The effect of functional lipids on the quality of walnut butter prepared from defatted walnut meal by ball mill grinding

In this study, walnut butter was produced by mixing functional lipids with defatted walnut meal. Three kinds of functional lipids (FL), medium-chain triglycerides (MCT), diacylglycerol (DG), and conjugated linoleic acid glycerides (CLA), were used to make functional lipids walnut butter (DG-WB, CLA-WB and MCT-WB) and their physical properties as well as microscopic morphology were compared with commercial walnut butter. The functional lipids walnut butter (FLWB) was prepared by grinding FL and defatted walnut meal through the ball milling technique. The mixing ratios of FL to defatted walnut meal were 6:4, 6.5:3.5, and 7:3. The volumetric mean particle size of emulsion formed by DG-WB and CLA-WB decreased by 36.23% and 20.88%, respectively when the additional amounts of DG, and CLA increased from 60 wt% to 70 wt%. The rheological and microrheological results further indicated that FLWB showed similar gel-like behavior to commercial walnut butter. Among the FLWB with three different kinds of FL, CLA-WB appeared more similar apparent viscosity, thixotropy, and elasticity with those of commercial walnut butter. Finally, CLA-WB with different CLA additive amount was analyzed for microstructure. The results showed that walnut butter prepared with 65 wt% CLA was closer to commercial walnut butter in terms of processed physical properties and micro-morphology.