Calcinated calcium and mild heat treatment on storage quality and microbial populations of fresh-cut iceberg lettuce

Abstract

The heated scallop shell powder, calcinated calcium (CC) alone or combination with mild heat treatment were investigated as potential sanitizers for maintaining storage quality and microbial safety of fresh-cut iceberg lettuce. Fresh iceberg lettuce leaves were cut into 3 × 3 cm slices and washed in normal tap water (TW), 50 μL·L−1 chlorinated water (pH 6.5), 1.5 g·L−1 CC, heat treatment (HT) in TW at 45°C, and CC dissolved in TW at 45° for 2 min separately. Samples were then packaged in 80 μm nylon/polyethylene bags and stored at 5°C. Results revealed that like 50 μL·L−1 chlorine, washing in CC at normal water temperature was effective in reducing microbial population in fresh-cut lettuce samples. Washing with CC combined with mild HT increased an electrical conductivity of fresh-cut lettuce tissue. Combined heat treatment with washing solutions reduced aerobic plate count on fresh-cut lettuce, only in initial period of storage. But, later on heat treatment induced injury of fresh-cut iceberg lettuce resulting to more microbial population compared to non HT. On the other hand, samples treated with CC had good quality with low off-odor at the end of storage. Thus, CC, an environment-friendly sanitizer can be an alternative to HT for washing of fresh-cut iceberg lettuce without affecting sensorial quality.