Hybrid Infrared and Heat Pump Drying Technology for Fruit-Based Nutritious Snack Production: Drying Kinetics and In Vitro Bioaccessibility of Phenolics and Antioxidant Capacity

Abstract

In this study, a fruit-based, nutritious snack without added sugar or salt was developed to promote healthy eating habits. An infrared (IR)-assisted heat pump drying (IR-HPD) system was employed as an alternative to conventional drying methods. Drying was conducted at two temperatures (35°C and 45°C) and two IR power levels (75 and 150 W). Additionally, control samples were produced at 35°C and 45°C without using IR, and the effects of combining IR drying with HPD were investigated. Results indicate that IR-HPD, particularly at 45°C and 150 W, significantly reduces drying time (by up to 136 min) and energy consumption (by up to 42.91%), showcasing its potential for an efficient dehydration process for selected food matrices. IR application increased the drying rate (DR) by 22.05%–42.64% at 35°C and by 11.30%–22.60% at 45°C. The effective moisture diffusivity (D_eff) ranged from 1.88 × 10⁻¹⁰ to 3.38 × 10⁻¹⁰ m²s⁻¹. Amidst the 10 drying models, the Page and Wang & Singh models were found to provide the most accurate depiction of the drying kinetics of the fruit-based snacks. Furthermore, the in vitro bioaccessibility of total phenolic content (TPC) and total antioxidant capacity (TAC) was assessed. In samples dried without IR, increased temperature enhanced both TPC and TAC (DPPH). Conversely, in IR-HPD samples, higher temperature adversely affected TPC values. Notably, both TPC and TAC significantly increased following in vitro small-intestine digestion, indicating improved bioaccessibility. These findings underscore the potential of IR-HPD as an effective method for producing nutritionally enhanced, heat-sensitive fruit-based snacks, offering valuable implications for the development of functional food products that support healthier dietary habits.