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Postharvest transfer and survival of S almonella enterica serotype enteritidis on living lettuce
Author(s) -
Waitt J.A.,
Kuhn D.D.,
Welbaum G.E.,
Ponder M.A.
Publication year - 2014
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.12170
Subject(s) - salmonella , postharvest , salmonella enterica , inoculation , biology , contamination , salmonella enteritidis , serotype , horticulture , food science , microbiology and biotechnology , bacteria , ecology , genetics
The potential for postharvest transfer of S almonella to ‘living lettuce’ is not well understood. In this study, the transfer of S almonella enterica E nteritidis (6 log CFU g −1 ) from worker hands or contaminated roots to leaves of living lettuce was quantified. Transfer rates of S almonella from contaminated gloves to sequentially handled lettuce heads ranged from 94% to head 1, 82% to head 2 and 69% to head 3. On average, 2·9 ± 0·1 log CFU g −1 (64%) S almonella was transferred from inoculated roots to leaves resulting from typical postharvest handling activities for living lettuce. Salmonella persisted on leaves stored at recommended storage temperatures (4°C) and increased 0·5 log CFU g −1 when stored at temperature abuse conditions (12°C). Salmonella increased 1·6 log CFU g −1 on roots after 18‐day storage at 12°C, emphasizing the need to maintain temperature control to reduce the risk of human illness. Significance and Impact of the Study Hydroponically grown lettuce packaged in plastic clamshells with intact roots, marketed as ‘living lettuce’, is increasing in popularity due to its extended shelf life. This study demonstrates the transfer of S almonella from contaminated worker hands and contaminated roots to leaves where it persisted at 4°C for 18 day. Temperature abuse (12°C) increased S almonella on roots and leaves. These findings suggest that failure to maintain temperatures below 12°C can pose a risk for consumers purchasing living lettuce at markets where recommended storage temperatures are not maintained.