Determining Carbohydrates for Increasing Safety: GC-FID Quantification of Lactose, Galactose, Glucose, Tagatose and Myo-Inositol in ‘Maturo’ PDO Pecorino Sardo Cheese

Abstract

Although PDO Pecorino Sardo is one of the oldest traditional cheeses of Sardinia, Italy, data on its nutritional properties and food safety are lacking. In particular, significant amounts of lactose and galactose may be a health concern for consumers. The primary objective of this study is to quantify, using a validated GC-FID method, the residual lactose and galactose content in “maturo” (i.e., ripened for at least two months) Protected Denomination of Origin (PDO) Pecorino Sardo cheese. A statistically representative sampling from seven dairies distributed throughout Sardinia has been selected for this aim. In addition to lactose and galactose, two of their metabolites (i.e., glucose and tagatose, respectively) and a bioactive polyol like myo-inositol were quantified. The concentration of lactose (mean 26 mg kg−1, range 4–90 mg kg−1) was below the strictest limit set in the European Union (i.e., 100 mg kg−1), while the galactose content was found to be in an amount (mean: 76 mg kg−1, range: 10–200 mg kg−1) that even patients afflicted with severe galactosemia, albeit with some circumspection, could consume this cheese. Ripening (two to four months) had no significant effect on the amount of all analytes, while a slight decrease in galactose levels was observed during the manufacturing season. Finally, the amounts of glucose, tagatose, and myo-inositol are constant in the range of a few tens of mg kg−1.