LAUSR

Walnut butter apart from its delicious taste and flavor is rich in monounsaturated fatty acid content and oil separation is one of the problems faced by walnut butter industry. In this investigation, effect of different level of emulsifying agents (mono-diglyceride and lecithin at 0, 0.5 and 1.5% w/w levels) on the rheological (time-independent and time-dependent), size distribution, texture homogeneity (GLCMs and fractal dimension) and stability of walnut butter have been studied. The results revealed that emulsifiers decreased droplets size, which was more pronounced for 1.5% Lecithin (21.58 µm). The walnut butter showed shear-thinning behaviour (n: 0.18–0.21) and the samples containing 1.5% lecithin had the highest consistency coefficient (370.23 Pa sn), thixotropy value (relative of hysteresis area = 39.31%) and stability (separation after 60 days: 14.45%). Increasing the concentration of lecithin increased η0/η∞ value, but no alteration was observed for monoglyceride samples. This increment of η0/η∞ values indicates that structural modification of walnut butter takes place at higher concentration of lecithin. Also, it was observed that the emulsifiers resulted in more uniform texture. Results could be useful in development of the walnut butter making process and packaging system design.