Sulfites in food

We can create optical sensors for specific analytes by placing a chemically sensitive layer at the end of the fiber. An optical fiber sensor is called an optode (or opt rode), derived from the words "optical and "electrode. Optodes have been designed to respond to diverse analytes such as sulfites in food, nitric oxide in cells, and explosives in groundwater.12... 

J. Greyson and S. Zeller, Analytical Coulometry in Monier-Williams Sulfite-in-Food Determinations, Am. Lab., July 1987, p. 44 D. T. Pierce, M. S. Applebee, C. Lacher, and J. Bessie, Low Parts Per Billion Determination of Sulfide by Coulometric Argentometry, Environ. Sci. TechnoL 1998,32, 1734. 

Roughly 10 years ago, an ion-pair HPLC was introduced for the determination of sulfites in foods (32). The method combined the chemical approach of the Monier-Williams technique for liberating the sulfite from the matrix with ion chromatography. The ion chromatographic procedure... 

This difference in kinetics was exploited to develop a procedure to determine free and reversibly bound sulfite in food. The mobile phase consisted of an aqueous solution of 0.05 M tetra-butylammonium hydroxide adjusted to the desired pH by the addition of glacial acetic acid (34). Fluorimetric detection is also possible, because a reaction of the formaldehyde-bisulfite complex with 5-aminofluorescein gives a nonfluorescent product. The sulfite is measured indirectly by its suppresion of the fluorescence of the reagent (31). This method is applicable to the determination of S02 at > 10 ppm and is not applicable to dark-colored foods or ingredients where SO, is strongly bound, e.g., caramel color. This method does not detect naturally occurring sulfite. Sulfur dioxide is released by direct alkali extraction. 

T Fazio, CR Warner. A review of sulfites in foods analytical methodology and reported findings. Food Addit Contam 7 433-454, 1990. 

C Anderson, RC Warner, HD Daniels, LK Padgett. Ion chromatographic determination of sulfites in foods. J Assoc Off Anal Chem 69 14-19, 1986. 

DM Sullivan, LR Smith. Determination of sulfite in foods by ion chromatography. Food Technol 39 45-48, 1985. 

HJ Kim, YG Park, KY Kim. Analysis of sulfites in foods by ion exclusion with electrochemical detection. Food Technol41 85—91, 1987. 

AOAC Official Method 990.31. Sulfites in foods and beverages. In P Cunniff, ed. Official Methods of Analysis of AOAC International. 16th ed. Arlington, VA AOAC International, 1995, pp 33-34. 

Anon (n.d.b) Dionex application note number 67 The determinadon of plant-derived neutral oligo- and polysaccharides. Available as a downloadable file from the Dionex website(http //www.Dionex.com). Anon (n.d.c) Dionex application note number 54 The determination of sulfite in food and beverages by ion exclusion chromatography with pulsed amperometric detection. Available as a downloadable file from the Dionex website (http //www.Dionex.com). 

Hypersensitivity reactions to potassium metabisulfite and other sulfites, mainly used as preservatives in food products, have been reported. Reactions include bronchospasm and anaphylaxis some deaths have also been reported, especially in those with a history of asthma or atopic allergy. " These reactions have led to restrictions by the FDA on the use of sulfites in food applications. However, this restriction has not been extended to their use in pharmaceutical applications. Indeed, epinephrine (adrenaline) injections used to treat severe allergic reactions may contain sulfites. ... 

An undesirable reaction of sulfite in food is the cleavage of thiamin by means of an attack at the pyrimidin moiety (Zoltewicz et al., 1984). This was one of the reasons for a ban, in many countries, on the use of sulfite in meat. Another reason is the preserving effect on the meat color, which makes stale meat look as if it were fresh. Sulfite, however, is unable to reduce metmyoglobin back to myoglobin (Wedzicha and Mountfort, 1991). 

Dionex Application Note, 34, Determination of sulfite in food and beverages by ion exclusion chromatography with pulsed amperometric detection, Dionex Corp., Sunnyvale, CA, 1999. 

Sullivan et al.(4S] used an FI gas-diffusion spectrophotometric system to determine sulfite in food products including fruits, vegetables, shrimps and wines. Sulphur dioxide is separated from the sample using a gas-diffusion membrane separator, and determined by decolorization of Malachite Green. The method shows good selectivity and sensitivity, and sulfite may be determined with a detection limit of 0.1 mg 1 in the food extracts, corresponding to 1-10 mg kg in the food product, and with a precision of 1-2% r.s.d.. 

Two other methods have been approved by AOAC for determination of sulfites in food. One is a quantitative assay based on malachite green decolorization using flow injection analysis. Sulfite is released from a sample slurry with alkali, then the test stream is acidified to produce sulfur dioxide gas which diffuses across a Teflon membrane into a flowing stream of malachite green, and the extent of decolorization is measured at 615 nm. The other method is based on ion exclusion chromatography with sulfur dioxide being released by alkali extraction, and the diluted filtrate is injected onto an anion exclusion column linked to an electrochemical detector. 

The wide use of sulfites in the food industry and the lack of critical information about their effects on foods prompted the editors to seek contributions in this field. Gehman and Osman and Joslyn and Braver-man have come forward with two excellent articles relating to both the fundamental and practical aspects of using sulfites in foods. The former authors have confined themselves to the all-important subject of sugar-sulfite reactions in foods while the latter discuss the many uses for, and effects of sulfites. 

Subsequently pulsing profiles have been employed to maintain electrode performance for some other difficult analytes, such as thiols (Chapter 5), and inorganic ions, such as sulfite in foods. A detailed description of the use and applications of PAD has been provided. ... 

J. F. Lawrence and K. R. Chadha, Head-space liquid chromatographic technique for the determination of sulfite in food., /. Chromatogr., 398, 355,1987... 

Other antioxidants include sulfites, often added to wine and fruits as a preservative and antibrowning agent, and EDTA, which immobilizes metal ions that often catalyze oxidation reactions. The presence of sulfites in foods is usually labeled because some people (especially asthmatics) are allergic to them. 

Romao-Sartori, E Hissashi-Takeda, H. and Fatibello-Filho, O. (2011) Glassy carbon electrode modified with fiictionalized carbon nanotubes within a poly(allylatnine hydrochloride) film for the voltammetric determination of sulfite in foods. Electroanalysis, 23, 2526-2533. 

This chapter provides an overview of the various procedures currently in use, with specific reference to those based on flow injection analysis (FIA), as this offers advantages such as sensitivity, selectivity, rapidity, low cost and automation, among others. FIA is reviewed here as an alternative to conventional methods for determining sulfites in foods and beverages, looking in detail at aspects of extraction, separation, detection and quantification procedures in different matrices. 

Various different extraction conditions (distillation, acid extractant, alkaline extractant, etc.) have been tried for determination of sulfites in foods and beverages. These processes require some procedure to remove and recover the total sulfites (free and reversibly bound) and avoid loss of sulfites during extraction, which can be substantial. This is especially important in complex food matrices where extraction is a crucial step in sulfite determination. 

Sulfites in foods or beverages need to be quantified to assure quality and compliance with legal regulations and to minimize the health risk to consumers. Because of its noticeable advantages, FIA has become one of the most widely used methods for determining sulfites. FIA gives a fast, simple and precise analytical response in real time, and small amounts of sulfite can be determined with low reagent consumption when small volumes of samples are available. The instrumentation is relatively simple and miniaturization is possible. It offers low interference and can be easily applied for routine analyses in control laboratories or industrial applications. 

Edberg, U. 1993. Enzymatic determination of sulfite in foods NMKL interlaboratory study. J. AOAC Int. 76 53-58. 

He, D. Y., Z. J. Zhang, and Y. Huang. 2005. Chemiluminescence microllow injection analysis system on a chip for the determination of sulfite in food. Anal. Lett. 38 563-571. 

Holak, W. and B. Patel, 1987. Differential pulse polarographic-determination of sulfites in foods—Collaborative study./. AOAC 70 572. 

Li, Y. and M. Zhao. 2006. Simple methods for rapid determination of sulfite in food products. Food Control 17 975-980. 

Taylor, S. L., N. A. Higley, and R. K. Bush. 1986. Sulfites in foods Uses, analytical methods, residues, fate, exposure assessment, metabolism, toxicity, and hypersensitivity. Adv. Food Res. 30 1-76. 

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