Isolation and identification of Alicyclobacillus spp. from different steps in the production line of tomato paste using culture-dependent and molecular methods and Evaluation of brix effecton Alicyclobacillus growth

Objective of study was isolation and identification of Alicyclobacillus spp. from different steps in production of tomato paste and efficiency of pasteurization for elimination aforementioned bacteria.From each step of processing line including puree, tomato paste before first pasteurization and after final pasteurization, and six samples were obtained in 3 days. Following the heat-shock, Alicyclobacillus spp were isolated using culture-dependent methods. To evaluate growth ability of Alicyclobacillus and effect of Brix on its growth, samples were prepared with dilution corresponding to Brix 8 and 11 from tomato paste with Brix= 25-27 and evaluated along with puree samples. 17 isolates following sequencing and BLAST were identified up to genus and species level. 13 identified strains belonged to Alicyclobacillus acidocaldarius and four other isolates were Bacillus licheniformisstrain TS_16, un known Bacterium, Brevibacillus thermoruber strain TS_05, and Brevibacillus thermoruber strain TS_06. Alicyclobacillus count was culturally calculated 2.34±0.29 and 2.31±0.17 cfu/ml±SD in tomato paste before and after pasteurization, respectively. This implies the effect of pasteurization in lowering the Alicyclobacillus count. Results of the paired t-test of tomato paste showed a weak correlation (correlation coefficient =0.491, 0.409) between microbial counts in tomato paste of Brix 8 with those of Brix 11 and also there was no significant difference of Alicyclobacillus count between Brix 8 and 11. This means that three-degree increase of Brix didn’t cause any significant variation in the microbial count.