Indian Institute of Horticultural Research, Bangalore-560 080.
Microbiological analysis of tomato fruits revealed that aerobic mesophilic bacteria outnumbered yeasts and moulds and thermophilic bacteria. Washing the fruits reduced the numbers of yeasts and moulds considerably. Five yeasts, three moulds and two bacteria were found to be the predominant micro-organisms responsible for spoilage of tomato crush. Thermophilic bacteria survived the heat treatment given during the preparation of crush. Addition of potassium sorbate or propyl paraben, or sodium benzoate in the presence of potassium metabisulphite (here used essentially as an antioxidant although it has antimicrobial activity) inhibited this bacteria and yeasts added to heat treated crush. Tomato crush stored in polyethylene pouches with potassium sorbate, or propyl paraben individually or with ferric chloride as preservative potentiator did not show any microbial spoilage for 60 days. Propyl paraben was more effective than sodium benzoate in controlling yeast in YNB broth. In the presence of preservative potentiator, the preservative dose could be reduced to 100 ppm as against the normal dose of 200 ppm without any microbial spoilage in tomato crush.
