Copper chloride crystallisation

Copper chloride crystallisation was validated and standardised in-house for carrots, among others, within the framework of the BÖL projects 02OE170 and 02OE170F [1]. The method shows specific dendritic crystallisation patterns for different plant extracts that crystallise on a glass plate together with an aqueous copper chloride dihydrate solution [2] [3] [4] [5] [6] [7] [8]. The spontaneous crystallisation in the form of needles occurs when the saturation limit of the salt solution is exceeded during the phase of evaporation of the liquid [9] [10] [11]. This takes place under standardised conditions, which are recorded for each sample with the aid of a laboratory documentation programme (LabDoc). In addition to visual evaluation [12] [13], the resulting images can also be evaluated by means of a computer-aided texture and structure analysis [14] [15].

So far, hundreds of samples have been tested in different trials and on different varieties [6] [5] [3] [7] [16]. Initial trials show that the method is also, or perhaps especially, suitable for investigating the influence of processing on the food quality (see studies on milk [3] [4] and baby carrots [17]). They are also suitable in combination with marker substance [10] [11] (mechanism of action of these particular methods). The visual evaluation of the crystal images is performed by a panel of trained persons. [12]

In preliminary tests, pectin [18] is used as a marker to explain the mechanism of action of the method; this polysaccharide (polysaccharide) is a component of carrots [19] [20] [21] . It is assumed that it modulates the effect of secondary carrot ingredients on humans and influences the crystallisation process. The following preliminary experiments are planned:

  • Investigation of the influence of different varieties on the quality of carrots.
  • Investigation of carrot juice samples with different pectin contents on the crystallisation behaviour and the resulting samples (clarification of the connection between processing and crystallisation).
  • Investigation of the behaviour of pectin depending on structure and mixing ratio on the crystallisation behaviour and the resulting samples (clarification of the influence of mixing ratio).
  • Investigation of the influence of different pectin structures on the crystallization behaviour and the resulting patterns (clarification of the sample-image relationship).

References

[1] Busscher N, Kahl J, Andersen J-O, Huber M, Mergardt G, Doesburg P et al. Standardization of the Biocrystallization Method for Carrot Samples Biological Agriculture and Horticulture 2010; 27: 1-23 doi.org/10.1080/01448765.2010.10510427.

[2] Kahl J, Busscher N, Doesburg P, Mergardt G, Huber M, Ploeger A. First tests of standardized biocrystallization on milk and milk products European Food Research and Technology 2009; 229: 175-178 doi.org/doi:10.1007/s00217-009-1039-7.

[3] Kahl J, Busscher N, Hoffmann W, Mergardt G, Clawin-Raedecker I, Kiesner C et al. Development and Performance of Crystallization with Additives Applied on Different Milk Samples Food Analytical Methods 2013; : 1-8 doi.org/doi:10.1007/s12161-013-9759-5.

[4] Kahl J, Busscher N, Hoffmann W, Mergardt G, Clawin-Raedecker I, Ploeger A. A novel approach for differentiation of milk fractions and polyvinylpyrrolidone with different molecular weight by patterns derived from cupric chloride crystallization with additives Anal. Methods 2014; 6: 3173-3176 doi.org/doi:10.1039/C3AY41568F.

[5] Kahl J, Busscher N, Mergardt G, Ploeger A. Standardization and performance test of crystallization with additives applied to wheat samples Food Analytical Methods 2014; 8: 2533-2543 doi.org/doi:10.1007/s12161-015-0142-6.

[6] Kahl J, Busscher N, Mergardt G, Maeder P, Torp T, Ploeger A. Differentiation of organic and non-organic winter wheat cultivars from a controlled field trial by crystallization patterns J. Sci. Food Agric. 2014; 95: 53-58 doi.org/doi:10.1002/jsfa.6818.

[7] Kahl J, Busscher N, Doesburg P, Mergardt G, Will F, Schulzova V et al. Application of Crystallization with Additives to Cloudy and Clear Apple Juice Food Analytical Methods 2016; 10: 1-9 doi.org/doi:10.1007/s12161-016-0575-6.

[8] Szulc M, Kahl J, Busscher N, Mergardt G, Doesburg P, Ploeger A. Discrimination between organically and conventionally grown winter wheat farm pair samples using the copper chloride crystallisation method in combination with computerised image analysis Computers and Electronics in Agriculture 2010; 74: 218-222 doi.org/doi:10.1016/j.compag.2010.08.001.

[9] Busscher N, Kahl J, Doesburg P, Mergardt G, Ploeger A. Evaporation influences on the crystallization of an aqueous dihydrate cupric chloride solution with additives Journal of Colloid and Interface Science 2010; 344: 556–562 doi.org/doi:10.1016/j.jcis.2009.12.045.

[10] Busscher N, Doesburg P, Mergardt G, Sokol A, Kahl J, Ploeger A. Influence of dewetting on the crystallization behavior of CuCl₂ in the presence of BSA during evaporation in a Petri dish Heliyon 2019; 5: e01102 doi.org/10.1016/j.heliyon.2018.e01102.

[11] Busscher N, Doesburg P, Mergardt G, Sokol A, Kahl J, Ploeger A. Crystallization patterns of an aqueous dihydrate cupric chloride solution in the presence of different amounts of Bovine Serum Albumin Journal of Crystal Growth 2019; doi.org/doi:10.1016/j.jcrysgro.2019.125272.

[12] Doesburg P, Huber M, Andersen J-O, Athmann M, van der Bie G, Fritz J et al. Standardization and performance of a visual Gestalt evaluation of biocrystallization patterns reflecting ripening and decomposition processes in food samples Biological Agriculture & Horticulture 2014; 31: 128-145.

[13] Fritz J, Athmann M, Andersen J-O, Doesburg P, Geier U, Mergardt G. Advanced panel training on visual Gestalt evaluation of biocrystallization images: ranking wheat samples from different extract decomposition stages and different production systems Biological Agriculture & Horticulture 2018; 35: 1-12 doi.org/doi:10.1080/01448765.2018.1492457.

[14] Andersen JO, Henriksen CB, Laursen J, Nielsen AA. Computerised image analysis of biocrystallograms originating from agricultural products Computers and Electronics in Agriculture 1999; 22: 51-69 doi.org/doi:10.1016/S0168-1699(98)00043-X.

[15] Doesburg P, Nierop AF. Development of a structure analysis algorithm on structures from CuCl2⋅2H2O crystallization with agricultural products Computers and Electronics in Agriculture 2013; 90: 63-67 doi.org/doi:10.1016/j.compag.2012.11.003.

[16] Kahl J. Entwicklung, in-house Validierung und Anwendung des ganzheitlichen Verfahrens Biokristallisation für die Unterscheidung von Weizen-, Möhren- und Apfelproben aus unterschiedlichem Anbau und Verarbeitungsschritten. PhD Thesis, University of Kassel. 2007.

[17] Seidel K, Kahl J, Paoletti F, Birlouez I, Busscher N, Kretzschmar U et al. Quality assessment of baby food made of different pre-processed organic raw materials under industrial processing conditions. Food Sci Technol 2013; : 1-10 doi.org/DOI 10.1007/s13197-013-1109-5.

[18] Flutto, L. 2003. In: Caballero, B. editors, Encyclopedia of Food Sciences and Nutrition (Second Edition), Academic Press.

[19] Schultz AK, Anthon GE, Dungan SR, Barrett DM. Effect of Pectin Methylesterase on Carrot (Daucus carota) Juice Cloud Stability J. Agric. Food Chem. 2014; 62: 1111-1118.

[20] Moelants KRN, Lemmens L, Vandebroeck M, Van Buggenhout S, Van Loey AM, Hendrickx ME. Relation between Particle Size and Carotenoid Bioaccessibility in Carrot- and Tomato-Derived Suspensions J. Agric. Food Chem. 2012; 60: 11995-12003 doi.org/10.1021/jf303502h.

[21] De Roeck A, Mols J, Duvetter T, Van Loey A, Hendrickx M. Carrot texture degradation kinetics and pectin changes during thermal versus high-pressure/high-temperature processing: A comparative study Food Chemistry 2010; 120: 1104-1112.