ISHS Acta Horticulturae 542: VII International Symposium on the Processing Tomato
CONTROL OF BACILLUS COAGULANS AND CLOSTRIDIUM PASTEURIANUM IN TOMATO PRODUCTS |
| Authors: | M. Rocelle, S. Clavero |
| Keywords: | Flat-sours, butyric anaerobes, pH, titratable acidity |
| Abstract:
Conditions that can influence outgrowth of Bacillus coagulans and Clostridium pasteurianum spores in tomato juice and various tomato purees were investigated. Tomato purees containing tomato soluble solids (TSS) of 5–18% were prepared from canned tomato paste, and pH was adjusted with citric acid or potassium hydroxide (KOH) to the desired pH value; titratable acidity of each combination was determined. Fifty grams of each puree were weighed into sterile centrifuge tubes, preheated to 195°F (90.6°C), inoculated with 50 µl spore suspension to achieve 103, 101, or 100 B. coagulans spores/g of puree, and held for 3 min. Samples were immediately cooled in running water and incubated at 35–55°C. Samples were analyzed weekly for manifestations of spoilage. For Clostridium pasteurianum, 211 × 300 cans were individually inoculated with 50 µl of the desired spore suspension, hot-filled with tomato puree, sealed, and cooled. Cans were stored at 25, 35, or 45°C. Uninoculated samples (control) were likewise prepared. Studies have demonstrated that process parameters designed to control spoilage caused by growth of B. coagulans will likewise prevent the occurrence of spoilage resulting from growth of C. pasteurianum in tomato products. Microbial stability can be achieved at higher pH values (pH > 4.2) if initial spore load during processing is low and the TSS of the product is high. However, process conditions need to be optimized for each type of product. An 18% TSS will not assure stability of the product if pH is greater than 4.5. Experimental data suggest that control of growth can be achieved by adjusting pH to ≤ 4.2, reducing the level of contamination to a minimum (< 10 spores/g), and keeping the products at temperatures < 35oC. | |
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