Comparison of ultra-high-pressure water jet and conventional rotating blade cutting for the production of fresh-cut iceberg (Lactuca sativa L.) and endive (Cichorium endivia L.)

Sensory, physiological, and microbial quality of fresh-cut iceberg lettuce (Lactuca sativa L.) and endive (Cichorium endivia L.) produced by ultra-high-pressure water jet cutting was compared to that obtained by conventional blade cutting. Two settings of water pressure (2500, 3300 bar) and nozzle size (0.10, 0.12 mm) were investigated at pilot-plant scale to provide insights into the industrial applicability of the water jet cutting technology. During the subsequent 12 days of storage of the fresh-cut products in consumer-sized film bags, headspace gas composition, activities of phenylalanine-ammonia-lyase, peroxidase and polyphenoloxidase, contents of phenolic compounds, and bacterial viable counts were monitored. Furthermore, visual appearance of the products was examined by stereo microscopy and sensory evaluation. When comparing blade cut and water jet cut products, differences in headspace gas composition, enzyme activities, phenolic contents and bacterial viable counts were insignificant for both fresh-cut iceberg lettuce and endive. Although water pressure and nozzle size only exerted a slight effect on sensory quality and the appearance of cut edges, tentatively, a pressure of 2500 bar and nozzle size of 0.10 mm ensured optimum sensory quality of the cut salads. Hence, fully equivalent product quality was achieved by water jet and conventional blade cutting. Despite higher investment, water jet cutting technology may be considered as a valuable alternative to blade cutting systems in the production of fresh-cut products, thus avoiding interruptions of the production chain due to time- and cost-intense sharpening of the knives.