Page 129 - 2013 ISPAM Mid-Year Mtg Book

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Pre-enrichment – time and temperature, other
considerations
Time and Temperature Requirements
AOAC 24 ± 2 h at 35 ± 2°C –
BAM (FDA) – 24 ± 2 h at 35 ± 2°C
MLG (FSIS-USDA) – varies with food, 18-24 h, 20-24h or 22-26h (all ± 2°C)
HC – 18-24h at 35 ± 1°C
ISO – 18 ± 2 h at 37 ± 1°C
Other considerations – variable requirements for:
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- Need for pH adjustment
- Pre-soaking of dry ingredients
- Thawing requirements for frozen product
- Formulation differences for “same named” broths.
Selective Enrichment – media, time and
temperature
AOAC - in 967.27 -selenite cystine (SC) and tetrathionate (TT) (both1 mL in 10, 35°C, 24± 2h) – one
exception for dry yeast substituting lauryl sulfate tryptose broth for selenite cystine)
i 995 20 d 2000 06 R t V ili di (RV) di (0 1 L i 10 42 0 2°C 24 2h) d - n . an . – appapor - ass a s me um . m n , ± . , ± an
TT (1 mL in 10, 43 ± 0.2°C, 24± 2h for foods with a high microbial load OR 1 mL in 10, 35 ± 2°C, 24± 2h
for foods with a low microbial load ) – some exceptions (e.g., guar gum)
BAM (FDA) – RV medium (0.1 mL in 10, 42 ± 0.2°C, 24± 2h) and TT (1 mL in 10, 43 ± 0.2°C, 24± 2h for
foods with a high microbial load OR 1 mL in 10, 35 ± 2°C, 24± 2h for foods with a low microbial load).
Exceptions as well for guar gum.
MLG (FSIS-USDA) – RV medium (mRV, RVS or RV R10 broth medium) and TT (both 0.5 mL in 10, 42 ±
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0.5°C, 22-24 h in an incubator or 18-24 h in a waterbath)
HC – RVS (0.1 mL in 10) and TT (1 mL in 10), RVS and TT (42.5 ± 0.2°C for 24 ±2h) – an option to substitute
RVS with SC
ISO – RVS (0.1 mL in 10, 41.5 ± 1.0°C for 24 ±3h) and MKTT (1 mL in 10, 37 ± 1.0°C for 24 ±3h)