Direct, simple SIFT-MS headspace analysis for small volatile fatty acids (VFAs) is highlighted in a new publication from the Department of Food Science and Technology at The Ohio State University, Columbus OH, USA.
Small VFAs, such as acetic acid and propionic acid, present a challenge for traditional analytical techniques, because most gas chromatographic columns are poorly suited to resolving them. This means that significant sample preparation is required (often including derivatization to form esters) before they can be analyzed.
By applying SIFT-MS, Professor Sheryl Barringer and coworkers determined absolute concentrations of VFAs directly in the headspace of Swiss cheese curd slurries, without sample modification. In their paper, they demonstrate that addition of volatile organic compounds (VOCs) to the Swiss cheese curd slurry inhibits production of the high-impact Swiss cheese aroma compounds: propionic acid, acetic acid, and 3-methylbutanoic acid. The reduction in measured headspace VFAs in the headspace of the slurry was supported by a parallel reduction in the enumerated propionic acid bacteria responsible for producing the characteristic Swiss cheese flavor. In the manufacturing facility, this reduction results in defective product.
The simple, direct SIFT-MS analysis for VFAs and other VOCs lends itself to rapid quality assurance applications, both in the laboratory and in-process.
You can read the full text of the article by Castada et al. titled “Suppression of propionic acid, acetic acid and 3-methylbutanoic acid production by other volatiles in a Swiss cheese curd slurry system” in the International Dairy Journal (volume 54, pages 29-32). It is accessible here.