Investigation of Growth and Shrinkage Mechanisms in Vapor-Induced Expansion of Extrusion-Cooked Corn Grits

Horvat, Mario; Schuchmann, Heike P.

doi:10.1007/s11947-012-0977-4

Cited by 12 publications

(14 citation statements)

References 21 publications

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“…In parallel, the sudden moisture loss leads to a decrease in temperature, which in turn increases the viscosity of the matrix. During drying, further moisture loss and lower temperatures were reported to facilitate the crossing of the T G to initiate a second decrease in the extrudate diameter [26]. However, we did not observe a second shrinkage stage for MS in this study, which can be attributed to differences in the chemical composition and physicochemical material properties compared to previous studies.…”

Section: Sectional Expansion Properties and Glass Transition Temperaturecontrasting

confidence: 87%

“…However, to account for all three main phases of expansion (growth directly after die exit, first shrinkage and second shrinkage), new expansion indices have been defined. The initial sectional expansion was evaluated according to Horvat and Schuchmann [ 26 ] with modifications. They proposed that the initial growth phase of starch-based extrudates was finalized after 25–115 ms.…”

Section: Methodsmentioning

confidence: 99%

“…The experimental studies of Horvat and Schuchmann [ 26 ] and Philipp et al [ 27 ] reported sectional expansion separately and investigated initial SEI and final SEI/LEI by imaging the extrudate at the die exit. This revealed that the initial and final expansion of starch-based blends differ, allowing the measurement of extrudate shrinkage.…”

Section: Introductionmentioning

confidence: 99%

“…This revealed that the initial and final expansion of starch-based blends differ, allowing the measurement of extrudate shrinkage. By also measuring the SEI after 24 h, Horvat and Schuchmann [ 26 ] observed a second shrinkage phase indicated by a time-dependent decrease in the SEI. Based on the online analysis of the rheological properties of the melt, the elastic and viscous properties of the melt were presumed to be associated with the initial growth of the extrudate, whereas the glass transition temperature was correlated with the final fixation of the extrudate.…”

Section: Introductionmentioning

confidence: 99%

“…Based on the online analysis of the rheological properties of the melt, the elastic and viscous properties of the melt were presumed to be associated with the initial growth of the extrudate, whereas the glass transition temperature was correlated with the final fixation of the extrudate. Shrinkage is only discussed in a limited number of previous studies and is often underestimated in prediction models, especially in extrusion processes where the moisture content is > 25 g/100 g [ 26 ].…”

Section: Introductionmentioning

confidence: 99%

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Impact of Rapeseed Press Cake on the Rheological Properties and Expansion Dynamics of Extruded Maize Starch

Martin

Osen

Karbstein

et al. 2021

Foods

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Rapeseed press cake (RPC), an oil pressing side product rich in protein and fiber, can be combined with starch and valorized into directly expanded products using extrusion technology. The mechanism of starch expansion has been studied in detail, but the impact of RPC on expansion behavior is poorly understood. However, it can be linked to rheological and physicochemical properties and is a key product quality parameter. Blends with different amounts of RPC (0, 10, 40 g/100 g) were extruded at different barrel temperatures (100, 120, 140 °C) and moisture contents (24 or 29 g/100 g). The initial, intermediate and final sectional, longitudinal and volumetric expansion indices (SEI, LEI, VEI) were monitored directly, 10 s and 24 h after die exit to measure extrudate growth and shrinkage. The viscous and elastic properties of the extruded blends were investigated in a closed cavity rheometer. Starch and blends with 10 g/100 g RPC achieved a high initial SEI followed by significant short-term shrinkage. Blends containing 40 g/100 g RPC did not show any initial expansion. With increasing RPC content, the intermediate SEI decreased, but all samples reached a similar final SEI due to time-dependent swelling of the RPC blends. With increasing RPC content, the elasticity of the starch-based extruded samples significantly increased. Our study shows that comprehensive control and understanding of expansion mechanisms can be achieved only by investigating all stages of extrudate growth and shrinkage. We also found that the closed cavity rheometer is a powerful tool to correlate the rheological properties and expansion mechanisms of biopolymers.

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Section: Sectional Expansion Properties and Glass Transition Temperaturecontrasting

confidence: 87%

Section: Methodsmentioning

confidence: 99%