Effects of solar‐ and oven‐drying on physicochemical and antioxidant characteristics of hihatsumodoki ( Piper retrofractum Vahl) fruit

The physicochemical and antioxidant properties of whole hihatsumodoki ( Piper retrofractum Vahl) pepper fruits were evaluated before and after solar‐ and oven‐drying. Desirable dry matter (24% relative mass) and a w (0.50) values were obtained after solar‐drying for 18 hr, and oven‐drying for 24, 6, and 4 hr at 50, 70, and 90 °C, respectively. The color parameters (Hunter a * and b * values) of the fruits were affected by their drying conditions. Principal component analysis was used to determine suitable drying conditions to obtain dried pepper fruits with desirable food and color properties. The piperine contents of the dried pepper fruits were maintained under all of the drying conditions tested. However, solar‐drying for 18 hr and oven‐drying at 90 °C for 6 hr resulted in significant reductions in their total phenol contents and DPPH radical scavenging activities. The results of this study may be useful for optimizing the drying of whole hihatsumodoki fruits. Practical applications This work aimed to study the effects of solar‐ and oven‐drying processes on the physicochemical properties of an economically important species of pepper fruits, hihatsumodoki. A range of drying conditions was examined, and the optimal conditions were determined to maintain pungency and antioxidant activity while achieving a sufficiently low water activity to prevent microbial growth and spoilage. The present study serves as an important work in providing insights into how the thermal and UV stabilities of piperine and phenolic compounds in hihatsumodoki pepper fruits affect the physicochemical and antioxidant properties when the fruits are subjected to different drying conditions. The work described in this paper will be of use to a wide range of readers interested in optimizing drying processes based on experimental data, and may be applicable to a variety of Piperaceae.