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Viability of Escherichia Coli on English Walnut Meats (Juglans regia)
Author(s) -
KOKAL DANIEL
Publication year - 1965
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1965.tb00310.x
Subject(s) - juglans , tannin , food science , chemistry , escherichia coli , population , substrate (aquarium) , biology , biochemistry , gene , ecology , demography , sociology
SUMMARY The effect of walnut meats on Escherichia coli viability was evaluated. Water‐washed and unwashed English walnut meats were immersed in E. coli suspension under controlled conditions. Meats were dried at room temperature, packed in plastic bags in 50‐g quantities, and stored under various conditions at room temperature and in the cold. Periodic examination of meats by bag over eight months revealed the following. The E. coli population was reduced 99% during two days of drying on unwashed substrate, but not on washed substrate. On the one hand, both unwashed and washed nuts stored at room temperature failed to show any E. coli after three and four months storage respectively; on the other hand, there was no significant loss of E. coli viability on either unwashed or washed nuts stored in the cold up to 240 days. The effect of walnut tannin extract on E. coli was determined. This effect was greater on cells suspended in saline than on cells suspended in 0.1% peptone water. In 0.9% saline, 1 × 10 7 cells were killed at 0.62% walnut tannin concentration and 1 × 10 6 cells at 0.1670, both within 1 hr, whereas 2.5% tannin concentration was required to kill 1 × 10 7 cells in 0.1% peptone water within 2 hr. The reliability of E. coli as the index organism to detect insanitation in English walnut meats is discussed.