Application of enzymatic alkalimetric method for identification of cream and palm oils

Nowadays the "butter" product category is widely falsified by non-dairy fats, mainly by palm oil. The methods recommended for the detection of palm oil in the fat- and oil industry products require a long-term sample preparation or the use of expensive complex equipment, which makes it urgent to search for new, more rapid analytical methods that can be used in small laboratories. An enzymatic- and alkalimetric method distinguishing between palm oil and butter is suggested in the work. The method consists in enzymatic hydrolysis of fat followed by titrimetric determination of the amount of excreted fatty acids with visual fixation of the equivalence point; titrant is the aqueous sodium hydroxide solution (0.1 mol / dm3) and indicator is phenolphthalein. Pancreatic lipase was used as the enzyme. The effect of enzyme activity, the medium pH, temperature and time on the hydrolysis of palm oil and butter was studied. The developed method peculiarity is the use of non-optimal conditions for lipid splitting. This makes it possible to reduce the rate of reaction to establish fine differences in the hydrolysis of different compositions fats. Conditions for the identification of fats - at pH = 7.9 (aqueous solution of sodium tetraborate 1% by weight) were justified. In the presence of pancreatic lipase 20000, the splitting of palm oil begins in 25 minutes after the experiment start, and butter splitting begins after 10 minutes. Optimum hydrolysis time allowing to distinguish between palm oil and butter is 20 min. Identification of fats is carried out by comparing the results of alkalimetric titration of the splitting products after 5 minutes (V5’) and 20 minutes (V20’) after the beginning of hydrolysis of the fat under study with the pancreatic lipase 20000. If the sample analyzed contains only butter, then V20’ / V5’ ? 2. Numerically equal values of V5’ and V20’ are obtained when analyzing a palm oil. The value V20’ / V5’, which is in the range of 1-2 indicates that the analyzed sample is a spread, and the closer the value of V20’ / V5’ to 1, the more palm oil the sample contains. The proposed method is economically efficient and simple in its procedure, it is applicable in the temperature range of 17–27o С.