Application of temporal dominance of sensations in sensory profiling of sourdough starter odour

Abstract

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.