Characterization of hot pepper spice phytochemicals, taste compounds content and volatile profiles in relation to the drying temperature

Abstract

The aim of this study was to investigate how the use of increasing hot air drying temperature affects the phytochemical content and the volatile profile of hot pepper spice. A comprehensive characterization of spice from Italian varieties dried at different temperatures (50, 57, and 64°C) was performed, including general quality indexes, phytochemicals, functional properties, and volatile profile. In dried peppers capsaicinoids were completely retained; a remarkable loss of ascorbic acid was observed, while carotenoids amount decreased of about 39%. The retention of tocopherols was higher at 50 and 57°C. The Folin Ciocalteu index showed a steep decrease after drying, but the opposite trend was observed when it was measured using a correction factor to exclude the ascorbate contribution. The volatile profile changed with the increase in drying temperature, due to the production of Strecker aldehydes, methional, and tetramethylpyrazine, and a reduction in esters, terpenoids, and 2-isobutyl-3-methoxypyrazine. Practical applications Among the processing methods used to produce spice, hot air drying is still the most common. Standard industrial drying process is carried out with air temperatures usually above 70°C, but, in order to enhance the product quality, the processing parameters should be carefully chosen. The appropriate use of lower drying temperatures may increase the retention of phytonutrients and the sensory properties, both aspects which meet the consumers’ expectations. The characterization of spice should be both related to the taste components and to the amounts of phytonutrients and vitamins, very high in hot peppers. The comprehensive results of this study suggest that a better preservation of quality characteristics could be achieved using temperatures under 60°C.