Physical properties of root crops treated with novel softening technology capable of retaining the shape, color, and nutritional value of foods.

Hard, difficult-to-eat root crops (carrots and burdock roots) were homogeneously softened by an enzyme permeation method so that they could be mashed easily by the tongue while retaining appearance, flavor, and nutrients. The appearance, color, and nutritional value of these foods were equivalent to those of normally cooked root crops of the same type. The firmness of the softened root crops was at least 100 times as low as normally cooked root crops and lower than some care food products for patients with swallowing disorders. Compared with control root crops, which were treated with a freeze-thaw infusion method, the treated foods were 10 to 25 times as soft, with significantly lower rates of foodstuff syneresis and better preservation of color and nutritional value. Furthermore, the cell walls of the treated burdock roots resembled those of normally cooked ones, while the cells of freeze-thaw infusion burdock roots were destroyed and few cell walls remained. It was expected that these root crops softened by the enzymatic processing could be one of the best model foods for patients with masticatory disturbance or swallowing disorders or both.