Department of Nutrition and Food Sciences, University of Vermont, Burlington 05405-0086, USA.
J Dairy Sci. 2013 Jun;96(6):3442-8. doi: 10.3168/jds.2012-5949. Epub 2013 Mar 30.
Previous studies have shown that storage temperature influences the formation of calcium lactate crystals on vacuum-packaged Cheddar cheese surfaces. However, the mechanisms by which crystallization is modulated by storage temperature are not completely understood. The objectives of this study were to evaluate the effect of storage temperature on smoked Cheddar cheese surfaces for (1) the number of discrete visible crystals formed per unit of cheese surface area; (2) growth rate and shape of discrete crystals (as measured by area and circularity); (3) percentage of total cheese surface area occupied by crystals. Three vacuum-packaged, random weight (∼300 g) retail samples of naturally smoked Cheddar cheese, produced from the same vat of cheese, were obtained from a retail source. The samples were cut parallel to the longitudinal axis at a depth of 10mm from the 2 surfaces to give six 10-mm-thick slabs, 4 of which were randomly assigned to 4 different storage temperature treatments: 1, 5, 10°C, and weekly cycling between 1 and 10°C. Samples were stored for 30 wk. Following the onset of visible surface crystals, digital photographs of surfaces were taken every other week and evaluated by image analysis for number of discrete crystal regions and total surface area occupied by crystals. Specific discrete crystals were chosen and evaluated biweekly for radius, area, and circularity. The entire experiment was conducted in triplicate. The effects of cheese surface, storage temperature, and storage time on crystal number and total crystal area were evaluated by ANOVA, according to a repeated-measures design. The number of discrete crystal regions increased significantly during storage but at different rates for different temperature treatments. Total crystal area also increased significantly during storage, at rates that varied with temperature treatment. Storage temperature did not appear to have a major effect on the growth rates and shapes of the individual crystals that were chosen for analysis. The data indicated that the effect of storage temperature was complex, likely involving solubility changes, the formation of d(-) and l(+) lactic acid, and the occurrence of syneresis, which in turn affected the number of crystal formation sites and total crystal area on the cheese surface.
先前的研究表明，储存温度会影响真空包装切达奶酪表面乳酸钙晶体的形成。然而，结晶受储存温度调制的机制尚不完全清楚。本研究的目的是评估储存温度对熏制切达奶酪表面的影响，具体涉及：（1）单位奶酪表面积上形成的离散可见晶体数量；（2）离散晶体的生长速度和形状（通过面积和圆度来衡量）；（3）晶体占据奶酪总表面积的百分比。从零售来源获得了三个真空包装的、随机重量（约 300g）的零售样品，这些样本均来自同一桶奶酪，且表面经自然熏制。从两个表面沿纵向以 10mm 的深度切割样本，以获得 6 个 10mm 厚的薄片，其中 4 个随机分配到 4 种不同的储存温度处理中：1、5、10°C，以及在 1 和 10°C 之间每周循环。样品储存 30 周。在可见表面晶体出现后，每隔两周拍摄一次表面的数字照片，并通过图像分析评估离散晶体区域的数量和晶体占据的总表面积。选择特定的离散晶体，并每两周评估一次其半径、面积和圆度。整个实验重复进行三次。根据重复测量设计，采用方差分析评估奶酪表面、储存温度和储存时间对晶体数量和总晶体面积的影响。在储存过程中，离散晶体区域的数量显著增加，但不同温度处理的增加速度不同。总晶体面积在储存过程中也显著增加，增加速度随温度处理而变化。储存温度似乎对所选用于分析的单个晶体的生长速度和形状没有重大影响。数据表明，储存温度的影响是复杂的，可能涉及溶解度变化、d(-)和 l(+)乳酸的形成以及乳清析出，这反过来又影响了奶酪表面晶体形成点的数量和总晶体面积。
