Influence of blanching on the quality of Brussels sprouts (Brassica oleracea L cv gemmifera).

Blanching of Brussels sprouts before freezing induces chemical, enzymatical and physico-chemical modifications. This blanching study was made at three temperatures (in water at 90 degrees C and 95 degrees C, in steam at 105 degrees C), The glucosinolate and glucose contents decrease when the technological treatment is extended. These losses are higher in water blanching, especially for external leaves, The myrosinase activity is reduced when treatment time and temperature increase. The peroxydase which is more thermoresistant than myrosinase is a good test for measuring inactivation of enzymes during the industrial blanching. Variations of the colour (green) are larger for external leaves than in the middle of the material. After two minutes of blanching, a hardening of Brussels sprouts is observed hut, after that time, the hardness decreases.