Quality of waterjet- and blade-cut romaine salad

Abstract

Cutting operations for fresh-cut produce are usually accomplished by stainless steel knives. Waterjet cutting employs a very small stream of high-pressure water, and the type of nozzle, conveyor speed, and water pressure are the main factors that affect the quality of the cut. Two tests were conducted, cutting romaine lettuce either by an Urschel Translicer 2500 on a pilot process line using new or used and reconditioned (e.g., 3× used and sharpened) blades or by a KMT pilot waterjet system using standard or food-grade nozzles. Cut romaine showed whitening dehydration and red discoloration defects on cut surfaces. In both tests, cut romaine packaged commercially in a modified atmosphere had only minor differences in cut surface defects between blade and waterjet cutting. However, large differences due to cutting treatments were observed in cut romaine stored in bags without modified atmosphere at 2.5°C. In test 1, pieces were of very high quality with no differences between cutting method until 18 days at 2.5°C, when waterjet-cut pieces had higher visual quality with less discoloration than blade-cut pieces. New knife blades produced less damage to cut surfaces than used and reconditioned blades. The food-grade nozzle was superior to the standard waterjet nozzle. In test 2, discoloration appeared by day 9 in bags with no modified atmosphere at 2.5°C, and there were clear quality differences between cutting methods, with waterjet cutting using the food-grade nozzle better than blade cutting. There were no persistent differences in total bacterial counts between cutting methods. Potentially, improved cutting technology could reduce the need for extreme package atmospheres and/or ensure higher product quality with package leakers.