FOOD. Science. Technology. Quality

Food. SCIENCE. Technology. Quality

Food. Science. TECHNOLOGY. Quality

Food. Science. Technology. QUALITY




Laboratory scale evaluation of starch extract ability of wheat varieties


Since several years the structure of the European starch industry undergoes exceptional changes. Potato starch production stagnates as a result of agro-political decisions of the EU commission resulting in strict quota regulations. With corn starch growth rates are rather marginal. In case of wheat starch production huge capacities have been installed just recently or are in state of construction. As a result, one of the main targets is to improve the competitive situation of wheat starch and to provide appropriate source material. Concerning isolation techniques, recent developments in process technology allowed at the same time a withdrawal from wheat and wheat flour quality standards based predominantly on protein and mineral content. These standards were valid in the minimum for bread wheat. They could maintain their strong position over a relative long period as long as the Martin process was the prevailing technology. However, modern processes based on centrifugal separation principles and pre-treated wheat flour and water mixtures opened a turn towards an economically more beneficial wheat and wheat flour quality. In fact, it became well known meanwhile that industry is able to process wheat flours having a significantly different property profile. If wheat quality characteristics of the German system of wheat classes are applied, these lots will probably be ascribed to feed wheat. The described situation that could not be ignored any more initiated investigations on wheat quality characteristics relevant for modem technology in industrial wheat starch extraction. Basis for first studies was the well-known extraction procedure using the Glutomatic 2000 system for recovering starch A and B fractions and gluten from a conventional flour dough. Besides also the so-called „mixer test“, a rather time and labour consuming testing system has been applied. Coming from industry its background is practical and achieved experimental results can be applied well in plant construction. At the same time a lately tested rapid method adapted to conditions of modern wheat starch production is used for evaluation of the formation of a workable wheat flour/water mixture. With regard to changes induced in the initial phase of the batter formation by mixing flour and water this method has been indicated as „gluten agglomeration test“. Two groups of test samples have been used in this investigation. The first set of wheat samples comprised breeding material produced in a normal agricultural regime while the second set was part of a N2-fertilisation and phyto-sanitation trial. The trial resulted in wheat samples and flours with well-defined protein concentrations that varied according to fertilisation level. Relationships between results of general bread wheat quality assessment and the described methods have been tested by rank correlation analysis. The lately established gluten agglomeration test allowed the desired differentiation and provided information about rate and extent of gluten agglomeration that differed extremely depending on cultivar and fertilisation regime. Characteristics of the gluten agglomeration test did not show very significant and close connections with grain and flour criteria. However, they all were related to protein quality. The results achieved in the mixer-test allowed evaluation and differentiation for the whole set of samples. It confirmed that only samples with adequate high protein level can be processed satisfactorily.