A high throughput method for total alcohol determination in fermentation broths

Background: The potassium dichromate oxidation method used in determination of alcohols in fermentation has two major disadvantages. This method cannot be used to determine alcohols in raw fermentation broth samples, which often contain various reducing sugars. The method is not environment friendly due to the carcinogenicity of Cr (VI) used. Results: A new method for determination of reducing sugars and total alcohols in raw fermentation broths was developed. The fermentation broth was pretreated to remove proteins, polysaccharides, glycerol and organic acids. The colorimetric change from both total alcohols and reducing sugars by potassium permanganate oxidation was measured. The portion of colorimetric change from oxidation of reducing sugars was determined by DNS test and subtracted. The remaining portion of colorimetric change was then used to calculate the total alcohol concentration in the sample. Conclusions: Using this method, total alcohol concentration can be easily and accurately determined in both distilled samples and raw fermentation broth samples. It is fast and environmental friendly.