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Browsing Scientific data by Author "Škrobot, Dubravka"

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    Application of temporal dominance of sensations in sensory profiling of sourdough starter odour
    (National Society of Processing and Energy in Agriculture, Novi Sad, Serbia, 2022-04-08) Škrobot, Dubravka; Tomić, Jelena; Dapčević-Hadnađev, Tamara; Maravić, Nikola; Jovanov, Pavle; Hadnađev, Miroslav
    Sourdough is one of the oldest examples of natural starters, obtained from the mixture of cereal flour and water, fermented with naturally occurring or selected lactic acid bacteria (LAB) and yeasts. Fermentation process depends on naturally occurring microbiota, type of flour, flour composition, additional ingredients, tap water, and temperature. During fermentation, acidification, proteolysis and activation of a number of enzymes, as well as the synthesis of microbial metabolites, influence not only the nutritional/functional quality of baked goods but also contribute to development of odour and flavour of starter and final product. In order to describe the evolution of the sourdough odour during starter activation, the method of temporal dominance of sensations is performed. Temporal Dominance of Sensations (TDS) is method used in sensory analysis which enables characterization of an entire profile of complex food in a short time. This approach is aimed at repeatedly recording the dominant sensations perceived during the tasting period. For the presented study experienced sensory panellists (n = 12, eight female and four male, 25 – 45 years old), used to participate in sensory profiling, were recruited. Whole grain wheat sourdough starter samples were collected and evaluated for each 1 h within six hours from the start of the sourdough activation. Samples were delivered to the panellists in a glass jars with a lid. The panellists were instructed that once they remove the lid, they have to click on the “START” button on the screen to begin the evaluation and to activate software. During an evaluation, the panellists had to select dominant odour sensation from ten simultaneously presented odour attributes (brans, flour, dough, yeast, acetic acid, lactic acid, sour milk, yoghurt, cheese, and fruity). When panellists noticed that one dominant odour perception changed, they had to score new dominant sensation. If none attribute was perceived as dominant sensation, panellists had to click the “End” button. TDS was performed for all samples within three replicate sessions by all panellists. TDS data was collected by Excel, while with XLSTAT software collected data was calculated and presented by curves showing dominance rate (Axis Y) for each 0.2 s step during the 1 min period (Axis X). TDS curves clearly showed changes in odour profile during period of sourdough starter activation. At the beginning of the activation process, flour-like, brans-like and dough-like attributes were dominant odour characteristics. However, during the time, these odour characteristics had little contribution to the overall odour profile since they became masked with more sharp odour notes reminiscent of sour milk, cheese, yoghurt and acetic acid. Over time, odour profile became more complex indicating complexity of biochemical processes.
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    Effect of substitution of wheat flour by sourdough and whey proteins on the properties of sponge cake
    (National Society of Processing and Energy in Agriculture, Novi Sad, Serbia, 2022-04-08) Tomić, Jelena; Škrobot, Dubravka; Dapčević-Hadnađev, Tamara; Maravić, Nikola; Hadnađev, Miroslav
    As a result of consumer preferences, including the demand for healthier and high protein and high dietary fibre plant-based food, there is a trend towards fortifying or completely replacing refined wheat flour with whole grains or alternative ingredients. Redesign of traditional foods in order to create optimal nutritional value becomes a common practice thus offering consumers a wider and healthier choice. Incorporation of proteins and/or fibres from different sources in food formulations present one of the most used approaches. Recently, the application of sourdough technology has gained research interest due to its complexity as well as its ability to promote beneficial modifications on sensory, technological and nutritional properties of bakery products. The technological application of sourdough can offer several advantages such as improving texture and palatability of cereal based products, stabilizing or increasing levels of various bioactive compounds, retarding starch bioavailability and improving mineral bioavailability. This study aims to investigate the effects of substitution of wheat flour by sourdough from whole wheat flour (at levels 20% and 30%) and whey protein concentrate (at level 10%) on the quality of sponge cakes. The characterization of sponge cakes included the evaluation of chemical composition, specific volume, colour and texture properties. The sensory evaluation of sponge cake samples was carried out by a panel of ten trained sensory assessors who evaluated following attributes: shape irregularity, density, pores uniformity, cohesiveness, elasticity, adhesiveness, crumbliness, odour (overall intensity, on eggs), flavour (overall, on eggs), taste (sweet and bitter) and sweet aftertaste. All experimental data were subjected to one-way analysis of variance (ANOVA). To the aim, a Tukey's honestly significant difference (Tukey's HSD) test was carried out to determinate significance differences (P < 0.05) between samples. Regarding the proximate composition and colour measurements, results were, as expected, strongly dependent on the raw materials used in the formulation. Generally, the incorporation of proteins resulted in creation of product which can be labelled as protein source since more than 12% of their energy value is provided by protein. Compared to the control sample, reduction of wheat flour by sourdough and whey proteins caused a significant decrease in specific volume while values of hardness of tested samples were significantly higher. Regarding the sensory analysis, samples with sourdough and proteins exhibited much denser structure with a noticeable number of non-uniform large pores. Reduction of wheat flour by sourdough and whey proteins caused the loss of bitter taste, flavour and odour on eggs while the sweetness for these samples was significantly pronounced. The results indicate that this combination of used ingredients have a potential to be considered as an alternative valueadded food ingredients for bakery products but further research should be conducted in this area.
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    Effects of spontaneously fermented ancient wheat sourdoughs on quality of refined wheat flour bread
    (Cereals & Europe; International Hellenic University, 2022-04-08) Dapčević-Hadnađev, Tamara; Tomić, Jelena; Škrobot, Dubravka; Popović, Nikola; Hadnađev, Miroslav
    Although ancient grains could represent an abundant source of protein, fibre and macro- and micro-elements, few studies are available on the characteristics of ancient wheat sourdough and it suitability for breadmaking. Therefore, the objective of this research was to study spontaneously fermented emmer, spelt and khorasan wholegrain flour sourdough and to evaluate its feasibility to leaven refined wheat flour bread. Spontaneous fermentation of three flours was carried out for 5 days with back-slopping every 24 h (dough yield of 200) at 25 °C. Sourdough was characterized for lactic acid bacteria and yeasts counts, pH, titratable acidity and rheological properties. The effects of 20% sourdough addition on physico-chemical, microbiological, and sensory properties of refined wheat flour pan bread was studied to elucidate the differences in performance of different ancient wheat sourdoughs. The average total lactic acid bacteria counts after 5 days of dough fermentation were 2.7x109, 2.8x109 and 4.2x109 cfu/g for spelt, khorasan and emmer sourdoughs, respectively. Although spelt, khorasan and emmer sourdoughs exhibited similar pH evolution (drop from 6.5 to 4.0) they differed in total titratable acidity and rheological properties. Khorasan sourdough was characterized with the lowest total titratable acidity, while emmer flour was less elastic than spelt and khorasan sourdoughs. Besides lactic acid bacteria microbiota, breadmaking performances of ancient wheat sourdoughs were influenced with wet gluten quantity and quality. Spelt flour, being characterized with the highest wet gluten content, yielded sourdough with the highest strength and bread with the highest specific volume. On the contrary, khorasan flour, having the lowest wet gluten content, produced sourdough bread with the highest crumb hardness. Bread containing khorasan sourdough was also characterized with the highest crust lightness (L*) and yellowness (b*) values and overall acceptability by consumers. The minimum mould-free shelf life was 8 days for all tested breads.
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    Fundamental rheological properties of spontaneously-fermented ancient wheat sourdoughs
    (Faculty of Technology, Leskovac, Serbia, 2021-10-23) Hadnađev, Miroslav; Tomić, Jelena; Škrobot, Dubravka; Dapčević-Hadnađev, Tamara
    The fundamental rheological behaviour of spontaneously-fermented wholegrain emmer, spelt and khorasan sourdoughs was studied from final backslopping over a 12‐hr fermentation period. Spontaneously-fermented sourdough was prepared through backslopping (every 24 h, 5 days) under laboratory conditions (temperature of 25 °C, dough yield of 200). Emmer, spelt and khorasan sourdoughs exhibited similar pH evolution, but they significantly differed in level of leavening (expressed as the increase in height between two backsloppings), gluten index values and dynamic viscoelastic properties. The pH of all sourdoughts decreased from 6.5 to 4.0 after four backslopping steps. Emmer flour which exhibited the lowest gluten quality (gluten index value) was characterized with the fastest and the highest level of leavening during sourdough propagation. Results of the dynamic oscillatory rheological analysis showed that there was a decrease in dough elasticity with fermentation time for all three sourdoughs, which could be ascribed to protein degradation and conformational changes due to proteolytic activity and acidic environment. Over the course of the fermentation period (12 hours) emmer sourdough was significantly less elastic and softer than the spelt and khorasan sourdoughs. It can be concluded that sourdough structure degrading processes was affected with the differences in gluten quality of ancient wheat.
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    The potential of Psyllium husk in re-shaping dough rheology of wholegrain spelt wheat flour
    (Editura Universitara, Ex Terra Aurum, Universitatea de Stiinte Agronomice si Medicina Veterinara Bucuresti, 2020-11-19) Dapčević-Hadnađev, Tamara; Škrobot, Dubravka; Tomić, Jelena; Hadnađev, Miroslav
    Since spelt wheat (Triticum aestivum subsp. spelta) is characterized with poor breadmaking properties, strategies to improve its rheological performance would contribute to satisfying the increasing demand for spelt flour based products and facilitate their large-scale production. It was shown that psyllium husk can improve workability of gluten‐free dough while acting as structure forming agent. On the contrary, addition of psyllium husk to wheat flour results in bread with deteriorated quality due to gluten dilution effect. Considering that, unlike common wheat, rheological properties of spelt gluten are predominated by gliadins, responsible for formation of weak, soft and sticky dough, difficult to handle, the aim of this study was to investigate the effect of psyllium husk addition on the rheological properties of spelt flour dough during mixing and heating. For that purpose, psyllium husk was added to wholegrain spelt flour at 0, 5 and 10% replacement level and evaluated for dough Mixolab® parameters. Incorporation of psyllium husk led to significantly increased water absorption, dough elasticity and stability to mechanical and thermal constraints of wholegrain spelt flour dough. Upon heating, there was a decrease in maximum starch paste consistency as well as final baked dough consistency, due to lower starch retrogradation rate in psyllium husk substituted dough. The obtained results indicate that psyllium husk can be successfully employed to modify rheological properties of wholegrain spelt wheat flour towards production of spelt bread with better handling and shelf-life properties, while preserving product health‐related composition.
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    Rheological behaviour of ancient wheat flours
    (University of East Sarajevo, Faculty of Technology, Zvornik, 2021-03-19) Hadnađev, Miroslav; Tomić, Jelena; Škrobot, Dubravka; Dapčević-Hadnađev, Tamara
    The need to preserve genetic diversity, the request for high adaptability to low agronomic input, along with the increasing demand for traditional products with better nutritional composition are recognized as a major driving forces behind the renewed consumers', manufacturers' and farmers' attention toward ancient wheat grains. In order to convert ancient grains into food products with acceptable techno-functional properties, dough’s rheological behaviour has to be considered. In this study a comparative evaluation of the rheological properties of ancient wheat species (emmer, spelt and khorasan) was conducted. The wholegrain flours of these varieties were prepared and evaluated for chemical composition, wet gluten quantity and quality and rheological properties in terms of gluten aggregation and disruption kinetics (GlutoPeak), dough proofing (Rheofermentometer), as well as mixing and thermal behaviour (Mixolab). Although emmer and spelt flours had higher protein and wet gluten content, they were characterized with lower gluten indexes (GI) in comparison to khorasan flour (GI were 64, 50 and 11% for khorasan, spelt and emmer, respectively). This influenced significant differences in dough rheology of investigated ancient wheat flours. High wet gluten content of spelt flour led to formation of strong gluten network (high maximum torque as measured by GlutoPeak) with the highest Mixolab water absorption (62.6%) and maximum dough height (Hm at Rheofermentometer curve) in comparison to other varieties. On the contrary, khorasan flour, although having very low wet gluten content, exhibited the highest dough stability both during mixing (Mixolab test) and fermentation (Rheofermentometer dough development curve) due to high gluten index value. Despite being characterized with high wet gluten content, very low gluten index value of emmer flour affected dough development process, resulting in the lowest maximum dough height and pronounced loss in dough height during fermentation and the lowest percentage of gas retained in the dough relative to the total gas production compared to other wheat species. Emmer flour was also unable to form gluten aggregation peak under the conditions used during GlutoPeak test. The results obtained in this study can be used to better understand the techno-functionality and target application in cereal based products of different ancient wheat species.