Holian Jennifer A, Bolton Malcolm D, Wilson D Ian
Department of Chemical Engineering and Biotechnology, Philippa Fawcett Drive, Cambridge, CB3 0AS, UK.
Department of Engineering, Schofield Centre, High Cross, Madingley Road, Cambridge, CB3 0EF, UK.
Curr Res Food Sci. 2025 May 24;10:101087. doi: 10.1016/j.crfs.2025.101087. eCollection 2025.
Addition of small amounts of glycerol to milk chocolate during the tempering stage can yield a product which exhibits enhanced mechanical strength and retards motion of the continuous phase (cocoa butter, a mixture of fats) of this dense granular suspension above the fat melting point. The mechanisms responsible for this 'heat stability' were probed by an extensive series of experimental investigations. Addition of glycerol did not alter the fat polymorph or melting behaviour. The increase in bulk yield strength, quantified by indentation, was found to be proportional to the square of the volume fraction of glycerol. A quantitative explanation of this behaviour was not identified. The glycerol is not soluble in the fat phase so the possibility of a cage network arising from a capillary suspension mechanism was pursued. The evidence did not support a 'normal' capillary suspension model, and suggested that absorption of glycerol into the lecithin layer coating the particulate phase either resulted in a viscous 'glue' which retards contact motion or rearrangement, or displaces lecithin to allow the formation of sugar-glycerol bridges.
在调温阶段向牛奶巧克力中添加少量甘油，可得到一种产品，该产品具有更高的机械强度，并且在高于脂肪熔点时能减缓这种致密颗粒悬浮液连续相（可可脂，一种脂肪混合物）的流动。通过一系列广泛的实验研究探究了导致这种“热稳定性”的机制。添加甘油并未改变脂肪多晶型或熔化行为。通过压痕量化的体积屈服强度的增加与甘油体积分数的平方成正比。未找到对此行为的定量解释。甘油不溶于脂肪相，因此研究了由毛细管悬浮机制产生笼状网络的可能性。证据不支持“正常”的毛细管悬浮模型，并表明甘油吸收到包裹颗粒相的卵磷脂层中，要么产生一种粘性“胶水”，减缓接触运动或重排，要么取代卵磷脂以允许形成糖 - 甘油桥。
