In the present study, the sensory characteristics and the volatile organic compound (VOC) profiles of high-moisture mozzarella made by different acidification techniques were compared. The cheeses were manufactured at the same dairy by fermentation by autochthonous natural whey starter (traditional backslopping method) and direct acidification with citric acid (the most used industrial technology). Three cheesemaking trials were performed from February to June using raw milk from a single farm. The mozzarella samples were subjected to assessment of the chemical, microbiological, and sensory characteristics and to VOC analysis by headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry. The relevant microbiological differences found between the 2 types of products were reflected in different sensory and VOC profiles. The cheeses were clearly discriminated by the panel, and traditional mozzarella had higher intensity attributes. The most discriminating descriptors were elasticity, overall odor and taste intensity, sour milk and fruity/vegetable odors, sour taste, and aftertaste. Even though some variability was observed among the trials, the VOC profile of traditional product was always much more complex than that obtained by direct acidification. In both products the carbonyl compounds were the most abundant chemical class, accounting for about 50% of the total. In detail, 51 compounds were identified in the entire set of samples, and their contribution to cheese aroma was roughly estimated by calculating the odor activity values on the basis of the odor thresholds available in the literature. The results allowed hypothesizing that only 12 of them could play a primary role. The most important among the odor-active compounds was 3-methyl-butanal that can both derive from metabolism of lactic acid bacteria and yeasts. The results of the study may be very useful in view of European Union PDO labeling of the traditional product, in terms of protecting it from imitations.

中文翻译：

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简短交流：通过传统的直接酸化技术制成的高水分干酪的感官特性和挥发性有机化合物特征。

在本研究中，比较了通过不同酸化技术制得的高水分马苏里拉的感官特性和挥发性有机化合物（VOC）谱。这些奶酪是在同一家乳制品厂生产的，方法是通过自然自然乳清发酵剂（传统的后冲法）发酵，再用柠檬酸直接酸化（最常用的工业技术）。从2月到6月，使用单个农场的原料奶进行了三个奶酪制作试验。对马苏里拉奶酪样品进行化学，微生物学和感官特性评估，并通过与气相色谱-质谱联用的顶空固相微萃取对挥发性有机化合物进行分析。在两种类型的产品之间发现的相关微生物差异反映在不同的感官和VOC曲线中。专家组清楚地区分了这些奶酪，而传统的马苏里拉奶酪具有较高的强度属性。最有区别的描述词是弹性，总体气味和味道强度，酸牛奶和水果/蔬菜味，酸味和回味。即使在试验中观察到一些可变性，传统产品的VOC特性始终比通过直接酸化获得的VOC特性要复杂得多。在这两种产品中，羰基化合物是最丰富的化学类别，约占总数的50％。详细地，在整个样本集中鉴定出51种化合物，并根据文献中提供的气味阈值计算气味活性值，粗略估计它们对奶酪香气的贡献。结果允许假设其中只有12个可以起主要作用。气味活性化合物中最重要的是3-甲基丁醛，它们都可以来源于乳酸菌和酵母的代谢。鉴于欧盟对传统产品的PDO标签，从保护其不受仿制的角度来看，研究结果可能非常有用。