Vacuum Infusion of Enzymes into Freeze-Thaw Food Materials Using a Vacuum Packaging Machine

Abstract

Vacuum infusion of enzymes into freeze-thaw food materials (FI) is a technique for softening food materials while retaining their shape. This technique enhances the infusion efficiency of a degradative enzyme under reduced pressure by using thawed materials.

This study aimed to develop a technique using a vacuum packaging machine instead of a vacuum pump. Bamboo shoots, lotus roots and burdock were used as the food materials.

The method of FI using a vacuum packaging machine was as follows. Frozen food materials were thawed in an enzyme solution so that the enzyme was absorbed onto their surface. They were then taken out of the solution and placed into packaging film. The enzyme was infused using a vacuum packaging machine. The enzyme reaction proceeded at 50℃ for 1 h.

The enzyme infusing efficiency was examined using the enzyme solution while food was being thawed and as enzyme was being infused. We also examined the degree of reduced pressure, concentration of degradative enzyme, and holding time under reduced pressure.

The bamboo shoots and lotus roots, which were thawed in the enzyme solution and then infused with enzymes without the solution, were significantly softer than when thawed into buffer solution and infused with enzyme in the enzyme solution. Burdock was not affected differently by the two methods. The softening effect on bamboo shoots and lotus roots was increased by reducing the pressure (15.30–5.10 kPa). Burdock was not affected by the degree of pressure. Softness that was equivalent to the conventional method was accomplished using 1.25–1.67 times the concentration of enzyme, and holding for 3–5 min under reduced pressure.

These results suggested it was possible to use a vacuum packaging machine for FI. This technique will help improve foods for the elderly or those with disorders, thus improving their quality of life.