Effect of Sweet Yeast Bread Formula on Evaluating Rapid Mix Test

DVOŘÁKOVÁ, P., KUČEROVÁ, J., KRÁČMAR, S.: Eff ect of sweet yeast bread formula on evaluating rapid mix test. Acta univ. agric. et silvic. Mendel. Brun., 2011, LIX, No. 5, pp. 39–46 The aim of this work was to detect how diff erent sweet yeast bread formulas infl uence results of rapid mix test and by the help of sensory analysis to discover consumer preferences and possible benefi t and use in bakery industry. Applied raw materials (ground wheat fl our T 530, yeast, sugar, salt, oil, egg, improver Hit) along with basic formula were taken from the Varmužova bakery in Boršice by Buchlovice. The basic formula served as a standard (I), other six formulas were then determined (II– VII). In each formula, the rate of yeast, sugar or oil was altered in the range of ± 10% compared with the standard. Flour bread-making quality – Hagberg Falling number [s], Sedimentation index [ml], wet gluten [%], ash [%], moisture [%], binding capacity [%], granulation [%], alveographic energy [10−4J] and alveographic rate P/L – was measured. Rapid mix test and parameters like pastry weight, volume, shape, dough yield, pastry yield, baking loss, penetration and sensory analysis were determined. To establish yeast fermentation activity, Engelke fermentation test was applied. The most evident diff erences among the samples appeared in the volume and shape. The results of sensory analysis showed that the samples with higher rate of altered raw materials were evaluated as the best. rapid mix test, sensory analysis, pastry formula Flour is a basic raw material for bread production, forming 60 and more percent of weight in most types of dough. It is obtained by grinding cereals and subsequent modifi cation of meal and grits. In bakeries and confectioneries, mostly wheat and rye fl ours are manufactured. Other types of fl our (maize, barley, soy-bean) are used predominately for special purposes (Skoupil, 1994). Wheat producers, bakers and millers have been trying to fi nd an easy method for evaluating the wheat quality since the discovery of gluten in the 18th century. The majority of the predictions is based on endosperm proteins. In the beginning, the rate of gliadin:glutenin fractions was investigated, later each fraction was examined. Although the dependence between wheat quality and these fractions was proved, there is a need of further research to state higher correlation (Lászity et al., 2007). The primary eff ect on the fl our quality have the seed quality, inclusion of wheat in crop rotation, soil cultivation before seeding, seeding process, support, fertilization, diseases, pest protection and harvest have Zimolka et al. (2005). Other factor is weather and its instability. The development of weather during vegetation aff ects almost all parameters of technological quality of the wheat kernel. Quality requirements then are: moisture maximum 14%, bulk weight at least 76 kg/hl, content of nitrogenous substance at least 11.5%, impurities maximum 6% (Burešová and Palík, 2008). Thus high-quality grain is ready for milling, in which the endosperm is processed. The endosperm structure belongs among the criteria which aff ect the technological parameters of grain (Hrušková and Švec, 2009). Concerning chemical composition of fl our, it depends on the quality of the raw material and changes during storage according to the conditions. A er milling, many biochemical modifi cations, which are identifi ed as maturing, occur. If the fl our is well-matured, it has a higher binding capacity, the dough is less sticky and has better ability to exclude fermentative gas. These properties refl ect in better workability of the dough and higher volume of bread (Hrušková and Machová, 2002). 40 P. Dvořáková, J. Kučerová, S. Kráčmar One of the most important chemical components of fl our are polysaccharides. Storage polysaccharide is starch in the form of granules, which absorb about 46% of water. Starch granules swell under increased temperature, moisture and time within baking and form coherent network of the crumb a er cooling. During storing, bread looses freshness and parches – the crust hardens, stiff ens and looses elasticity, generally, the bread looses taste. This is mostly caused by migration of the water from starch retrogradation (Goesaert et al., 2005). Similarly to starch, proteins play a considerable role too. They are biopolymers which consist of amino acids connected with peptide structure (Příhoda et al., 2003a) and in terms of bakery, two groups of proteins are important – prolamins and glutelins. Prolamins (gliadins) are single-stranded macromolecules while glutelins (glutenin) are described as macromolecules composed of more strands (Hrušková, 2001). Prolamins and glutelins swell due to mechanical stress and atmospheric oxygen and they form a solid gel called gluten. Gluten is a mould of dough and it is a reason of the unique properties of the dough – extensibility and elasticity (Příhoda et al., 2003b). When discussing the properties of dough, fats have to be mentioned. Müllerová and Chroust (1993) explain that fat content in light fl our is about 1.5%, and approximately 2% in the dark types of fl our and they are regularly added into breads, sweet yeast bread and confectioneries. Fats have a number of favourable technological properties, but the disadvantage is their high energy value. A number of them (for example shortening, margarine, butter, lard, plant oils) according to the purpose are used in bakery. In the kneading phase, fat creates a fi lm between the protein fi bers and starch grains, thereby reducing the swelling of the fl our particles. Predominantly phospholipids and unsaturated fatty acids apply in dough maturing. In the phase of baking, fat retards starch gelation, thus prolonging the baking time. The function of the fat is to improve the structure, aroma, taste and shelf life of the product (Švec and Hrušková, 2004). The fi nal quality of fl our is aff ected by minerals, which are expressed as ash, which consists mainly of carbon, phosphorus, magnesium, potassium, calcium and ferrum. Uneven distribution of minerals in the grain became the basis for assessing the fl our quality (Kučerová, 2004), and on the basis of chemical composition and physical properties of fl our Hrušková et al. (2008) provide fl our quality requirements – ash content 0.60% in dry matter, granulation at least 96% (si ings of 257 μm mesh size) and 75% maximum (mesh size 162 μm), wet gluten content at least 28% in dry matter, Hagberg falling number minimum 220 s and sedimentation index at least 30 ml. Another part of formulas for bread-making then is Saccharomyces cerevisiae Hansen, which is used as baker’s yeast, and it is able to ferment sugar into ethanol and carbon dioxide. Released carbon dioxide causes dough loosening and aff ects the product within baking. Good baker’s yeast should contain at least 26% of dry matter and 35% of proteins in dry matter (Beneš, 1979). The usual addition of 1–5% of yeast causes changes in the structure of the dough, the dough volume increases and the typical sensory properties of leavened bread develop. As yeast is osmosensitive, greater addition of salt and sugar aff ects the rate of fermentation. It is reported that 1.5% of salt decreases production of carbon dioxide generation by 20% compared with the dough without salt, while the addition of sugar increases gas production by 5%. For fermentation, the optimum pH of 4–6 and temperature around 32 °C are required (Švec and Hrušková, 2004). According to Skoupil (2002a), salt is present in a vast range of bakery products as a fl avour component except for some kinds of sweet pastry. In bakery production salt with iodine – fi nely ground – which contains at least 98% NaCl, compounds of calcium, magnesium and small amounts of trace elements essential for human beings, is used. Salt aff ects the rheological properties of dough by reducing water binding capacity, strengthening gluten structure and extending the time of dough development. The eff ect depends on the addition and the properties of the fl our (Švec and Hrušková, 2004). Another important component of dough is substance called “improver” which refers to a broad group of materials that can be added to fl our or dough to improve some properties of the dough and quality of fi nal products (Cauvain and Young, 2001). As regards water, Skoupil (2002b), Příhoda et al. (2003b) claim that only fresh water can be used for food processing. The basic quality indicator of water is hardness (calcium and magnesium salts). So water gives sticky dough and reduces water binding capacity. Hard water, on the other hand, slows down fermentation of the dough and strengthens gluten. The basic requirement on water used in food processing is health safety. In the baking process, water addition to the dough and also its loss during baking is monitored, because there is an evident infl uence on rheological properties of the dough. In the storage process its decrease depends on the time and conditions (Cauvain and Young, 2007). Properties of the wheat dough and its behaviour during baking process are determined by two main factors: • rheological behaviour of the dough based on the balance between elastic and viscosity properties on the molecular level given by the representation of diff erent molecular weight glutenin and gliadin in fl our, • distribution and stability of air bubbles primarily rising during the formation of dough and then expanding by the infl uence of fermentation. Both of these factors are related to the formula and basic components − wheat fl our, water, yeast, salt, sugar and fat, which also infl uence each other (Cauvain and Young, 2007). Eff ect of sweet yeast bread formula on evaluating rapid mix test 41 For the formation of homogeneous dough, addition of 45% water is expected. This amount gives a good consistency. It is the liquid component of the dough that seems to be essential for the formation and stability of air bubbles. These arise primarily at the mixing stage, in which the dough has the optimum viscoelastic parameters. Fermentation gases during subsequent fermentation fi rst dissolve in the liquid phase of the dough, and then evaporate and enlarge the generated bubbles (Švec and Hrušková, 2004). Taking these factors into account, we conducted this experiment in cooperation with Varmužova bakery in Boršice by Buchlovice. The main goal was to verify the eff ect of raw materials ratio in the formula of sweet yeast bread on the results of the rapid mix test. A further aim was to determine consumer preferences and potential benefi ts for use in the bakery industry. MATERIALS AND METHODS The material for rapid mix test was obtained from bakery in Boršice by Buchlovice. Three charges of fl our T 530, yeast Vivo (Lesaff re Czech Republic, Olomouc), oil, sugar, salt, eggs and improver Hit were used. For determination of fl our baking quality, moisture ČSN ISO 461014 (2010a), falling number ČSN ISO 3093 (2010b), Zeleny test ČSN ISO 5529 (2000b), ash ČSN ISO 2171 (2008), gluten quantity ČSN ISO 56 0512-10 (1995) and alveographic values AACC 54-30A (2000a) were determined. The rapid mix test was then done and evaluated – fi rst, loose components were homogenized and solutions of sugar, salt and yeast suspension were prepared. Thus prepared material was kneaded on Zelmer profi for one minute. The dough then rose at the optimum temperature 30–32 °C and relative humidity 80–85% for 20 minutes, next it was divided into clones of 80 g weight. These clones were put into the proofer and rose for 25 minutes and fi nally were baked for 20 minutes at the temperature of 220 °C. In the next step, sensory analysis and penetration at penetrometer TIRA test 27025 with fl at adapter of 5 mm diameter were done. The whole experiment was conducted twice. To establish yeast fermentation activity, Engelke fermentation in 10% sucrose solution test was applied. Loaf volume, shape and penetration were analysed using analysis of variance (ANOVA) (Statistica 9) with subsequent Tukey test. ANOVA provides a statistical test, which shows whether the means of several groups are equal or not. Tukey test, which is commonly used in conjunction with ANOVA, fi nds which means are signifi cantly diff erent. These tests had proven to be the most appropriate for the results evaluation. To determine the diff erences between the products with varying formulas, the following prescriptions were used (see Tab. I). Sample I (the basic formula from the bakery) was considered as the standard. Then, the sensory analysis was done. Five trained assessors evaluated the fi nal product and following descriptors were established as the I: Formulas of sweet yeast bread