Ripening and spoilage of sugar salted herring with and without nitrate.

The technological effect of nitrate and the possible role of this compound in the formation of volatile nitrosamines during ripening and spoilage of sugar salted herring have been examined. In total, 600 barrels of fish with various amounts of nitrate added to the curing salt were prepared and stored under commercial conditions. During storage (18 months) the organoleptic, microbiological and chemical changes were studied. Additionally, a number of model experiments were carried out to evaluate the effect of nitrate on microbial growth and chemical changes. It was found that addition of nitrate significantly influences the colour of the fish while texture and flavour are not affected. Based on both the practical experiments and the model studies it is concluded that nitrate per se does not inhibit any microbial growth. Growth of strict anaerobes does not occur until the substrate is depleted of TMAO, and nitrate is effective in delaying the most common type of spoilage by delaying the TMAO reduction.
Small amounts of nitrosodimethylamine—up to 2.9 ppb has been detected—was formed in the sugar salted herring, but the addition of nitrate to the curing salt had no influence.