Physicochemical and Rheological Characterization of Roll-in Shortenings [Erratum: May 2017, v.94(5); p.747]

The composition and physical properties of roll-in shortenings, commonly rich in trans and saturated fatty acids, were investigated and compared to other specialty fats, to provide insights into the physico-chemical origins of their functionality. Triacylglycerols and fatty acid composition, polymorphic and melting behavior, solid fat content and large deformation rheological properties were determined. Roll-in shortenings contained higher amounts of trisaturated and unsaturated triacylglycerols (12–27 %; 47–62 %) than other shortenings (9–11 %; 6–44 %). However, all exhibited high levels of saturates and trans fatty acids and similar crystal characteristics: β′ or mixed β′ and β, irrespective of their end use. Roll-in shortenings had comparable melting peaks (42–52 °C) but sharper melting endotherms with higher enthalpies (38.6–43.3 J/g) than other bakery fats (18.7–25.4 J/g). This was in accordance with their well-defined short spacings, indicative of smaller crystallites with more-ordered packing. Solid fat profiles of roll-in shortenings were akin to all purpose and cake interesterified shortenings, but not to all-purpose and icing shortenings which displayed substantial melting as temperature rises. Differences in large deformation rheology (yield stress: σ * , apparent Young modulus: E ₐₚₚ, yield value: C) were marginal and inconsistent with their solid fat content. Roll-in shortenings exhibited E ₐₚₚ, σ and C in the order of 1–2 × 10⁶, 4–7 × 10⁴, and 7–29 × 10⁴ Pa, respectively. Particularly, the σ*and C, previously established as major parameters to specify the functionality of roll-in shortenings, were not significantly different (p > 0.05). Overall, roll-in shortening differed from other samples in regard to molecular makeup but not greatly in their physical parameters, suggesting that triacylglycerol composition has important implications on their functionality.