M. KUREK et al.: Wheat Bread Rolls with Oat Fibre, Food Technol. Biotechnol. 54 (1) 45–51 (2016) 45 View metadata, citationISSN and 1330-9862 similar papers at core.ac.uk original scientifi c paperbrought to you by CORE doi: 10.17113/ft b.54.01.16.4177 The Effect of Oat Fibre Powder Particle Size on the Physical Properties of Wheat Bread Rolls Marcin Kurek*, Jarosław Wyrwisz, Monika Piwińska and Agnieszka Wierzbicka Division of Engineering in Nutrition, Faculty of Human Nutrition and Consumer Sciences, Warsaw University of Life Sciences, PL-02-776 Warsaw, Poland Received: March 18, 2015 Accepted: October 23, 2015 Summary In response to the growing interest of modern society in functional food products, this study att empts to develop a bakery product with high dietary fi bre content added in the form of an oat fi bre powder. Oat fi bre powder with particle sizes of 75 μm (OFP1) and 150 μm (OFP2) was used, substituting 4, 8, 12, 16 and 20 % of the fl our. The physical properties of the dough and the fi nal bakery products were then measured. Results indicated that dough with added fi bre had higher elasticity than the control group. The storage modulus values of dough with OFP1 most closely approximated those of the control group. The addition of OFP1 did not aff ect signifi cantly the colour compared to the other samples. In- creasing the proportion of oat fi bre powder resulted in increased fi rmness, which was most prominent in wheat bread rolls with oat fi bre powder of smaller particle sizes. The addition of oat fi bre powder with smaller particles resulted in a product with the rheologi- cal and colour parameters that more closely resembled control sample. Key words: dietary fi bre, oat fi bre, bread, particle size Introduction dance with European Food Safety Authority (EFSA) health claims and European Union Commission Regula- The contemporary consumption model, character- tion No 432/2012 of 16 May 2012 (8,9), which established a ized by high ingestion of products rich in sugar and fat, list of permitt ed health claims for foods, apart from those yet low in vitamins, minerals, and dietary fi bre, is respon- referring to the reduction of disease risk and to children’s sible for many diseases of affl uence, such as diabetes, development and health. This health claim states that asthma, coronary heart disease and obesity (1). Mean- ‘oats increase the faecal bulk’ when a product has a high while, general consumption of bread products decreases level of dietary fi bre. This means more than 6 g of dietary as the society’s gross domestic product increases (2). How- fi bre in each 100 g of product, therefore complying with ever, in developed countries there is also a demand for a European Union Commission Regulation (EU) No 1047/ greater variety of bread with oat, bran, seeds, etc. (3). In 2012 of 8 November 2012 amending Regulation (EC) No such cases, the most probable solution is to fortify white 1924/2006 (9) regarding the list of nutrition claims. The bread products with dietary fi bre that has many functions addition of dietary fi bre to the bread matrix can lead con- (e.g. caloric reduction, available carbohydrate reduction, sumers to conclude that a product is healthy. This study moisture control, anticaking properties, textural modifi - was conducted to investigate whether that common belief cation and structural enhancement) (4,5). has merit. Dietary fi bre is an essential component in nutrition Principally, dietary fi bre is comprised of a non-carbo- and health (6,7). Thus, the present study will explore the hydrate component called lignin and non-cellulosic poly- addition of oat fi bre in wheat roll production in accor- saccharides, such as pectin substances and hemicellulos- ______________________________ *Corresponding author: Phone: +48 22 590 37 014; E-mail: [email protected] 46 M. KUREK et al.: Wheat Bread Rolls with Oat Fibre, Food Technol. Biotechnol. 54 (1) 45–51 (2016) es. The structural components are found mainly in the Particle size distribution cell wall of plants (7). Dietary fi bre is primarily a constitu- Fibre particle size distribution was determined using ent of plant foods and includes materials that have di- Morphologi® G3SE (Malvern Instruments Ltd, Malvern, verse morphological and chemical structure. UK) equipped with a sample dispersion unit for dry sam- Basically, the process involved in the production of ples and a wet cell for hydrated samples. Size distribution bread is a highly complex one that entails a range of pa- was calculated as the relative volume of particles in size rameters that must be regulated. According to Almeida et bands presented as size distribution curves (Malvern Mi- al. (10), rheological measurements are used in the predic- cro soft ware v. 5.40, Malvern Instruments Ltd.). Particle tion of both the behaviour of wheat dough during bread size distribution parameters included the largest particle production and of the fi nal product quality. Despite the size (d(v,0.9)), mean particle volume (d(v,0.5)), smallest parti- fact that there are diff erent sources of dietary fi bre, Al- cle size (d(v,0.1)), Sauter mean diameter (d(3,2)), and mean meida et al. (10) argue that the dietary fi bre used in bread particle diameter (d(4,3)). Water-holding capacity of the fi - production aff ects both processing and fi nal product bre was determined as follows: 10 g of dietary fi bre was quality. soaked in 100 mL of distilled water and left overnight. Baking is the most important step in the bread pro- Then the bulk was fi ltered through a Büchner funnel and duction that transforms the raw dough to the bread using the water-holding capacity was calculated as the diff er- the heating. During baking, the mass loss is observed due ence between the amount of water used in the soaking to the loss of water that was incorporated into the dough process and the amount remaining in the bulk aft er fi ltra- during mixing. As already documented, dietary fi bre may tion. have a negative eff ect on the fi nal bread quality, leading to reduced volume of the bakery product, i.e. loaf volume Bread preparation (11,12). Components of the bread dough included (in %): The addition of large amounts of fi bre to bread re- fl our or fl our partly replaced with dietary fi bre 92, sults in a change in the bread physical properties, such as pressed yeasts 4, salt 2, sugar 1 and vegetable fat 1. Flour increased crumb fi rmness, crumb darkening, or changes was replaced by dietary fi bre at 4, 8, 12, 16 and 20 % of the in taste (13). These negative eff ects can be reduced by fl our wet mass. The water content was calculated based using an appropriate proportion of soluble to insoluble on the water-holding capacity of the dietary fi bre, and it fi bre fractions (14), and the addition of enzymes such as was: 58, 61, 64, 67, 70 and 72 % when the fl our was re- hemicellulose and pentosans (15). Reducing fi bre powder placed with 0, 4, 8, 12, 16 and 20 % of dietary fi bre, respec- particle size increases water-holding capacity by increasing tively. The obtained dough had a vis cosity of up to 500 the surface area. In the bread production, this is ex treme- Brabender Units (BU) measured with rheometer Rotovis- ly important, because water is involved in the processes co RT20 (Haake, Vreden, Germany). All components, of starch gelatinization, protein denaturation, for mation apart from fat, were mixed with a spiral mixer (TRQ–42; of fl a vour characteristics and it also signifi cantly aff ects RM Gastro, Ustron, Poland) at 100 rpm for 4 min. Aft er colour (14,15). the addition of oil, the dough was mixed for 6 min at 250 The aim of the study is to investigate the eff ects of the rpm, left to rest for 15 min, and then divided into 60-gram addition of oat dietary fi bre powder of two particle sizes rolls. The divided rolls rested for 15 min at room temper- on the physicochemical properties of wheat bread rolls ature, and were then put into the proofi ng chamber for 60 during storage and to provide recommendations on the min (35 °C, 80 % relative humidity) to double in volume. extent to which it is advisable to fortify wheat bread rolls Bread rolls were then baked at 210 °C for 15 min in a con- with oat fi bre. vection oven (CPE 110; Kuppersbuch, Gelsenkirchen, Germany). Aft er cooling, the bread was packaged into pa- per bags and stored for 3, 24 and 48 h at 20 °C. Materials and Methods Rheology Materials Rheological measurements were conducted with a Commercial wheat fl our was provided by a local sup- Rotovisco RT20 rheometer (Haake). The rheological ex- plier (Mlyny Zbozowe Zabczynscy, Łaskarzew, Poland). It amination was done using standard dough preparation, contained (in %): protein 10.62, ash 0.52, gluten 28.14 and but without yeast to avoid the infl uence of fermentation moisture 14.23. The composition of the fl our was mea- on the results. The creep and recovery test was followed sured with near-infrared spectroscopy (NIRFlex N-500; by a fi ve-minute period of relaxation. Next, the examined Buchi, Flawil, Switzerland). dough was subjected to the creep test with a constant The oat fi bre powder (provided by Micro Inc., War- shear stress of 50 Pa for 60 s, allowing the sample to re- saw, Poland) had 80 % dietary fi bre (78 % insoluble frac- cover for 180 s aft er the removal of the load.