NIR analysis of capillary butterfat in correlation with fatty acid composition of milk and cheese.

Aim ofthe tria1 was to ex ami ne the NIR technique for a rapid and ear1y characterisation oflipids composition of mi1k and, eventually, of the corresponding manufactured cheese. From 55 Va1dostana red pied cows reared at an experimental station in Sauze d'Oulx ('l'O), 28 samples of milk cream and 13 samples of Toma cheese were collected, then stored at -20°C. The thawed creams were centrifuged at 20.000 rpm, for 20' in a glass haematocrit capillary. Then the lighter pole was scanned by a FT-NIR PE Spectrum IdentiChek instrument. Lipid extraction was performed both in milk cream and in cheese according to Rara and Radin and transesterification of fatty acids according to Christie, with modifications described by Chouinard et al .. Fatty acid methyl esters in hexane were then injected into a gas chromatograph equipped with a flame ionization detector (FID) and a PTV injection port. Separation of fatty acid methyl esters was performed with a SupeIcowaxlO fused silica capillary column (60m x 0.32 mm (i.d.), with 0.25 ~m film thickness). The FT-NIR spectra of cream and cheese were calibrated, then internally cross-validated in 12 subgroups, allowing one passage for outliers elimination (NIRS2 software) resulting the descending 1-VR values >0.26 (for Milk cream: C18:1n9 = 0.67; C6:0 = 0.65; C4:0 = 0.58; C18:0 = 0.57; C12:0 = 0.55; C16:0 = 0.52; C8:0 = 0.50; C14:0 = 0.50; C18:1n7 = 0.50; C10:0 = 0.48; CLA = 0.46; week of production = 0.32; far Cheese: C16:0 = 0.88; C14:1 = 0.78; C12:0 = 0.77; C18:2n6 = 0.66; week ofproduction = 0.65; C4:0 = 0.60; C16:1n7 = 0.54; C14:0 = 0.51; C18:1n9 = 051; C15:0 = 0.50; C18:3n3 = 0.50; C17:0 = 0.27). It was unfartunately enhanced a lack of correlation with CLA in cheese compared to milk cream (0.46). Rowever, because of many appreciating results in e1even fatty acids (FA), this rapid methodology ought to be confirmed both far milk :F'A composition and for predictability of some FAs in the future cheese.