Contribution of Factors of the Plant on the Texture of Frozen-thawed Carrot

Effect of freezing process on the texture of vegetables. Part III

Abstract

The deterioration on mechanical properties of carrot caused by freeze-thawing are usually unavoidable. Contributions of factors of the plant itself to the deterioration were determined during two years by the experiment using the same variety of carrot, treatment and methods. The data of uniaxial compressive rupture test by Instron type instrument were analyzed by 2k type fractional factorial experiment using orthogonal arrays. Varieties, tissues of phloem and xylem, product years, and existence of treatment of blanching and freeze-thawing were taken up as the factors. Level means and variance ratio of main effects were investigated. Low values of variance ratio were obtained for the factors of varieties, product years and tissues, whereas large effects of treatments of blanching and freeze-thawing were recognized. Accordingly, it seems that prevention of texture change of carrot is more effective by improvement of freezing process than by plant breeding. An index of texture deterioration on freezing process of carrot was estimated by the apparent modulus of elasticity, but no relation was recognized between the apparent modulus of native raw carrot and the modulus of frozen-thawed sample of the same individual.