Quality Control of Soybean Oils by Thermogravimetry
M . W e s o t o w s k i *
On the example of analysis of 53 soybean oil samples an estimation of the usefulness of thermoanalytical methods for the quality inspection of this product has been made, and as well as a method to make possible carrying'out the tests which allow to evaluate the stability of soybean oils in technological processing and during their storage. The existence of strong relationship between the values of the temperatures of successive weight losses and the values of the parameters of physico-chemical quality assessment of soybean oils has been stated. The possibility of practical utilization of regression equations for the assessment of the degree of deterioration of oil products has been indicated.
I n t r o d u c t i o n
Thermoanalytical methods are generally applied t o investigate the physical and chemical changes which may occur when sample tested is heated. These changes are usually observed by measuring the temperature (Differential Thermal Analysis -DTA), the heat (Differential Scanning Calorimetry -DSC), the weight (Thermogravimetry -T G ) or its rate (Derivative T G -DTG).
In recent years, with the advent of robust, versatile, easy to operate and relatively inexpensive commercial instruments, application of thermoanalytical methods to the study of edible oils and fats has increased dramatically as evidenced b y the growing number of publications in this area. DTA, DSC and T G methods are widely used in the fusion of edible fats and oils, solidification behaviour, quality control in the process of manufacturing edible oils, polymorphic transformations and as alternative methods of measuring oil stability.
Yamazaki e t al.' used high pressure DTA to study the stability of fatty methyl esters and triglycerides in an Qualitatsbeurteilung von Sojaol durch Thermogravimetrie Am Beispiel der Analyse von 53 Sojaol-Proben wurde die Anwendbarkeit thermoanalytischer Methoden fur die Qualitatsbeurteilung dieser Produkte gepruft. Ebenso wurde diese Analysentechnik als eine Methode eingesetzt, um Tests zur Beurteilung der Stabilitat von SojaoI in technologischen Prozessen und wahrend ihrer Lagerung durchzufuhren. Es wurde eine ausgepragte Abhangigkeit zwischen den Gewichtsverlusten bei unterschiedlichen Temperaturen und den physikochemischen Parametern der Qualitatsbeurteilung von Sojaol gefunden. Die Moglichkeit der praktischen Verwendung von Regressionsgleichungen fur die Beurteilung der Qualitatsverringerung von 0 1 fur Nahrungszwecke wird aufgezeigt.