Potential of dry fractionation of wheat bran for the development of food ingredients, part II: Electrostatic separation of particles

Wheat bran is a composite material made of several layers, such as pericarp, testa and aleurone. It could be fractionated into purified fractions, which might either be used as food ingredients, or serve as a starting material for extraction of bioactive compounds. The aim of this work was to evaluate the potential of using electrostatic separation as a way to obtain purified fractions from wheat bran. Ultrafine-ground bran obtained either by cryogenic grinding or by grinding at ambient temperature was used as starting material. The ultrafine bran was then charged by tribo-electrification and introduced in a chamber containing two high voltage electrodes, where bran particles were separated depending on their acquired charge, allowing positively and negatively charged fractions to be collected separately. The particle size distribution, microstructure and biochemical composition of the obtained fractions were studied. The charge of the particles was influenced by their biochemical composition: particles rich in highly branched and cross-linked arabinoxylans (pericarp) were separated from particles rich in β-glucan, ferulic acid and para-coumaric acid (aleurone cell walls). The testa and the intracellular compounds from aleurone were not highly charged, neither positively nor negatively. The most positively charged fraction represented 34% of the initial bran, and contained 62% of the ferulic acid present in the initial bran. The yield of the separation process was good (5.4% loss), and could be further increased.

[1]  Y. Pomeranz.  Advances in Cereal Science and Technology , 1986, Journal of Pediatric Gastroenterology and Nutrition.

[2]  Joel Abecassis,et al.  Dry processes to develop wheat fractions and products with enhanced nutritional quality , 2007 .

[3]  R. Mensink,et al.  Effects of plant sterols and stanols on lipid metabolism and cardiovascular risk. , 2001, Nutrition, metabolism, and cardiovascular diseases : NMCD.

[4]  J. Dexter,et al.  Recent applications of debranning of wheat before milling , 1996 .

[5]  V. Piironen,et al.  Effect of Baking Method and Fermentation on Folate Content of Rye and Wheat Breads , 2004 .

[6]  V. Piironen,et al.  Folate in wheat genotypes in the HEALTHGRAIN Diversity Screen. , 2008, Journal of agricultural and food chemistry.

[7]  C. Miller,et al.  A diet containing food rich in soluble and insoluble fiber improves glycemic control and reduces hyperlipidemia among patients with type 2 diabetes mellitus. , 2009, Nutrition reviews.

[8]  M. Latta,et al.  A simple and rapid colorimetric method for phytate determination , 1980 .

[9]  Rui Hai Liu,et al.  Whole grain phytochemicals and health , 2007 .

[10]  D. Topping.  Cereal complex carbohydrates and their contribution to human health , 2007 .

[11]  V. Piironen,et al.  Phytosterols in wheat genotypes in the HEALTHGRAIN Diversity Screen. , 2008, Journal of agricultural and food chemistry.

[12]  M. Sadek,et al.  Hydroxycinnamic Acids in Walls of Wheat Aleurone Cells , 2002 .

[13]  B. Knuckles,et al.  β-glucan enrichment of barley fractions by air classification and sieving , 1995 .

[14]  W. Cui,et al.  Nonstarch Polysaccharides from Preprocessed Wheat Bran: Carbohydrate Analysis and Novel Rheological Properties , 1999 .

[15]  Young-In Kim.  Folate and colorectal cancer: an evidence-based critical review. , 2007, Molecular nutrition & food research.

[16]  P. Wood.  Cereal β-glucans in diet and health , 2007 .

[17]  Y. Hemery,et al.  Dry-fractionation of wheat bran increases the bioaccessibility of phenolic acids in breads made from processed bran fractions , 2010 .

[18]  J. Abecassis,et al.  Wheat bran tissue fractionation using biochemical markers , 2004 .

[19]  P. Shewry,et al.  Phenolic acids in wheat varieties in the HEALTHGRAIN Diversity Screen. , 2008, Journal of agricultural and food chemistry.

[20]  I. Vaintraub,et al.  Colorimetric determination of phytate in unpurified extracts of seeds and the products of their processing. , 1988, Analytical biochemistry.

[21]  D. E. Briggs,et al.  Hydrocarbons, phenols and sterols of the testa and pigment strand in the grain of Hordeum distichon , 1974 .

[22]  Y. Pomeranz,et al.  Microscopic structure of the wheat grain. , 1988 .

[23]  Lucian Dascalescu,et al.  Electrostatic properties of wheat bran and its constitutive layers: Influence of particle size, composition, and moisture content , 2009 .

[24]  G. Fincher,et al.  Cell walls and their components in cereal grain technology , 1986 .

[25]  V. Piironen,et al.  Total plant sterols, steryl ferulates and steryl glycosides in milling fractions of wheat and rye , 2007 .

[26]  Malay K. Mazumder,et al.  Twenty-first century research needs in electrostatic processes applied to industry and medicine , 2006 .

[27]  Peter R. Shewry,et al.  Wheat: chemistry and technology. , 2009 .

[28]  P. Åman,et al.  Localization of alkylresorcinols in wheat, rye and barley kernels , 2008 .

[29]  R. Buri,et al.  Description and characterization of wheat aleurone , 2004 .

[30]  Y. Pomeranz,et al.  Chemical composition of kernel structures. , 1988 .

[31]  Frank Simon,et al.  Polymer tribo-electric charging: dependence on thermodynamic surface properties and relative humidity , 2003 .

[32]  V. Piironen,et al.  Plant Sterols in Cereals and Cereal Products , 2002 .

[33]  R. Henry,et al.  A SIMPLE AND RAPID PREPARATION OF ALDITOL ACETATES FOR MONOSACCHARIDE ANALYSIS , 1983 .

[34]  X. Rouau,et al.  Relative amounts of tissues in mature wheat (Triticum aestivum L.) grain and their carbohydrate and phenolic acid composition , 2007 .

[35]  V. Piironen,et al.  Potential of dry fractionation of wheat bran for the development of food ingredients, part I: Influence of ultra-fine grinding , 2011 .

[36]  J. Abecassis,et al.  Biochemical markers: Efficient tools for the assessment of wheat grain tissue proportions in milling fractions , 2009 .