Electronic nose for volatile organic compounds analysis in rice aging

Rice plays a significant role in providing basic energy and essential nutrients for humans. Its quality is of great concern to the agricultural industries and consumers. Due to the changes of external storage conditions and its own enzyme activity, rice undergoes the aging process, thus significantly decreasing its quality. Consequently, the development of a rapid, non-destructive, real-time detection method for rice quality inspection is urgently needed. In this article, the characteristics of volatile organic compounds (VOCs) that greatly contribute to aroma profiles of rice are introduced. Meanwhile, the working principles and applications of an electronic nose (E-nose) device as a reliable measurement in rice quality assessment based on the variation of aroma profiles are highlighted. Furthermore, comparisons between E-nose and traditional instrumental assessment methods, such as sensory evaluation, physical and chemical indicators, instrumental analysis, are made. In addition, this article also offers an insight into the challenges and future trends of the application of E-nose for rice quality inspection. 2-acetyl-1-pyrroline (2-AP), aldehydes, heterocycles and alcohols have been identified as the major VOCs in rice aging. Through the comparison between E-nose and traditional instrumental measurements, E-nose has a huge potential for the rapid inspection of rice quality as it has numerous advantages in routine analysis. Furthermore, reducing the working temperature, utilizing appropriate pattern recognition methods and establishing new prediction models should be the future trends of E-nose employed as an effective detection method in rice quality inspection.