Bonaïti C, Irlinger F, Spinnler H E, Engel E
UMR INA P-G/INRA Génie et Microbiologie des Procédés Alimentaires, F-78850 Thiverval-Grignon, France.
J Dairy Sci. 2005 May;88(5):1671-84. doi: 10.3168/jds.S0022-0302(05)72839-3.
The aim of this study was to develop and validate an iterative procedure based on odor assessment to select odor-active associations of microorganisms from a starting association of 82 strains (G1), which were chosen to be representative of Livarot cheese biodiversity. A 3-step dichotomous procedure was applied to reduce the starting association G1. At each step, 3 methods were used to evaluate the odor proximity between mother (n strains) and daughter (n/2 strains) associations: a direct assessment of odor dissimilarity using an original bidimensional scale system and 2 indirect methods based on comparisons of odor profile or hedonic scores. Odor dissimilarity ratings and odor profile gave reliable and sometimes complementary criteria to select G3 and G4 at the first iteration, G31 and G42 at the second iteration, and G312 and G421 at the final iteration. Principal component analysis of odor profile data permitted the interpretation at least in part, of the 2D multidimensional scaling representation of the similarity data. The second part of the study was dedicated to 1) validating the choice of the dichotomous procedure made at each iteration, and 2) evaluating together the magnitude of odor differences that may exist between G1 and its subsequent simplified associations. The strategy consisted of assessing odor similarity between the 13 cheese models by comparing the contents of their odor-active compounds. By using a purge-and-trap gas chromatography-olfactory/mass spectrometry device, 50 potent odorants were identified in models G312, G421, and in a typical Protected Denomination of Origin Livarot cheese. Their contributions to the odor profile of both selected model cheeses are discussed. These compounds were quantified by purge and trap-gas chromatography-mass spectrometry in the 13 products and the normalized data matrix was transformed to a between-product distance matrix. This instrumental assessment of odor similarities allowed validation of the choice of G312 as the best 10-strain ecosystem.
本研究的目的是开发并验证一种基于气味评估的迭代程序，以便从82株菌株的起始组合（G1）中选择具有气味活性的微生物组合，这些菌株被选为里瓦罗奶酪生物多样性的代表。采用三步二分法程序来减少起始组合G1。在每一步中，使用三种方法评估母组合（n株菌株）和子组合（n/2株菌株）之间的气味相似度：使用原始二维量表系统直接评估气味差异，以及基于气味特征或享乐评分比较的两种间接方法。气味差异评级和气味特征为在第一次迭代时选择G3和G4、第二次迭代时选择G31和G42以及最终迭代时选择G312和G421提供了可靠且有时互补的标准。气味特征数据的主成分分析至少部分地解释了相似性数据的二维多维标度表示。研究的第二部分致力于：1）验证每次迭代时二分法程序的选择；2）共同评估G1与其后续简化组合之间可能存在的气味差异程度。该策略包括通过比较13种奶酪模型中气味活性化合物的含量来评估气味相似性。通过使用吹扫捕集气相色谱 - 嗅觉/质谱仪，在模型G312、G421和一种典型的受保护原产地命名里瓦罗奶酪中鉴定出50种强效气味物质。讨论了它们对两种选定模型奶酪气味特征的贡献。通过吹扫捕集 - 气相色谱 - 质谱法对这13种产品中的这些化合物进行了定量，并将归一化数据矩阵转换为产品间距离矩阵。这种对气味相似性的仪器评估验证了选择G312作为最佳的10株菌株生态系统的合理性。
