Manca G, Camin F, Coloru G C, Del Caro A, Depentori D, Franco M A, Versini G
Dipartimento di Chimica, Università di Sassari, via Vienna 2, 07100 Sassari, Italy.
J Agric Food Chem. 2001 Mar;49(3):1404-9. doi: 10.1021/jf000706c.
The stable isotope ratios ((13)C/(12)C and (15)N/(14)N) of casein measured by isotope ratio mass spectrometry (IRMS) and some free amino acid ratios (His/Pro, Ile/Pro, Met/Pro, and Thr/Pro) determined by HPLC in samples of ewes' milk cheese from Sardinia, Sicily, and Apulia were found to be parameters independent of ripening time. Multivariate data treatments performed by applying both unsupervised (principal component analysis and cluster analysis) and supervised [linear discriminant analysis (LDA)] methods revealed good discrimination possibilities for the cheeses according to place of origin. In this respect, particularly significant were the variables Ile/Pro, Thr/Pro, (13)C/(12)C, and (15) N/(14)N ratios on which basis 100% discrimination and classification of the samples by LDA was obtained.
通过同位素比质谱法（IRMS）测定的酪蛋白稳定同位素比率（（13）C/（12）C和（15）N/（14）N）以及通过高效液相色谱法（HPLC）测定的撒丁岛、西西里岛和普利亚地区母羊奶酪样品中的一些游离氨基酸比率（His/Pro、Ile/Pro、Met/Pro和Thr/Pro）被发现是与成熟时间无关的参数。通过应用无监督（主成分分析和聚类分析）和有监督[线性判别分析（LDA）]方法进行的多变量数据处理显示，根据奶酪的产地可以很好地区分这些奶酪。在这方面，特别重要的变量是Ile/Pro、Thr/Pro、（13）C/（12）C和（15）N/（14）N比率，基于这些比率，通过LDA获得了样品100%的区分和分类。
