Detection of αs1-I casein in mozzarella Fiordilatte: A possible tool to reveal the use of stored curd in cheesemaking

Impact of Milk Thermization on the Quality Characteristics of P.D.O. "Canestrato Pugliese" Ovine Hard Cheese

The use of raw milk is compulsory in the manufacturing process of most of the European protected designation of origin (PDO) cheeses but, for ovine products, it is often responsible for faulty productions. Since pasteurization is hardly compatible with the PDO concept, a milder treatment (thermization) is allowed in some cases. An investigation was undertaken to assess the effect of thermization on the overall quality of Canestrato Pugliese, a PDO ovine hard cheese of Southern Italy that can be manufactured exclusively from raw milk. Three types of cheese were produced using raw, mild-thermized and high-thermized milk inoculated with a thermophilic commercial starter. The results demonstrated that the heat treatment did not cause remarkable differences in the gross composition, but the microbiological profiles had some differences despite the use of the selected starter. The raw milk cheese contained higher levels (0.5-1 log units) of mesophilic lactobacilli, total viables, total coliforms and enterococci with respect to the thermized counterparts, with the high-thermized cheese showing the lowest levels; these microbiological differences fitted well with the higher content and the different High Performance Liquid Chromatography (HPLC) pattern of soluble nitrogen. The sensory analysis revealed that the thermized cheeses lost some typical sensory characteristics, probably as a consequence of the reduced indigenous microbiota populations. It was concluded that milk thermization could be applied to Canestrato Pugliese manufacturing only together with the development and use of an autochthonous starter.

Quality Characteristics and Consumer Acceptance of High-Moisture Mozzarella Obtained from Heat-Treated Goat Milk

High-moisture mozzarella is a pasta filata cheese manufactured from cow or buffalo milk that has spread all over the world. Its manufacturing from the milk of small ruminants (goat and sheep) has been recently proposed to innovate this ailing sector. Previously, a protocol was reported for making goat mozzarella from unpasteurized milk but, according to legislation, the microbiological safety of raw milk fresh cheeses is not guaranteed. In the present research, two new protocols were tested for producing mozzarella from pasteurized milk prepared by two different low-temperature long-time treatments (67 °C or 63 °C × 30 min). The obtained cheeses were subjected to physical–chemical and microbiological analyses and to consumer testing. The results showed that the heat treatments caused longer coagulation times than those reported in the literature, despite pre-acidification (at pH 5.93 or 6.35) having been performed to counterbalance the expected worsening of the coagulation aptitude. The obtained products showed differences in the chemical composition, texture, proteolysis, and lipolysis. Both pasteurization and pre-acidification played a role in determining these variations. Consumer testing indicated that mozzarella obtained from milk heated at the lower temperature and coagulated at a higher pH reached a good level of appreciation (62%).

Freezing as a solution to preserve the quality of dairy products: the case of milk, curds and cheese

When thinking of the freezing process in dairy, products consumed in frozen state, such as ice creams come to mind. However, freezing is also considered a viable solutions for many other dairy products, due to increasing interest to reduce food waste and to create more robust supply chains. Freezing is a solution to production seasonality, or to extend the market reach for high-value products with otherwise short shelf life. This review focuses on the physical and chemical changes occurring during freezing of milk, curds and cheeses, critical to maintaining quality of the final product. However, freezing is energy consuming, and therefore the process needs to be optimized to maintain product's quality and reduce its environmental footprint. Furthermore, the processing steps leading to the freezing stage may require some changes compared to traditional, fresh products. Unwanted reactions occur at low water activity, and during modifications such as ice crystals growth and recrystallization. These events cause major physical destabilizations of the proteins due to cryoconcentration, including modification of the colloidal-soluble equilibrium. The presence of residual proteases and lipases also cause important modifications to the texture and flavor of the frozen dairy product.

Effect of frozen and refrigerated storage on proteolysis and physicochemical properties of high-moisture citric mozzarella cheese

High-moisture mozzarella is one of the most-exported Italian cheeses worldwide, but its quality is affected by storage. Freezing is regarded as a solution to decrease product waste, extend market reach, and increase convenience, but its effect on quality has to be estimated. In this study, the details related to proteolysis, physicochemical properties, and sensory quality parameters of high-moisture mozzarella as a function of frozen storage (1, 3, and 4 mo) and subsequent refrigerated storage after thawing (1, 3, and 8 d) were evaluated. Frozen cheeses stored at -18°C showed a higher extent of proteolysis, as well as different colorimetric and sensory properties, compared with the fresh, nonfrozen control. Sensory evaluation showed the emergence of oxidized and bitter taste after 1 mo of frozen storage, which supports the proteolysis data. The extent of proteolysis of frozen-stored cheese after thawing was greater than that measured in fresh cheese during refrigerated storage. These results help better understand the changes occurring during frozen storage of high-moisture mozzarella cheese and evaluate possible means to decrease the effect of freezing on the cheese matrix.

Production and characterisation of reduced-fat and PUFA-enriched Burrata cheese

Burrata is an Italian fresh 'pasta filata' cheese made from cow's milk and cream that is rapidly spreading in Europe. It has very high caloric content, and a technological protocol was developed for producing a reduced-fat type and fortifying it with polyunsaturated fatty acids (PUFA) of vegetable origin. A satisfactory reduced-fat prototype was obtained by using a 14% fat cream, which was specifically developed by diluting double cream with a suspension of carob seed flour. The composition of the new cheese changed with respect to the control, but the sensory characteristics were not impaired. Moisture increased from 62·6 to 68·4%, fat on dry matter decreased from 59·1 to 34·7%, and the caloric content decreased from 1060·8 to 718 J/100 g. Proteolysis and lipolysis were not affected by the technological modifications: after 7 d storage, the electrophoretic pattern of caseins and the free fatty acids profile of experimental and control cheeses were not significantly different. Fortification of reduced-fat Burrata with PUFA was obtained by using two commercial formulates available at a compatible price with the current economic values of the cheese. The two formulates derived from flaxseeds and Carthamus tinctorius oil and allowed enrichment in C18 :3 : n3 (α-linolenic acid, ALA), and 9cis,11trans- and 10trans,12cis- conjugated linoleic acid (CLA), respectively. Fortification was easy to perform under a technical point of view, but the negative sensory impact limited fortification at a maximum of 7·0 mg g-1 fat ALA and 6·8 g-1 fat CLA.

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.

A control method to inspect the compositional authenticity of Minas Frescal cheese by gel electrophoresis

This study introduces a qualitative method to inspect the compositional authenticity of white nonripened cheeses like Minas Frescal, a typical Brazilian cheese, especially when irregular replacement of milk by whey is suspected. A sodium dodecyl sulfate gel electrophoresis (SDS-PAGE) method, followed by image densitometry, was validated. Cheeses were freeze-dried to electrophoresis, and β-lactoglobulin (β-LG) was chosen as the adulteration marker. In gel trypsin digestion followed by matrix assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry provided its identification. Cheeses with a minimum of 14 mg·g(-1) of β-LG are considered to be adulterated. The method shows satisfactory precision with a detection limit of 7 mg·g(-1). Forty-two commercial samples from inspected establishments were then assessed and subjected to cluster analysis. Compliant and noncompliant groups were set with 24 (57%) authentic samples and 18 (43%) adulterated samples, respectively, showing that proper analytical monitoring is required to inhibit this practice.