Alessandro Gori

Classification of Pecorino cheeses using electronic nose combined with artificial neural network and comparison with GC–MS analysis of volatile compounds

An electronic nose based on an array of 6 metal oxide semiconductor sensors was used, jointly with artificial neural network (ANN) method, to classify Pecorino cheeses according to their ripening time and manufacturing techniques. For this purpose different pre-treatments of electronic nose signals have been tested. In particular, four different features extraction algorithms were compared with a principal component analysis (PCA) using to reduce the dimensionality of data set (data consisted of 900 data points per sensor). All the ANN models (with different pre-treatment data) have different capability to predict the Pecorino cheeses categories. In particular, PCA show better results (classification performance: 100%; RMSE: 0.024) in comparison with other pre-treatment systems.

Classification of Pecorino cheeses produced in Italy according to their ripening time and manufacturing technique using Fourier transform infrared spectroscopy

Fourier-transform infrared spectroscopy, followed by linear discriminant analysis of the spectral data, was used to classify Italian Pecorino cheeses according to their ripening time and manufacturing technique. The Fourier transform infrared spectra of the cheeses were divided into 18 regions and the normalized absorbance peak areas within these regions were used as predictors. Linear discriminant analysis models were constructed to classify Pecorino cheeses according to different ripening stages (hard and semi-hard) or according to their manufacturing technique (fossa and nonfossa cheeses). An excellent resolution was achieved according to both ripening time and manufacturing technique. Also, a final linear discriminant analysis model considering the 3 categories (hard nonfossa, hard fossa, and semi-hard nonfossa) was constructed. A good resolution among the 3 categories was obtained.

Bioactive lipids in the butter production chain from Parmigiano Reggiano cheese area

BACKGROUNDnBovine milk contains hundreds of diverse components, including proteins, peptides, amino acids, lipids, lactose, vitamins and minerals. Specifically, the lipid composition is influenced by different variables such as breed, feed and technological process. In this study the fatty acid and phospholipid compositions of different samples of butter and its by-products from the Parmigiano Reggiano cheese area, produced by industrial and traditional churning processes, were determined.nnnRESULTSnThe fatty acid composition of samples manufactured by the traditional method showed higher levels of monounsaturated and polyunsaturated fatty acids compared with industrial samples. In particular, the contents of n-3 fatty acids and conjugated linoleic acids were higher in samples produced by the traditional method than in samples produced industrially. Sample phospholipid composition also varied between the two technological processes. Phosphatidylethanolamine was the major phospholipid in cream, butter and buttermilk samples obtained by the industrial process as well as in cream and buttermilk samples from the traditional process, while phosphatidylcholine was the major phospholipid in traditionally produced butter. This result may be explained by the different churning processes causing different types of membrane disruption. Generally, samples produced traditionally had higher contents of total phospholipids; in particular, butter produced by the traditional method had a total phospholipid content 33% higher than that of industrially produced butter.nnnCONCLUSIONnThe samples studied represent the two types of products present in the Parmigiano Reggiano cheese area, where the industrial churning process is widespread compared with the traditional processing of Reggiana cows milk. This is because Reggiana cows milk production is lower than that of other breeds and the traditional churning process is time-consuming and economically disadvantageous. However, its products have been demonstrated to contain more bioactive lipids compared with products obtained from other breeds and by the industrial process.

Lipid fraction of creams collected in the Parmigiano‐Reggiano cheese production area in response to extruded linseed supplementation of dairy cows’ diets: GC‐FID and FT‐MIR evaluation

This study evaluated the effect of dietary supplementation with extruded linseed on the fatty acid and triglyceride composition of creams obtained by natural creaming of cows’ milk and collected in the ‘Parmigiano-Reggiano cheese’ protected designation of origin area. The inclusion of linseed in the diet of experimental dairy cows’, resulted in creams with increased unsaturated fat levels and healthy fatty acids such as omega-3 and conjugated linoleic acid isomers, as well as higher levels of long-chain triglycerides. The combination of infrared spectroscopy and chemometric methods was able to differentiate cream samples based upon differences in cows’ diets and supplemented extruded linseed.