Determination of benzoic and sorbic acids in packaged vegetable products. Comparative evaluation of methods.
Three analytical methods for determining sorbic and benzoic acids in various packaged vegetable products were evaluated, with special attention being paid to green olives. Two of these methods used a simple, isocratic, reversed-phase HPLC technique for separating and detecting the preservatives, but differed in the preparation of the sample (extraction with 60% methanol or steam distillation). The third method was based on separation by steam distillation and determination of the acids in the distillate by spectrophotometry. For the olives, while this method proved to be excellent (total error < 25%) for high concentrations (> 100 ppm), the HPLC methods were more efficient for the whole range of concentrations studied (5-500 ppm). Both HPLC methods had detection limits of approximately 1 ppm for the two preservatives. With other sample matrices (tomatoes, cucumbers, caperberries, silver-skinned onions and hot peppers), the three methods proved to be excellent for high concentrations of preservatives (500 ppm), but at low levels (20 ppm), the spectrophotometric method and the HPLC method with extraction by 60% methanol proved to be unacceptable (total error > 50%) in some cases.
Departamento de Biotecnología de Alimentos, Instituto de la Grasa (CSIC), Seville, Spain.
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A
Montaño
A H
AH
Sánchez
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L
Rejano
D001565:Benzoates / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D005504:Food Analysis / Q000379:methods; D018857:Food Packaging; D005519:Food Preservation; D005520:Food Preservatives / Q000032:analysis*; D013011:Sorbic Acid / Q000032:analysis*; D014675:Vegetables / Q000737:chemistry*
D001565:Benzoates; D005520:Food Preservatives; D013011:Sorbic Acid