0.0724 and 325.0 mu g for the extract of fresh ginger. The results show that the antioxidant and proteolytic activities of ginger were retained during paste preparation also.