Rajbhandari P, Patel J, Valentine E, Kindstedt P S
Department of Nutrition and Food Sciences, University of Vermont, Burlington, Vermont 05405-0086, USA.
J Dairy Sci. 2009 Aug;92(8):3616-22. doi: 10.3168/jds.2009-2157.
We have observed a high incidence of calcium lactate surface crystals on naturally smoked Cheddar cheese in the retail marketplace. The objective of this study was to identify chemical changes that may occur during natural smoking that render Cheddar cheese more susceptible to calcium lactate crystal formation. Nine random-weight (approximately 300 g) retail-packaged samples of smoked Cheddar cheese were obtained from a commercial manufacturer immediately after the samples were smoked for about 6 h at 20 degrees C in a commercial smokehouse. Three similarly sized samples that originated from the same 19.1-kg block of cheese and that were not smoked were also obtained. Within 2 d after smoking, 3 smoked and 3 control (not smoked) samples were sectioned into 5 subsamples at different depths representing 0 to 2, 2 to 4, 4 to 6, 6 to 8, and 8 to 10 mm from the cheese surface. Six additional smoked cheese samples were similarly sectioned at 4 wk and again at 10 wk of storage at 5 degrees C. Sample sections were analyzed for moisture, L(+) and D(-) lactate, pH, and water-soluble calcium. The effects of treatment (smoked, control), depth from cheese surface, and their interactions were analyzed by ANOVA according to a repeated measures design with 2 within-subject variables. Smoked samples contained significantly lower moisture and lower pH, and higher total lactate-in-moisture (TLIM) and water-soluble calcium-in-moisture (WSCIM) than control cheeses. Smoked samples also contained significant gradients of moisture, pH, TLIM, and WSCIM, with lower moisture and pH, and higher TLIM and WSCIM, occurring at the cheese surface. Gradients of moisture were still present in smoked samples at 4 and 10 wk of storage. In contrast, the pH, TLIM, and WSCIM equilibrated and showed no gradients at 4 and 10 wk. The results indicate that calcium and lactate in the serum phase of the cheese were elevated because of smoking, especially at the cheese surface immediately after smoking treatment, which presumably predisposes the smoked cheeses to increased susceptibility to calcium lactate surface crystallization.
我们观察到零售市场上天然烟熏切达干酪表面乳酸钙晶体的发生率很高。本研究的目的是确定在天然烟熏过程中可能发生的化学变化，这些变化使切达干酪更容易形成乳酸钙晶体。从一家商业制造商处获得了9个随机重量（约300克）的零售包装烟熏切达干酪样品，这些样品在商业烟熏室中于20摄氏度烟熏约6小时后立即获取。还获得了3个同样大小、来自同一19.1千克奶酪块且未烟熏的样品。烟熏后2天内，将3个烟熏样品和3个对照（未烟熏）样品在不同深度切成5个亚样本，分别代表距奶酪表面0至2毫米、2至4毫米、4至6毫米、6至8毫米和8至10毫米。另外6个烟熏奶酪样品在5摄氏度储存4周和10周时同样进行切片。对样品切片进行水分、L(+)和D(-)乳酸、pH值以及水溶性钙的分析。根据具有2个受试者内变量的重复测量设计，通过方差分析（ANOVA）分析处理（烟熏、对照）、距奶酪表面深度及其相互作用的影响。烟熏样品的水分含量和pH值显著较低，而总水分乳酸含量（TLIM）和水分水溶性钙含量（WSCIM）高于对照奶酪。烟熏样品的水分含量、pH值、TLIM和WSCIM也存在显著梯度，奶酪表面的水分含量和pH值较低，而TLIM和WSCIM较高。在储存4周和10周时，烟熏样品中仍存在水分梯度。相比之下，pH值、TLIM和WSCIM在4周和10周时达到平衡且无梯度。结果表明，由于烟熏，奶酪血清相中钙和乳酸升高，尤其是在烟熏处理后立即在奶酪表面，这可能使烟熏奶酪更易形成乳酸钙表面结晶。
