Evaluation of the Wholegrain Flour Baking Properties Depending on a Wheat Variety

Transcription

1 ISSN MAISTO CHEMIJA IR TECHNOLOGIJA T. 41, Nr. 2 Evaluation of the Wholegrain Flour Baking Properties Depending on a Wheat Variety Daiga Kunkulberga 1, Antons Ruza 2, Anda Linina 2, Ruta Galoburda 1 1 Latvia University of Agriculture, Department of Food Technology Faculty of Food Technology; 2 Institute of Agrobiotechnology, Faculty of Agriculture, Liela iela 2, LV-3001 Jelgava, Latvia; daiga.kunkulberga@llu.lv The winter wheat varieties Cubus and Tarso and rye grain varieties Kaupo and Hacada were studied in the research. In the wheat and rye grain samples the following quality indices were determined: content of protein, Hagberg falling number, starch, hectolitre mass, thousand kernel mass, and grain evenness. The quality and sedimentation value of gluten were measured in wheat. The grain was used for the wholegrain flour production, with quality assessment that followed. The acidity was considered as one of the indirect indicators of flour freshness during storage. No significant changes in flour acidity were observed during the experimental storage. The wholegrain bread samples were baked from the obtained flour according to the baking test developed in Latvia for fast evaluation of bread baking properties. The results of the current research show that the quality of all the studied varieties meet the requirements for high-grade wheat and rye grains for food consumption and are suitable for the wholegrain flour production and bread baking. Keywords: wheat, rye, quality indices, wholegrain flour, baking properties. Introduction Cereals are an important part of human diet. They provide necessary carbohydrates and proteins for the body as well as mineral substances, vitamins and dietary fiber. Fiber assists in the regulation of digestion, intestinal tract activity and avoiding obesity [1]. Bran, wholegrain bread, cereals and vegetables are the products containing the highest amount of fibre. Wheat and rye is the major field crop grown in Latvia. The environmental conditions are known to have significant influence on the end-use quality characteristics of the grain. Environmental variation often has been considered the most important factor influencing wheat quality characteristics [2]. The quality of grain is mainly determined by management techniques and environmental conditions; however, it can be influenced by the genetic basis [3]. Grain quality depends not only on its genetic potential for particular characters but also on its ability to realize this potential in actual production and under different environmental conditions [4]. Wheat varieties differ significantly in their grain quality. Nonetheless, environmental factors play a major role in the expression of genotype characteristics [5]. Their impact, however, is rarely optimal; one or more of them will always limit the yield and quality of the product. Quality parameters of winter wheat are not stable between production years because of the inconsistency of the variables such as initiation of growing season, distribution of rainfall and heat units available for crop growth during corresponding phases of plant growth and development [6]. Addition of nitrogen fertilizer in accordance with the plant requirement is necessary to attain high yields and quality of winter wheat [7]. In Latvia, cereals maturation and harvesting can occur during rainfall period, which often can be a reason for a lower grain quality and even grain sprouting in ears. Cereal grain is of the highest quality during the growth period, between wax maturity and full maturity. During this period, cereal harvest forming is already finished and in case of unfavourable weather conditions grains can start sprouting, which would result in a reduced grain quality. The possibility for the increase of dietary fibre intake is the increased use of coarse flour, cereal products, and wholegrain bread products. The fibre content in bread depends not only on the growing conditions of grains, but also on the properties of a certain variety as well. There has been technological study available on the wholegrain flour baking properties in Latvia. A small-scale and insufficient 24

2 study was performed on the wholegrain flour production, its technological and baking properties. Our objectives were to determine the quality and suitability of the most popular wheat and rye grain varieties in Latvia for wholegrain flour production and bread baking. Materials and methods In Latvian farms nowadays the most popular winter wheat varieties are Cubus and Tarso, and rye grain varieties Kaupo and Hacada which were chosen for the current research. Meteorological conditions is an important factor affecting grain quality. In 2005/2006, the overwintering of winter cereals was good. In April, a monthly mean temperature was by C higher than the long-term average, but rainfall occurring was 30 mm. May was warm but dry as rainfall was 17.9 mm, which was 36 % of long-term average. June was hot with daily temperature exceeding 30 C. Weather conditions favoured rapid formation and ripening of cereal grain. During grain harvest in the third decade of July, the weather was dry and sunny. In general, the vegetation period of winter cereals in 2006 was favourable to achieve high yields and good quality cereals. For experiments cereal grains were harvested with a combine harvester Sampo-500 during the maturity phase stage in the year Quality characteristics were calculated at 100 % purity and 14 % moisture level, but protein and starch, in dry mater basis. A sampling procedure for grain quality evaluation was performed according to ICC 101/1 standard for obtaining a mean sample. Grain quality indices were tested in the Research laboratory of grains and seeds at Latvia University of Agriculture (LLU) and in the Research Laboratory of Agronomy Analysis (LLU) using the following standards and methods: grain moisture content ICC 109/1, grain protein content by Kjeldahl procedure (N 5,7; moisture basis) by ICC 105/2; wet gluten, gluten index, dry gluten, water binding capacity in wet gluten content according to Perten-ICC method ICC 155; sedimentation value according to Zeleny as an approximate measure of baking quality according to ISO 5529, hectolitre mass by ISO , thousand kernel weight according to ISTA method, Hagberg falling number according to Hagberg Perten method as measure of the degree of alphaamylase activity in grain and flour by ICC 107/1, starch determined using ICC 123. Grain glassiness was estimated by the structure of grain cross-cut, and it was expressed in percentage after proportional calculations. Grain evenness was evaluated after sorting grains through the sieves and expressing the biggest mass of grains on two subsequent sieves as a per cent of all grains of the analyzed sample. Wheat and rye grain samples were ground in two type mills: Perten Laboratory Mill 3100 and ETA As a result, the flour of various grinds was obtained. Moisture content, ash and coarseness after sieving were determined using standard methods. A test baking method developed in Latvia on the basis of German test baking method for fast evaluation of rye flour baking properties was used [8, 9]. Results and discussions Wheat grain quality Grain protein content (Table 1) was high in both varieties: Cubus,13.5 % but Tarso was 1.1 % higher. Table 1. Quality of wheat grains Indices Cubus Tarso Requirements of quality indices, (minimum value) in Latvia Protein, % Gluten, % Gluten index Gluten quality group Hidratation ability of gluten I II I and II group Sedimentation value, ml Class of sedimentation value Hagberg falling number, s Starch, % Hectolitre mass, kg hl Thousand kernel mass, g Grain evenness, % Grain glassiness, % , 2, 3 class 25

3 The content of gluten in both studied varieties meets the requirements for high quality food grade grain, but for the variety Tarso it was higher by 5.5 %. Only grain containing gluten of the first or second gluten quality group is suitable for bread production. The variety Cubus contains a higher quality gluten (gluten index 86) corresponding to the first gluten quality group, while for the Tarso (52) variety the grains correspond to the second gluten quality group. Gluten hydration ability describes the water amount which can be bound by dry gluten. For both studied varieties a water binding capacity exceeds 2/3 of gluten. n mass: it is by 55 % higher in the Cubus variety. This indicates good grain baking properties because during dough making the flour would bind a relatively high water amount. Sedimentation value is a protein quality attribute. First quality class (>60 ml) flour is very hard and useful for mixing with comparatively weak flour, second class (40 60 ml) flour is hard and useful for direct baking or mixing with comparatively weak flour, third: (22 40 ml) useful for direct baking, but fourth (<22 ml) is very weak flour. Sedimentation value exceeds the minimum value (22 ml) in both varieties Cubus and Tarso (51.0 ml and 56.2 ml, respectively) and corresponds to the second class of sedimentation value. It proves that flour made from these grains is suitable for bread making. The starch content (67.2 %) in the grains of Cubus variety is by 3.2 % higher than in Tarso variety (64.0 %). The intensity of starch splitting is expressed by Hagberg falling number. The Falling number is essentially affected by the enzyme activity in the grain. As winter wheat was harvested duly, reaching the maturation phase (90 92 stages), and were not subjected to unfavourable weather conditions, Hagberg falling number for both studied varieties is high: for Cubus variety, 464 s, but for Tarso variety, 459 s, which considerably exceed the minimum value of 220 s. The hectolitre mass of both studied grain varieties exceeded 80 kg hl -1, which is considerably higher than the minimum value (73 kg hl -1 ). The grain size is expressed by a thousand kernels mass. The bigger grains among those of the same variety are typically more developed and more mature, therefore their quality is higher. As the summer of 2006 was dry, there was not sufficient moisture for plant development, therefore the formed grains were small, the thousand kernels mass was relatively low: for Cubus variety (41.8 g), but for Tarso variety it was by 3.4 g smaller (38.4 g). The evenness of grain was acceptable for both varieties, although a higher value was observed for Tarso variety (81.7 %), while for Cubus variety, the evenness was by 8.8 % lower (72.9 %). The glassy grain has a higher protein content, better flour outcome and better baking properties. The glassy endosperm is more transparent and in a cross-cut it seems to be as a glass or horn. In the glassy endosperm starch grains are located denser and among them there is protein. Whereas in mealy endosperm cells are located loosely in the space between the cells air is mainly included. The glassiness for both varieties was low: for Cubus variety it reached 31 %, but for Tarso variety it was 38 %. The quality indices show that the quality of the studied varieties meets the requirements for highgrade wheat grains for food consumption, and are suitable for wholegrain flour production and baking. Rye grain quality Hagberg falling number is the major quality attribute of rye. In the year 2006, the weather during rye harvest was dry and sunny, therefore Hagberg falling number for both varieties is high, 262 s, respectively (Table 2) for the Kaupo variety, and 247 s, for the Hacada variety, which considerably exceeds the minimum requirements for grain processing (100 sec). The results of rye grain quality assessment are presented in Table 2. Table 2. Quality of rye grains Indices Kaupo Hacada Requirements of quality indices in Latvia (minimum value) Protein, % Hagberg falling number, sec Starch, % Hectolitre mass, kg hl Thousand kernel mass, g Grain evenness

4 The protein content in the Hacada variety is 8.5 %, while in Kaupo variety, it is 10.0 %. Starch content in the grains of Hacada variety (63.1 %) is by 1.2 % higher than in the Kaupo variety (61.9 %). A thousand kernels mass for Hacada variety is by 1.6 g smaller than for Kaupo, variety because genetically this variety has smaller grains. Hectolitre mass for both studied varieties is high; in average, it exceeds the minimum requirements (68 kg hl -1 ) of rye grain by 10.5 kg hl -1. Grains of Kaupo variety has a high evenness (63.7 %), while the Hacada variety has a lower by 8.1 % evenness. Generally, the harvest of both varieties meets the requirements of high quality food grade rye grain. Wholegrain flour and its quality Moisture content, ash and coarseness of wholegrain flour obtained in Perten Laboratory Mill 3100 and ETA 0010 were determined after sieving of flour samples (Table 3). The obtained results allow to conclude that the moisture content is within the specified limits and do not exceed the critical value of 15 %. Ash content corresponds to the ash content of wholegrain flour, and correlates to the ash content in the grains. It is higher than typically in flour from which the outer layer of grain containing high amount of mineral substances is separated. During flour storage the acidity was monitored. Acidity is an indirect indicator of flour freshness. If the flour is stored under unacceptable conditions (warm or long time), the acidity increases. The wholegrain flour contains all grain constituents, including lipid rich germ, and increase of the titratable acidity is possible due to the fatty acid splitting. The obtained results show that no significant changes of flour acidity were observed during storage at (19±1) ºC, relative humidity (60±3) % (Table 4). It shows that flour quality was not changed and it is still suitable for bread making. Table 3. Quality attributes of wholegrain flour Sample Moisture, % Ash, % Coarseness Perten Laboratory Mill 3100 ETA 0010 Residue on the Throughput Residue on the metal network through silk metal network sieve, No./% sieve, No./% sieve, No./% Throughput through silk sieve, No./% Wheat Cubus /36 067/ Tarso /4 38/35 067/7 38/54 Rye Kaupo /3 38/39 067/5 38/56 Hacada /3 38/39 067/5.5 38/56 Table 4. Titratable acidity dynamics of flour samples during their storage Flour After 1 month Fresh flour sample storage Wheat Cubus 3.0±2 3.2±2 Tarso 3.2±1 3.1±1 Rye Kaupo 3.4±1 3.4±3 Hacada 3.6±2 3.4±2 Evaluation of wholegrain bread samples The wholegrain bread samples were baked from the obtained flour. Bread making was completed according to the test baking method. The recipes and parameters for bread making are presented in Table 5. For each bread sample preparation 500 g flour were used and the bread samples were baked in a mould or in a pan. To obtain dough with optimal properties, i. e. well forming and not sticky, more (by ml water) has to be added to wholegrain flour compared to fine flour. It can be explained by a better water binding ability of more coarse particles. Even a higher amount of water has to be added to rye wholegrain flour, which is determined by the rye flour properties. The temperature of all prepared dough samples was C, which is considered the optimal temperature for yeast activity. In rye wholegrain bread making the acidity regulator Roggenvollkornsauer of the German company Böcker was used. This helped to improve 27

5 the bread crumb properties and bread flavour. During the experiments, various amounts of acidity regulator were added (2 %, 4 %, 6 %, and 8 %) from the whole flour. The 6 % additive was found to be the optimal value. The size of the bread sample was g, therefore the optimal bread baking time accepted was 17 minutes at C. The wholegrain bread samples (Fig. 1, 2 and 3) correspond by their appearance and shape to the required flour and bran bread properties. In the crust and crumb grain outer layer particles can be seen. Table 5. Recipe and parameters for making a wholegrain bread Indices Rye wholegrain bread Wheat wholegrain bread Flour, g Water, g Yeast, g Salt, g 7 7 Sugar, g Acidity regulator, g 30 - Margarine, g - 10 Kneading time, min Fermentation time, 20 min Final proofing, min 45 Baking time, min 17 Fig. 1. Rye wholegrain bread from fine flour (rye varieties Kaupo ) Fig. 2. Wheat wholegrain bread from fine flour (wheat varieties Tarso ) Fig. 3. Wheat wholegrain bread from coarse flour of different varieties ( Tarso left and Cubus right) The bread samples made out of more coarse flour do not have a good shape. The bread crumb is crumbly, but the flavour is pleasant, typical for this type products. There were no differences found between the wholegrain bread samples made from different varieties. Conclusions Results show that the quality of the studied winter wheat varieties Cubus and Tarso, and rye grain varieties Kaupo and Hacada meet the requirements for high-grade wheat and rye grains for food consumption. 28

6 Wholegrain flour obtained from the studied varieties has an acceptable quality and is suitable for good quality bread baking. No significant differences were found between the studied varieties. References 1. Kujala T. Rye: Nutrition, Health and Functionality. Helsinki: Nordic Cereal Industry, p. 2. Finney P. L., Bains G. S. Protein functionality differences in eastern US soft wheat cultivars and interrelation with end-use quality test // Lebemsmittel-Wissenschaft und-technologie Vol. 32, No. 7. P Grausgruber H., Oberforster M., Werteker M., Ruckenbauer P., Vollmann J. Stability of quality traits in Austrian-grown winter wheats // Field Crops Research Vol. 66, No. 3. P Dotlacil L., Toman K. The stability of the yield of different wheat varieties // Rostlinna Vyroba Vol. 37. P Ruza A. Crop Farming (in Latvian). LLU, p. 6. Linina A., Ruza A. Variety and environment effects on quality traits in Latvian-grown winter wheat // Proceedings of the 4 th International Crop Science Congress. Brisbane, Australia, P. 6: 7. Mašauskiene A., Gaurilčikienė I., Mašauskas V. Augalų apsaugos priemonių, naudojamų atskirai ir kartu su azoto trąšomis, įtaka žieminių kviečių grūdų kokybei ir tešlos savybėms [Effects of plant protecting substances applied individually or in combination with the nitrogen fertilizers on the quality of winter wheat grain and the quality of dough] // Maisto chemija ir technologija T. 35. P Straumite E., Kunkulberga D., Ivanova S. Development of Baking Test Methods for Evaluation of Rye Flour Baking Properties (in Latvian) // Proceedings of the Latvia University of Agriculture, Vol. 13(308). P Brümmer J.-M., Neumann H. Basis-Backversuch-1. Mitteilung: Brot und Kleingebäck // Getreide Mehl und Brot Vol. 56. S Pateikta spaudai D. Kunkulberga, A. Ruža, A. Linina, R. Galoburda RUPIŲ MILTŲ KEPIMO SAVYBIŲ ĮVERTINIMAS PRIKLAUSOMAI NUO GRŪDŲ RŪŠIES Santrauka Tirtos žieminių kviečių rūšys Cubus ir Tarso ir rugių rūšys Kaupo ir Hacada. Kviečių ir rugių mėginiuose nustatyti šie rodikliai: baltymų kiekis, Hagbergo kritimo skaičius, krakmolas, hektolitro masė, tūkstančio grūdų masė ir grūdų vienodumas, glitimas, jo kokybė ir sedimentacija. Grūdai naudoti rupiems miltams gaminti, įvertinus miltų kokybę. Pagal rūgštingumą netiesiogiai vertintas miltų šviežumas laikymo metu. Eksperimentinio miltų laikymo metu nenustatyta didelio rūgštingumo pokyčio. Iš gautų miltų iškepti rupios duonos mėginiai pagal Latvijoje taikomą kepimo testą, skirtą greitai įvertinti duonos savybes. Rezultatai rodo, kad tirtų rūšių kokybė atitinka aukštos rūšies maistinių kviečių ir rugių grūdų reikalavimus ir yra tinkami rupiems miltams gaminti ir duonai kepti. Raktažodžiai: kviečiai, rugiai, kokybės rodikliai, rupūs miltai, kepimo savybės. D. Kyнкyлберга, A. Pужа, A. Линина, P. Галoбypда ИССЛЕДОВАНИЯ ХЛЕБОПЕКАРНЫХ СВОЙСТВ МУКИ ЦЕЛЬНОСМОЛОТОГО ЗЕРНА РАЗЛИЧНЫХ СОРТОВ Резюме Исследованы зимние сорта пщеницы Cubus и Tarso, ржаные сорта Kaupo и Hacada c целью определения их пригодности для производства муки из цельносмолотого зерна. С целью контроля качества зерна определили количество белка, количество и качество клейковины, величину седиментации, число падения и другие технологические показатели. Из исследуемых образцов зерна была смолота мука, определены показатели качества. Муку использовали для проведения пробной выпечки хлеба. Полученные результаты показали, что анализируемые сорта зерна имеют хорошие показатели качества и пригодны для производства муки цельносмолотого зерна и выпечки хлеба. 29