I have done a lot of cold-stage, hot stage light microscopy of various fats and oils. I can heat or cool the sample live and do time laps imaging, or movies, or stop and hold, then continue. I can also hold the temperture at any degree with control to 0.1 degree. Since there is only a small amount of product present on the stage, a drop or less, I can easily see the result, and document with microscopy. The product is between to cover glass sheets, so the thin film of oil allow a near instantaneous result, which can be held at any given temperature. I use heat and liquid nitrogen in very controlled conditions. I can use either transmitted or reflected light. The method is very adaptable. I hope this helps.

Dear Niloufar Shahbazi

sorry it is not my speciality

Good day! Please, find an attached links that may be useful:

http://lib3.dss.go.th/fulltext/Journal/J.AOCS/J.AOCS/2001/no.4/2001v78n4p395-399.pdf

http://journal.pan.olsztyn.pl/TRENDS-IN-EDIBLE-VEGETABLE-OILS-ANALYSIS-PART-B-APPLICATION-OF-DIFFERENT-ANALYTICAL,98294,0,2.html