The Persian granular caviar traditionally is made in two forms of additives (1) with salt but without any preservative and (2) with salt and preservative (Boric acid and Borax). This preservative has a very weak antimicrobial activity and beside its use is illegal in most western countries. Therefore because of an urgent need for a new formulation of additive in this product, 16 formulations of additives were used and evaluated in this study. These formulations, contained 3 concentrations of salt (4.5, 5 and 5.5%) and 4 combinations of preservatives incuding (1) a mixture of 0.3% Boric acid with 0.4% of Borax, (2) a mixture of 0.26% K- sorbate with 80 ppm of Na-nitrite, (3) 0.1% of methyl paraben and (4) 0.2% of methyl paraben. All of these formula were made in Brain Heart Infusion (BEI) broth and inoculated with 2 bacteria (C. botulinum type E spores and E. coli type 0111 ells) using >105 spores or cells per ml of broth and stared for up to 7d at 30C Clostridium botulinum was examined for both growth and toxicity testing using bioassay technic. The results indicated that the lowest antimicrobial activity belonged to the combination of Boric acid and Borax plus salt concentration of 4.5 to 5.5% with only bacteriostatic activity. The highest antimicrobial activity belonged to the combination of 0.1 to 0.2% methylparaben plus salt concentration of 4.5 to 5.5% with a strong bacteriocidic activity. Increasing of salt from 4.5 to 5.5 concentration slightly icreased the antimicrobil activity of the additive combination. Therefore methyl paraben which is a GRAS (Generally Recognized As Safe) preservative, and has a strog antimicrobial activity at high pH values, was selected for use in caviar.
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