Enzyme inactivation kinetics and colour changes in Garlic (Allium sativum L) blanched under different conditions

摘要

The inactivation kinetics of the enzymes peroxidase, polyphenoloxidase and inulinase and changes in the color parameters L", a" and b" of garlic cloves cut in slices, were studied during steam blanching at 100 ℃ and water at 80 and 90 ℃. The garlic cloves were peeled, cut into slices and distributed uniformly in metal baskets and one batch placed in an autoclave generating steam at a temperature of 100 ℃; and the others in water baths at 80 and 90 ℃. The best blanching conditions were in steam for 4 min, where no changes in texture were observed, and the enzymatic activities were reduced by 93.53%, 92.15% and 81.96% for peroxidase, polyphenoloxidase and inulinase, respectively. Under these conditions the inulin concentration reduced by 3.72%. The color parameter V increased with increase in blanching time, the samples becoming lighter in color, and the parameters a* and b* decreased, obtaining slices that were greener and bluer.