Buffered Peptone Water: Salmonella Recovery.pdf

Pre-enrichment medium for food samples prior to selective enrichment and isolation of Salmonella.
- Composition (per liter): Peptone (10g), Sodium chloride (5g), Disodium phosphate anhydrous (3.5g), Monopotassium phosphate (1.5g).
- Preparation: Dissolve 20g in 1L purified water, mix thoroughly, autoclave at 121°C for 15 minutes.
- Storage: Tubes, bottles, bags: 2-25°C; Dehydrated media: 2-30°C.
- Inoculation (ISO 11133): 10-102 CFU/ml, streaking at T0 and T45mn, reference media TSA, incubation 24±3 hours at 37±1°C.
- References: ISO 6579, ISO 6785, ISO 6887-1 to -6, ISO 8261, ISO/TS 11133.

Half-Fraser Broth

- Use: Selective and differential enrichment of Listeria monocytogenes in food and feed products.
- Composition (per liter): Polypeptone (10g), Meat extract (5g), Yeast extract (5g), Sodium chloride (20g), Disodium phosphate (9.6g), Monopotassium phosphate (1.35g), Esculin (1g), Lithium chloride (3g), Nalidixic acid (10mg), Acriflavin (HCl) (12.5mg), Ferric ammonium citrate (0.5g).
- Storage: Store between 2 and 25°C in the dark until expiry date.
- Usage: Inoculate 25g product in 225ml broth, homogenize, incubate 24h±3h at 30°C. After incubation, inoculate 0.1ml in 10ml Fraser broth, incubate at 37°C for 24h twice. Isolate on Palcam or Oxford agar.
- Quality Control: Typical culture response after 24 hours at 30°C, followed by subculture on Ottaviani and Agosti agar. Selectivity and productivity tests using Enterococcus faecalis, Escherichia coli, and Listeria monocytogenes.
- References: Fraser & Sperber (1988), ISO/TS 11133, ISO 11290-1, ISO 11290-2.