Effect of Lactoperoxidase System on Microbiological and Quality Markers of Minimally Processed Lettuce

Abstract

Minimally processed lettuce is sensitive to microbial attack caused by the loss of natural resistance and their high water content and nutrients. The use of natural anti-microbial agents such as the lactoperoxidase system (LPS) represents an interesting alternative to the use of chemical treatments. This study focused on the importance of LPS and its efficiency as a bioprotective agent. The effect of washing with LPS, at two different concentrations (4 and 5 IU) and four different treatment times (1, 2, 3 and 4 h) on microbial growth in fresh-cut lettuce, was determined at 30˚C and compared with a 80 ppm chlorine at 4˚C for 20 min. The results deduced that both doses of LPS showed significant reductions in microbial growth when applied during 4 h, but the highest dose proved to be more effective. No significant differences were found between the LPS treatment and chlorine considering native microflora reduction and quality markers during storage.

Effects of Lactoperoxidase System Activation-Oregano Essential Oilor Chlorine on the Quality of Modified Atmosphere Packaged Fresh-Cut Iceberg Lettuce

“…Taking into account the position of processed and packaged lettuce samples under the two modified atmospheres with respect to CP1, we can easily discriminate samples treated with chlorine or LPS and oregano stored during 9 days of those stored for 7 days at +4˚C, underlining that the hygienic, physico-chemical and sensory quality of the lettuce treated with chlorine or LPS-oregano was considered satisfactory until the 7 th day of their conservation, as previously discussed [6].…”

“…The fresh-cut lettuce was washed with distilled water to remove soil residues. Subsequently, the excess water was removed by centrifugation in a manual salad spinner.After that, the fresh-cut lettuce was treated with a distilled water containing the activated lactoperoxidase system (5 UI, 30˚C, 4 h) and the oregano essential oil (75 ppm, 20˚C, 15 min) or chlorine (80 ppm, 4˚C, 20 min) [6]. Then, the samples were stored were weighted (15 ± 1 g) in oriented polypropylene film bags (12 cm × 20 cm) (Oxygen transmission rate: 1500 mL•mm −2 •day −1 ) under modified atmosphere 1 (5% O 2 and 10% CO 2 ) or 2 (2% O 2 and 5% CO 2 ).…”

“…For this reason, the demand for natural alternatives has increased. In this context, Lactoperoxidase System (LPS) is attracting interest for this potential as natural food preservative and displays a wide spectrum of antimicrobial activity, with potential for control of foodborne pathogens and spoilage bacteria associated with minimally-processed vegetables [6]. The lactopero-…”