Reduction of Listeria innocua in fresh-cut Chinese cabbage by a combined washing treatment of sweeping frequency ultrasound and sodium hypochlorite

Publication date: March 2019Source: LWT, Volume 101Author(s): Evans Adingba Alenyorege, Haile Ma, Ishmael Ayim, Joshua Harrington Aheto, Chen Hong, Cunshan ZhouAbstractThe investigation compared the efficiency of single treatments and their combinations in reducing Listeria innocua on fresh-cut Chinese cabbage. Samples were inoculated and treated separately with sweeping frequency ultrasound (SFUS; 28 ± 2–68 ± 2 kHz) and sodium hypochlorite solution (NaOCl; 20–100 mg/L) and their combinations. Treatments were evaluated based on attainable bacterial reduction and treatment synergy. The L. innocua population in the samples reduced to 0.36–0.95 and 0.22–1.29 log CFU/g after treatment with NaOCl and SFUS respectively. The combined application of 40 ± 2 kHz SFUS and 100 mg/L NaOCl accomplished a 3.35 log CFU/g reduction of L. innocua, exhibiting an additional 2.06 log CFU/g reduction compared to single treatments, without causing adverse quality changes to leaf colour, texture, pigments and microstructure. L. innocua population reduction in Chinese cabbage was frequency-dependent rather than NaOCl concentration. Synergistic reductions of L. innocua were recorded in 85% of the combined treatments, though most of the values are below 1.0 log-cycle. The maximum synergistic values of 1.14 or 1.20 log CFU/g were achieved when 40 ± 2 kHz SFUS and 100 mg/L NaOCl or SFUS 68 kHz and 100 mg/L NaOCl were combined respectively.
Source: LWT Food Science and Technology - Category: Food Science Source Type: research