Characterisation of high 1,3‐distearoyl‐2‐oleoyl‐sn‐glycerol content stearins produced by acidolysis of high oleic sunflower oil with stearic and palmitic acids

Abstract

Nine different stearin fractions with 1,3‐distearoyl‐2‐oleoyl‐sn‐glycerol (StOSt) contents ranging from 69–84% were obtained via fractionation from fats produced by acidolysis of high oleic sunflower oil (HOSO) with various mixtures of stearic (either 95 or 98% pure) and palmitic acids (98% pure). Samples were further treated with silica to reduce the oxidised glyceride and DAG content. Isothermal crystallisation at 20°C showed a single main peak, but evidence of crystallisation during the initial DSC transient was also apparent for high StOSt content samples. This was confirmed as the α form by stop‐and‐return DSC and XRD. The main crystallisation event was generally faster (including a shorter induction time) for samples with higher StOSt levels (lower POSt levels). Silica treatment generally accelerated transformations to higher polymorphs (γ, β′ and β). Raman microscopy experiments showed that crystallisation of the β‐form was achieved after 7 days storage at 20°C but only in the silica treated stearin samples. This is consistent with higher solid fat content (SFC) values that were obtained with silica treated samples, which also increased with higher levels of StOSt. The results suggest that such stearins could potentially replace shea stearin in cocoa butter equivalents (CBE) formulations. Practical applications: This paper has two main practical applications: (i) Provides knowledge and understanding of the crystallisation and polymorphic behaviour of isolated hard stearins, obtained from enzymatic acidolysis of high oleic sunflower oil, which can be further used in CBE formulations. (ii) The presence of minor components significantly delays the crystallisation of the stearins, confirming the desirability of higher quality (less oxidised/hydrolysed) fat ingredients.

Characteristics of palm mid-fractions produced from different fractionation paths and their potential usages

“…Fractionation is the preferred technique for obtaining triacylglycerols as diacylglycerols are removed as filtrates [8,21] , which could explain the low diacylglycerol levels in PMF-C. High amounts of diacylglycerols would greatly delay the transition of symmetrical monounsaturated triacylglycerols into more stable polymorph and further give the chocolate products undesirable physical properties. [22][23][24] Rather, as Ray et al [22] reported, low diacylglycerol levels (0.7%) had less influence on the transformation from γ into β form. In this regard, PMF-C is more suitable for producing chocolate fats compared to PMF-A and PMF-B.…”

Lipase Catalyzed Synthesis of ABA-Type Structured Lipid from Single Cell Oil and Tripalmitin

“…; Ray et al . ). However, the incorporation of LC‐PUFAs to the TAG is a challenge due to the susceptibility of LC PUFA to oxidation in acidolysis reaction.…”

“…Moreover, the use of enzyme technology is well acceptable for food application. It has been reported that SLs are synthesized by acidolysis, esterification, and interesterification reactions with the form of free fatty acids, methyl esters and TAGs (Torres et al 2002;Srivastava et al 2006;Ray et al 2014). However, the incorporation of LC-PUFAs to the TAG is a challenge due to the susceptibility of LC PUFA to oxidation in acidolysis reaction.…”

Crystallization and Polymorphism of Cocoa Butter Equivalents from Blends of Palm Mid Fraction and Hard Stearins Produced by Enzymatic Acidolysis of High Oleic Sunflower Oil

“…[ 14 ] This yielded novel fat compositions with a high Sat‐O‐Sat content (≈40%), particularly StOSt. The stearin fractions were further isolated via solvent fractionation, with final Sat‐O‐Sat levels of ≈90, [ 15 ] and compositions similar to that of shea stearin. The levels of minor components in the stearins (diacylglycerol (DAGs) and oxidized glycerides) were reduced by silica treatment to minimize their effect on crystallization and polymorphic behavior.…”