2.1. Chemicals/reagents
2-Nitrophenol (98%) was purchased from Sigma–Aldrich
(Poole, UK) and 2-nitrophenyl-b-D-glucoside was obtained from
Apollo Scientific (Stockport, UK). 3-Fluoroaniline (99%) was
obtained from Alfa Aesar (Morecambe, UK).
Columbia blood agar with 5% defibrinated horse blood, brain
heart infusion broth, Listeria enrichment broth and Listeria
selective enrichment supplement containing cycloheximide
25.0 mg, nalidixic acid 20.0 mg and acriflavine HCl 7.5 mg
500 ml1 broth were purchased from Oxoid (Basingstoke, UK).
Types of milk used: whole milk (3.6% fat), semi-skimmed milk
(1.8% fat), unhomogenised milk (5.2% fat), soya milk, whole goat's
milk (3.6% fat), skimmed milk (0.1% fat) and unpasteurised milk