91C-15 |
Crystallization and polymorphic transitions of cocoa butter induced by high hydrostatic pressure |
J. H. OH and B. G. Swanson. Food Science and Human Nutrition, Washington State University, P.O. Box 646736, Pullman, WA 99164-6376 Crystallization and polymorphism of cocoa butter (CB) are of great interest in the chocolate industry. High hydrostatic pressure (HHP) treatment is a promising nonthermal process to alter the functionality of foods. Although HHP treatment may affect fat crystallization, there is no available research on HHP treatment and CB crystallization or polymorphism. The objectives of this research are to investigate the effects of HHP treatment of the CB melt on subsequent crystallization at 21oC and to investigate polymorphic ransitions of CB after HHP treatments of the CB melts. HHP of 100 to 600 MPa was applied to CB melts at either 60oC for 30 min or 21oC for 60 min. Subsequent crystallization of HHP treated CB was performed at 21oC and monitored using spectroscopy and differential scanning calorimetry (DSC). The polymorphic forms of CB during crystallization were identified using DSC and X-ray diffractometry (XRD). HHP treatments of CB melt at either 60 or 21oC increased absorbance and ¥ÄH values during subsequent crystallization at 21oC, and maximum increases were observed in the 300 MPa treated CB melts. The 300 MPa HHP treated CB melts at 60 or 21oC induced primarily Form IV or Form III crystals during crystallization at 21oC within 60 min, compared to a mixture of Form IV and V crystals for control CB. Form IV or Form III crystals from the 300 MPa treated CB melt at 60 or 21oC transitioned to Form V crystals in 180 min or 360 min, respectively, both longer than 120 min transition of the control. HHP treatment of the CB melt accelerates subsequent crystallization inducing less stable Form III or Form IV crystals. Slow polymorphic transitions from HHP induced CB forms to Form V crystals are attributed to the induction of less stable forms by HHP treatments. HHP treatment of fat melts may potentially be used to control fat crystallization.
Session 91C, Food Engineering: Food process engineering
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