|Barish, A - NCSU|
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 14, 2003
Publication Date: February 1, 2003
Citation: McFeeters, R.F., Barish, A.O. 2003. Sulfite analysis of fruits and vegetables by high-performance liquid chromatography (HPLC) with ultraviolet spectrophotometric detection. Journal of Agricultural and Food Chemistry. 51:1513-1517. Interpretive Summary: Sulfite is used as a preservative in a variety of different foods to prevent development of off-colors and growth of undesirable microorganisms. Sulfite has been used in dried fruits and vegetables, wine, shrimp and acidified vegetables. In addition to its useful effects in foods, however, it can cause allergic-like reactions in a small proportion of people. Analysis of sulfite in foods is difficult because it can react both reversibly and irreversibly with food components so the amount present in foods often declines during storage. A number of different methods have been used to measure it in foods. This publication describes a method of chromatography followed by measurement of the absorption of ultraviolet light by the sulfite. Light absorption has not been previously used as a means for detection of sulfite after its separation from other food components. The advantages of this procedure are a low minimum level of detection, good analytical reproducibility and the use of a detection method that is commonly available to food analysts.
Technical Abstract: Free and total sulfite were analyzed in acidified vegetable products, instant mashed potatoes and dried apples. Sulfite was separated by HPLC and quantified with a UV/VIS detector. Good resolution from components of food samples was achieved by varying the acid concentration of the eluant solution and by appropriate choice of the analytical wavelength. The minimum detectable level for sulfite was 0.5 ppm for a 10-cm analytical column and 1.5 ppm for a 30-cm column. For analyses done with a 30-cm column, the coefficient of variation was less than 2% for analysis of free sulfite and total sulfite in acidified vegetables. For dried apples and instant potatoes, it ranged from 1-6.5%. The corresponding analytical errors were less than 4% and 1.2-5.6%, respectively for the 10-cm column.