Effects on Xe hydrate formation for texture in vegetable tissue

We have attempted to make the gas hydrate crystal in vegetable in order to extend the shelf life of fresh vegetable as preservation technique instead of freezing. As a result, it was confirmed that gas hydrate can be formed in onion tissue at 5 o C by pressurizing between 0.4 and 0.8 MPa Xe pressure. However, the detail conditions regarding to gas hydrate formation in vegetable tissue and their effect for the quality have not yet reported. In this report, in order to understand the effect of Xe hydrate formation for vegetable tissue, it was measured the texture change depending on Xe hydrate formation amount in onion tissue. The hydrate formation amount in onion tissue block is 4 x 4 x 10 mm 3 , was controlled to the ratio of 15-25, 26-35, 36-45, and 46-55 % (gas hydrate/ free water) by pressurizing between 0.4 and 0.8 MPa Xe pressure at 5 o C. The formation ratio of Xe hydrate was measured by using the NMR method. As texture characteristics on onion tissue after gas hydrate formation-decomposition, a fracture stress and initial modulus were determined from pressure-strain curve by using texture analyzer at room temperature. As the result, the elasticity in onion tissue decreased depending on the formation ratio increasingly. Particularly, when the hydrate formation in onion tissue was 36 % or over, it was dramatically decrease to one-third of the value in fresh tissue. On the other hand, the fracture stress of the tissue showed constant value regarding less with the formation. In conclusion, it was suggested that there is a possibility in application of gas hydrate crystal as a preservation technique for fresh vegetable by controlling the gas hydrate amount in the tissue.