Comparative Profiling of Volatile Compounds in Popular South Indian Traditional and Modern Rice Varieties by Gas Chromatography-Mass Spectrometry Analysis.

Adhimoolam Karthikeyan,Kaliyaperumal Ashokkumar,Manoharan Akilan,Sampathrajan Vellaikumar,V G Shobhana,Mahalingam Govindaraj,Jeyaraman Sathishkumar

doi:10.3389/fnut.2020.599119

Abstract

Rice (Oryza sativa L.) is one of the major cereal crops cultivated across the world, particularly in Southeast Asia with 95% of global production. The present study was aimed to evaluate the total phenolic content (TPC) and to profile all the volatile organic compounds (VOCs) of eight popular traditional and two modern rice varieties cultivated in South India. Thirty-one VOCs were estimated by gas chromatography–mass spectrometry (GC-MS). The identified volatile compounds in the 10 rice varieties belong to the chemical classes of fatty acids, terpenes, alkanes, alkenes, alcohols, phenols, esters, amides, and others. Interestingly, most of the identified predominant components were not identical, which indicate the latent variation among the rice varieties. Significant variations exist for fatty acids (46.9–76.2%), total terpenes (12.6–30.7%), total phenols (0.9–10.0%), total aliphatic alcohols (0.8–5.9%), total alkanes (0.5–5.1%), and total alkenes (1.0–4.9%) among the rice varieties. Of all the fatty acid compounds, palmitic acid, elaidic acid, linoleic acid, and oleic acid predominantly varied in the range of 11.1–33.7, 6.1–31.1, 6.0–28.0, and 0.7–15.1%, respectively. The modern varieties recorded the highest palmitic acid contents (28.7–33.7%) than the traditional varieties (11.1–20.6%). However, all the traditional varieties had higher linoleic acid (10.0–28.0%) than the modern varieties (6.0–8.5%). Traditional varieties had key phenolic compounds, stearic acid, butyric acid, and glycidyl oleate, which are absent in the modern varieties. The traditional varieties Seeraga samba and Kichilli samba had the highest azulene and oleic acid, respectively. All these indicate the higher variability for nutrients and aroma in traditional varieties. These varieties can be used as potential parents to improve the largely cultivated high-yielding varieties for the evolving nutritional market. The hierarchical cluster analysis showed three different clusters implying the distinctness of the traditional and modern varieties. This study provided a comprehensive volatile profile of traditional and modern rice as a staple food for energy as well as for aroma with nutrition.

Highlights

Rice is a leading staple crop after wheat, and two-thirds of the world population consumed rice as their primary food source [1]
Eight traditional and two modern rice varieties of southern India were chosen for assessing the variability of yield, total phenolic content (TPC), and grain phytochemical constituents
The present study revealed that the pigmented traditional varieties recorded higher plant height and 1,000 grain weight (g)

Summary

Introduction

Rice is a leading staple crop after wheat, and two-thirds of the world population consumed rice as their primary food source [1]. The global production of rice is 769.4 m tons from 167.2 m ha [2], and it plays a critical role in food systems. Rice production in developing countries achieved a 117% yield increase through the efforts of the Green Revolution, which helped to prevent starvation in developing countries [3]. Future demand for rice supply is predicted to reach 9.7 billion by 2050 for promising food and nutritional security to the growing population [4]. Modern rice varieties are often lacking in essential micronutrients compared with traditional varieties and landraces [7]. A recent study exposed that traditional rice grains accumulated a 2-fold higher folate concentration than the grains of modern varieties of rice [7]

Methods

Results

Discussion

Conclusion