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

Abstract

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 (<three days) but promoted its rate at more advanced stages, likely due to build-up of ethylene in the bags. An approach was developed to the processing of hyperspectral data for non-invasive monitoring of the lettuce leaves with a potential for implementation in greenhouses and packing lines.

Intelligent detection for fresh‐cut fruit and vegetable processing: Imaging technology

“…Based on the differences in absorption or reflection spectra caused by changes in chlorophyll, anthocyanin, carotenoids, water, cellulose, and other compounds in the leaves of fresh-cut products during storage, HSI and CFI can be used for quality evaluation and shelf-life prediction of fresh-cut products. Shurygin et al (2021) used HSI and CFI to monitor early changes in fresh-cut lettuce leaf quality. Eshkabilov et al (2021) used HSI to measure the nutritional level of freshly cut lettuce leaves in the wavelength range of 400-1000 nm, including total chlorophyll concentration, pH, soluble solids content (SSC), potassium (K + ), calcium (Ca 2+ ), and nitrate (NO 3 -).…”

Efficiency of the Photoluminescent Method for Monitoring the Homogeneity of Feed Mixtures in Animal Husbandry

“…EQUIPMENT FOR ANIMAL HUSBANDRY П роцесс кормления сельскохозяйственых животных формируется из длинной цепочки последовательных технологических операций, выполняемых механизированными средствами, роботами, а также непосредственно человеком [1].…”

Enrichment of the Information Extracted From Hyperspectral Reflectance Images for Noninvasive Phenotyping

“…The reflectance indices for hyperspectral datasets were calculated essentially as described previously [36,37]. Briefly, for each pixel of the hyperspectral images, two indices were computed.…”

“…In the experiments with lettuce, we followed changes in the reflective properties accompanying the transformation of the pigments, Chl and Car, during 11-day storage of fresh-cut leaves (Figures 1 and S1; for more details, see Methods and [37]). Towards this end, we have measured the distribution of foliar Chl over the leaf surface using the Chlorophyll Index (CI) based on the reflectance in the Red Edge band (700 nm), CI700, featuring a wide dynamic range and high linearity in a broad range of Chl contents (see e.g.…”

“…In addition to the monitoring of plant condition based solely on changes in Chl content, we have further investigated the approach to gauging plant senescence and fruit ripening based on the Plant Senescence Reflectance Index (Figure 1b; [32]). The applicability of PSRI for HRI processing, particularly to the HRIs of salad, has been established recently [37]. Here, we have analyzed the connection between heterogeneity and changes in distribution of PSRI values over the leaf surface (Figure 1b).…”