Daliborka Koceva Komlenić

Influence of Acidification on Dough Rheological Properties

Due to increasing consumer demands for more natural, tasty and healthy food, the traditional process of sourdough bread production has been enjoyed renewed success in recent years, (Brummer & Lorenz, 1991 ; Thiele et al., 2002 ; Lopez et al., 2003). The use of sourdoughs is a necessary prerequisite for the preparation of rye and rye-wheat combination breads (Hammes & Ganzle, 1998). The acidification process effected by the application of sourdoughs is mainly used to improve quality, taste and flavour of wheat breads (Brummer & Lorenz, 1991 ; Katina et al., 2006a ; Arendt et al., 2007), and the slow staling (Katina et al., 2006b ; Plessas et al., 2007). The addition of sourdough during production of wheat bread causes major changes in the dough characteristics (Clarke et al., 2002 ; Clarke et al., 2004 ; Ketabi et al., 2008), especially in the rheological properties of dough. The effect of the fermentation process of wheat doughs containing lactic acid bacteria are complex and depending on variations between sourdoughs. It regards on starter culture type, fermentation regime and used additives (Wehrle et al., 1997). Many of the effects of sourdough have been considered by pH value decrease which has been caused with organic acid production. Rheological properties, acidification and flavour development are the most important parameters in fermentation processes control. The rheological characteristics of dough have been changed with fermentation. Types of microorganisms, metabolic activity and time-dependent development pH value effect on rheological properties (Wehrle & Arendt, 1998). Acids strongly influence on the mixing properties of dough. Dough with lower pH require a slightly shorter mixing time and have less stability than dough with normal pH level (Hoseney, 1994). Changes in pH values caused by production of lactic acid also influence on the rheological properties of dough (Wehrle et al., 1997). Dough with containing acid has been characterized by increased phase angle and reduced complex modulus indicative of overmixing (Wehrle et al 1997). Small physical and chemical changes in the gluten network can result in significant changes in rheological properties. Clarke et al. (2002) were concluded that addition of sourdough prepared either from a single strain starter culture or a mixed strain starter culture had significant impact on the rheological properties of wheat flour dough. Koceva Komlenic et al (2010) investigated the influence of chemical and biological acidification on dough rheological properties. According to their experimental results, rheological properties strongly depend on acidification type. Dough with lower pH value showed less stability during mixing, decreased extensibility and gelatinization maximum. In general, the rheological properties of dough greatly improved when the sourdough was added.

Influence of cookies composition on temperature profiles and qualitative parameters during baking.

Summary During baking of bakery products temperature of baking, temperature profiles, moisture content, volume and colour changes are strongly coupled. The objective of this paper was to study the influence of the cookies composition on temperature profiles and quality parameters (width and thickness, colour formation and textural properties: hardness, fracturability and work of breaking force) during baking process. Composition of cookies differs due to flour type and initial moisture content. Cookies were baked at 205 °C and temperature was measured in the centre of samples which were 7 mm thick with a 60 mm diameter. The results of temperature profiles of the cookies during baking have shown the same trend for all of the 18 samples. Samples with the higher initial water content have lower values of total colour difference and also significantly affect textural properties.

Quality evaluation of biscuits produced from composite blends of pumpkin seed oil press cake and wheat flour

Pumpkin seed oil press cake (PSOPC) is a by-product of pumpkin oil production, and after cold pressing, a significant amount of oil still remains in the press cake. The aim of this study was to investigate the possible use of PSOPC flour as a substitute for wheat flour in biscuit production and, consequently, for reducing shortening usage. Biscuits have been produced from composite blends of plain white flour and PSOPC flour in ratios 100:0, 80:20, 60:40 and 40:60, respectively. Shortening addition was gradually reduced depending on the PSOPC flour addition. Biscuit baking quality was determined by width, thickness, spread factor, volume and textural properties. Computer vision was used to evaluate biscuit colour, and sensory evaluation was conducted for colour, taste, texture and overall acceptance. Results showed that PSOPC flour decreased biscuit diameter, height and volume and also caused a softer texture of biscuit. PSOPC flour contributed to the greenish colour of biscuits and the pleasant taste of roasted pumpkin seed. PSOPC flour can be successfully used as a functional and nutritionally valuable substitute for wheat flour and shortening, even in quantities up to 60%, without significant deterioration of the technological quality of biscuits.

Influence of chestnut flour addition on quality characteristics of pasta made on extruder and minipress

Durum semolina was replaced with 10, 15, and 20% of chestnut flour. Pasta was produced on a single screw extruder with the temperature profile of 80/90/90°C and on a laboratory minipress. Pasta samples were dried at room temperature and physical and sensory properties were determined. Generally, the chestnut flour addition to durum wheat pasta decreased optimum cooking time, hardness, cohesiveness, and chewiness, but increased cooking losses and pasta adhesiveness. Samples made on an extruder showed shorter optimum cooking times in relation to samples made on a minipress. Absorbed water was decreased with chestnut flour addition. Pasta made on an extruder showed a higher sensory score in comparison with pasta made on a minipress. The addition of chestnut flour influenced the colour of the samples. Samples made on an extruder showed darker colour in dried and cooked pasta samples in relation to minipress samples. In dried pasta samples, the extruder gave yellower samples in relation to the minipress, while in cooked pasta samples it was reversed. Overall, the extruder gave higher-quality pasta compared to the minipress.