The role of pentosans and starch in baking of wholemeal rye bread Krzysztof Buksa a, ⁎, Anna Nowotna a , Werner Praznik b , Halina Gambuś a , Rafał Ziobro a , Jan Krawontka a a University of Agriculture Kraków, Department of Carbohydrates Technology, Balicka 122, 30-149 Krakow, Poland b University of Natural Resources and Applied Life Sciences, Department of Chemistry, Vienna, Austria abstract article info Article history: Received 15 March 2010 Accepted 8 June 2010 Keywords: Rye bread Wholemeal Pentosans Starch In case of rye wholemeal with low enzymatic activity, high bread volume is obtained in cases, when pentosan fraction contains many water extractable polymers, and there is an optimum ratio of water extractable pentosans to starch, which should be in the range 1:16–1:20. This is also accompanied by starch properties such as high amylose content, good swelling capacity (big swelling factor) and consequently high solubility and pasting temperature. Moisture content of wholemeal rye bread is mainly controlled by the level of fiber, including soluble pentosans, compared to the amount of starch. Starch properties which seem to be important for establishing this value are amylose content, and the susceptibility to swelling and gelatinization. Hardness of wholemeal rye bread is influenced by the level of fiber, including soluble pentosans. Decline of bread texture is observed in the presence of extractable pentosans with high molecular weight. Use of starch with high amylose level, high swelling factor and low molecular weight is accompanied by increased crumb hardening. © 2010 Elsevier Ltd. All rights reserved. 1. Introduction Pentosans and starch play important (although different) roles in basic technological steps of rye bread production as well as in its staling process. Their optimal ratio in flour is estimated to be 1:16 (Bushuk, 2001). Starch, an irreplaceable component of the dough plays a key-role in establishing crumb structure (Gambuś, 2000; Hug-Iten, Handschin, Conde-Petit, & Escher, 1999; Sandstedt, 1961). Model breads with artificial flour containing vital gluten and starches of various botanical origin demonstrate, that rye and barley starch are as good as wheat starch in baking quality (D'Appolonia & Gilles, 1971; Hoseney, Finney, Pomeranz, & Shogren, 1971; Hoseney, Lineback, & Seib, 1978). It is known, that baking properties of starch depend mostly on its swelling and gelatinization). In the studies on rye bread starch was evaluated only by scanning microscopy of dough and crumb (Autio & Salmenkallio-Marttila, 2001). Influence of swelling and gelatinization of starch on bread baking was checked only for mixtures of wheat starch and gluten (Gambuś, 2000). Pentosans are an important component of rye dough as well. They bind water and contribute to the formation of viscous dough. Water extractable pentosans (WEP) play an important structural role in dough and bread, compared to insoluble (water unextractable) pentosans (WUP) (Eliasson, 2006; Vinkx & Delcour, 1996). In the studies, where wheat or rye WEP were added to wheat flour, maximum volume of loaves were observed after the addition of rye pentosans (Denli & Ercan, 2001; Michniewicz, Biliaderis, & Bushuk, 1992). It was also found that wheat bread parameters are improved by the addition of lower amounts of high molecular weight WEP, compared to low molecular weight pentosans (Biliaderis, Izydorczyk, & Rattan, 1995; Vinkx & Delcour, 1996). No data about the concurrent influence of starch and pentosans on rye bread were found. The aim of the study was to correlate bread baking parameters of rye wholemeal with the properties of those carbohydrates isolated from different Polish varieties of rye. 2. Materials and methods 2.1. Grain was obtained from rye cultivated during three following years (2004–2006) Chosen varieties include three populations: Amilo (due to low enzymatic activity), Dankowskie Złote (one of the oldest registered cultivars in Poland) and Kier; one hybrid Nawid and one synthetic Caroass. Estimation of enzymatic activity and basic chemical composition of rye grains: • enzymatic activity, as falling number (FN – in Falling Number apparatus 1800) according to PN-ISO 3093:1993, after milling the grain in laboratory mill (produced by Perten). Food Research International 43 (2010) 2045–2051 ⁎ Corresponding author. E-mail address: krzysiek_b@onet.eu (K. Buksa). 0963-9969/$ – see front matter © 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2010.06.005 Contents lists available at ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres