Near-infrared Spectroscopy for Direct Investigation of Quality Compounds in Capsicum spp (Capsicum annuum L. and Capsicum frutescens L.)

Introduction Capsicum spp., commonly known as peppers or chili peppers, are essential horticultural crops. The unique flavors, pungency levels, and nutritional profiles of these peppers are determined by a complex composition of quality compounds such as antioxidant activity, capsaicin, and dihydrocapsaicin. Assessing and quantifying these compounds is crucial for both agricultural and industrial purposes. Methods This research provides fresh insight into the use of near-infrared spectroscopy (NIRS) to investigate quality compounds in Capsicum spp., such as antioxidant activity, capsaicin, and dihydrocapsaicin. The NIRS utilized wavelengths ranging from 702 to 1065 nm with intervals of 3 nm. The total sample size was 400, consisting of 7 varieties of Capsicum spp., including cayenne pepper 'Domba', 'Manik', and 'Ratuni', as well as red chili peppers 'CB2', 'Tanjung 2', 'Lingga', and 'Tanjung'. The sample was divided into a calibration (n=300) and a prediction set (n=100), and then modeling was carried out using statistical software. Results Accuracy values for antioxidant activity, capsaicin, and dihydrocapsaicin obtained were R cal ≤ 0.86, R pred ≤ 0.79, RMSEC ≤ 28.16, RMSEP ≤ 34.58, and RPD ≤ 1.66. Conclusion These findings suggested that NIRS is a rapid and precise method for investigating quality compounds in Capsicum spp., such as antioxidant activity, capsaicin, and dihydrocapsaicin.