Sensory and biochemical changes in Swiss chard (Beta vulgaris) during blanching

The effects of blanching chard leaves under steam individually and in 3 and 5 leaves deep beds was investigated. Blanching for 30 s sufficed to inactivate peroxidase. Both the duration of the blanching process and the depth of blanching beds affected the loss of ascorbic acid, with a 31.35% retention for chard leaves blanched for 120 s in 5 leaves beds. Chlorophyll contents were not greatly affected. Reductions of about 2 orders of magnitude in mesophillic bacterial counts were obtained under all conditions tested. Sensory attributes of chard were best preserved when leaves were blanched individually.