Fast and green method for analysis of Serra da Estrella

Abstract

Serra da Estrela (SE) cheese is a regional product making part of the gastronomic and socio-cultural heritage of Portugal. It has several aspects that make it unique, namely the manufacturing by the coagulation of raw sheep milk using the thistle flower of Cynara cardunculus L., obtaining a final buttery texture with an exclusive typical flavour. The aroma compounds of Serra da Estrela cheese result partially from the action of indigenous microorganisms and enzymes on lactose, lipids and proteins. Although SE production is very ancient, there are few studies concerning its nutritional composition but nowadays consumers demonstrate interest in understanding the global composition of cheese, since it's a product highly appreciated. In the last decades, the use of near infrared spectroscopy (FT-NIR) has become comparable with those of the classical methods with representative advantages such as minimum time sample preparation; it is a green technique (without using toxic reagents) and allows multiparametric determinations. To perform the present study, a total of 24 SE cheese samples were evaluated, originated from 6 representative producers and analysed with a FT-NIR Buchi NIRMaster ™ standalone spectrometer with a spectral range of 800-2500 nm and compared with classical methods. SE cheese samples were evaluated in terms of salt, moisture, protein and fat content. In all the studied samples the moisture varied between 42% and 53%, the fat content between 19.6 and 33.3%, the protein content between 18.6 and 26.7% and the salt between 0.7 and 2.2%. The results showed a significant agreement between the pairs of values obtained for the studied parameters.