Volatile Organic Compound Profiling of Commercial Poi Products in Fresh and Aged States Using Comprehensive Two-Dimensional Gas Chromatography

Abstract

Taro (Colocasia esculenta L.) is a plant originating from Southeast Asia now prevalent throughout the Pacific Islands. Growing taro was and remains an important facet of the Hawaiian culture. Poi is a food product prepared from steamed taro that has been macerated and allowed to ferment. While poi is commonly prepared at home, it can also be found commercially from select Hawaiian brands. The general fermentation process of poi produces volatile organic compounds (VOCs) such as alcohols, aldehydes, ketones, organic acids, esters, and heterocycles, among others, through microbial and enzymatic reactions. The VOCs found in poi are a class of compounds traditionally analyzed through gas chromatography (GC)–mass spectrometry (GC–MS) but have not previously been characterized in the literature. This study aimed to identify a core VOC profile of commercial poi products to better understand sample composition. Changes in fresh to aged poi were observed as well as its brand specific profiles. Analysis was conducted using comprehensive two-dimensional GC-quadrupole mass spectrometry with flame ionization detection (GC×GC–qMS). Samples were prepared according to package instructions, extracted via headspace SPME Arrow, and analyzed in replicates of 10. A total of 56 analytes were identified across three brands of commercial poi, ranging from 11 different compound classes. All brands showed a clear distinction between fresh and aged samples. Fresh samples across all brands contained 4,4-dimethoxy-3-methylbutan-2-one while aged samples all contained 2,5-dimethylfuran. Within the fresh state, the VOC profiles from each brand appeared to be distinct from one another. Taro brand poi was the least similar to Hanalei brand poi and He Mea Ono brand poi. He Mea Ono and Hanalei had some overlap in VOCs, but a substantial portion of their VOC profile was unique to the individual brand. In the aged state, there was a significant overlap among all three brands, which indicates that fermentation caused the VOC profiles to become more similar to one another. Visual distinctions in chromatographic plots were supplemented by principal component analysis and box plots, identifying distinguishing compounds. Investigating the profile of poi via GC×GC–qMS enhanced our understanding of its unique qualities, historical context, and contemporary use.