Growth and toxigenesis behavior ofClostridium botulinum type E in Persian sturgeon (Acipenserpersicus) Caviar prepared with various preservatives

Growth behavior ofclostridium botulinum type e beluga was studied in acipenserpersicus granular caviar treated with 5°1o naci, 50/0naci plus 0.3°/0 boric acid and 0.4°/oborax and 5°/onaci plus 0.15°/0 methyl paraben incubated at temperatures -2, 5 and 15 °c for 224 days.the initial number of inoculated bacterial spore was 5.1x104 cfu/g caviar in each treated sample. the numberofbacterial spores in samples treated with 5°1o naci changed to 3.59 x 104 , 1.02xl05 and 9.9xl05 cfu/g at _2°c, 5 °c and 15°c, respectively, while those samples treated with 5°/onaci plus 0.3°/0 boric acid and 0.4°/oborax changed to 1.56xl04 , 3.65xl04 and 9.22xl04 cfu/g respectively. also, number of bacterial spores in samples treated with 5°1o naci plus444 0.15~'o methyl paraben changed to lxl0 ,2.86xi0 and 3.56xi0 cfu/g at the above storage temperatures, respectively. fourteen days post-inoculation, toxin production was positive in samples treated with 50/0 naci incubated at 5 °c and 15°c, while those samples treated with5°/onaci plus 0.3°/0boric acid and 0.4°/0borax were positive for toxin production only at 15°c. toxin production was negative in samples treated with 5°/onaci plus 0.15°/0 methyl paraben incubated at all three above mentioned temperatures. these data showed that 5°/onaci plusmethyl paraben had more inhibitory effect than boric, borax and naci. also, such inhibitory effects can be increased at lower storage temperature of-2°c. therefore, due to restricted usageofboric acid and borax in granular caviar, use ofmethyl paraben can be recommended as a safe preservative with a strong antimicrobial effect at caviar ph.