Optimization of Heat Pump Dryer Conditions on Bioaccessibility of Some Secondary Metabolites of Cornelian Cherry-Capia Pepper Pestil

Abstract

Pestil is a traditional and functional snack produced by removing moisture from fruit pulp using different methods. Although solar drying is common in traditional pestil drying, modern drying methods are preferred in industrial production. As one of these methods, heat pump drying (HPD) is considered to be the most favorable technique owing to its notable efficiency in the drying process and low energy consumption. Additionally, it has the capability to accurately regulate drying conditions, thereby enhancing the overall quality of the dried foods. The aim of this study was to investigate the effects of HPD conditions on drying kinetics and quality profile (total monomeric anthocyanin (TMA) content, total phenolic content (TPC), antioxidant capacity (AC), and carotenoid content) and their in vitro bioaccessibility of the cornelian cherry-capia pepper pestil. Also, it was aimed to produce high-quality pestil having bioactive properties by optimizing HPD conditions. Drying temperature (40–50°C) and cornelian cherry concentration (30–40%) were selected as independent variables for the response surface methodology (RSM). After in vitro digestion, pestil samples have higher bioaccessible β-carotene, α-carotene, lutein, and AC (especially for the DPPH method), whereas the drying process reduced the bioaccessibility of TPC in pestil samples. Using a RSM, we found that the way the responses (TMA, TPC, AC, and carotenoids) were related to the independent variables can be best explained by quadratic (Qc), reduced quadratic (RQc), and reduced cubic (RCc) models. These models had high R2 values, which mean they can accurately predict the outcomes. The optimal condition of responses with composite desirability of 0.852 was drying temperature at 46.68°C and 44.94% cornelian cherry concentration.