Comparison of two methods of volatile analysis for determining the causes of off-odors in white beet sugars SPME and headspace

摘要

White beet sugars periodically have off-odors, causing them to be rejected by customers. An understanding of the nature and source of the compounds responsible will help in eventually eradicating the problems that cause them. However, determining volatile substances in white sugar is challenging because the amounts present are very small, often in the parts-per-million or even parts-per-billion range. In this study, we describe a set of white beet sugar samples that were received from several locations. Each sugar was given an over-all sensory rating of: 1 = acceptable; 2 = borderline; or 3 = reject, by a sensory panel. The samples were analyzed by two methods of volatile analysis. The two methods investigated were Solid-Phase Micro Extraction (SPME) and headspace analysis. Sample chro-matograms were evaluated for compounds at mass to charge ratio (m/z) 60, where volatile fatty acids are found, with the exception of propionic acid. Representative chro-matograms illustrating acceptable, borderline, and reject sugars are shown. It was found that samples in the acceptable and borderline categories appeared to have lower levels of the more volatile fatty acids than did the reject sugars. This was true for both SPME and Headspace. However, it was apparent that SPME was a better technique for volatile analysis.