A comparison of nuclear magnetic resonance and dilatometry for estimating solids content of fats and shortenings

Abstract

The percent solids values of fats and shortenings using nuclear magnetic resonance (NMR) and solid fat index (SFI) have been compared. The samples used were: blends of hard fat and safflower oil, safflower oil hydrogenated to varying degrees, and different types of shortenings. This investigation demonstrated the empirical nature of the SFI technique and shows the nature of the deviations from the solids content determined by the NMR method. The magnitude of the deviation of SFI from the NMR solids content increased with the level of the solids. The SFI values and the NMR solids content were similar at the lower levels (SFI values of 10) but at the upper limit for the SFI method (SFI values of 50) the solids content by the NMR method can be 80% or more, a difference of 30 units. Although the determination of solids content by NMR is reliable, the relationship between SFI values and NMR values for different types of samples is so variable that the calculation of the SFI value from percent solids by NMR, or percent solids from SFI values from prediction equations is not very reliable. Since NMR measures the solids content more accurately than SFI and is applicable over the entire range of solids, 0 to 100%, it will be very useful in fat and oil research and control.

Feasibility Study on the Determination of the Solid Fat Content of Fats Using Temperature‐Modulated Optical Refractometry

“…In order to properly account for these it would be necessary to have detailed data on the specific lipid composition considered. Because this is not only cumbersome but also impractical average values are used resulting in data obtained from standard dilatometry of fat compositions of limited accuracy . As improvement of this approach it was suggested to determine the density of fat compositions via vibrating tube density meters .…”

“…Because this is not only cumbersome but also impractical average values are used resulting in data obtained from standard dilatometry of fat compositions of limited accuracy. [7][8][9][10][11][12] As improvement of this approach it was suggested to determine the density of fat compositions via vibrating tube density meters. [7] Even though beneficial compared to dilatometry this method has not gained much attention.…”

Determination of the solid fat content of commercial fats by pulsed nuclear magnetic resonance

“…The wideline NMR technique (5)(6)(7)(8)(9)(10)(11)(12) provided the first attempt at a direct measurement of solids in fats since it depended on the dipole-dipole interactions of rotating glyceride molecules~ This approach compares the area under a liquid signal at a given temperature with that of a reference oil. Pohle et al (7) indicated that the precision of the wideline NMR method decreases with increasing solids level. Swindells and Ferguson (11) found that a dilatometric type of tempering was necessary to eliminate anomalous sample behavior.…”

Wide‐line NMR for product and process control in fat industries1

“…Since Chapman and co-workers (1) introduced the wide line NMR technique for the determination of the amount of solid phase in fats, this method has been studied by various authors (2)(3)(4)(5)(6)(7)(8). However, since they all worked with the same type of instrument (Schlumberger NMR analyzer or Varian PA-7), they also come to more or less the same conclusions.…”