Modelling of drying characteristics and some quality parameters of carrot leathers dried by different methods and determination of in vitro bioavailability

In this study, it was aimed to determine physicochemical, textural, sensorial properties and in vitro bioaccessibility of carrot+tomato, carrot+red pepper and carrot pestils produced using hot air (60, 70 °C), vacuum (60, 70 °C and 150, 250 mbar) and microwave (90, 180 W) drying methods. In addition, zero and first order reaction models were applied to determine the bioactive component and color change kinetics, and mathematical modeling of the drying characteristics of the pestil samples produced under different drying methods and conditions. The most suitable models revealing the drying characteristics of the pestil samples were determined as Page, Modified Page and Wang&Sing for carrot+tomato pestils and Page and Modified Page for other pestil samples. While the total phenolic content increased with drying time for carrot+tomato and carrot+red pepper pestils, it decreased with drying time for carrot pestils. However, total antioxidant capacity values and carotenoid content decreased with drying for all pestil samples. In addition, after in vitro gastrointestinal digestion, it was observed that the pestil samples had more bioaccessible total phenolic content, total antioxidant capacity and carotenoid content compared to their mixtures. L*, a*, b* color values of all pestil samples decreased with drying, exceptionally, a* value increased with drying of tomato+carrot pestil. The mineral content of the pestils was higher than their non-dried mixtures. Statistically significant differences were found between the textural properties of the pestil samples (p < 0,05). The amount of minimum and maximum HMF were obtained as a result of 60 °C hot air and 180 W microwave drying, respectively in all pestil samples. According to the sensory analysis results, the drying conditions that received the highest scores from the panelists were 60 °C hot air and 90 W microwave for carrot + tomato and carrot pestil samples, while 70 °C hot air for carrot + red pepper pestils.