Standardization and Validation of the Visual Evaluation of Biocrystallizations
Machteld Huber, Jens-Otto Andersen, Johannes Kahl, Nicolaas Busscher, Paul Doesburg, Gaby Mergardt, Sebastian Kretschmer, Aneta Zalecka, Aumaporn Meelursarn, Angelika Ploeger, Dré Nierop, Lucy van de Vijver and Erik Baars
ABSTRACT
The biocrystallization method has been used as a holistic method for evaluating food samples since
the 1930s and has, as recent reviews have concluded, been successful in discriminating farming
systems in several studies. However, it is noted that a standardization and validation for more
objective means of evaluation of biocrystallization pictures and a clearly defined and communicable
language, as well as possibilities for verification, are still lacking. During the years 2002–2006
a project for standardizing and validating the visual evaluation of these biocrystallizations took
place, performed by a group consisting of three European research institutes. As no pre-set
methodology nor norms for the visual evaluation existed, the choice was made to work according
to existing norms on sensory analysis and to adapt these to the visual evaluation. The main
norm, ISO-Norm 11035, for establishing sensory profiles was adapted towards these pictures.
A panel was formed, mainly morphological descriptors were selected and defined, a scale with
references was established, the panel trained and tested for pictures, produced on the basis of
carrots of different qualities. Reliability and validity aspects of the panel, as well as the structure
of the set of criteria were evaluated. According to standard rates for diverse statistical tests the
panel has been validated for the evaluation of carrots with a defined set of descriptors. The set
of descriptors contains sub-domains which can be used for further development of the evaluation
method, towards a more integrated, holistic ‘Gestalt’-evaluation, and towards finally interpretation
of these pictures. The followed process and results are unique in connection to this method.