Comparison of the Non-Invasive Monitoring of Fresh-Cut Lettuce Condition with Imaging Reflectance Hyperspectrometer and Imaging PAM-Fluorimeter

We compared two approaches to non-invasive proximal sensing of the early changes in fresh-cut lettuce leaf quality: hyperspectral imaging and imaging of variable chlorophyll fluorescence contained in the leaves. The estimations made by the imaging techniques were confronted with the quality assessments made by traditional biochemical assays (i.e., relative water content and foliar pigment (chlorophyll and carotenoid) composition. The hyperspectral imaging-based approach provided the highest sensitivity to the decline of fresh-cut lettuce leaf quality taking place within 24 h from cutting. Using of the imaging pulse-amplitude modulated PAM chlorophyll fluorometer was complicated by (i) weak correlation of the spatial distribution pattern of the Qy parameter with the actual physiological condition of the plant object and (ii) its high degree of heterogeneity. Accordingly, the imaging PAM-based approach was sensitive only to the manifestations of leaf quality degradation at advanced stages of the process. Sealing the leaves in polyethylene bags slowed down the leaf quality degradation at the initial stages

Automated summary

The study compared two approaches, hyperspectral imaging and chlorophyll fluorescence imaging, for non-invasive sensing of the early changes in fresh-cut lettuce leaf quality. Hyperspectral imaging was found to be more sensitive to the decline in leaf quality within 24 hours post-cutting, while chlorophyll fluorescence imaging showed sensitivity only at advanced stages of leaf quality degradation. Additionally, sealing the leaves in polyethylene bags was effective in slowing down the initial stages of leaf quality degradation.