Near infrared reflectance spectrum of red pepper and its applicability to determination of capsaicin content.

Abstract

An applicability of near infrared reflectance (NIR) technique was examined to determine a capsaicin content in red pepper. Spectra of the 13 red pepper samples were measured in the region of 1.1 to 2.5μm by a computer-controlled spectrophotometric instrument and the major absorption, bands were investigated with regard to the bands of its related substances such as capsaicin, sucrose fructose and glucose. The stepwise multiple linear regression analysis was made to select the five wavelengths in the order of 2.422, 2.358, 1.974, 1.622 and 1.820μm so that chemically analyzed capsaicin contents could be correlated to the derivative values of absorption at the wavelengths. The correlation coefficient was 0.993 and the standard error of estimation was ±0.0036%.