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Polymorphism & its influence on solid fats in foods. Audrey Girard FSTC 605 April 22, 2014. Shortening in Foods. “Shortens” the bite Texture Mouthfeel Structural integrity Lubrication Incorporation of air Heat transfer Extended shelf life. Polymorphism: What is it?.
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Polymorphism & its influence on solid fats in foods Audrey Girard FSTC 605 April 22, 2014
Shortening in Foods • “Shortens” the bite • Texture • Mouthfeel • Structural integrity • Lubrication • Incorporation of air • Heat transfer • Extended shelf life
Polymorphism: What is it? • Ability to exist in different crystalline structures with different molecular packing • Dependent on composition of lipids, cooling rate, holding temperature, shearing, storage • Three most common forms: • α – lowest melting point; least stable • β’ – most desirable for wide range of applications • Β – highest melting point; most stable
Polymorphism: α-form • Hexagonal subcell • Triacylglycerols often start here because of low activation energy for nuclei formation • Transitory – readily transformed into higher melting fats
Polymorphism: β’-form • Orthorhombic perpendicular subcell • Favored in rapid cooling • Need diversity in TAG • Delicate needle-like structures • <1 micron • Intermediate – 5 microns • Give shortening a smooth appearance, low melt point, extended plasticity • Beef tallow
Polymorphism: β-form • Triclinic parallel subcell • Favored in slow cooling • Common with homogeneity of TAG • Most stable of three forms • 20+ microns • Grainy texture • Poor aeration and laminating properties • Good for flakiness (PIE!) • Lard
Polymorphism: Stabilizing β’ • Adding β’-tending fat to β-tending fat • Palmitic acid • Palm oil in blend to disrupt homogeneity • Delays or prevents conversion to β • Incorporate selectively hydrogenated fat • Maybe not a good long term solution • Addition of diglycerides and sorbitan esters • Chemical interesterification
Crystallinity in Fats/Oils • Very dependent of TAG composition • Soybean – 11% palmitic acid • Palm – 44% palmitic acid
β’-form in Shortening for Foods • For aeration and mouthfeel • Examples: • All-purpose • Cake • Icing • Filler fat • Bread
β-form in Shortening for Foods • Imparts flakiness • Smoothness not needed • Examples • Pie • Pastry • Confectioner’s • Fluid • Frying Martha Stewart approved pies
Sources Ghotra, B. S., Dyal, S. D., and Narine, S. S. 2002. Lipid shortenings: A review. Food Res.Int. 35:1015-1048. Himawan, C., Starov, V. M., and Stapley, A. G. F. 2006. Thermodynamic and kinetic aspects of fat crystallization. Adv.Colloid Interface Sci. 122:3-33. Lonchampt, P., and Hartel, R. W. 2004. Fat bloom in chocolate and compound coatings. European Journal of Lipid Science and Technology. 106:241-274. McClements, D. J., and Decker, E. A. 2008. Lipids. Pages 155-216 in: Fennema's Food Chemistry. S. Damodaran, K. L. Parkin and O. Fennema eds. Boca Raton : CRC Press: Boca Raton. Narine, S. S., and Marangoni, A. G. 1999. Relating structure of fat crystal networks to mechanical properties: A review. Food Res.Int. 32:227-248. Pyler, E. J., and Gorton, L. A. 2008. Part A: Major ingredients. Pages 113-270 in: Baking science & technology. Anonymous . Merriam, Kan. : Sosland Pub. Co: Merriam, Kan. Images: http://www.washingtonsgreengrocer.com/catalog/product/lyon-bakery-french-baguette/24506/detail.htm http://static.guim.co.uk/sys-images/Guardian/Pix/pictures/2013/1/16/1358359579274/Wonder-Bread-010.jpg http://www.foodsubs.com/Fatsoils.html http://cupcakemojo.com/ http://www.marthastewart.com/274216/making-decorative-piecrusts/@center/276949/everything-thanksgiving
