Aging of cream is an important process to manage production time and to produce butter with consistent quality. The objective of this study was to evaluate the combined effect of temperature (5, 10, and 15°C) and agitation rate (0, 40, and 240 rpm) during aging of cream on the physical properties of cream and butter in a model system. Cream's solid fat content (SFC), melting behavior, and droplet size distribution were measured during and after 90 min of aging. Butter physical properties such as melting behavior, water content, and hardness were measured. The effects of agitation on SFC and droplet size are dependent on aging and churning temperature. Solid fat content increased faster at 5°C, and the maximum SFC was the highest at this temperature. An effect of agitation on SFC was observed only when cream was aged at 15°C. Agitating cream at 40 rpm increased the droplet size regardless of aging temperature. Two melting peaks, medium melting fraction (MMF) and high melting fraction (HMF), were found in cream samples aged at 5 and 10°C, but only a HMF melting peak was seen in the cream aged at 15°C. The enthalpy of MMF in the cream aged at 10°C with 40 rpm and without agitation was significantly lower than that in samples aged at 5°C regardless of agitation rate. Butter can be formed only from cream aged under certain conditions during 14.5 min of churning, which are 5°C with high agitation and 10°C regardless of agitation level. Butter produced with cream aged at 5°C with high agitation showed significantly higher MMF and total enthalpy values. However, no significant difference in enthalpy values was observed among the butter samples made from the cream aged at 10°C. Further crystallization of MMF occurred in the butter produced with cream aged at 10°C during 24 h of storage at 5°C, whereas no further crystallization occurred in the butter made with the cream aged at 5°C with high agitation. The hardest butter was obtained when cream was aged at 5°C with 240 rpm and at 10°C with 40 rpm. Softer butter was obtained when cream aged at 10°C with 240 rpm was used. This butter also had the highest water content. This study shows that butter hardness can be tailored by changing the aging conditions of the cream. Cream can be aged at higher temperature with low agitation without altering the hardness of butter. These results will help dairy producers to optimize butter making processes to obtain desired properties in the final product.

奶油的老化是控制生产时间和生产质量稳定的黄油的重要过程。这项研究的目的是评估奶油老化过程中温度（5、10和15°C）和搅拌速率（0、40和240 rpm）对模型中奶油和黄油的物理性能的综合影响系统。在老化过程中和老化90分钟后，测量奶油的固体脂肪含量（SFC），熔融行为和液滴尺寸分布。测量了黄油的物理性能，如熔融行为，水含量和硬度。搅拌对SFC和液滴大小的影响取决于老化和搅拌温度。固体脂肪含量在5°C时增长更快，在此温度下最大SFC最高。仅当乳霜在15°C下陈化时才观察到搅拌对SFC的影响。无论老化温度如何，以40 rpm的速度搅拌奶油都会增加液滴尺寸。在5和10°C下老化的奶油样品中发现了两个熔化峰，中等熔化分数（MMF）和高熔化分数（HMF），但是在15°C老化的奶油中只有HMF熔化峰。不论搅拌速度如何，在10°C，40 rpm且未搅拌的条件下老化的奶油中的MMF焓均显着低于5°C时的样品中的MMF焓。黄油只能由在搅拌条件为14.5分钟的特定条件下老化的奶油形成，奶油在5°C的条件下进行高搅拌，而在10°C的条件下进行搅拌（无论搅拌水平如何）。在高搅拌下于5°C时效的奶油所产生的黄油显示出更高的MMF和总焓值。然而，在由10°C老化的奶油制成的黄油样品中，焓值没有显着差异。在5°C储存24小时期间，在10°C时效的奶油所制得的黄油中，发生了MMF的进一步结晶，而在5°C时效下进行高搅拌的奶油所制得的黄油中没有发生进一步的结晶。当奶油在5°C下以240 rpm和10°C下以40 rpm老化时，获得最硬的黄油。当使用在10°C下以240 rpm老化的奶油时，可获得较软的黄油。这种黄油的含水量也最高。这项研究表明，可以通过改变奶油的老化条件来调整黄油的硬度。奶油可以在较低的搅拌下在较高的温度下老化，而不会改变黄油的硬度。