Combined use of variable pressure scanning electron microscopy and confocal laser scanning microscopy best reveal microstructure of comminuted meat gels

Abstract

Observing the distribution of protein and fat phases in comminuted meat products can be helpful to understanding the mechanisms of texture development and fat/water binding. In this study variable pressure scanning electron microscopy (VP-SEM) was compared to conventional scanning electron microscopy (SEM), and contrasted with confocal laser scanning microcopy (CLSM), as tools to characterize gel morphology of cooked meat batters or non-fat pastes. Gel morphology was varied by inclusion of whey protein isolate (WPI) that gels only at high temperature, in partial substitution of myofibrillar protein (MFP). CLSM (magnification:10–1000×) revealed that, when no WPI was added, a homogeneous gel structure was produced enmeshing small, well-distributed fat particles. Substituting 30 g/100 g MFP by WPI produced a coarse gel structure with clear microphase separation of fat. VP-SEM (magnification:1000–2000×) enabled visualization of small pore structure of gel matrix whereas SEM obscured details of this, as well as of the relationship between fat globules and gel matrix that were visible by VP-SEM. Since meat gels properties can be affected by multiple morphological features, visible only at different levels of magnification, the relationships between microstructure and important properties of meat gels can be most advantageously observed when both VP-SEM and CLSM are used in tandem.