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Comparative study of composition and technological quality of amaranth

I. Gross chemical composition, amino acid and mineral content

Acta Alimentaria
Authors: S. Tömösközi, I. Baracskai, R. Schönlechner, E. Berghofer, and R. Läsztity

Eight groups of amaranth grain samples, belonging to the species Amaranthus cruentus and A. hypochondriacus , grown in Austria and Hungary were studied. Gross chemical composition, amino acid content and mineral composition of the whole grain were determined. The effect of heat treatment on amino acid content was also investigated. The range of concentration of main constituents of samples studied corresponded to the average data reported by other researchers. However, the relatively big difference between lowest (14.23%) and highest (17.40%) protein content suggests that genetic potential for increasing the protein content may be realized in breeding. Amino acid composition profile is generally closer to Leguminosae than to cereal grains except for sulphur containing amino acids being present in higher amount in amaranth than in legumes. The concentrations of minerals in seeds varied in a relatively wide range, and the micro-components, like Fe, Cu, Zn, were present in higher amount in amaranth seeds compared to the average values found in wheat. It was confirmed that heat treatment of amaranth grain (e.g. popping) might reduce the available lysine content. Contradictory data published in the literature may be explained by differences in initial sugar and moisture content of grain, which influence the rate of potential Maillard-reaction.

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Abstract

Amaranth, buckwheat, quinoa, and less known, canihua are the most important pseudocereals. Their high nutritional value is well recognized and they are increasingly used for the development of a wide range of starch-based foods, which has been fostered by intensified research data performed in recent years. In addition to health driven motivations, also environmental aspects like the ongoing climate change are an important stimulus to increase agricultural biodiversity again. As pseudocereals are botanically classified as dicotyledonous plants their chemical, physical and processing properties differ significantly from the monocotyledonous cereals. Most important factors that need to be addressed for processing is their smaller seed kernel size, their specific starch structure and granule architecture, their gluten-free protein, but also their dietary fibre and secondary plant metabolites composition. This review gives a condensed overview of the recent developments and gained knowledge with special attention to the technological and food processing aspects of these pseudocereals.

Open access
Acta Alimentaria
Authors: A. Harasztos, G. Balázs, P.N. Csőke, S. D’Amico, R. Schönlechner, and S. Tömösközi

The positive nutritional impact of dietary fibres (DF) gives growing interest to their role in the formation of wheat product quality. Although we are getting closer to characterize the effect of DF on the end use quality, the roles of individual components are not well described yet. Arabinoxylans (AX) are the main compounds of wheat DF, therefore getting more knowledge about its behaviour in wheat based food systems, like dough or end products, could be useful from both theoretical and practical points of view. The aim of this study was to investigate the impact of the AX content on wheat flour quality using a dough model system provided by blends of flour and AX isolate. Rapid Visco Analyser (RVA) and recently developed micro Zeleny test were used for characterization of mixtures.

We found that although Zeleny values are basically related to protein-dependent quality, the addition of AX isolate has major impact on the sedimentation volume of flour. In the RVA studies we demonstrated that AX has influence not only on the viscosity values but also on the rate of viscosity change. The effect of AX addition was compared to that of starch addition and was corrected by the rate of dilution. The model system and the experimental method applied here can be suitable to separate the individual effects of non-starchy carbohydrates.

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