Volatile compounds, affecting factors and evaluation methods for rice aroma: A review

Rice aroma was a comprehensive result of numerous volatiles and human sense. More than 300 volatiles were reported in rice. Rice aroma was widely researched by using sensory evaluation , gas chromatography (GC) method, and electronic nose (E-nose). Genetic factor was the main cause for rice aroma. However, the same rice variety might result in different aroma quality due to different planting, processing and storage. The main purpose of this review is to elaborate the main volatiles contributing rice aroma, methods used for rice aroma evaluation and factors affecting rice aroma. Most volatiles with odor descriptions, odor thresholds and retention indices were summarized. Sensory evaluation, GC method, and E-nose were elaborated with respect to rice aroma analysis. The effects of gene, planting, processing and storage on rice sample were pointed out. 2-Acetyl-1-pyrroline (2-AP), aldehydes, heterocyclics, alcohols play important roles in rice aroma quality. GC-O-MS which combines the advantages of sensory descriptive analysis and GC-MS, can not only realize detailed sensory analysis of odor quality but also realize quantitative and qualitative detection of volatiles, playing an important role in exploring key aroma-active compounds. Besides of traditional electronic sensors, mass spectrometry and colorimetric sensors were used for E-nose, making it more novel and applicable. Water washing, high hydrostatic pressure, roasting and parboiling were thought as effective processing to improve rice flavor. Degree of milling and storage significantly affected rice flavor. • The main volatiles contributing rice aroma were reviewed. • Volatiles with odor descriptions, thresholds and retention indices were summarized. • Methods used for rice aroma evaluation were elaborated. • Rice aroma was affected by gene, planting, processing and storage.