A. Di Luccia

Short communication: Relationships between milk quality and acidification in the production of table Mozzarella without starters

The effect of some quality parameters of the milk (refrigeration time, pH, protein, and fat/protein ratio) on the extent of acidification in the production technology of table Mozzarella without starters was investigated. A screening phase carried out at the laboratory level demonstrated that variations of the milk characteristics require different levels of acidification to keep constant the quality of the cheese. The elaboration of the data collected throughout the successive experimentation on industrial scale allowed us to find a mathematical model to describe the relationships between the pH of the curd at stretching time and the milk characteristics, of which the protein concentration and the refrigeration time play the main roles.

Study of proteolysis in river buffalo mozzarella cheese using a proteomics approach

The guarantee of the origin and quality of raw material is essential for the protection and valorization of Campana buffalo mozzarella cheese. The risk of utilization of semifinished products and stored milk in substitution for fresh milk is increasing, due to the continuous desire to reduce production costs. A proteomics approach and electrophoresis survey of retail mozzarella cheeses indicated different rates of proteolysis in the production of dairy industries. The use of fresh milk and correct cheesemaking protocol yielded only γ-caseins, which are derived from β-casein by plasmin, and para-κ-casein, which is derived from κ-casein by chymosin. The detection of abnormal hydrolysis resulting in β- and αS1-casein fragments, identified by mass spectrometry, indicates the use of stored milk or stored and pressed curd, or the reuse of unsold mozzarella cheese, to produce mozzarella. The formation of γ-caseins and other fragments during a long storage of raw materials at room or refrigeration temperature was ascribed to plasmin (endogenous milk enzyme), whereas formation of αS1-casein fragments, mainly αS1-I(6P)- and αS1-I(7P)-casein during the storage of curd was ascribed to the action of chymosin (exogenous enzyme) from rennet. Sodium dodecyl sulfate-PAGE and alkaline urea-PAGE permitted us to evaluate the freshness of the raw materials used in the manufacturing of buffalo mozzarella cheese and to reveal possible inappropriate preservation.

Polymeric protein formation during pasta-making with barley and semolina mixtures, and prediction of its effect on cooking behaviour and acceptability

Spaghetti were produced in a pilot plant from semolina and semolina blended with increasing amounts of barley flour. According to size exclusion high-performance liquid chromatography (SE-HPLC), barley proteins interact with semolina proteins during pasta making, forming polymers of high molecular weight. Of these, the unextractable polymeric proteins (UPP) were at significantly higher concentrations than in spaghetti made from semolina. The decrease of both S-S bonds and -SH free groups in barley semolina spaghetti, with respect to that made of semolina, suggested that polymerisation among the different classes of proteins involves a new bonding arrangement. Due to β-glucan hydrophilicity and competition with starch for water, the replacement of increasing amounts of semolina with barley flour was able to increase the optimal cooking time. The sensory properties of composite spaghetti were judged as better than the control because of the higher firmness and the lower bulkiness and stickiness of the former.