The synergistic effect of thurincin H and power ultrasound: An alternative for the inactivation of Listeria innocua ATCC 33090 and Escherichia coli K-12 in liquid food matrices

Microorganisms in flowing water were disinfected by UV radiation from two excimer (excited dimer) lamps (emitting at 172 and 222 nm) in combination with two low-pressure mercury lamps (emitting at 254 nm). Synergies were investigated among the three types of radiation in the treatment of water spiked in turn with Escherichia coli, Listeria innocua, Shewanella putrefaciens, and spores of Bacillus subtilis and Bacillus cereus. Synergy was demonstrated between radiations at 222 and 254 nm in the treatment of E. coli, L. innocua, and S. putrefaciens, but little or no synergy was observed in the treatment of B. subtilis and B. cereus. At maximum flow rates (60 liters/min), 5-log reductions in E. coli were achieved at 254 nm, although at 222 nm, less than 1-log reductions were observed. No bacterial kill was observed with 172-nm radiation alone, despite increasing exposure time by reducing flow rates to less than 3 liters/min.

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Efficacy of a Novel Sanitizer Composed of Lactic Acid and Peroxyacetic Acid against Single Strains of Nonpathogenic Escherichia coli K-12, Listeria innocua, and Lactobacillus plantarum in Aqueous Solution and on Surfaces of Romaine Lettuce and Spinach

Journal of Food Protection ◽

10.4315/0362-028x.jfp-11-110 ◽

2011 ◽

Vol 74 (9) ◽

pp. 1468-1474 ◽

Cited By ~ 19

Author(s):

KAI-LAI GRACE HO ◽

DIEGO A. LUZURIAGA ◽

KENNETH M. RODDE ◽

SHANNON TANG ◽

CUONG PHAN

Keyword(s):

Escherichia Coli ◽

Lactic Acid ◽

Lactobacillus Plantarum ◽

Ph Value ◽

Fresh Produce ◽

Microbial Reduction ◽

Listeria Innocua ◽

Peroxyacetic Acid ◽

Log Reduction ◽

K 12

A novel sanitizer composed of lactic acid and peroxyacetic acid (LA-PAA) was developed as an alternative to chlorinated water (CW) for fresh produce processing. Single strains of Lactobacillus plantarum, nonpathogenic Escherichia coli K-12, and Listeria innocua were used to demonstrate the microbial efficacy of LA-PAA. LA-PAA achieved a >7.8-log reduction of L. innocua and L. plantarum suspended in water at 4°C for 20 s, and LA, PAA, and CW achieved reductions of 0.4, 4.8, and 2.7 log, respectively. LA-PAA, when compared with LA, PAA, and CW, enhanced the reduction of L. innocua attached to romaine leaves by >2.2 log, and improved the removal of E. coli attached to spinach leaves by >2.4 log. The exponential improvement in the microbial efficacy of LA-PAA showed synergism between LA and PAA. LA-PAA microbial efficacy was inversely proportional to pH value and directly correlated with residence time and concentration. Despite an improvement in microbial reduction through the addition of surfactant to LA-PAA, the usage of surfactant in washing fresh produce was impeded by excessive foaming during actual processing. Effects of organic matter on the performance of LA-PAA were minimal. External sensory evaluations showed that LA-PAA had no negative effects on the quality of lettuce and tender leaves. Temperature-abuse studies demonstrated that LA-PAA reduced decay by ~50% when compared with CW. Overall, these results support the premise that LA-PAA has significant potential to be an alternative to CW for fresh produce processing.

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