Rajbhandari P, Kindstedt P S
Department of Nutrition and Food Sciences, University of Vermont, Burlington 05405-0086, USA.
J Dairy Sci. 2008 Jun;91(6):2190-5. doi: 10.3168/jds.2008-1077.
Previous research demonstrated that crystal coverage on the surface of Cheddar cheese can be quantitatively and nondestructively measured using image analysis of digital photographs of the cheese surface. The objective of the present study was to extend image analysis methodology to quantify and characterize additional features of visible crystals on cheese surfaces as they grow over time. A random weight (approximately 300 g) retail sample of naturally smoked Cheddar cheese exhibiting white surface crystals was obtained from a commercial source. The total area occupied by crystals and total number of discrete crystal regions on one of the surfaces (approximately 55 x 120 mm) was measured at 3-wk intervals for 30 wk using image analysis. In addition, 5 small (approximately 0.3 mm radius) individual crystals on that surface were chosen for observation over the 30-wk period. The crystals were evaluated for area, radius, and shape factor (circularity) every third week using image analysis. The total area occupied by crystals increased in a linear manner (R(2) = 0.95) from about 0.44 to 7.42% of the total cheese surface area over the 30-wk period. The total number of discrete crystal regions also increased but in a nonlinear manner that was best described by a quadratic relationship. Measurement of discrete crystal regions underestimated the true number of crystals present at the cheese surface due to merging of adjacent crystals as they grew and merged into a single crystal region over time. Throughout this period, the shapes of the 5 individual crystals closely approximated perfect circles, except when adjacent crystals merged to form a single irregular crystal region, and the area occupied by each of the 5 crystals increased in a near-linear manner (R(2) = 0.95). Image analysis approaches may be used to evaluate crystal formation and growth rates and morphology on cheese.
先前的研究表明，通过对切达干酪表面数字照片进行图像分析，可以对切达干酪表面的晶体覆盖情况进行定量和无损测量。本研究的目的是扩展图像分析方法，以量化和表征奶酪表面可见晶体随着时间推移生长时的其他特征。从商业渠道获得了一个随机重量（约300克）的天然烟熏切达干酪零售样品，其表面有白色晶体。使用图像分析，在30周内每隔3周测量一次其中一个表面（约55×120毫米）上晶体所占的总面积和离散晶体区域的总数。此外，在这30周内选择该表面上的5个小晶体（半径约0.3毫米）进行观察。每隔三周使用图像分析对晶体的面积、半径和形状因子（圆形度）进行评估。在30周的时间里，晶体所占的总面积以线性方式增加（R² = 0.95），从约占奶酪总表面积的0.44%增加到7.42%。离散晶体区域的总数也增加了，但呈非线性增加，用二次关系描述最为合适。由于相邻晶体随着时间的推移生长并合并成一个单一的晶体区域，对离散晶体区域的测量低估了奶酪表面实际存在的晶体数量。在整个这段时间里，5个单个晶体的形状非常接近完美圆形，除非相邻晶体合并形成一个单一的不规则晶体区域，并且这5个晶体中每个晶体所占的面积以近线性方式增加（R² = 0.95）。图像分析方法可用于评估奶酪上晶体的形成、生长速率和形态。
