Evaluating and correlating the mechanical, nutritional, and structural properties of carrots after multiple freezing/thawing processing.

This work evaluated and correlated the mechanical and nutritional properties of carrots after five freezing/thawing cycles (FTC). Results showed that after one FTC, the mechanical parameters (hardness, chewiness, springiness, cohesiveness, resilience, and storage modulus) and the glucose and fructose content sharply decreased and the tangent (Tanδ) dramatically increased in samples. The contents of lycopene and lutein reached the maximum level after two FTC. And there were no significant changes in the content of α- and β-carotene (around 90 and 50 mg 100 g-1 dry matter, respectively) among all samples. Correlation analysis showed that the mechanical parameters were positively correlated with soluble sugars (fructose, glucose, and sucrose) and negatively with lycopene and lutein Tanδ were negatively related with soluble sugar. These results suggested that the first freezing/thawing condition could be the key factor for obtaining the products with acceptable quality. The changes in macroscopic mechanics could be used to predict the variations of potential nutritional components in tissues during FTC processing. The deteriorated structural changes (i.g. cell wall dissociation and turgidity loss) could be responsible for these results.