Acids in Combination with Sodium Dodecyl Sulfate Caused Quality Deterioration of Fresh‐Cut Iceberg Lettuce during Storage in Modified Atmosphere Package

Abstract

Recent studies showed that sodium acid sulfate (SAS) and levulinic acid (LA) in combination with sodium dodecyl sulfate (SDS) was effective in inactivating human pathogens on Romaine lettuce. The present study investigated the effects of LA and SAS in combination with SDS (as compared with citric acid and chlorine) on the inactivation of E. coli O157:H7 and sensory quality of fresh-cut Iceberg lettuce in modified atmosphere packages during storage at 4 °C. Results showed that LA (0.5% to 3%) and SAS (0.25% to 0.75%) with 0.05% SDS caused detrimental effects on visual quality and texture of lettuce. LA- and SAS-treated samples were sensorially unacceptable due to development of sogginess and softening after 7 and 14 d storage. It appears that the combined treatments caused an increase in the respiration rate of fresh-cut lettuce as indicated by higher CO(2) and lower O(2) in modified atmosphere packages. On the positive side, the acid treatments inhibited cut edge browning of lettuce pieces developed during storage. LA (0.5%), SAS (0.25%), and citric acid (approximately 0.25%) in combination with SDS reduced population of E. coli OH157:H7 by 0.41, 0.87, and 0.58 log CFU/g, respectively, while chlorine achieved a reduction of 0.94 log CFU/g without damage to the lettuce. Therefore, compared to chlorine, LA and SAS in combination with SDS have limited commercial value for fresh-cut Iceberg lettuce due to quality deterioration during storage.

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

“…Similar to other studies that showed significant improvements in microbial efficacy with surfactants (11,18,32), the inactivation of L. innocua suspended in solution by LA, PAA, and LA-PAA was increased by 3.0, 1.8, and 1.4 log, respectively. In the case of L. innocua and E. coli K-12 that were attached to romaine and spinach leaves, the average improvement in the antimicrobial activities of LA-PAA with the addition of SLS was from 0.26 to 0.90 log.…”

“…These testing parameters are normal commercial processing conditions for leafy greens; thus, the results are valid and applicable for commercial scale-up. Previous works on other sanitizers were performed at higher temperatures (20 to 25uC) and longer dwell times (1 to 10 min) (11,17,20,24,30,32), which did not simulate commercial processing conditions. LA-PAA demonstrated significant enhancement in reducing microorganisms that were suspended in wash water and attached to surfaces of the leaves, when compared with CW, LA, and PAA.…”

“…Studies using more than one sanitizer in sequence from the same category (ozone and sodium hypochlorite) (8,20) or the addition of surfactants like sodium lauryl sulfate (SLS) to organic acids (11,18,32), have demonstrated the increase of the microbial efficacy of such sanitizers to overcome high organic loads and low temperatures in fresh-cut produce wash water. A novel sanitizer, lactic acid plus peroxyacetic acid (LA-PAA), trademarked as Fresh Rinse, was invented (12) to enhance microbial efficacy for fresh produce processing.…”

The Effects of Produce Washes on the Quality and Shelf Life of “Cantaloupe” (Cucumis Melo var. Cantalupensis) and “Watermelon” (Citrullus Lantus var. Lanatus)

“…Fan and group (2009) found fungal reductions after sanitizing melons with peroxyacetic acid at 80 ppm, but noted sensory reductions of aroma and appearance. These same effects in melons have been seen in other produce types with losses in color and texture associated with application of acids and hydrogen peroxide (Fonesca and Rushing 2006;Guan et al 2010;Alexandre et al 2012a,b;Lignou et al 2014). Silveira et al (2008) reported that the firmness of the "Galia" melons over a 10 day shelf life decreased significantly after the application of chlorine dioxide at 3 mg/L, peracetic acid at 80 mg/L, hydrogen peroxide at 50 mg/L and nisin at 250 mg/L.…”

“…These same effects in melons have been seen in other produce types with losses in color and texture associated with application of acids and hydrogen peroxide (Fonesca and Rushing ; Guan et al . ; Alexandre et al . ; Lignou et al .…”