Rajbhandari P, Kindstedt P S
Department of Nutrition and Food Sciences, University of Vermont, Burlington 05405-0086.
Department of Nutrition and Food Sciences, University of Vermont, Burlington 05405-0086.
J Dairy Sci. 2014;97(4):1885-92. doi: 10.3168/jds.2013-7204. Epub 2014 Jan 31.
Calcium lactate crystals that sometimes form on Cheddar cheese surfaces are a significant expense to manufacturers. Researchers have identified several postmanufacture conditions such as storage temperature and packaging tightness that contribute to crystal formation. Anecdotal reports suggest that physical characteristics at the cheese surface, such as roughness, cracks, and irregularities, may also affect crystallization. The aim of this study was to evaluate the combined effects of surface roughness and packaging tightness on crystal formation in smoked Cheddar cheese. Four 20-mm-thick cross-section slices were cut perpendicular to the long axis of a retail block (~300g) of smoked Cheddar cheese using a wire cutting device. One cut surface of each slice was lightly etched with a cheese grater to create a rough, grooved surface; the opposite cut surface was left undisturbed (smooth). The 4 slices were vacuum packaged at 1, 10, 50, and 90kPa (very tight, moderately tight, loose, very loose, respectively) and stored at 1°C. Digital images were taken at 1, 4, and 8 wk following the first appearance of crystals. The area occupied by crystals and number of discrete crystal regions (DCR) were quantified by image analysis. The experiment was conducted in triplicate. Effects of storage time, packaging tightness, surface roughness, and their interactions were evaluated by repeated-measures ANOVA. Surface roughness, packaging tightness, storage time, and their 2-way interactions significantly affected crystal area and DCR number. Extremely heavy crystallization occurred on both rough and smooth surfaces when slices were packaged loosely or very loosely and on rough surfaces with moderately tight packaging. In contrast, the combination of rough surface plus very tight packaging resulted in dramatic decreases in crystal area and DCR number. The combination of smooth surface plus very tight packaging virtually eliminated crystal formation, presumably by eliminating available sites for nucleation. Cut-and-wrap operations may significantly influence the crystallization behavior of Cheddar cheeses that are saturated with respect to calcium lactate and thus predisposed to form crystals.
有时在切达干酪表面形成的乳酸钙晶体对制造商来说是一项巨大的成本。研究人员已经确定了几种制造后的条件，如储存温度和包装紧密度，这些都会导致晶体形成。轶事报告表明，奶酪表面的物理特性，如粗糙度、裂缝和不规则性，也可能影响结晶。本研究的目的是评估表面粗糙度和包装紧密度对烟熏切达干酪晶体形成的综合影响。使用线切割设备，垂直于一块零售装（约300克）烟熏切达干酪的长轴切出四个20毫米厚的横截面切片。每个切片的一个切割面用奶酪刨轻轻蚀刻，以形成粗糙、有凹槽的表面；相对的切割面保持不变（光滑）。将这4个切片分别在1、10、50和90千帕（分别为非常紧密、中等紧密、宽松、非常宽松）下真空包装，并在1°C下储存。在晶体首次出现后的第1、4和8周拍摄数字图像。通过图像分析对晶体所占面积和离散晶体区域（DCR）的数量进行量化。该实验重复进行了三次。通过重复测量方差分析评估储存时间、包装紧密度、表面粗糙度及其相互作用的影响。表面粗糙度、包装紧密度、储存时间及其双向相互作用显著影响晶体面积和DCR数量。当切片包装松散或非常松散时，粗糙和光滑表面都会出现极其严重的结晶，中等紧密包装的粗糙表面也会出现这种情况。相比之下，粗糙表面加非常紧密包装的组合导致晶体面积和DCR数量大幅减少。光滑表面加非常紧密包装的组合几乎消除了晶体形成，可能是通过消除成核的可用位点。切割和包装操作可能会显著影响相对于乳酸钙饱和且因此易于形成晶体的切达干酪的结晶行为。
