Description and Microbiology of Home-Canned Tomatoes and Tomato Juice

Abstract

Home canners completed questionnaires and submitted 378 jars of tomatoes and 382 jars of tomato juice for analysis. Nearly 50% of the containers were non-canning jars, and 25 jars had held food items such as instant tea or coffee or jelly. A few closures were reused from grocery stock; the remainder were the two-part rim and lid or zinc cap and ring. The headspace in 14% of the jars was below 16/32 inch and in 17% between 31/32 and 64/32 inch. Serum layers in 70% of the jars of tomato juice ranged from 20 to 64% of the volume. Eleven percent of the samples were processed with the method of hot fill and seal only, 66% were processed in boiling water, and 23% in the pressure canner. Vacuums of 13 to 15 inches of mercury were most frequently recorded in jars processed with any of the three methods. The pH ranged from 3.5 to 4.7. The average titratable acidity as citric acid, of tomatoes was 0.444% and of tomato juice 0.471%. Microorganisms were recovered from 33% of the jars of tomatoes and from 15% of the tomato juice; however, the percentage of recovery decreased during the period of analysis, suggesting autosterilization. The microorganisms recovered included three fermentative yeasts, one Rhodotorula, three filamentous fungi, 15 Bacillus licheniformis, and the remainder were Klebsiella pneumoniae. It is concluded that directions given to home canners are adequate for home preservation of tomatoes and tomato juice, and that most canners engage in good canning practices.