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Time-dependent adhesion behaviour of dough - relation to surface structure, surface energy and microbial contamination
R. LAUKEMPER (1), M. Jekle (1), T. Becker (1) (1) Technical University of Munich, Institute for Brewing and Beverage Technology, Freising, Germany.

In order to improve the safety and efficiency in bakeries it is essential to develop a better understanding of the interaction between cereal dough and material surfaces. Therefore, a new measurement rig for a texture analyzer was developed to determine the separation behavior of dough after different practically applied contact times (e.g. 60 minutes of fermentation time) and for a huge variety of materials. Using this method differences concerning the adhesion behavior for higher contact times have been shown in relation to material composition and structure. For some of the analyzed proofing trays, the factor of the adhesion force increased from 2.3 to 8.0, when varying the contact time from 1 minute to 30 minutes. To precisely elucidate these adhesion phenomena different influencing factors have been considered. In this context, especially the specific adhesion was analyzed by identifying the surface energy of the two contact partners. For trays with a low adhesion to dough, low surface energy values were observed (5.0 - 5.7 Nm/m). Contrary, trays with high adhesion to dough showed high surface energy values (58.0 - 70.5 Nm/m), which roughly matched the energy of the investigated dough surface, indicating strong interaction of the two contact partners. In order to identify the correlation between adhesion and microbial contamination an adjusted method was applied to determine the microbial contamination of three differentiating proofing trays during a 12 week practical application. Thereby, a higher increase of nearly one decimal power was observed for materials with higher adhesive behavior to dough. In consideration of hygienic safety, the elucidation of the relations enables a targeted selection of materials with low adhesion for industrial use.