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 plus 444 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 with 5°/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 plus methyl 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 usage ofboric acid and borax in granular caviar, use ofmethyl paraben can be recommended as a safe preservative with a strong antimicrobial effect at caviar pH.