Comparison of mould filament counting techniques for industrialized tomato sauces

Abstract

The objective of this study was to compare different techniques for counting mould filaments in industrialized tomato sauces available on the Brazilian market. In order to do so, 42 samples of the product “traditional tomato sauce” (from 21 different brands), sold in supermarkets in the municipality of the city of Bauru, Brazil, were collected during the period from April to June, 2016. The mycelial moulds were counted by the Howard method according to the official methodology recommended by the Association of Official Analytical Chemists (AOAC), applying techniques 965.41 and 945.92. Notably, the application of technique 945.92 using sodium hydroxide (NaOH) to eliminate the starch in the samples, facilitated counting of the hyphae and, consequently, the percentages of positive fields observed were significantly higher (median = 10%) when compared with the percentages obtained after using technique 965.41 (median = 6%) (p < 0.001). The present findings reveal the need to expand the discussion concerning the application of different techniques for the counting of mould filaments in industrialized tomato sauces, especially in Brazil and in other countries that do not prohibit the addition of starch to this kind of product.