Charakterisierung von Getreide aus ökologischem und konventionellem Anbau - Anwendung von Protein-Profiling-Techniques und Inhaltsstoffanalysen

Ökologisch und konventionell angebauter Weizen aus dem kontrollierten DOK-Feldversuch (Schweiz) wurde umfassend hinsichtlich biochemischer Unterschiede charakterisiert. Dazu wurden die Profiling-Techniken Proteomics und Metabolomics, sowie Analytik von Einzelverbindungen eingesetzt. Metaboliten-Profile und Analytik von Einzelverbindungen ergaben geringfügige Unterschiede im DOK-Weizen aus unterschiedlichen Anbauvarianten. Statistisch signifikante Abweichungen konnten meist nur für eines von zwei untersuchten Anbaujahren gefunden werden. Abweichungen lagen innerhalb der bekannten Schwankungsbreiten bei Weizen. Beim Protein-Profiling, durchgeführt mit zweidimensionaler Gel-Elektrophorese, Bildauswertung und Proteinidentifizierung wurden die relativen Gehalte von ca. 1000 Proteinen in Weizen bestimmt. Die Gehalte von 16 Proteinen waren in ökologischem und konventionellem Weizen aus zwei Anbaujahren signifikant verschieden. Diese 16 Proteine bilden eine Signatur, anhand derer die Anbauvarianten des DOK-Weizens unterschieden werden können. In einem nächsten Schritt soll untersucht werden, ob diese Signatur gleichfalls bei ökologischem und konventionellem Weizen gilt, der von verschiedenen Standorten und von verschiedenen Sorten stammt. Vor dem Hintergrund des komplexen Gesamtstoffwechsels von Pflanzen ergeben die relativ wenigen mit verschiedenen Gehalten auftretenden Proteine keinen Hinweis auf Änderungen von Stoffwechselaktivitäten, die für die menschliche Ernährung kritisch wären. Die signifikante Reduzierung des Gesamtproteingehalts ist unter Ernährungsgesichtspunkten eher ungünstig, bei der in Deutschland üblichen Zusammensetzung der Diät aber unbedenklich. Zusammenfassend wird mit Blick auf die Ergebnisse des Protein-Profiling, des Metaboliten-Profiling und der Analytik von Einzelverbindungen gefolgert, dass ökologischer und konventioneller DOK-Weizen hinsichtlich der untersuchten Parameter ernährungsphysiologisch gleich wertvoll ist

Free sugars in spelt wholemeal and flour

Spelt (Triticum aestivum L. ssp. spelta) is experiencing a renaissance in Europe and North America, where it is used for baking, brewing, production of pasta, and self-supplied animal feed. One of the characteristics of spelt is that in comparison to modern wheat it is more resistant to harsh climatic and poor soil conditions. In contrast to wheat the hulls remain on the grain after threshing. Drawbacks are that spelt yields are quite low compared to modern wheat. The subject of the current study was to gain information about the composition of soluble sugars and their concentrations in spelt wholemeal and flour. High performance liquid chromatography (HPLC) was used for analysis. Concentrations of nine free sugars in spelt wholemeal and flour are reported. Flour cumulative free sugar concentrations were 63% lower than in wholemeal. For comparisons, we also analyzed wholemeal of wheat. The cumulative concentration of free sugars was 27% lower than in spelt wholemeal. However, when published data for sugar concentration ranges of wheat are taken into account, the total concentration of free sugar was not different between spelt and modern wheats. Low concentrations of xylose and stachyose were detected in spelt. Higher concentrations of fructans such as 1-kestose and kestotetraose were detected in spelt when compared with wheat. Generally, concentrations of free sugars in spelt were in the range of free sugar levels published for wheat, except for maltose which was higher in spelt

Nutritional quality of organic and conventional wheat

The popularity of organic food and the farming area managed according to organic agriculture practices have been increasing during the last years. It is not clear, whether foods from organic and conventional agriculture are equal with respect to nutritional quality. We chose wheat (Triticum aestivum L., cv. Titlis) as one of the most important crop plants to determine a range of substances relevant for human nutrition in crops from organic and conventional agriculture systems. Wheat grains of 2003 originating from a long term field experiment, the Swiss DOK trial, consisting of bio-dynamic, bio-organic and conventional farming systems were used. Thousand seed weight, protein content, phosphate levels, antioxidative capacity, levels of phenols, fibre, fructan, oxalate and phytic acid were determined in whole wheat meal from the various organic and conventional growing systems of the DOK trial. Levels of these substances fell into a range that is known to occur in other wheat crops, indicating that wheat from the DOK trial was not special. Clearcut differences were observed for none-fertilised wheat, which was significantly lowest in thousand seed weight, protein and significantly highest in total oxalate. For the majority of the nutritionally important substances analysed, there were no significant differences between bio-dynamic, bio-organic, and conventional growing systems. Only protein content and levels of fibres were statistically different. Taken together, the magnitude of observed variations was very small. The results of our investigations do not provide evidence that wheat of one or the other agriculture system would be better or worse

Protein composition and techno-functional properties of transgenic wheat with reduced α-gliadin content obtained by RNA interference

An RNA interference approach was applied to silence α-gliadin genes in hexaploid wheat. A 313 bp fragment from the 5’ coding region of an α-gliadin sequence was cloned into the “hairpin” (hpRNAi) constructs pGliaRNAiSpacer and transformed into winter wheat cv. Florida by biolistic transformation. The resulting transgenic lines were then analysed for their α-gliadin content by an extraction/RPHPLC method. Distinct differences of the α-gliadin content ranging from unaltered to strongly reduced were found. Kernels of two lines with strongly reduced α-gliadin content were mixed, milled to white fl our, analysed for quantitative protein composition and used for functional testing in comparison with the wild type fl our. Protein analysis revealed that the lack of α-gliadins was compensated by an increase of albumins/globulins, ω-gliadins, γ-gliadins and HMW glutenin subunits. Dough resistance and extensibility of wild type and transgenic lines were similar, whereas gluten resistance of the transgenic increased drastically and extensibility decreased slightly. 2D gel electrophoresis showed that the transgenic wheat #6/6 lacked at least 20 storage proteins, but other distinct proteins were more abundant compared with the wild type. Major reductions in the α-gliadins do not make discernable differences in micro-scale measurements of flour functionality and have only a slightly detrimental effect in micro-baking tests

Anthocyanin management in fruits by fertilization

Anthocyanins are water-soluble vacuolar plant pigments that are mainly synthesized in epidermal layers and the flesh of fruits such as apples, cherries, grapes, and other berries. Because of their attractive red to purple coloration and their health-promoting potential, anthocyanins are significant determinants for the quality and market value of fruits and fruit-derived products. In crops, anthocyanin accumulation in leaves can be caused by nutrient deficiency which is usually ascribed to insufficient nitrogen or phosphorus fertilization. However, it is a little-known fact that the plant’s nutrient status also impacts anthocyanin synthesis in fruits. Hence, strategic nutrient supply can be a powerful tool to modify the anthocyanin content and consequently the quality and market value of important agricultural commodities. Here we summarize the current knowledge of the influence of plant nutrients on anthocyanin synthesis in fruits of major global market value and discuss the underlying cellular processes that integrate nutrient signaling with fruit anthocyanin formation. It is highlighted that fertilization that is finely tuned in amount and timing has the potential to positively influence the fruit quality by regulating anthocyanin levels. We outline new approaches to enrich plant based foods with health-promoting anthocyanins

Considering Soil Potassium Pools with Dissimilar Plant Availability

Soil potassium (K) has traditionally been portrayed as residing in four functional pools: solution K, exchangeable K, interlayer (sometimes referred to as “fixed” or “nonexchangeable”) K, and structural K in primary minerals. However, this four-pool model and associated terminology have created confusion in understanding the dynamics of K supply to plants and the fate of K returned to the soil in fertilizers, residues, or waste products. This chapter presents an alternative framework to depict soil K pools. The framework distinguishes between micas and feldspars as K-bearing primary minerals, based on the presence of K in interlayer positions or three-dimensional framework structures, respectively; identifies a pool of K in neoformed secondary minerals that can include fertilizer reaction products; and replaces the “exchangeable” K pool with a pool defined as “surface-adsorbed” K, identifying where the K is located and the mechanism by which it is held rather than identification based on particular soil testing procedures. In this chapter, we discuss these K pools and their behavior in relation to plant K acquisition and soil K dynamics