Effects of freezing conditions on enzyme impregnation into food materials by freeze-thaw infusion

Freeze-thaw infusion (FI) is a new technique for rapid impregnation of enzymes into food materials. Volume expansion has been observed when freeze-thawed potatoes were exposed to vacuum. Therefore, the effects of freezing treatment on volume expansion and enzyme impregnation were investigated. According to the progress in freezing, the volume expansion ratio increased to over 20%, and enzyme impregnation efficiency was also increased. A distinctive correlation was found between the volume expansion ratio and enzyme impregnation efficiency. During volume expansion, the air expanded in the materials, thereby pushing out the inner liquid from the materials. Thus, enzyme impregnation by FI appears to result from rapid influx of the enzyme solution into the expanding space formed in the materials.