Investigation of optimum ohmic heating conditions for inactivation of Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes in apple juice

Table 1 Log reductions of E. coli O157:H7 in 72, 48, 36, 24, and 18 °Brix apple juice subjected to ohmic heating at 30 and 60 V/cm

Voltage		Log reduction [log₁₀ (N₀/N)]^a by treatment time (s)
gradient	°Brix	0		10		20		30		40		50		60
30 V/cm	72	0.00 ± 0.00	A	0.44 ± 0.22	B	0.42 ± 0.05	B	0.53 ± 0.16	B	0.56 ± 0.32	B	0.71 ± 0.22	BC	0.95 ± 0.03	C
	48	0.00 ± 0.00	A	0.26 ± 0.07	A	0.34 ± 0.02	A	0.41 ± 0.05	A	0.89 ± 0.22	B	1.38 ± 0.22	C	2.59 ± 0.63	D
	36	0.00 ± 0.00	A	0.28 ± 0.14	A	0.34 ± 0.04	A	0.91 ± 0.37	B	1.40 ± 0.30	C	3.33 ± 0.31	D	6.78 ± 0.11	E
	24	0.00 ± 0.00	A	0.24 ± 0.08	AB	0.22 ± 0.13	AB	0.71 ± 0.48	BC	1.26 ± 0.46	C	2.97 ± 0.47	D	5.21 ± 0.36	E
	18	0.00 ± 0.00	A	0.09 ± 0.08	A	0.17 ± 0.30	AB	0.17 ± 0.06	AB	0.67 ± 0.31	B	1.34 ± 0.50	C	2.71 ± 0.29	D
60 V/cm	72	0.00 ± 0.00	A	0.38 ± 0.22	AB	0.67 ± 0.22	B	0.62 ± 0.06	B	0.55 ± 0.29	AB	0.73 ± 0.32	B	0.73 ± 0.60	B
	48	0.00 ± 0.00	A	0.42 ± 0.13	B	6.33 ± 0.13	C	ND		ND		ND		ND
	36	0.00 ± 0.00	A	0.82 ± 0.17	B	6.58 ± 0.22	C	ND		ND		ND		ND
	24	0.00 ± 0.00	A	0.74 ± 0.58	B	6.88 ± 0.06	C	ND		ND		ND		ND
	18	0.00 ± 0.00	A	0.50 ± 0.41	B	6.93 ± 0.11	C	ND		ND		ND		ND

^aThe values are means ± standard deviations from three replications. Values in the same row followed by the same letter are not significantly different (P > 0.05). ND not detected.

ISSN: 1471-2180