Large Amplitude Oscillatory Shear (LAOS) analysis of gluten-free cake batters: The effect of dietary fiber enrichment
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The aim of this study is to investigate the effect of dietary fiber enrichment on non-linear viscoelastic behavior of gluten-free cake batters by using Large Amplitude Oscillatory Shear (LAOS) analysis. Textural properties and specific volume of gluten-free cakes were also determined to investigate the possible correlations with LAOS parameters. Gluten-free cake batters were formulated by replacing buckwheat flour with two different dietary fiber sources, namely orange fiber (OF) and orange pomace powder (OPP) at five different levels (0%, 4%, %8, %12 and 16%). All gluten-free cake batter samples exhibited linear viscoelastic properties at small strain amplitudes but Theological properties enters the non-linear region by increasing strain amplitude. The Lissajous-Bowditch curves revealed that stored energy increased by increasing dietary fiber amount and gluten-free cake batters became more elastic in the non-linear region. The normalized elastic Chebyshev coeffients (e(3)/e(1)) indicated the strain hardening behavior of cake batters at small strain amplitudes shifted to strain softening in the non-linear region. The e(3)/e(1) and v(3)/v(1) ratios as a function of strain amplitude indicated that non-linearity is more pronounced in the elastic component compared to the viscous component. The S and T values calculated at 50% strain amplitude showed strong correlation with water retention capacity, hardness and specific volume of gluten-free cakes enriched with OF whereas softer correlations were obtained for the OPP-containing ones due to elastic instability of the batters. Principal component (PCA) and hierarchical cluster analysis (HCA) were performed to provide basic graphical comparison of the differences/similarities between non-linear Theological properties of gluten-free cake batters by considering LAOS parameters. The viscoelastic properties of the cake batters containing 16% OPP were found to be suitable for high gas retention capacity since the highest cake specific volume was obtained.