Near-Infrared Hyperspectral Imaging (NIR-HSI) for Nondestructive Prediction of Anthocyanins Content in Black Rice Seeds

Hanim Z Amanah,Byoung-Kwan Cho,Kyung-Hwan Kim,Rudiati Evi Masithoh,Wang-Hee Lee,Salma Sultana Tunny,Mohammad Akbar Faqeerzada,Myoung-Gun Choung,Collins Wakholi,Mukasa Perez

doi:10.3390/app11114841

Abstract

Anthocyanins are an important micro-component that contributes to the quality factors and health benefits of black rice. Anthocyanins concentration and compositions differ among rice seeds depending on the varieties, growth conditions, and maturity level at harvesting. Chemical composition-based seeds inspection on a real-time, non-destructive, and accurate basis is essential to establish industries to optimize the cost and quality of the product. Therefore, this research aimed to evaluate the feasibility of near-infrared hyperspectral imaging (NIR-HSI) to predict the content of anthocyanins in black rice seeds, which will open up the possibility to develop a sorting machine based on rice micro-components. Images of thirty-two samples of black rice seeds, harvested in 2019 and 2020, were captured using the NIR-HSI system with a wavelength of 895–2504 nm. The spectral data extracted from the image were then synchronized with the rice anthocyanins reference value analyzed using high-performance liquid chromatography (HPLC). For comparison, the seed samples were ground into powder, which was also captured using the same NIR-HSI system to obtain the data and was then analyzed using the same method. The model performance of partial least square regression (PLSR) of the seed sample developed based on harvesting time, and mixed data revealed the model consistency with R2 over 0.85 for calibration datasets. The best prediction models for 2019, 2020, and mixed data were obtained by applying standard normal variate (SNV) pre-processing, indicated by the highest coefficient of determination (R2) of 0.85, 0.95, 0.90, and the lowest standard error of prediction (SEP) of 0.11, 0.17, and 0.16 mg/g, respectively. The obtained R2 and SEP values of the seed model were comparable to the result of powder of 0.92–0.95 and 0.09–0.15 mg/g, respectively. Additionally, the obtained beta coefficients from the developed model were used to generate seed chemical images for predicting anthocyanins in rice seed. The root mean square error (RMSE) value for seed prediction evaluation showed an acceptable result of 0.21 mg/g. This result exhibits the potential of NIR-HSI to be applied in a seed sorting machine based on the anthocyanins content.

Highlights

Rice (Oryza sativa L.) is a vital cereal food in Asia and is consumed by almost half of the world’s population [1]
In this research, twenty grams of rice seeds were collected from each rice variety of each year, and among them, 36 seeds were selected randomly for the image data acquisition using the near-infrared hyperspectral imaging (NIR-hyperspectral imaging (HSI)) system
The powder sample was placed on the sample plate and scanned using the same NIR-HSI system for data acquisition

Summary

Introduction

Rice (Oryza sativa L.) is a vital cereal food in Asia and is consumed by almost half of the world’s population [1]. There are many different kinds of rice, including white rice, which is widely consumed, and pigmented rice. Pigmented rice, such as purple and black rice, contains important bioactive compounds beneficial for human health. The bran of black rice is rich in fiber and many kinds of phytochemicals, such as tocopherols, tocotrienols, oryzanols, vitamin B complex, and other phenolic compounds [3,4]. The protein content of black rice was reported to be higher than white rice. Black rice contains anthocyanins and proanthocyanidin in its aleurone layer, meaning that black rice is considered an essential health product

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