Effects of knife material and sharpness on the quality of shredded iceberg lettuce in modified atmosphere packaging
The influence of stainless steel (SS), ceramic (CR), and titanium ultrasonic (TU) blades on shredded iceberg lettuce quality was tested in terms of relative leakage rate (RLR), microstructure of tissue, enzymatic browning, and microbial spoilage. Lettuce was shredded, washed in chlorinated water (100 ppm C12), spin dried, packaged under modified atmosphere (5% CO2, 5% O 2 and 90% N2), and stored at 4°C for 15 days. CR and SS knives caused slightly lower damage to the tissue than TU knife. Influence of four SS knives of different sharpness was also tested on the storage quality of lettuce. A slight difference in sharpness did not dramatically lower the quality of shredded lettuce. However, samples cut with the dullest (Kn1) knife were found significantly different in appearance, RLR and microbial counts than those cut with sharpest (Kn5), whereas respiration rate was only slightly affected. These results emphasize the importance of maintaining the sharpness of cutting blades, to achieve a better quality fresh-cut produce.