Browsing by Person "Grossmann, Lutz"

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Effect of oil-water colloidal states in liquid feeds on extrudability and textural attributes of high-moisture meat alternatives
(2024) Stehle, Florian; Woern, Carlos; Tan, Nicholle Kirsten; Weiss, Jochen; Grossmann, Lutz; Stehle, Florian; Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, 70599 Stuttgart, Germany; Woern, Carlos; Department of Food Science, University of Massachusetts, 100 Holdsworth Way, Amherst, MA 01003, USA; Tan, Nicholle Kirsten; Department of Food Science, University of Massachusetts, 100 Holdsworth Way, Amherst, MA 01003, USA; Weiss, Jochen; Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, 70599 Stuttgart, Germany; Grossmann, Lutz; Department of Food Science, University of Massachusetts, 100 Holdsworth Way, Amherst, MA 01003, USA
The incorporation of lipids in the extrusion process to produce composite protein–lipid high-moisture meat alternatives is a major challenge due to slip conditions induced by the oil phase. This study investigates the impact of non-emulsified and emulsified liquid feeds – using soy protein isolate and Quillaja saponin as two different emulsifiers – at 6% oil content on the extrudability, visual appearance, textural and structural properties of a soy-based meat alternative. Homogenization pressures from 20 MPa to 140 MPa were used to achieve d4,3 droplet sizes ranging from 1053 nm to 117 nm, respectively. The emulsions stabilized by soy protein isolate exhibited a larger droplet size at low pressures and a smaller droplet size at higher pressures compared to the emulsions containing Quillaja saponin (1053 nm vs. 659 nm at 20 MPa and 117 nm vs. 243 nm at 140 MPa, respectively). The addition of any kind of lipid feed resulted in a lower specific mechanical energy input compared to the standard with no oil. Non-emulsified oil reduced the directional protein fiber formation and enhanced the protein cross-linking into bulk strips, which resulted in significantly lower mechanical anisotropy compared to the standard. Emulsions stabilized by Quillaja saponin were able to resemble the degree of anisotropy with the smallest mean oil droplet size (243 nm) yielding a slightly higher anisotropic index than the control. Microstructural analyses revealed embedded oil droplets between protein fibers, which increased the visual fibrousness. However, only minor changes in the color measurements were observed among all treatments. The results demonstrate the potential of using emulsified liquid feeds to manufacture high-moisture meat alternatives with an incorporated oil phase by extrusion processing without losing the anisotropic character due to oil slip.
High molecular weight λ-carrageenan improves the color stability of phycocyanin by associative interactions
(2022) Buecker, Stephan; Grossmann, Lutz; Loeffler, Myriam; Leeb, Elena; Weiss, Jochen
Phycocyanin is a protein-chromophore structure present in Arthrospira platensis commonly used as a blue-colorant in food. Color losses of phycocyanin can be reduced by electrostatic complexation with λ-carrageenan. The aim of this study was to investigate the effect of molecular weight (MW) of λ-carrageenan on the color stabilization of electrostatic complexes formed with phycocyanin and λ-carrageenan. Samples were heated to 70 or 90°C at pH 3.0 and stored at 25°C for 14 days. The MW of λ-carrageenan was reduced by ultrasound treatments for 15, 30, 60, and 90 min. Prolonged ultrasonication had a pronounced effect on the Mw, which decreased from 2,341 to 228 kDa (0–90 min). Complexes prepared with low MW λ-carrageenan showed greater color changes compared to complexes prepared with high MW λ-carrageenan. The MW had no visible effect on color stability on day 0, but green/yellow shifts were observed during storage and after heating to 70°C. Medium MW showed less color stabilization effects compared to low MW when heated to 70°C. Moreover, for solutions prepared with ultrasonicated λ-carrageenan, significant hue shifts toward green/yellow, and precipitation were observed after a heat treatment at 90°C. In addition, the sizes of the complexes were significantly reduced (646–102 nm) by using ultrasonicated λ-carrageenan, except for the lowest MW λ-carrageenan when heated to 90°C. Overall, these findings demonstrated that decreasing the MW of λC had adverse effects on the color stability of PC:λC complexes heated to 70 and 90°C.