Oil-binding capacity of plastic fats: Effects of intermediate melting point TAG

The oil-binding capacity (OBC) of fat crystals was investigated as a function of intermediate melting point TAG (IMP-TAG) and stearin composition. Samples were prepared by melting 14% hard fraction (palm-canola stearin and IMP-TAG blends) in 86% liquid oil (olive, canola, safflower, and triolein) and crystallizing the mixture under fast and slow cooling conditions. Under fast cooling conditions, the OBC increased as the IMP-TAG/stearin ratio increased. The OBC is the grams of bound oil (determined by centrifugation) divided by the grams of solid fat (determined by pulse NMR). The maximum OBC was observed at 14% IMP-TAG and 0% stearin. In constrast, under slow cooling conditions, the 14% IMP-TAG and 0% stearin sample did not form crystals, and only free oil was present. The OBC for each liquid oil was lower under slow cooling conditions than under fast cooling conditions when compared at the same IMP-TAG/ stearin ratio. Solid fat content and RP-HPLC analyses indicated that IMP-TAG were retained in the crystal structure when processed under fast cooling conditions. RP-HPLC analyses also revealed that TAG with two saturated FA were retained in the crystal structure and that the monosaturated TAG were not. It was concluded that the TAG composition and cooling conditions played an important role in determining the OBC.