Design and Fabrication of a Real-Time Measurement System for the Capsaicinoid Content of Korean Red Pepper (Capsicum annuum L.) Powder by Visible and Near-Infrared Spectroscopy.

Jongguk Lim,Giyoung Kim,Moon Kim,Changyeun Mo

doi:10.3390/s151127420

Abstract

This research aims to design and fabricate a system to measure the capsaicinoid content of red pepper powder in a non-destructive and rapid method using visible and near infrared spectroscopy (VNIR). The developed system scans a well-leveled powder surface continuously to minimize the influence of the placenta distribution, thus acquiring stable and representative reflectance spectra. The system incorporates flat belts driven by a sample input hopper and stepping motor, a powder surface leveler, charge-coupled device (CCD) image sensor-embedded VNIR spectrometer, fiber optic probe, and tungsten halogen lamp, and an automated reference measuring unit with a reference panel to measure the standard spectrum. The operation program includes device interface, standard reflectivity measurement, and a graphical user interface to measure the capsaicinoid content. A partial least square regression (PLSR) model was developed to predict the capsaicinoid content; 44 red pepper powder samples whose measured capsaicinoid content ranged 13.45–159.48 mg/100 g by per high-performance liquid chromatography (HPLC) and 1242 VNIR absorbance spectra acquired by the pungency measurement system were used. The determination coefficient of validation (RV2) and standard error of prediction (SEP) for the model with the first-order derivative pretreatment method for Korean red pepper powder were 0.8484 and ±13.6388 mg/100 g, respectively.

Highlights

Red peppers (Capsicum annuum L.) are an annual plant that belongs to the Solanaceae family, native to South America
A system was designed and fabricated for measuring the capsaicinoid content of red pepper powder; the system can determine the pungency of red pepper powder in a non-destructive and rapid manner by using a visible and near infrared spectroscopy (VNIR) spectrometer with an effective wavelength range 450 nm to 950 nm
To overcome the disadvantages and limitations resulting from the use of existing chemical assay methods and commercial near-infrared spectroscopy (NIRS), we developed equipment that can acquire the reflectance spectra of red pepper powder samples continuously

Summary

Introduction

Red peppers (Capsicum annuum L.) are an annual plant that belongs to the Solanaceae family, native to South America. They are widely grown in tropical to temperate climates and have been important crop in Korea for a long time. Among the capsaicinoid components of red pepper account, capsaicin (C18H27NO3) and dihydrocapsaicin (C18H29NO3) account for 80% to 90% of the total pungency, and other components such as nordihydrocapsaicin (C17H27NO3), homocapsaicin (C19H29NO3), and homodihydrocapsaicin (C19H31NO3) are homologs [4,5,6,7]. Uniformity and scale of hotness are main criteria for grading quality of red pepper powder. To produce high quality red pepper powder and increase farmer’s income, measurement of the capsaicinoids content of red pepper is necessary

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