Saponification Value of Fats and Oils as Determined from <sup>1</sup>H-NMR Data: The Case of Dairy Fats
Mihaela Ivanova,
Anamaria Hanganu,
Raluca Dumitriu,
Mihaela Tociu,
Galin Ivanov,
Cristina Stavarache,
Liliana Popescu,
Aliona Ghendov-Mosanu,
Rodica Sturza,
Calin Deleanu,
Nicoleta-Aurelia Chira
Affiliations
Mihaela Ivanova
Department of Milk and Dairy Products, Technological Faculty, University of Food Technologies, 26 “Maritsa” Blvd., 4002 Plovdiv, Bulgaria
Anamaria Hanganu
Department of Organic Chemistry, Biochemistry and Catalysis, Research Centre of Applied Organic Chemistry, Faculty of Chemistry, University of Bucharest, 90-92 Panduri Street, 050663 Bucharest, Romania
Raluca Dumitriu
“C.D. Nenitescu” Organic Chemistry Department, Faculty of Chemical Engineering and Biotechnologies, University POLITEHNICA of Bucharest, 1-7 Polizu Street, 011061 Bucharest, Romania
Mihaela Tociu
“C.D. Nenitescu” Organic Chemistry Department, Faculty of Chemical Engineering and Biotechnologies, University POLITEHNICA of Bucharest, 1-7 Polizu Street, 011061 Bucharest, Romania
Galin Ivanov
Department of Milk and Dairy Products, Technological Faculty, University of Food Technologies, 26 “Maritsa” Blvd., 4002 Plovdiv, Bulgaria
Cristina Stavarache
“C.D. Nenitescu” Centre of Organic Chemistry of the Romanian Academy, 202B Spl. Independentei, 060023 Bucharest, Romania
Liliana Popescu
Department of Oenology and Chemistry, Food Technology, Faculty of Food Technology, Technical University of Moldova, 9/9 Studentilor Street, MD-2045 Chisinau, Moldova
Aliona Ghendov-Mosanu
Department of Oenology and Chemistry, Food Technology, Faculty of Food Technology, Technical University of Moldova, 9/9 Studentilor Street, MD-2045 Chisinau, Moldova
Rodica Sturza
Department of Oenology and Chemistry, Food Technology, Faculty of Food Technology, Technical University of Moldova, 9/9 Studentilor Street, MD-2045 Chisinau, Moldova
Calin Deleanu
“C.D. Nenitescu” Centre of Organic Chemistry of the Romanian Academy, 202B Spl. Independentei, 060023 Bucharest, Romania
Nicoleta-Aurelia Chira
“C.D. Nenitescu” Organic Chemistry Department, Faculty of Chemical Engineering and Biotechnologies, University POLITEHNICA of Bucharest, 1-7 Polizu Street, 011061 Bucharest, Romania
The saponification value of fats and oils is one of the most common quality indices, reflecting the mean molecular weight of the constituting triacylglycerols. Proton nuclear magnetic resonance (1H-NMR) spectra of fats and oils display specific resonances for the protons from the structural patterns of the triacylglycerols (i.e., the glycerol backbone), methylene (-CH2-) groups, double bonds (-CH=CH-) and the terminal methyl (-CH3) group from the three fatty acyl chains. Consequently, chemometric equations based on the integral values of the 1H-NMR resonances allow for the calculation of the mean molecular weight of triacylglycerol species, leading to the determination of the number of moles of triacylglycerol species per 1 g of fat and eventually to the calculation of the saponification value (SV), expressed as mg KOH/g of fat. The algorithm was verified on a series of binary mixtures of tributyrin (TB) and vegetable oils (i.e., soybean and rapeseed oils) in various ratios, ensuring a wide range of SV. Compared to the conventional technique for SV determination (ISO 3657:2013) based on titration, the obtained 1H-NMR-based saponification values differed by a mean percent deviation of 3%, suggesting the new method is a convenient and rapid alternate approach. Moreover, compared to other reported methods of determining the SV from spectroscopic data, this method is not based on regression equations and, consequently, does not require calibration from a database, as the SV is computed directly and independently from the 1H-NMR spectrum of a given oil/fat sample.
