PEKMEZ-TAHİN KARIŞIMLARININ TRİBOLOJİSİ

Son zamanlarda, gıdanın ağızda çiğnenirkenki yapısını açıklayabilecek “triboloji” ya da “ince film reolojisi” adı verilen bir yaklaşım önemli hale gelmiştir. Bu çalışmada, ağırlıkça 30:70, 40:60, 50:50 oranlarındaki pekmez-tahin karışımlarının tribolojik deneyleri modifiye edilmiş bir sensörle tribometre kullanılarak yürütülmüştür. Bu ölçümlerden sürükleme hızına karşı sürtünme katsayılarının çizildiği Stribeck eğrisi adı verilen grafikleri elde edilmiştir. Bu grafiklerde her bir örnek için hidrodinamik (sürtünme viskozite yüzünden hız ile doğrusal olarak artar) ve sınır bölgeleri (nispeten sabit sürtünme görülür) tespit edilmiştir. Ağırlıkça 50:50 pekmez-tahin içeren örnek diğer örneklere göre daha düşük bir hızda, temas yüzeyleri arasında ince bir yağlama tabakasının geliştiğini gösteren hidrodinamik bölgeye girmiştir. Diğer yandan sürtünme, örneklerin yağ içeriği arttıkça azalmıştır. Bu durum bütün örnekler için düşük hız bölgesinde daha belirgindir. Bileşimi birbirine yakın dolayısıyla viskoziteleri birbirine yakın bu örneklerin tribolojik ölçümleri, yapısal farklılıkları daha iyi ortaya koymuştur. Gıdaların tribolojik özellikleri, bunların reolojik ve duyusal özelliklerle ilişkisinin araştırılması için çalışmalar yapılması gerekmektedir.

Anahtar Kelimeler:

triboloji, sürtünme, yağlama, tahin, pekmez

TRIBOLOGY OF PEKMEZ (GRAPE MOLASSES)-TAHİN (SESAME PASTE) MIXTURES

A new field of texture analysis called “tribology” or “thin film rheology” that might explain the food texture throughout oral processing has become important. In this study, tribological experiments for samples containing pekmez and tahin at 30:70, 40:60 and 50:50 (w/w) were conducted by using a modified pin-on-disk tribometer. In the Stribeck curves hydrodynamic and boundary regions were determined. For the mixture containing pekmez:tahin at 50:50, hydrodynamic region started at a lower speed compared to other samples, which indicated a developing a thin lubrication film between contact surfaces. The friction decreased with the oil content of the sample. This was more profound in the lower speed region for all samples. Tribological data provided more distinct evaluation compared to the viscosity data which were close to each other due to similar composition of samples. Further research are needed on tribological properties of foods, their relation to rheology and sensory analysis.

Keywords:

tribology, friction, lubrication, sesame paste, grape molasses,

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