The relation between (bio-)chemical, morphological, and mechanical properties of thermally processed carrots as influenced by high-pressure pretreatment condition

Thermal texture evolution kinetics (90–110 °C) of nonpretreated and high-pressure pretreated (HP = 400 MPa, 60 °C, 15 min) carrots were determined using a multiparameter approach (cutting, compression). Alcohol Insoluble Residues (AIR) were extracted before and after thermal processing of the samples and the degree of methylation (DM) was estimated. The β-elimination kinetics of the water soluble pectin extract from the AIR was studied and related to the changes in material properties. Morphological changes and tissue-failure characteristics were monitored. The mechanical properties were strongly dependent on the processing temperature and the DM of the samples. Texture degradation rate constants were independent of the texture measurement method. Increasing temperature accelerated the β-elimination reaction (k _b) and the thermosoftening (k _x) rates, but pretreatment condition slowed down the rates. Interestingly, a strong correlation (r > 0.99) between k _b and k _x occurred. Thermal processing resulted in cell-wall thickening accompanied by a transition from cell rupture to cell separation, a process retarded by pretreatment condition.