Effects of contact times and concentrations of LA and AO on E. coli O157:H7 reduction^a.

Treatment		E. coli O157:H7 reduction (log CFU g−1)
First stage	Second stage
Tap water 120 s		0.38 ± 0.15a
1% LA 120 s	Tap water 30 s	1.41 ± 0.18c
1% LA 60 s	0.5 mg L−1 AO 60 s	1.12 ± 0.16b
1% LA 60 s	1.0 mg L−1 AO 60 s	1.28 ± 0.15bc
1% LA 60 s	2.0 mg L−1 AO 60 s	1.38 ± 0.03c
1% LA 90 s	0.5 mg L−1 AO 30 s	1.45 ± 0.10c
1% LA 90 s	1.0 mg L−1 AO 30 s	1.70 ± 0.08d
1% LA 90 s	2.0 mg L−1 AO 30 s	1.72 ± 0.16d

^aAO, aqueous ozone; LA, lactic acid. Different letters in a column indicate a significant difference (P < 0.05). Values are expressed as means ± standard deviations.