Angelika Ploeger

Standardization of the Biocrystallization Method for Carrot Samples

ABSTRACT The growing organic market demands methods which can describe food quality within the organic system (authentication). Several studies indicate that methods, such as the biocrystallization method, are suitable for this question. More or less reproducible crystallization patterns emerge when an aqueous dihydrate cupric chloride solution with plant extract is crystallized on a glass dish. The emerging patterns are characteristic of sample material. To be applied in routine analysis for example for authentication of organic products, the biocrystallization method has to be standardized. After the laboratory process was documented and a computerized pattern evaluation tool was further developed and applied, the method was standardized for selected carrot samples, which is described here. For standardization, several factors of influence were tested and the reproducibility between three different laboratories in the EU was investigated. The method is able to differentiate patterns from samples from different farming treatments and processing steps as statistically significant. This represents a significant step forward beyond the state of the art.

Standardization and validation of the visual evaluation of biocrystallizations.

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.

Evaporation influences on the crystallization of an aqueous dihydrate cupric chloride solution with additives

The overall structure of the crystallization results of dihydrate cupric chloride with additives in a petri dish is affected by the duration between the beginning of the evaporation and the start of the crystallization. Experiments done with polyvinylpyrrolidone and freeze-dried carrot as additive are compared with those of the additive free case. The dependency of dewetting on the dihydrate cupric chloride amount is discussed in terms of depletion of the solution and the surface tension properties of the system. The possible influence of the depletion is depending on the moment the crystallization starts. This is defined by the size of the evaporated area on the dish.

Questions on the Validation of Holistic Methods of Testing Organic Food Quality

ABSTRACT The regulation of organic production and processing focuses on process-related quality concepts rather than product oriented quality management. Therefore no standards exist that define the product oriented quality aspects of organic food. Methods such as the biocrystallization method seem to be able to classify organic products. Methods that are applied must reflect the history of the sample in growth and processing. These methods can be applied either for authentication or in relation to technical aspects (storage, processing steps) as well as human health. Each quality determination needs a question which will be answered from the laboratory method. The question needs to be specific enough and the method needs validation. Validation means testing if the method can answer the question or not. The process of validation is defined for analytical methods (single compound determination) in international norms such as the ISO 17025 for testing laboratories. The article describes how validation procedures can be applied to biocrystallization methods for quality tests of organic products.

Can the Authenticity of Products be Proved by Plant Substances

ABSTRACT The market for organic produce is growing since consumers lost confidence in conventional food products in view of food scandals in the EU. There is thus an urgent need for suitable methods that can be used to demonstrate the authenticity of organic produce. In addition, consumers expect health benefits from organic products. For that the question of secondary plant compounds has been intensively discussed. Whether produce from organic farming results in higher content of health-related substances has been examined in several studies but no clear evidence was found. Secondary plant compounds may also be used in authentication of organic products. In this literature review various factors which may influence the content of carotenoids and polyphenols as two important classes of secondary metabolites in carrots are evaluated. For polyphenols in carrots there is a lack of studies apart from the influence of the variety. It has been shown that variety and environmental factors, like climate and soil, have greater influence on the carotenoid content than cultivation related factors such as fertilization and weed control. In organic fanning, more intensive attempts are required to select location- and production-related varieties. Without inclusion of these factors, which are not covered in the EU regulations, an authenticity test of organic produce using secondary plant compounds seems not possible. Further research is needed on basis of large data sets to test, whether the use of multivariate statistical methods could be a practical approach to the routine analysis.

Standardization of the Steigbild Method

ABSTRACT The growing organic market demands methods which can describe food quality within the organic system. With the Steigbild technique, patterns are produced on thin-layer chromatographic paper and evaluated as a fingerprint of the sample as a whole. To be applied in routine analysis the method has to be standardized. After the laboratory process was documented and a standardized visual pattern evaluation method was developed and applied, the method was standardized for selected carrot and wheat samples, which is described here. For standardization, several factors of influence were tested and the reproducibility between three different laboratories in the EU was investigated. The method is able to differentiate patterns from samples from different farming treatments and processing steps. Farm pairs of organic and conventional farm management can be distinguished as statistically significant and classified according to the farming system (carrots, wheat). This represents a significant step forward beyond the state of the art. This work was performed in a collaboration between the University of Kassel (Germany) the Louis Bolk Institute (LBI, The Netherlands) and the Biodynamic Research Association Denmark (BRAD, Denmark).

Development and Performance of Crystallization with Additives Applied on Different Milk Samples

Crystallization with additives is developed on milk samples from different processing treatments. Performance tests are carried out based on structure analysis of the crystallization patterns. Crystallization with milk as additive is applied following changes in milk after different processing treatments. When an aqueous cupric chloride dihydrate solution crystallizes in the presence of milk as additive, specific patterns emerge, which can be evaluated by image analysis. Milk samples were heated and homogenized in a pilot plant and characterized by various parameters. Furthermore, milk samples from the market were tested. Patterns from milk after heat treatment and homogenization are significantly different from those derived from untreated milk. The experiments could be reproduced for other milk samples, on different days and in another laboratory.

A Pilot Investigation of the Relationship between Climate Variability and Milk Compounds under the Bootstrap Technique

This study analyzes the linear relationship between climate variables and milk components in Iran by applying bootstrapping to include and assess the uncertainty. The climate parameters, Temperature Humidity Index (THI) and Equivalent Temperature Index (ETI) are computed from the NASA-Modern Era Retrospective-Analysis for Research and Applications (NASA-MERRA) reanalysis (2002–2010). Milk data for fat, protein (measured on fresh matter bases), and milk yield are taken from 936,227 milk records for the same period, using cows fed by natural pasture from April to September. Confidence intervals for the regression model are calculated using the bootstrap technique. This method is applied to the original times series, generating statistically equivalent surrogate samples. As a result, despite the short time data and the related uncertainties, an interesting behavior of the relationships between milk compound and the climate parameters is visible. During spring only, a weak dependency of milk yield and climate variations is obvious, while fat and protein concentrations show reasonable correlations. In summer, milk yield shows a similar level of relationship with ETI, but not with temperature and THI. We suggest this methodology for studies in the field of the impacts of climate change and agriculture, also environment and food with short-term data.

Differentiation of organic and non-organic winter wheat cultivars from a controlled field trial by crystallization patterns

BACKGROUND There is a need for authentication tools in order to verify the existing certification system. Recently, markers for analytical authentication of organic products were evaluated. Herein, crystallization with additives was described as an interesting fingerprint approach which needs further evidence, based on a standardized method and well-documented sample origin. RESULTS The fingerprint of wheat cultivars from a controlled field trial is generated from structure analysis variables of crystal patterns. Method performance was tested on factors such as crystallization chamber, day of experiment and region of interest of the patterns. Two different organic treatments and two different treatments of the non-organic regime can be grouped together in each of three consecutive seasons. When the k-nearest-neighbor classification method was applied, approximately 84% of Runal samples and 95% of Titlis samples were classified correctly into organic and non-organic origin using cross-validation. CONCLUSION Crystallization with additive offers an interesting complementary fingerprint method for organic wheat samples. When the method is applied to winter wheat from the DOK trial, organic and non-organic treated samples can be differentiated significantly based on pattern recognition. Therefore crystallization with additives seems to be a promising tool in organic wheat authentication.

The Concept of ‘Structure’ in the Evaluation of Food Quality

ABSTRACT The concept of structure and the term ‘structure’ are widely used in manifold applications and disciplines in the conventional and organic sector of food research. This literature survey focuses on the tension charged field of food quality. After the identification of very differing meanings and contrasting attributes of the concept of structure in the two traditions, the usage and interpretation of the term were examined and explained against the background of underlying paradigms and in the context of application. Processes in the agricultural production and food processing were among others directed and controlled on the basis of different interpretations of the term ‘structure’. This could have severe consequences for the quality and safety of food. In the organic tradition the concepts of wholefood nutrition which are referring to the term ‘structure’ are not accomplished but seem to uphold core aspects of food quality and safety which have been lost in current mainstream concepts. Structure has to be brought into relation to health related aspects of food quality. Basic concepts of the organic movement like the whole food nutrition already practise methods which integrated structural aspects of food quality.