1H-NMR spectra – a highly sensitive tool in the analysis of Grana Parmigiano-Reggiano type hard cheese
Suspensions/solutions of grated Grana Parmigiano-Reggiano type hard cheese give well-resolved 1H-NMR spectra. These spectra show very specific patterns, which are also sensitive to inner inhomogeneities of these hard cheeses. This enables to use the 1H-NMR spectra obtained from Grana Parmigiano-Reggiano as indicators of subtle changes in the concentration gradients of its parts. This possibility was used to analyze the phenomenon of crumbling of this cheese yielding pieces of a few centimetre size. The results indicate, that sample size should be preferably >5 g before homogenization by grinding or grating.
Cheeses are complex mixtures of organic and of some inorganic compounds. In these systems also minor components are of importance, sensitively influencing nutritive properties, taste, flavour and, therefore, also the commercial value of these popular products.
The complex character of the analytical problem required that a broad range of instrumental analytical methods were adapted to cheeses, such as GC-MS (1), for volatile components in combination with P&T (1l,n,o,p 2) and SPME (3) (or both (1p)) type sampling, variations of HPLC (1d, 4), high-pressure TLC (5), electrophoretic techniques (4f,g 6), occasionally in combination with biochemical methods (6h, 7), as well as spectroscopic analyses (UV-VIS (8), IR (9)), to name only the most efficient ones. Several excellent reviews cover the field too. We cite here a few (10). Interestingly, the use of NMR spectroscopy, one of the most popular tools in the organic analysis, was reported only in a few communications (11). In the present paper we describe an application of 1H-NMR spectra for some problems of Grana Parmigiano-Reggiano hard cheeses.
The Parmigiano ...