The Effect of Degree of Milling on the Nutraceutical Content in Ecofriendly and Conventional Rice (Oryza sativa L.).

Seung-Hyun Kim,Yu-Jin Yang,Ill-Min Chung

doi:10.3390/foods9091297

Abstract

We investigated the effects of the type of rice and degree of milling (DOM) on the nutraceutical content and antioxidant activity of rice (Oryza sativa L.). The fatty acid (FA), vitamin E homolog, and phenolic contents in organic (OR), pesticide-free (PFR), and conventional rice (CR) decreased significantly with an increase in the DOM of rice grains, particularly for a DOM of 7 and 9 (p < 0.05). The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity also decreased with the DOM; particularly, this activity decreased significantly, by approximately 60%, in rice grains with a DOM between 7 and 11, as compared to that of brown rice (p < 0.05). α-Tocopherol (r = 0.854) and p-coumaric acid (r = 0.501) showed the strongest correlation with DPPH activity in each chemical group. Stepwise discriminant analysis enabled the correct original and cross-validated classification of 87.0% and 81.5% of rice types, respectively. Additionally, the original and cross-validated classification of rice DOM levels showed that, overall, 93.8% and 92.6% of rice samples were correctly classified. Our findings reveal variations in the nutraceutical levels and antioxidant activities in rice grains based on the rice type and DOM, which can help improve the nutritional evaluation of human-health-promoting rice grains.

Highlights

Rice (Oryza sativa L.) is a staple food for nearly half of the world’s population, especially in most Asian countries
The total fatty acid (FA) content was decreased by an average of 14.52 mg·g−1 as degree of milling (DOM) increased from brown rice (BR) to
FA (UFA) content was greatly decreased by approximately 11 mg·g−1 between BR and 13 DOM rice, whereas the saturated FA (SFA) content was decreased by around 3 mg·g−1 from BR to 13 DOM

Summary

Introduction

Rice (Oryza sativa L.) is a staple food for nearly half of the world’s population, especially in most Asian countries. Rice grains contain many nutrient components, including carbohydrates, proteins, crude fat, dietary fiber, and micronutrients such as vitamins and minerals [1]. They contain essential amino acids and many bioactive non-nutrient compounds, such as phenolic compounds [2]. A rice grain consists of the husk, bran (pericarp, seed coat, and aleurone layer), embryo, and inner endosperm. The process of milling strips away the bran layer from the grain. Rice can be classified as either brown rice (BR) or polished rice based on the degree of milling (DOM). If the bran layer is stripped away, the grain is classified as diverse polished rice according to the DOM.

Methods

Results

Conclusion