Eur Food Res Technol (2010) 230:437–445 DOI 10.1007/s00217-009-1184-z ORIGINAL PAPER Baking properties and microstructure of pseudocereal Xours in gluten-free bread formulations Laura Alvarez-Jubete · Mark Auty · Elke K. Arendt · Eimear Gallagher Received: 30 June 2009 / Revised: 22 September 2009 / Accepted: 3 November 2009 / Published online: 25 November 2009 © Springer-Verlag 2009 Abstract In the present study, the baking properties of Introduction the pseudocereals amaranth, quinoa and buckwheat as potential healthy and high-quality ingredients in gluten-free To date, the only treatment available for celiac disease is a breads were investigated. Scanning electron micrographs strict lifelong adhesion to a gluten-free diet [1]. Therefore, were taken of each of the Xours. The pasting properties of celiac patients must avoid the consumption of gluten-con- these Xours were assessed using a rapid visco analyser. taining foods. However, this may prove a diYcult and over- Standard baking tests and texture proWle analysis were whelming task for the celiac patients as the majority of the performed on the gluten-free control and pseudocereal- cereal-based foods available in the market (such as pasta, containing gluten-free breads. Confocal laser scanning baked products, snacks and breakfast cereals) are prepared microscopy (CLSM) images were also obtained from the with gluten-containing grains, such as wheat [2]. Although baked breads and digital image analysis was conducted on gluten-free alternatives are readily available, Wnding good- the bread slices. Bread volumes were found to signiWcantly quality gluten-free products has been reported as a major increase for the buckwheat and quinoa breads in compari- issue for celiac patients who are trying to adhere to a glu- son with the control. In addition, the pseudocereal-contain- ten-free diet [3, 4]. ing breads were characterised by a signiWcantly softer Despite recent advances in the formulation of high- crumb texture eVect that was attributed to the presence of quality gluten-free products, the replacement of gluten in natural emulsiWers in the pseudocereal Xours and conWrmed cereal-based products, such as bread, biscuit, cake and by the confocal images. No signiWcant diVerences were pasta, still represents a signiWcant technological challenge obtained in the acceptability of the pseudocereal-containing [5]. The formulation of gluten-free breads possibly repre- gluten-free breads in comparison with the control. sents the greatest challenge, due to the fundamental role of gluten in breadmaking [6]. Gluten is an essential struc- Keywords Pseudocereals · Gluten free · Bread · ture-building protein that provides viscoelasticity to the Microscopy · Baking properties · Pasting properties dough, good gas-holding ability and good crumb structure of the resulting baked product [5]. Some of the most important approaches developed to date to mimic the L. Alvarez-Jubete · E. Gallagher (&) Ashtown Food Research Centre, properties of gluten in gluten-free bakery products Teagasc, Ashtown, Dublin 15, Ireland involve the use of gums, hydrocolloids and protein-based e-mail: [email protected] ingredients [6]. Considerably, fewer studies have been dedicated to L. Alvarez-Jubete · E. K. Arendt Department of Food and Nutritional Sciences, improving the nutritional quality of gluten-free products. National University of Ireland, Cork, Ireland Gluten-free cereal foods are frequently made using reWned gluten-free Xour or starch and are generally not enriched or M. Auty fortiWed [7]. As a result, many gluten-free cereal foods do National Food Imaging Centre, W Moorepark Food Research Centre, not contain the same levels of B-vitamins, iron and bre as Teagasc, Moorepark, Fermoy, Co. Cork, Ireland their gluten-containing counterparts [7, 8]. A need to 123 438 Eur Food Res Technol (2010) 230:437–445 improve their nutritional quality has been raised by many Table 1 Bread formulations medical and nutritional experts [2, 9]. Ingredient Gluten-free Amaranth Quinoa Buckwheat Several gluten-free grains exist, such as the pseudocere- (% Xour/ control (A) (Q) (B) als amaranth, quinoa and buckwheat. These seeds are also starch base) (GFC) characterised by an excellent nutrient proWle. Besides being Rice Xour 50 50 50 50 important energy sources due to their starch content, ama- ranth, quinoa and buckwheat provide good-quality protein, Potato starch 50 – – – X dietary Wbre and lipids rich in unsaturated fats [10]. More- Amaranth our – 50 – – X over, they contain adequate levels of important micronutri- Quinoa our – – 50 – X ents, such as minerals and vitamins and signiWcant amounts Buckwheat our – – – 50 of other bioactive components, such as saponins, phytoster- Yeast 3 3 3 3 ols, squalene, fagopyritols and polyphenols [11–14]. A recent Sugar 3 3 3 3 trend by researchers has focused on their use in the formu- Salt 2 2 2 2 lation of high-quality healthy gluten-free products, such as Xanthan gum 0.5 0.5 0.5 0.5 bread and pasta. SunXower oil 6 6 6 6 In a series of recent studies, the nutritional properties Water 87 87 87 87 and baking characteristics of amaranth, quinoa and buck- wheat have been assessed [10, 12, 15]. The authors found that the replacement of potato starch with a pseudocereal were mixed together for 1 min using an A120 Hobart mixer Xour resulted in gluten-free breads with an increased con- (Hobart Food Equipment, Sydney, Australia) at speed 1, tent of important nutrients, such as protein, Wbre, calcium, yeast was dissolved in the water and added to the dry ingre- iron and vitamin E. The resulting breads also had a signiW- dients together with the oil and the batter formed was cantly higher content of polyphenol compounds and their mixed for a further minute. After scraping the base of the in vitro antioxidant activity was increased. bowl, the batter was further mixed for 2 min at speed 2. The In the present study, technological aspects (i.e. batter/ batter was then scaled into baking tins (400 g) and placed in dough and baking properties) related to the application of a proofer (Koma, Roermond, The Netherlands) for 30 min the pseudocereals as ingredients in the production of glu- at 35 °C and 80% relative humidity. The loaves were baked ten-free breads were evaluated. in a deck oven (Tom Chandley Ovens, Manchester, UK) at 220–225 °C for 25 min. They were then cooled to room temperature and stored in polyethylene bags. Six loaves Materials and methods were produced per bake and the preparation of the breads was done in triplicate (i.e. 3 bakes per each type of bread). Bread ingredients Flour pasting properties Amaranth Xour (Ziegler & Co., Wunsiedel, Germany), qui- noa Xour (Ziegler & Co., Wunsiedel, Germany), rice Xour The pasting properties of the Xours and starches were eval- (S&B Herba, Orpington, Kent, UK), potato starch (Healy uated using a Rapid Visco Analyser (RVA, Newport Scien- Chemicals Ltd, Dublin, Ireland), wheat Xour (Odlum tiWc Pty. Ltd, Warriewood, Australia). The method used Group, Dublin, Ireland), sunXower oil (Flora, Liverpool, was the RVA General Pasting Method (Newport ScientiWc UK), xanthan gum (All In All Ingredients, Dublin, Ireland), Pty. Ltd, 1998). fresh yeast (Yeast Product, Dublin, Ireland), salt (Imeos Enterprises, Runcorn, Cheshire, UK) and caster cane sugar Bread evaluation (Tate & Lyle, London, UK) were the materials used in the study. Loaf volume was measured using a volume meter (TexVol BVM-L370, Sweden). Loaf weight was recorded and loaf Preparation of breads speciWc volume (ml/g) calculated. Bake loss deWned as the amount of water and organic material (sugars fermented V The di erent bread formulations are presented in Table 1. and released as CO2) lost during baking was also calculated The amount of water used in the control and in each of ([weight of the loaf before baking ¡ weight of the loaf after the pseudocereal-containing breads was kept the same; the baking and cooling]/[weight of the loaf before baking] £ 100). only diVerence in the formulation of the breads was the Moisture was measured following a procedure based on the type of Xour used as a composite with rice Xour. The glu- ICC method 110.1 [16] using a Brabender moisture oven ten-free batter was prepared as follows: dry ingredients (Brabender, Duisberg, Germany). 123 Eur Food Res Technol (2010) 230:437–445 439 Crust and crumb colour were measured using a Minolta Massachusetts, US). Data were analysed using analysis of Chromameter (Minolta CR-100, Osaka, Japan) and results variance (ANOVA) and the mean were separated by the were expressed using the L*, a*, b* colour scale. Crumb Tukey–Kramer test. DiVerences of p <0.05 were consid- structure of the loaves was evaluated using the C-Cell ered signiWcant. Bread Imaging System (Calibre Control International Ltd., UK). The procedure followed in this study consists of the standardised procedure described by the C-Cell Bread Results Imaging System manufacturer (Calibre Control Interna- tional Ltd., UK). Crumb texture was assessed by conduct- Scanning electron microscopy of the Xours ing a texture proWle analysis (TPA) using a texture analyser (TA-XT2i, Stable Micro Systems, Surrey, UK) equipped SigniWcant diVerences can be observed in the scanning with a 25 Kg load cell and a 36 mm aluminium cylindrical electron micrographs of the pseudocereal Xours, rice Xour, probe. Pre-test, test and post-test speed were 2, 1 and 5 mm/ wheat Xour and potato starch (Fig. 1). In particular, the size s, respectively, and compression was set at 40%. All bread of the Xour particles seems to diVer considerably among the evaluation analysis were conducted 24 h after baking (day Xours under study. Smallest particle size can be observed in 1) and moisture and TPA analysis were repeated 72 and potato starch and wheat Xour, followed by rice, buckwheat, 120 h after baking (days 3 and 5, respectively). amaranth and quinoa Xours.