Evaluation of Water Status and Thermal Characteristics of Dried Carrot Half-Slices in Correlation with Physicochemical and Sensory Properties

The aim of the study was to investigate the effect of enriching carrot slices by NFC (not from concentrate) juices from chokeberry (CH), sea buckthorn (SB), cherry (CHE) and carrot (CA) before microwave-vacuum (MVD) and freeze-drying (FD) carrot on the physicochemical and thermal properties. While water activity (AW) was not dependent on enrichment treatment but only on drying method, NFC juices significantly enriched carrot slices with biocomponents. Freeze-dried samples, as a reference, had significantly lower AW than those dried by the MVD method. Both FD and MVD-dried samples had comparable polyphenol content and DPPH antioxidant activity (AA), but the MVD-dried samples exhibited higher ABTS antioxidant activity. Carrot enrichment in chokeberry and cherry juices resulted in up to six and 10 times higher TPC than in the raw material. In addition, samples enriched in these juices and dried with FD proved to be the most stable in terms of water state and glass transition temperature (61.4 and 69.6 °C) and water activity (approx. 0.10). In FTIR analysis, all samples exhibited similar spectral shapes, indicating similar chemical composition and functional group composition. Only in the spectral region below 900 cm−1 were unique molecular vibrations induced by various organic compounds present. Enriching carrot in juices and MVD can lead to increased hardness (Fmax and breaking work), although this is associated with increased crispness, resulting from the microstructure with a large number of small pores, especially in MVD samples enriched with cherry, chokeberry, and carrot juices, with scores of 8.0–8.4 In this respect, the average crispness rating of the MVD samples (7.2) exceeded that of the FD samples (6.8). If there is a requirement for crunchiness in the future production of dried vegetables as snacks, changes in hardness should be prioritized, along with color and biocomponent content.