Abstract
Freeze-thaw infusion (FI) is a technique rapidly to impregnate enzymes and so on into food materials. FI produces soft food materials retaining their original shape. We investigated the digestibility of softened lotus roots treated with FI using an artificial digestion test and administrating the lotus roots into the rats' stomachs. In the artificial digestion test with pancreatin for 3h, the amount of insoluble solids of softened lotus roots treated with FI was artificially digested 4.3±0.1 (g/100g). The amount of the insoluble solids obtained by artificial digestion for 9h of the controlled samples without FI was 6.7±0.1 (g/100g). The amount of insoluble solids after artificial digestion correlated with the degree of hardness of the original lotus roots (rs=0.95, p<0.01). According to this result, it was deduced that the materials softened with FI increased the digestible amount of materials and shortened the digestion time. As a result of the gastric administration in rats, the samples treated with FI had a higher residual ratio of gastric soluble pigments, and a smaller modal diameter of gastric insoluble solids compared with the controlled samples. These results suggest that the softened materials are expected to delay the rate of gastric emptying of soluble materials and to prevent the feeling of fullness in the abdomen. These results also suggest that the softened food materials treated with FI can enhance digestibility.
