Inactivation of salmonella strains in acidified broth and raw egg yolk as a function of pH and acid type
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Inactivation of salmonella strains in acidified broth and raw egg yolk as a function of pH and acid type. / Nielsen, Line; Knøchel, Susanne.
I: Food Microbiology, Bind 92, 103574, 2020.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Inactivation of salmonella strains in acidified broth and raw egg yolk as a function of pH and acid type
AU - Nielsen, Line
AU - Knøchel, Susanne
PY - 2020
Y1 - 2020
N2 - Raw egg-based dishes present a safety risk when eggs of uncertain Salmonella status are used. Here, the inactivation of four Salmonella serovars at different combinations of acid, pH and temperature were investigated. Strains of egg or broiler-associated Salmonella serovars Enteritidis, Infantis, Typhimurium, and a heat resistant Senftenberg 775W were tested in broth and egg yolk. It was observed that although S. Senftenberg 775W survived better than its mutant lacking the loci of heat resistance, the wild type per se was not acid tolerant. For all strains, egg yolk acidification with vinegar to pH 3.9 and storage at 25 °C or 8 °C resulted in >4Log(cfu/mL) reductions within 2h or 24h, respectively. At pH 4.2, 2-3Log(cfu/mL) reductions were seen within 6h at 25 °C. In contrast, acidification with lemon juice to pH of 3.9 allowed for growth at 25 °C, while a pH of 2.9 ensured >4Log(cfu/mL) reductions within 24h. Egg yolk and acid form the basis for many recipes and with a ratio of 0.82 of vinegar (≥5% acetic acid) to egg yolk or 1.23 of lemon juice to yolk and storage at 25 °C for 2h or 24h, respectively, a high degree of safety can be obtained, if properly chilled raw eggs are used.
AB - Raw egg-based dishes present a safety risk when eggs of uncertain Salmonella status are used. Here, the inactivation of four Salmonella serovars at different combinations of acid, pH and temperature were investigated. Strains of egg or broiler-associated Salmonella serovars Enteritidis, Infantis, Typhimurium, and a heat resistant Senftenberg 775W were tested in broth and egg yolk. It was observed that although S. Senftenberg 775W survived better than its mutant lacking the loci of heat resistance, the wild type per se was not acid tolerant. For all strains, egg yolk acidification with vinegar to pH 3.9 and storage at 25 °C or 8 °C resulted in >4Log(cfu/mL) reductions within 2h or 24h, respectively. At pH 4.2, 2-3Log(cfu/mL) reductions were seen within 6h at 25 °C. In contrast, acidification with lemon juice to pH of 3.9 allowed for growth at 25 °C, while a pH of 2.9 ensured >4Log(cfu/mL) reductions within 24h. Egg yolk and acid form the basis for many recipes and with a ratio of 0.82 of vinegar (≥5% acetic acid) to egg yolk or 1.23 of lemon juice to yolk and storage at 25 °C for 2h or 24h, respectively, a high degree of safety can be obtained, if properly chilled raw eggs are used.
KW - Acetic acid
KW - Citric acid
KW - Food borne illness
KW - Inactivation
KW - Mayonnaise
KW - Raw egg
KW - Salmonella
U2 - 10.1016/j.fm.2020.103574
DO - 10.1016/j.fm.2020.103574
M3 - Journal article
C2 - 32950158
AN - SCOPUS:85087880454
VL - 92
JO - Food Microbiology
JF - Food Microbiology
SN - 0740-0020
M1 - 103574
ER -
ID: 245004832