An update on image forming methods: structure analysis and Gestalt evaluation of images from rocket lettuce with shading, N supply, organic or mineral fertilization, and biodynamic preparations

Abstract

In the image forming methods, copper chloride crystallization (CCCryst), capillary dynamolysis (CapDyn), and circular chromatography (CChrom), characteristic patterns emerge in response to different food extracts. These patterns reflect the resistance to decomposition as an aspect of resilience and are therefore used in product quality assessment complementary to chemical analyses. In the presented study, rocket lettuce from a field trial with different radiation intensities, nitrogen supply, biodynamic, organic and mineral fertilization, and with or without horn silica application was investigated with all three image forming methods. The main objective was to compare two different evaluation approaches, differing in the type of image forming method leading the evaluation, the amount of factors analyzed, and the deployed perceptual strategy: Firstly, image evaluation of samples from all four experimental factors simultaneously by two individual evaluators was based mainly on analyzing structural features in CapDyn (analytical perception). Secondly, a panel of eight evaluators applied a Gestalt evaluation imbued with a kinesthetic engagement of CCCryst patterns from either fertilization treatments or horn silica treatments, followed by a confirmatory analysis of individual structural features. With the analytical approach, samples from different radiation intensities and N supply levels were identified correctly in two out of two sample sets with groups of five samples per treatment each (Cohen’s kappa, p = 0.0079), and the two organic fertilizer treatments were differentiated from the mineral fertilizer treatment in eight out of eight sample sets with groups of three manure and two minerally fertilized samples each (Cohen’s kappa, p = 0.0048). With the panel approach based on Gestalt evaluation, biodynamic fertilization was differentiated from organic and mineral fertilization in two out of two exams with 16 comparisons each (Friedman test, p < 0.001), and samples with horn silica application were successfully identified in two out of two exams with 32 comparisons each (Friedman test, p < 0.001). Further research will show which properties of the food decisive for resistance to decomposition are reflected by analytical and Gestalt criteria, respectively, in CCCryst and CapDyn images.

Analytical perception and kinesthetic engagement in evaluation of copper chloride crystallization patterns of wheat, grape juice and rocket samples from conventional, organic and biodynamic cultivation

“…The error in the classification of the two organic variants compared to the conventional variant was 52% in both exams. The additional training before the second exam did not improve the results (Table 4, Appendix Table 7) [41].…”

“…Although the results from Fritz et al [32,40] and Athmann et al [41] were encouraging, the accuracy varied considerably among panel members, likely due to the different strategies applied by panel members in the perception of the gestalt decomposition. To confirm whether, and if so, which different perceptual strategies were utilized by the different panel members, a qualitative thinkaloud methodology was performed [43].…”

“…The organic and the biodynamic treatment differed only in the application of the biodynamic preparations. For more detailed descriptions, see Athmann [13,41].…”

“…Using the copper chloride crystallization method, it was possible to visually characterize and rank samples from wheat, carrots, cabbage, tomato and lettuce according to the degree of ripening and tendency to decompose by using coded images [7]. Samples from different cultivation methods could be grouped, characterized and classified according to the criterion associated with decomposition by individual assessors [6,15,21,23,39,40] and by an ISO-standardized visual evaluation panel [32,41]. Conceptually, this relates to estimating the samples' resistance to autolytic deterioration in the sense of 'resilience' (elasticity, capacity to cope) in response to controlled aging of the samples [42].…”

“…Based on the experience with aging series [47] our first hypothesis was that kinesthetic priming of the panel will improve the performance of the ranking tests. Based on the outcome of previous studies with cultivation methods [6,15,21,23,32,[39][40][41] our second hypothesis was that, according to the criterion of increasing decomposition, we expect the tested treatments to rank in the order biodynamic < organic < conventional with mineral fertilization < mineral fertilization.…”