Preparation of specialty fats from beef tallow and canola oil by chemical interesterification: physico-chemical properties and bread applications of the products

Blends of beef tallow (BT)/canola oil (CO) (85:15, 65:35, w/w) were interesterified under the following conditions: 0.4% CH₃ONa, 60 °C, 30 min. Triacylglycerol (TAG) composition, polymorphic forms, crystal morphology, thermal properties, rheological properties and oxidative stability of the original and interesterified blends were evaluated. Chemical interesterification (CIE) caused a more balanced rearrangement of TAG species, reduction of trisaturated (S₃), triunsaturated (U₃) TAG content and increase in monosaturate-diunsaturated (SU₂) TAG content. X-ray diffraction (XRD) revealed that all the interesterified blends were exclusively double chain (2L) stacking β′ crystal. Thermal curves confirmed slight narrow melting and crystallization temperature ranges appearing in interesterified blends, mainly due to decreased S₃ and U₃ type TAGs and increased SU₂ after CIE. Rheological analysis showed that CIE led to dropping in both hardness, storage modulus (G′) and loss modulus (G″) of BT/CO blends. The oxidative stability of the interesterified fats, which was reduced compared with the substrate blends, was significantly improved using 0.02% TBHQ. A shortening and a margarine, both containing low trans were prepared by interesterified BT/CO 85:15, 65:35 blends, respectively, which were crystallized in a votator and tested in bread baking. The results of instrumental and sensory analyses showed similar acceptability of the two types of breads. The present study suggests that the interesterified fats fulfill the requirements of marketable bakery shortenings and margarines, respectively.