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Cheese | Pasta-Filata Cheeses: Traditional Pasta-Filata Cheese
Pasta-Filata Cheeses: Traditional Pasta-Filata Cheese M De Angelis and M Gobbetti, University of Bari, Bari, Italy ª 2011 Elsevier Ltd. All rights reserved.
Introduction Pasta-filata cheeses are a diverse group of cheese varieties manufactured from the milk of cows, water buffalo, goats, or sheep. Pasta-filata cheeses originated in northern Mediterranean areas, encompassing Italy, Greece, the Balkans, Turkey, and eastern Europe. The term pastafilata derives from an Italian phrase that literally means ‘spun paste’ or ‘stretched curd’. Some cheeses are soft or semisoft and are consumed fresh or after a short period of ripening (e.g., high-moisture Mozzarella, low-moisture Mozzarella or Pizza cheese, and Scamorza). Other cheeses are hard or especially semihard and undergo extensive ripening before consumption (e.g., Caciocavallo, Ragusano, Kashkaval, and Provolone). All pasta-filata cheeses share a unique processing step toward the end of manufacture, when the curd is immersed in hot water or salt brine and manually or mechanically worked (stretched) to a semiflowable plastic consistency that may be formed or molded into a variety of shapes. The main chemical composition of some pasta-filata cheeses is shown in Table 1. Before describing the texture, microbiology, and ripening aspects, brief details of the specific technological traits of the main pasta-filata cheeses will be given.
Mozzarella di Bufala Campana Mozzarella di Bufala Campana has a protected designation of origin (PDO) and is manufactured from only raw milk of water buffalo (Bubalus bubalis) in southern Italy (Campania and Lazio regions). An optimal ratio of protein ( 4.3–4.7%) and fat (7.0% or above) is required to get optimal functional characteristics of the cheese. Natural whey cultures are used as starters (2.5% of the cheese milk). The whey from previous cheesemaking is incubated at room temperature until it reaches an acidity of 40–60 SH 100 ml 1. Liquid calf rennet is added to the milk at 34–38 C and coagulation takes 30 min. After cutting into grains of dimensions of a nut (2–3 cm), the curd is allowed to ripen in the whey for a variable time period, in most of the cases 5 h from the addition of rennet. Stretching of the curd is initiated by adding hot water (95 C) to raise the curd temperature to 68 C. Stretched curd is then immersed in cool water and further in brine, before packaging. Mozzarella di Bufala Campana
has a round shape, although other typical shapes (e.g., bocconcini, trecce, and nodini) are manufactured. It weighs 20–800 g, depending on the shape. The color is porcelain white, with very thin rind (1 mm) and smooth surface. The flavor is very characteristic and delicate, mainly originating from the lactic acid fermentation by starter organisms.
High-Moisture Mozzarella High-moisture Mozzarella cheese is recognized in Italy as traditional speciality guaranteed (TSG). Since it is traditional and not specific to one region, the cheese is manufactured throughout Italy, mainly using cows’ milk. In Italy, the annual production of cows’ milk high-moisture Mozzarella cheese is noticeably higher than that of water buffalo Mozzarella and it is estimated to be 160 000 tonnes, and is increasing yearly. The fat-indry matter (FDM) content of high-moisture Mozzarella cheese is standardized in the range 13–20%. The technology reflects the protocol described for water buffalo Mozzarella but pasteurized (71.7 C for 15 s) cows’ milk may also be used for the manufacture and natural milk cultures are also frequently used as starters. LowMoisture Mozzarella (Pizza Cheese) During recent decades, the global production of lowmoisture Mozzarella cheese has markedly increased and now it exceeds that of all other pasta-filata cheeses because of premier status as a pizza topping. The FDM content of low-moisture Mozzarella cheese is standardized in the range 30–45%. Therefore, the cheese milk is characterized by a higher casein to fat ratio either by adding nonfat milk solids or, less often, by removal of cream. The standardized milk is pasteurized and then inoculated with starter cultures. The inoculated milk is coagulated with rennet and the coagulum is cut and held at 41 C, especially if a thermophilic starter is used, after which part of the whey is drained off. Curd is then subjected to further draining, matting, and cheddaring until the pH reaches 5.3–5.1. In most of the cases, curd is drysalted and plasticized and stretched mechanically in hot water. The hot plastic curd is forced under pressure into a chilled mold, which gives the cheese its shape and which precools the block so that it retains its shape when removed from the mold.
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746 Cheese | Pasta-Filata Cheeses: Traditional Pasta-Filata Cheese Table 1 Gross chemical composition of some pasta-filata cheeses
Cheese
Moisture (%)
Fat (%)
Total protein (%)
NaCl (%)
pH
pH 4.6-soluble N /(total N)
Mozzarella di Bufala Campana High-moisture Mozzarella Low-moisture Mozzarella Caciocavallo Silano Caciocavallo Pugliese Ragusano Kashkaval Provolone Valpadana
58.0 54.0 47.0 40.0 38.0 38.0 38.0 38.0
21.0 18.0 24.0 27.0 24.0 30.0 32.0 28.5
19.0 22.0 21.0 33.0 23.5 30.0 21.0 24.0
0.8 0.7 1.5 3.9 2.5 2.5 3.0 3.2
5.3 5.7 5.4 5.4 5.4 5.3 5.2 5.3
4.5 4.6 7.5 37.0 18.0 16.0 16 n.a.
The values indicated represent the average of several determinations made by different authors in cheeses that had a slightly different ripening time. n.a., not available.
Caciocavallo Silano and Related Varieties Legally, the manufacture of Caciocavallo Silano is limited to the regions of Calabria, Campania, Molise, Puglia, and Basilicata (southern Italy), where the mountain chains of the ‘Sila’ are located. It is a semihard pasta-filata cheese with PDO status and is manufactured from raw or mildly thermally treated (58 C for 30 s) cows’ milk. Thermophilic natural whey cultures are used as starters. Milk coagulation is achieved using calf rennet paste at 36–38 C. The curd is cut at dimensions of a nut (2–3 cm). Curd grains are allowed to ripen under whey for a time period ranging from 4 to 10 h, depending on acidity, temperature, and size of the cheese. Manual stretching under hot water (70–80 C) results in the typical flask-like shape of the cheese with the head closed by strings. After cooling in water, the curd is salted in brine for at least 6 h. The heads of the curds are tied with a slipknot to poles to favor aeration and allowed to ripen for 15 days to several months. The cheese weighs 1–2.5 kg, with smooth, thin, and yellow rind. The flavor is delicate with a tendency toward sweet for young cheeses, while ripened cheeses tend to become piquant. In the southern Italy, large amounts of other types of Caciocavallo cheeses are manufactured (e.g., Caciocavallo Pugliese and Podolico), the typical feature of which is the use of natural whey starter cultures. These starters are obtained by incubating the fresh whey, derived from a previous cheesemaking, at 40–42 C for 24 h. The protocols for manufacture of these varieties of Caciocavallo mainly reflect those described for Caciocavallo Silano cheese.
Ragusano Ragusano, previously named Caciocavallo Ragusano, is a semihard PDO pasta-filata cheese manufactured in Sicily from raw cows’ milk. It is produced from cows reared mainly on natural pastures of the Hyblean plain region of
the province of Ragusa. Cows’ milk from one or more milkings is coagulated at 34 C using lamb or kid rennet paste. Coagulation generally takes 60–80 min. The curd is progressively cut to dimensions of rice grains (0.7 cm). After draining of almost all the whey, the curd is pressed and hot water is added; the curd is held under these conditions for 85 min. The curd is further subjected to drying for 20 h and cut in slices. Stretching is carried out manually by the addition of hot water (80 C), and giving to the curd a parallelepiped shape with a square section. Salting is carried out in brine. Traditionally, the cheese is ripened in caves for 6–12 months, depending on the varieties. During ripening, the curd may be treated with olive oil several times. The cheese weighs 10–16 kg, with smooth and yellow rind. The flavor is delicate and sweet for young cheeses, while extensively ripened varieties tend to become moderate piquant.
Kashkaval Several varieties of Kaskaval-type cheese are manufactured, generally in Mediterranean areas other than Italy: Kashkaval Balkan, Kashkaval Preslav, Kashkaval Vitosha (Bulgaria), Kackavaly (Croatia), Kachekavalo (Russia), Kasseri (Greece), Kasar (Turkey), and Cascaval Dobrogen (Romania). These varieties of Kashkaval are manufactured from raw or pasteurized milk from cow, sheep, or goat, or from mixed milk. Traditionally, Kashkaval cheese is manufactured from raw milk, which is generally of poor microbiological quality, without the addition of starter cultures. During the last decade, the use of pasteurized milk and starter cultures has been introduced gradually to standardize the quality of Kashkaval cheese. Calf rennet is generally used as the coagulant. The coagulum is usually cut finely into pieces of 6–8 mm and stirred at 32 C for 5 min. Scalding (e.g., 42 C for 35 min) of the curd may or may not be practiced, depending on the varieties. The curd is then ladled into molds and
Cheese | Pasta-Filata Cheeses: Traditional Pasta-Filata Cheese
allowed to drain and press under its own weight for 30 min. The bed of fused curds is then sliced into blocks and cheddared to allow the lactic fermentation to continue. The ripened curd is texturized, which is accomplished by soaking the blocks of curd of different dimensions in hot (72–75 C) brine. The curd mass is agitated with a strong wooden stick in order to obtain a compact structure. The hot curd is then hand-kneaded like a dough, which makes it more plastic and elastic. In traditional manufacturing, Kashkaval cheese is partially dry salted during kneading of the texturized curd. Kashkaval is generally ripened for 3–4 months. The typical form of Kashkaval is flat cylindrical with a smooth, amber-colored rind, and the cheese is 30 cm in diameter, 10–13 cm in height, and 7–8 kg in weight. The flavor is generally full, sharp, balanced, and moderately piquant.
Provolone Valpadana and Related Varieties Although certainly derived from the tradition of pastafilata varieties from southern Italy, Provolone Valpadana is a semihard PDO cheese manufactured from raw cows’ milk in the north of Italy (Lombardia, Emilia-Romagna, Veneto, and Trentino regions). Thermophilic natural whey or milk cultures are used as starters. Milk coagulation is achieved using calf rennet or calf rennet paste, depending on the variety of cheese (sweet or piquant) to be manufactured. After cutting, the curd is allowed to ripen under whey until the desirable acidity is reached. Stretching is carried out manually in hot water giving the curd the typical flask-like shape with the head closed by strings. Salting is carried out in brine and the cheese is ripened for different time periods, depending on the variety (in some cases up to 6 months); during ripening, the cheeses are bound by strings and hung. The cheese weighs 500 g to 100 kg, and for the ripened cheeses the flavor is rather piquant. Provolone del Monaco is another semihard pasta-filata cheese traditionally manufactured in the Lattari mountains area of Campania region from raw cows’ milk and without starter addition. Currently, it has transitory PDO recognition. The protocol for manufacture of this variety of Provolone cheese mainly reflects that described for Provolone Valpadana.
Texture The stretching process is the main characteristic feature of pasta-filata cheeses and profoundly influences their texture. Stretching transforms the amorphous threedimensional protein matrix of the curd into an oriented, quasilaminated structure, consisting of parallel-aligned
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protein fibers separated by long channels containing accumulated fat and serum. This ability of the curd seems to be governed primarily by the amount of casein-associated calcium (calcium phosphate) that is available to cross-link the amorphous para-casein matrix at the time heat is applied to the curd. The hydration of para-casein increases as the level of casein-associated calcium decreases, which probably contributes greatly to the ability of the curd to plasticize. Curd that contains too much casein-associated calcium fails to attain a smooth, stretchable consistency upon heating, while curd with too little casein-associated calcium becomes excessively soft and fluid-like during stretching. Two parameters determine the amount of casein-associated calcium in the curd at the time of stretching: (1) the total calcium content of the curd and (2) the distribution of total calcium between the soluble and insoluble (e.g., casein-associated) states. Casein-associated calcium dissociates from the para-casein matrix to the water phase as the pH of the curd decreases and syneresis progresses. Calcium losses are marked when acidification occurs before the onset of syneresis, as in the manufacture of preacidified and directly acidified Mozzarella cheeses. Overall, curd that contains a high total calcium content at stretching (e.g., 30 mg g 1 protein, as for low-moisture Mozzarella cheese) must have a low pH, in the range of 5.1–5.3, in order to attain a casein-associated calcium level that is low enough to allow the curd to plasticize and stretch. On the contrary, curd with a low total calcium content (e.g., 22 mg g 1protein, as for directly acidified Mozzarella cheese) is optimally stretched at a higher pH value (e.g., 5.6–5.7). Therefore, controlled acidification, demineralization, and dehydration, coupled with attaining a critical curd pH at the time of stretching, are the key technological parameters for all pasta-filata cheeses. This unique curd architecture gives rise to a number of important functional characteristics. For example, traditional high-moisture Mozzarella cheese, which is typically shaped into balls and packed in a dilute salt solution, retains a tender, slightly springy and chewy texture despite having a very juicy body that is very high in moisture. The surface of high-moisture Mozzarella can be peeled off in layers, reminiscent of peeling an onion. Similarly, low-moisture Mozzarella (Pizza cheese) that is extruded continuously to form string cheese is extremely springy and elastic and peels easily into layers along the axis parallel to the fiber direction, making it well suited as a snacking cheese for children. The elastic fibrous structure also lends itself well to breading and deep frying, for use as an appetizer or snacking cheese. The fibrous structure of low-moisture Mozzarella enables it to melt on pizza to a stringy, elastic, comparatively chewy consistency that has come to be accepted as the standard for Pizza cheese. Textural defects are particularly problematic in Pizza cheese because the quality of
748 Cheese | Pasta-Filata Cheeses: Traditional Pasta-Filata Cheese
Pizza cheese is largely defined by its shredding and melting properties. Pizza cheese with a soft body due to high fat or moisture content, low calcium content, or excessive proteolysis may gum-up the shredding equipment and take longer to process through the equipment. The resulting cheese shreds may be deformed in shape, sticky, and prone to matting. Such cheese when melted may flow excessively (soupy) and lack stretch, elasticity, and chewiness. At the other extreme, Pizza cheese with an abnormally firm body due to low moisture or fat content may also take longer to shred and shatter and form fines during shredding. Such cheese may melt to a very tough and elastic consistency that is overly chewy. In long-ripened pasta-filata cheeses, such as Caciocavallo and Provolone, the unique stretched curd architecture manifests itself as a flaky texture.
Microbiology Thermophilic lactic acid bacteria such as Streptococcus thermophilus, alone or mainly in combination with Lactobacillus delbrueckii subsp. bulgaricus or Lb. helveticus, are used as starters for most pasta-filata cheeses. However, low-moisture Mozzarella for pizza may also be manufactured using mesophilic starters (e.g., Lactococcus lactis subsp. lactis and Lc. lactis subsp. cremoris) or some varieties of Kashkaval cheese also include in the starter formulation Leuconostoc sp. and Lb. casei; this is because the high temperature used in cheesemaking is more tolerated by thermophilic starters. Streptococcus thermophilus, Lb. delbrueckii subsp. bulgaricus, and Lb. helveticus survive and remain metabolically active when the curd temperature at stretching is 55 C. However, the activity of thermophilic starters is substantially decreased at the higher stretching temperature of the curd (e.g., 62–66 C). Besides, thermophilic starters more easily allow to attain the range of moisture desired for Pizza cheese (48–52%). Nevertheless, in several cases, natural starter cultures have a very heterogeneous composition. In addition to thermophilic lactic acid bacteria, natural whey starter cultures used for the manufacture of high-moisture Mozzarella cheese contain large numbers of mesophilic lactic acid bacteria such as Lb. plantarum, Lb. casei subsp. casei, Lc. lactis subsp. lactis, and enterococci (mainly Enterococcus faecium and Ec. durans). A study on a large number of natural whey cultures for Caciocavallo Silano cheese revealed mainly thermophilic lactic acid bacteria, even though the mesophilic Lc. lactis subsp. lactis was also present in several preparations. Natural whey cultures for the manufacture of Caciocavallo Pugliese are dominated by strains of Sc. thermophilus, Lb. delbrueckii ssp., Lb. helveticus, Lb. fermentum, and Lb. gasseri. Modifications in the composition of the microbial population are generally seen during ripening of semihard pastafilata cheeses. Although the thermophilic lactic acid bacteria
from the natural whey cultures dominate during early ripening, Caciocavallo Pugliese harbors a heterogeneous population of non-starter lactic acid bacteria (NSLAB) during late ripening, which is dominated by Lb. parabuchneri and Lb. paracasei subsp. paracasei. Lactobacillus paracasei subsp. paracasei, Lb. fermentum, and Lb. plantarum generally dominate in Caciocavallo Silano cheese during late ripening. Ripening of Provolone del Monaco, made without the use of deliberately added starters, is typically characterized by the dominance of thermophilic lactic acid bacteria (Sc. thermophilus, Sc. macedonicus, Lb. delbrueckii spp., and Lb. fermentum), together with enterococci and NSLAB of the Lb. casei group, especially Lb. rhamnosus. The main role of starter cultures during the manufacture of pasta-filata cheeses is to synthesize enough lactic acid to demineralize and transform the curd into the state that undergoes stretching in hot water at the target pH. Furthermore, microbial acidification has to proceed at a rate that allows an adequate syneresis during manufacture to achieve the target moisture content. Rapid acidification allows the manufacturing time to be shortened, which reduces syneresis and enables a high moisture content to be achieved in the final cheese. Starter cultures may be eliminated altogether and replaced by direct chemical acidification of the milk during manufacture of high- or lowmoisture Mozzarella, provided that an appropriate level of demineralization in combination with an appropriate pH at stretching is achieved. The secondary role of starters in ripened pasta-filata cheeses, including Pizza cheese, is concerning secondary proteolysis. Nevertheless, the significance of microbial proteolysis is largely influenced by the temperature of stretching. The synthesis of small peptides and free amino acids (FAAs) by starters is also important in low-moisture Mozzarella because they markedly influence the browning properties of the cheese during melting and baking in pizza making, which is an important functional attribute. Furthermore, Mozzarella cheeses that are manufactured using thermophilic starters generally have a characteristic yogurt-like note resulting from the synthesis of acetaldehyde by Sc. thermophilus and Lb. delbrueckii subsp. bulgaricus. Mozzarella that is manufactured without starter cultures through direct acidification will assume the flavor of the chemical compounds used. For example, when vinegar is used as the acidulant, the resulting cheese will possess a mild acetic acid flavor note. On the contrary, if citric acid is used, the cheese will be insipid, due to the lack of flavor other than that arising from milk constituents.
Ripening Some pasta-filata cheeses such as high-moisture Mozzarella and Mozzarella di Bufala Campana are eaten immediately after manufacture without ripening. On the contrary, low-moisture Mozzarella (Pizza cheese)
Cheese | Pasta-Filata Cheeses: Traditional Pasta-Filata Cheese
undergoes a brief but essential ripening period (less than 1 month at 4 C) to develop the desirable functional characteristics. Immediately after manufacture, Pizza cheese is generally difficult to shred because it contains free moisture at the cut surfaces. Besides, unripened Pizza cheese melts to an excessively tough and fibrous consistency with limited ability to flow and releases a considerable amount of watery serum. After 2 or 3 weeks of ripening, the shredding and melting characteristics of the cheese improve markedly. This is due to both proteolytic and physicochemical changes. Proteolysis is initiated by the residual coagulant and plasmin. Hydrolysis of s1- and -caseins results in an increase of meltability (e.g., capacity to flow) and a decrease in the toughness and fibrous consistency of the melted cheese. The hydrolysis of caseins leads to an increased proportion of pH 4.6-soluble nitrogen (N). The ratio of pH 4.6-soluble N/total N is higher for low-moisture Mozzarella than for high-moisture Mozzarella and Mozzarella di Bufala Campana (Table 1). The rate of primary proteolysis will depend on the period of ripening and the degree of thermal inactivation of the coagulant during stretching. Curd that is stretched at a high temperature (e.g., >65 C) has limited residual coagulant activity and requires a longer ripening time to develop functional characteristics than curd that is stretched at a low temperature (e.g., 55 C) with a relatively high residual coagulant activity. Peptides that are produced through primary proteolysis by coagulant serve as the substrate for further hydrolysis to smaller peptides and FAAs by starter bacteria, provided that they survive during stretching. Besides primary proteolysis, physicochemical changes occur during the first few weeks. Initially, much of the water within the
Table 2 Concentration (mg kg
1
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cheese structure exists in the form of serum pockets that are loosely held within open channels that separate the network of parallel protein fibers. Nevertheless, under the influence of the sodium chloride that is dissolved in the water phase of the curd, casein aggregates that serve as the building blocks of the protein fibers interact and bind free water through a process of casein solvation and solubilization. As a consequence, protein fibers become more hydrated and the water-holding capacity of the cheese increases, giving rise to improved shredding and melting characteristics. The development of flavor is of limited concern during the brief ripening of Pizza cheese with low concentrations of total FAAs and total free fatty acids (FFAs) (500 and 360 mg kg 1 cheese, respectively), as the cheese is expected to be very mild in flavor. Strong flavor development is essential during the ripening of long-ripened pastafilata cheeses such as Caciocavallo Silano, Ragusano, Provolone Valpadana, and Kashkaval. Proteolysis and lipolysis are considered as the two primary biochemical processes of long-ripened pasta-filata cheeses, which involve many chemical, physical, and microbiological changes under controlled environmental conditions. During ripening, the distribution pattern of FAAs and FFAs changes due to the complexity of the maturation process, resulting in the formation of the characteristic flavor of long-ripened pasta-filata cheeses (Tables 2 and 3). Proteolysis of long-ripened pasta-filata cheeses is influenced by chymosin, plasmin, and peptidases from starters and NSLAB, pH, moisture of curds, temperature and time of storage, salt, and humidity. Urea-polyacrylamide gel electrophoresis (urea-PAGE)
cheese) of individual and total free amino acids in some pasta-filata cheeses
Amino acid
Caciocavallo Silano
Caciocavallo Pugliese
Ragusano
Kashkaval
Provolone Valpadana
Aspartic acid Cysteic acid Threonine Serine Glutamic acid Glycine Alanine Cysteine Valine Methionine Isoleucine Leucine Tyrosine Phenylalanine Histidine Lysine Arginine Proline Total free amino acids
660 530 670 1790 3860 430 690 140 1500 460 1200 2430 680 1100 160 2560 0 2320 21 180
646 43 449 612 1969 410 640 109 991 395 992 1552 458 1286 267 1414 53 1632 13 918
800 0 800 1100 6000 500 540 120 210 650 156 2800 430 1900 850 3000 0 2000 21 856
182 0 109 41 401 67 191 0 104 66 81 260 130 295 62 126 80 173 2368
1000 0 30 700 2000 300 800 0 1000 200 0 3000 0 0 30 3000 0 0 12 060
The values indicated represent the average of several determinations made by different authors in cheeses that had a slightly different ripening time.
Table 3 Concentration (mg kg Butyric (C4:0) Caciocavallo Silano Caciocavallo Pugliese Ragusano Kashkaval Provolone Valpadana a
1
cheese) of individual and total free fatty acids in some pasta-filata cheeses
Caproic (C6:0)
Caprylic (C8:0)
Capric (C10:0)
Lauric (C12:0)
Myristic (C14:0)
Palmitic (C16:0)
Stearic (C18:0)
Oleic (C18:1)
Linoleic (C18:2)
Linolenic (C18:3)
Total free fatty acids
4
2
540
985
875
924
11 650
300
2600
680
170
18 730
320
100
35
70
50
95
160
20
145
25
18
1038
1093 5 782
437 5 308
161 3 81
309 5 172
317 17 122
597 168 120
123 554 199
1285 180 334a
371 456
1232 45
40 16
5965 1454 2118
C18 congeners refer to stearic (C18:0), oleic (C18:1), linoleic (C18:2), and linolenic (C18:3) acids. The values indicated represent the average of several determinations made by different authors in cheeses that had a slightly different ripening time.
Cheese | Pasta-Filata Cheeses: Traditional Pasta-Filata Cheese 1
2
3
4
5
6
7
8
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9 10 11 12 13
γ-Casein β-Casein β-Casein (f1–192) αs1-Casein αs1-Casein (f24–199)
Figure 1 Urea-PAGE of pH 4.6-insoluble nitrogen fraction from different sections of Caciocavallo Pugliese cheese during ripening. Lane 1, sodium caseinate standard; lanes 2–5, outer section at 1, 21, 42, and 60 days; lanes 6–9, middle section at 1, 21, 42, and 60 days; and lanes 10–13, inner section at 1, 21, 42, and 60 days.
indicated that both s1- and -casein are hydrolyzed during ripening. Owing to the large size of most of the longripened pasta-filata cheeses, persistence of gradients of temperature, and especially of NaCl between the center and rind of the curd, may influence proteolysis during cheese ripening (Figure 1). The action of both plasmin and chymosin on s1- and -casein is clearly evident from their characteristic proteolytic products. Chymosin readily hydrolyzes s1-casein with the concomitant formation of a peptide identified as s1-casein (f24–199). The primary cleavage site of chymosin in -casein is Leu192–Tyr193. In solution, chymosin cleaves -casein at seven sites. The resulting large peptides are -casein f1–192, f1–189, f1–163/4/5, and f1–139. Plasmin has been shown to be active in long-ripened pasta-filata cheeses since it is heat stable and not inactivated under the time, temperature, and pH conditions that occur during stretching. Evidence of plasmin activity in Caciocavallo Pugliese cheese is shown by the degradation of -casein with the concomitant formation of -caseins. The primary proteolysis may also differ for different pasta-filata varieties depending on the stretching temperature. For instance, the high stretching temperature used during the manufacture of Provolone cheese results in limited residual coagulant activity and, therefore, proteolysis proceeds slowly. On the contrary, Kashkaval is stretched at a lower temperature, which results in higher residual coagulant activity and greater primary and further secondary proteolysis during ripening. The same is generally found in Ragusano and Caciocavallo Pugliese cheeses. The ratio of water-soluble N/total N may vary from 13 to 37% in long-ripened pasta-filata
cheeses (Caciocavallo Silano, Caciocavallo Pugliese, Ragusano, Kashkaval, and Provolone Valpadana), depending on the specifics of manufacture (Table 1). The concentration of FAAs in the water-soluble extract of cheeses may vary from 2368 to 21 856 mg kg 1, indicating a very different level of secondary proteolysis among the different cheeses (Table 2). At the end of ripening, the average concentration of FAAs in Caciocavallo Silano and Ragusano cheeses is 21 180 mg kg 1 (corresponding to 6.6% of the total protein content), which may be considered relatively high compared to Caciocavallo Pugliese (13 918 mg kg 1), Provolone Valpadana (12 060 mg kg 1), and especially Kashkaval, which typically has 2368 mg kg 1 (corresponding to 1% of the total protein content). Glutamic acid, valine, leucine, and lysine are the FAAs commonly present at high concentrations in all long-ripened pasta-filata cheeses. The other FAAs are present at different concentrations among the cheeses. Long-ripened pasta-filata cheeses are characterized by a different level of lipolysis. The concentration of total FFAs may vary from 1388 to 18 730 mg kg 1 (Table 3). Probably also due to the use of calf rennet paste, Caciocavallo Silano contains high concentrations of FFAs (18 730 mg kg 1), the principal of which are caprylic, capric, lauric, palmitic, myristic, and oleic acids. During the ripening of Ragusano cheese, lipolysis by lamb or kid rennet paste liberates 5965 mg kg 1 of free FFAs. Compared to proteolysis, lipolysis seems to proceed at higher rates on the exterior portion of the curd blocks. The opposite characterizes ripening of Caciocavallo Pugliese where the main liberation of FFAs
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(e.g., butyric, caproic, palmitic, and oleic) decreases from the middle and inner to outer sections of the cheese. See also: Cheese: Cheese Flavor; Hard Italian Cheeses; Pasta-Filata Cheeses: Low-Moisture Part-Skim Mozzarella (Pizza Cheese). Lactic Acid Bacteria: Lactobacillus spp.: General Characteristics.
Further Reading Collins YF, McSweeney PLH, and Wilkinson MG (2004) Lypolysis and catabolism of fatty acids in cheese. In: Fox PF, McSweeney PLH, Cogan TM, and Guinee TP (eds.) Cheese:
Chemistry, Physics and Microbiology, Vol. 2, pp. 373–389. London, UK. Beresford: Elsevier Ltd. Kindstedt P, Caric M, and Milanovic S (2004) Pasta-filata cheeses. In: Fox PF, McSweeney PLH, Cogan TM, and Guinee TP (eds.) Cheese: Chemistry, Physics and Microbiology, Vol. 2, pp. 251–277. Beresford: Elsevier Ltd. Lucey JA, Johnson ME, and Horne DS (2003) Perspectives on the basis of the rheology and texture properties of cheese. Journal of Dairy Science 86: 2725–2743. McSweeney PLH (2004) Biochemistry of cheese ripening: Introduction and overview. In: Fox PF, McSweeney PLH, Cogan TM, and Guinee TP (eds.) Cheese: Chemistry, Physics and Microbiology, Vol. 2, pp. 347–360. Beresford: Elsevier Ltd. Piraino P, Zotta T, Ricciardi A, Parente E, and Salzano G (2008) Acid production, proteolysis, autolytic and inhibitory properties of lactic acid bacteria isolated from pasta-filata cheeses: A multivariate screening study. International Dairy Journal 18: 81–92.
Introduction Pasta-filata cheeses are a diverse group of cheese varieties manufactured from the milk of cows, water buffalo, goats, or sheep. Pasta-filata cheeses originated in northern Mediterranean areas, encompassing Italy, Greece, the Balkans, Turkey, and eastern Europe. The term pastafilata derives from an Italian phrase that literally means ‘spun paste’ or ‘stretched curd’. Some cheeses are soft or semisoft and are consumed fresh or after a short period of ripening (e.g., high-moisture Mozzarella, low-moisture Mozzarella or Pizza cheese, and Scamorza). Other cheeses are hard or especially semihard and undergo extensive ripening before consumption (e.g., Caciocavallo, Ragusano, Kashkaval, and Provolone). All pasta-filata cheeses share a unique processing step toward the end of manufacture, when the curd is immersed in hot water or salt brine and manually or mechanically worked (stretched) to a semiflowable plastic consistency that may be formed or molded into a variety of shapes. The main chemical composition of some pasta-filata cheeses is shown in Table 1. Before describing the texture, microbiology, and ripening aspects, brief details of the specific technological traits of the main pasta-filata cheeses will be given.
Mozzarella di Bufala Campana Mozzarella di Bufala Campana has a protected designation of origin (PDO) and is manufactured from only raw milk of water buffalo (Bubalus bubalis) in southern Italy (Campania and Lazio regions). An optimal ratio of protein ( 4.3–4.7%) and fat (7.0% or above) is required to get optimal functional characteristics of the cheese. Natural whey cultures are used as starters (2.5% of the cheese milk). The whey from previous cheesemaking is incubated at room temperature until it reaches an acidity of 40–60 SH 100 ml 1. Liquid calf rennet is added to the milk at 34–38 C and coagulation takes 30 min. After cutting into grains of dimensions of a nut (2–3 cm), the curd is allowed to ripen in the whey for a variable time period, in most of the cases 5 h from the addition of rennet. Stretching of the curd is initiated by adding hot water (95 C) to raise the curd temperature to 68 C. Stretched curd is then immersed in cool water and further in brine, before packaging. Mozzarella di Bufala Campana
has a round shape, although other typical shapes (e.g., bocconcini, trecce, and nodini) are manufactured. It weighs 20–800 g, depending on the shape. The color is porcelain white, with very thin rind (1 mm) and smooth surface. The flavor is very characteristic and delicate, mainly originating from the lactic acid fermentation by starter organisms.
High-Moisture Mozzarella High-moisture Mozzarella cheese is recognized in Italy as traditional speciality guaranteed (TSG). Since it is traditional and not specific to one region, the cheese is manufactured throughout Italy, mainly using cows’ milk. In Italy, the annual production of cows’ milk high-moisture Mozzarella cheese is noticeably higher than that of water buffalo Mozzarella and it is estimated to be 160 000 tonnes, and is increasing yearly. The fat-indry matter (FDM) content of high-moisture Mozzarella cheese is standardized in the range 13–20%. The technology reflects the protocol described for water buffalo Mozzarella but pasteurized (71.7 C for 15 s) cows’ milk may also be used for the manufacture and natural milk cultures are also frequently used as starters. LowMoisture Mozzarella (Pizza Cheese) During recent decades, the global production of lowmoisture Mozzarella cheese has markedly increased and now it exceeds that of all other pasta-filata cheeses because of premier status as a pizza topping. The FDM content of low-moisture Mozzarella cheese is standardized in the range 30–45%. Therefore, the cheese milk is characterized by a higher casein to fat ratio either by adding nonfat milk solids or, less often, by removal of cream. The standardized milk is pasteurized and then inoculated with starter cultures. The inoculated milk is coagulated with rennet and the coagulum is cut and held at 41 C, especially if a thermophilic starter is used, after which part of the whey is drained off. Curd is then subjected to further draining, matting, and cheddaring until the pH reaches 5.3–5.1. In most of the cases, curd is drysalted and plasticized and stretched mechanically in hot water. The hot plastic curd is forced under pressure into a chilled mold, which gives the cheese its shape and which precools the block so that it retains its shape when removed from the mold.
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746 Cheese | Pasta-Filata Cheeses: Traditional Pasta-Filata Cheese Table 1 Gross chemical composition of some pasta-filata cheeses
Cheese
Moisture (%)
Fat (%)
Total protein (%)
NaCl (%)
pH
pH 4.6-soluble N /(total N)
Mozzarella di Bufala Campana High-moisture Mozzarella Low-moisture Mozzarella Caciocavallo Silano Caciocavallo Pugliese Ragusano Kashkaval Provolone Valpadana
58.0 54.0 47.0 40.0 38.0 38.0 38.0 38.0
21.0 18.0 24.0 27.0 24.0 30.0 32.0 28.5
19.0 22.0 21.0 33.0 23.5 30.0 21.0 24.0
0.8 0.7 1.5 3.9 2.5 2.5 3.0 3.2
5.3 5.7 5.4 5.4 5.4 5.3 5.2 5.3
4.5 4.6 7.5 37.0 18.0 16.0 16 n.a.
The values indicated represent the average of several determinations made by different authors in cheeses that had a slightly different ripening time. n.a., not available.
Caciocavallo Silano and Related Varieties Legally, the manufacture of Caciocavallo Silano is limited to the regions of Calabria, Campania, Molise, Puglia, and Basilicata (southern Italy), where the mountain chains of the ‘Sila’ are located. It is a semihard pasta-filata cheese with PDO status and is manufactured from raw or mildly thermally treated (58 C for 30 s) cows’ milk. Thermophilic natural whey cultures are used as starters. Milk coagulation is achieved using calf rennet paste at 36–38 C. The curd is cut at dimensions of a nut (2–3 cm). Curd grains are allowed to ripen under whey for a time period ranging from 4 to 10 h, depending on acidity, temperature, and size of the cheese. Manual stretching under hot water (70–80 C) results in the typical flask-like shape of the cheese with the head closed by strings. After cooling in water, the curd is salted in brine for at least 6 h. The heads of the curds are tied with a slipknot to poles to favor aeration and allowed to ripen for 15 days to several months. The cheese weighs 1–2.5 kg, with smooth, thin, and yellow rind. The flavor is delicate with a tendency toward sweet for young cheeses, while ripened cheeses tend to become piquant. In the southern Italy, large amounts of other types of Caciocavallo cheeses are manufactured (e.g., Caciocavallo Pugliese and Podolico), the typical feature of which is the use of natural whey starter cultures. These starters are obtained by incubating the fresh whey, derived from a previous cheesemaking, at 40–42 C for 24 h. The protocols for manufacture of these varieties of Caciocavallo mainly reflect those described for Caciocavallo Silano cheese.
Ragusano Ragusano, previously named Caciocavallo Ragusano, is a semihard PDO pasta-filata cheese manufactured in Sicily from raw cows’ milk. It is produced from cows reared mainly on natural pastures of the Hyblean plain region of
the province of Ragusa. Cows’ milk from one or more milkings is coagulated at 34 C using lamb or kid rennet paste. Coagulation generally takes 60–80 min. The curd is progressively cut to dimensions of rice grains (0.7 cm). After draining of almost all the whey, the curd is pressed and hot water is added; the curd is held under these conditions for 85 min. The curd is further subjected to drying for 20 h and cut in slices. Stretching is carried out manually by the addition of hot water (80 C), and giving to the curd a parallelepiped shape with a square section. Salting is carried out in brine. Traditionally, the cheese is ripened in caves for 6–12 months, depending on the varieties. During ripening, the curd may be treated with olive oil several times. The cheese weighs 10–16 kg, with smooth and yellow rind. The flavor is delicate and sweet for young cheeses, while extensively ripened varieties tend to become moderate piquant.
Kashkaval Several varieties of Kaskaval-type cheese are manufactured, generally in Mediterranean areas other than Italy: Kashkaval Balkan, Kashkaval Preslav, Kashkaval Vitosha (Bulgaria), Kackavaly (Croatia), Kachekavalo (Russia), Kasseri (Greece), Kasar (Turkey), and Cascaval Dobrogen (Romania). These varieties of Kashkaval are manufactured from raw or pasteurized milk from cow, sheep, or goat, or from mixed milk. Traditionally, Kashkaval cheese is manufactured from raw milk, which is generally of poor microbiological quality, without the addition of starter cultures. During the last decade, the use of pasteurized milk and starter cultures has been introduced gradually to standardize the quality of Kashkaval cheese. Calf rennet is generally used as the coagulant. The coagulum is usually cut finely into pieces of 6–8 mm and stirred at 32 C for 5 min. Scalding (e.g., 42 C for 35 min) of the curd may or may not be practiced, depending on the varieties. The curd is then ladled into molds and
Cheese | Pasta-Filata Cheeses: Traditional Pasta-Filata Cheese
allowed to drain and press under its own weight for 30 min. The bed of fused curds is then sliced into blocks and cheddared to allow the lactic fermentation to continue. The ripened curd is texturized, which is accomplished by soaking the blocks of curd of different dimensions in hot (72–75 C) brine. The curd mass is agitated with a strong wooden stick in order to obtain a compact structure. The hot curd is then hand-kneaded like a dough, which makes it more plastic and elastic. In traditional manufacturing, Kashkaval cheese is partially dry salted during kneading of the texturized curd. Kashkaval is generally ripened for 3–4 months. The typical form of Kashkaval is flat cylindrical with a smooth, amber-colored rind, and the cheese is 30 cm in diameter, 10–13 cm in height, and 7–8 kg in weight. The flavor is generally full, sharp, balanced, and moderately piquant.
Provolone Valpadana and Related Varieties Although certainly derived from the tradition of pastafilata varieties from southern Italy, Provolone Valpadana is a semihard PDO cheese manufactured from raw cows’ milk in the north of Italy (Lombardia, Emilia-Romagna, Veneto, and Trentino regions). Thermophilic natural whey or milk cultures are used as starters. Milk coagulation is achieved using calf rennet or calf rennet paste, depending on the variety of cheese (sweet or piquant) to be manufactured. After cutting, the curd is allowed to ripen under whey until the desirable acidity is reached. Stretching is carried out manually in hot water giving the curd the typical flask-like shape with the head closed by strings. Salting is carried out in brine and the cheese is ripened for different time periods, depending on the variety (in some cases up to 6 months); during ripening, the cheeses are bound by strings and hung. The cheese weighs 500 g to 100 kg, and for the ripened cheeses the flavor is rather piquant. Provolone del Monaco is another semihard pasta-filata cheese traditionally manufactured in the Lattari mountains area of Campania region from raw cows’ milk and without starter addition. Currently, it has transitory PDO recognition. The protocol for manufacture of this variety of Provolone cheese mainly reflects that described for Provolone Valpadana.
Texture The stretching process is the main characteristic feature of pasta-filata cheeses and profoundly influences their texture. Stretching transforms the amorphous threedimensional protein matrix of the curd into an oriented, quasilaminated structure, consisting of parallel-aligned
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protein fibers separated by long channels containing accumulated fat and serum. This ability of the curd seems to be governed primarily by the amount of casein-associated calcium (calcium phosphate) that is available to cross-link the amorphous para-casein matrix at the time heat is applied to the curd. The hydration of para-casein increases as the level of casein-associated calcium decreases, which probably contributes greatly to the ability of the curd to plasticize. Curd that contains too much casein-associated calcium fails to attain a smooth, stretchable consistency upon heating, while curd with too little casein-associated calcium becomes excessively soft and fluid-like during stretching. Two parameters determine the amount of casein-associated calcium in the curd at the time of stretching: (1) the total calcium content of the curd and (2) the distribution of total calcium between the soluble and insoluble (e.g., casein-associated) states. Casein-associated calcium dissociates from the para-casein matrix to the water phase as the pH of the curd decreases and syneresis progresses. Calcium losses are marked when acidification occurs before the onset of syneresis, as in the manufacture of preacidified and directly acidified Mozzarella cheeses. Overall, curd that contains a high total calcium content at stretching (e.g., 30 mg g 1 protein, as for low-moisture Mozzarella cheese) must have a low pH, in the range of 5.1–5.3, in order to attain a casein-associated calcium level that is low enough to allow the curd to plasticize and stretch. On the contrary, curd with a low total calcium content (e.g., 22 mg g 1protein, as for directly acidified Mozzarella cheese) is optimally stretched at a higher pH value (e.g., 5.6–5.7). Therefore, controlled acidification, demineralization, and dehydration, coupled with attaining a critical curd pH at the time of stretching, are the key technological parameters for all pasta-filata cheeses. This unique curd architecture gives rise to a number of important functional characteristics. For example, traditional high-moisture Mozzarella cheese, which is typically shaped into balls and packed in a dilute salt solution, retains a tender, slightly springy and chewy texture despite having a very juicy body that is very high in moisture. The surface of high-moisture Mozzarella can be peeled off in layers, reminiscent of peeling an onion. Similarly, low-moisture Mozzarella (Pizza cheese) that is extruded continuously to form string cheese is extremely springy and elastic and peels easily into layers along the axis parallel to the fiber direction, making it well suited as a snacking cheese for children. The elastic fibrous structure also lends itself well to breading and deep frying, for use as an appetizer or snacking cheese. The fibrous structure of low-moisture Mozzarella enables it to melt on pizza to a stringy, elastic, comparatively chewy consistency that has come to be accepted as the standard for Pizza cheese. Textural defects are particularly problematic in Pizza cheese because the quality of
748 Cheese | Pasta-Filata Cheeses: Traditional Pasta-Filata Cheese
Pizza cheese is largely defined by its shredding and melting properties. Pizza cheese with a soft body due to high fat or moisture content, low calcium content, or excessive proteolysis may gum-up the shredding equipment and take longer to process through the equipment. The resulting cheese shreds may be deformed in shape, sticky, and prone to matting. Such cheese when melted may flow excessively (soupy) and lack stretch, elasticity, and chewiness. At the other extreme, Pizza cheese with an abnormally firm body due to low moisture or fat content may also take longer to shred and shatter and form fines during shredding. Such cheese may melt to a very tough and elastic consistency that is overly chewy. In long-ripened pasta-filata cheeses, such as Caciocavallo and Provolone, the unique stretched curd architecture manifests itself as a flaky texture.
Microbiology Thermophilic lactic acid bacteria such as Streptococcus thermophilus, alone or mainly in combination with Lactobacillus delbrueckii subsp. bulgaricus or Lb. helveticus, are used as starters for most pasta-filata cheeses. However, low-moisture Mozzarella for pizza may also be manufactured using mesophilic starters (e.g., Lactococcus lactis subsp. lactis and Lc. lactis subsp. cremoris) or some varieties of Kashkaval cheese also include in the starter formulation Leuconostoc sp. and Lb. casei; this is because the high temperature used in cheesemaking is more tolerated by thermophilic starters. Streptococcus thermophilus, Lb. delbrueckii subsp. bulgaricus, and Lb. helveticus survive and remain metabolically active when the curd temperature at stretching is 55 C. However, the activity of thermophilic starters is substantially decreased at the higher stretching temperature of the curd (e.g., 62–66 C). Besides, thermophilic starters more easily allow to attain the range of moisture desired for Pizza cheese (48–52%). Nevertheless, in several cases, natural starter cultures have a very heterogeneous composition. In addition to thermophilic lactic acid bacteria, natural whey starter cultures used for the manufacture of high-moisture Mozzarella cheese contain large numbers of mesophilic lactic acid bacteria such as Lb. plantarum, Lb. casei subsp. casei, Lc. lactis subsp. lactis, and enterococci (mainly Enterococcus faecium and Ec. durans). A study on a large number of natural whey cultures for Caciocavallo Silano cheese revealed mainly thermophilic lactic acid bacteria, even though the mesophilic Lc. lactis subsp. lactis was also present in several preparations. Natural whey cultures for the manufacture of Caciocavallo Pugliese are dominated by strains of Sc. thermophilus, Lb. delbrueckii ssp., Lb. helveticus, Lb. fermentum, and Lb. gasseri. Modifications in the composition of the microbial population are generally seen during ripening of semihard pastafilata cheeses. Although the thermophilic lactic acid bacteria
from the natural whey cultures dominate during early ripening, Caciocavallo Pugliese harbors a heterogeneous population of non-starter lactic acid bacteria (NSLAB) during late ripening, which is dominated by Lb. parabuchneri and Lb. paracasei subsp. paracasei. Lactobacillus paracasei subsp. paracasei, Lb. fermentum, and Lb. plantarum generally dominate in Caciocavallo Silano cheese during late ripening. Ripening of Provolone del Monaco, made without the use of deliberately added starters, is typically characterized by the dominance of thermophilic lactic acid bacteria (Sc. thermophilus, Sc. macedonicus, Lb. delbrueckii spp., and Lb. fermentum), together with enterococci and NSLAB of the Lb. casei group, especially Lb. rhamnosus. The main role of starter cultures during the manufacture of pasta-filata cheeses is to synthesize enough lactic acid to demineralize and transform the curd into the state that undergoes stretching in hot water at the target pH. Furthermore, microbial acidification has to proceed at a rate that allows an adequate syneresis during manufacture to achieve the target moisture content. Rapid acidification allows the manufacturing time to be shortened, which reduces syneresis and enables a high moisture content to be achieved in the final cheese. Starter cultures may be eliminated altogether and replaced by direct chemical acidification of the milk during manufacture of high- or lowmoisture Mozzarella, provided that an appropriate level of demineralization in combination with an appropriate pH at stretching is achieved. The secondary role of starters in ripened pasta-filata cheeses, including Pizza cheese, is concerning secondary proteolysis. Nevertheless, the significance of microbial proteolysis is largely influenced by the temperature of stretching. The synthesis of small peptides and free amino acids (FAAs) by starters is also important in low-moisture Mozzarella because they markedly influence the browning properties of the cheese during melting and baking in pizza making, which is an important functional attribute. Furthermore, Mozzarella cheeses that are manufactured using thermophilic starters generally have a characteristic yogurt-like note resulting from the synthesis of acetaldehyde by Sc. thermophilus and Lb. delbrueckii subsp. bulgaricus. Mozzarella that is manufactured without starter cultures through direct acidification will assume the flavor of the chemical compounds used. For example, when vinegar is used as the acidulant, the resulting cheese will possess a mild acetic acid flavor note. On the contrary, if citric acid is used, the cheese will be insipid, due to the lack of flavor other than that arising from milk constituents.
Ripening Some pasta-filata cheeses such as high-moisture Mozzarella and Mozzarella di Bufala Campana are eaten immediately after manufacture without ripening. On the contrary, low-moisture Mozzarella (Pizza cheese)
Cheese | Pasta-Filata Cheeses: Traditional Pasta-Filata Cheese
undergoes a brief but essential ripening period (less than 1 month at 4 C) to develop the desirable functional characteristics. Immediately after manufacture, Pizza cheese is generally difficult to shred because it contains free moisture at the cut surfaces. Besides, unripened Pizza cheese melts to an excessively tough and fibrous consistency with limited ability to flow and releases a considerable amount of watery serum. After 2 or 3 weeks of ripening, the shredding and melting characteristics of the cheese improve markedly. This is due to both proteolytic and physicochemical changes. Proteolysis is initiated by the residual coagulant and plasmin. Hydrolysis of s1- and -caseins results in an increase of meltability (e.g., capacity to flow) and a decrease in the toughness and fibrous consistency of the melted cheese. The hydrolysis of caseins leads to an increased proportion of pH 4.6-soluble nitrogen (N). The ratio of pH 4.6-soluble N/total N is higher for low-moisture Mozzarella than for high-moisture Mozzarella and Mozzarella di Bufala Campana (Table 1). The rate of primary proteolysis will depend on the period of ripening and the degree of thermal inactivation of the coagulant during stretching. Curd that is stretched at a high temperature (e.g., >65 C) has limited residual coagulant activity and requires a longer ripening time to develop functional characteristics than curd that is stretched at a low temperature (e.g., 55 C) with a relatively high residual coagulant activity. Peptides that are produced through primary proteolysis by coagulant serve as the substrate for further hydrolysis to smaller peptides and FAAs by starter bacteria, provided that they survive during stretching. Besides primary proteolysis, physicochemical changes occur during the first few weeks. Initially, much of the water within the
Table 2 Concentration (mg kg
1
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cheese structure exists in the form of serum pockets that are loosely held within open channels that separate the network of parallel protein fibers. Nevertheless, under the influence of the sodium chloride that is dissolved in the water phase of the curd, casein aggregates that serve as the building blocks of the protein fibers interact and bind free water through a process of casein solvation and solubilization. As a consequence, protein fibers become more hydrated and the water-holding capacity of the cheese increases, giving rise to improved shredding and melting characteristics. The development of flavor is of limited concern during the brief ripening of Pizza cheese with low concentrations of total FAAs and total free fatty acids (FFAs) (500 and 360 mg kg 1 cheese, respectively), as the cheese is expected to be very mild in flavor. Strong flavor development is essential during the ripening of long-ripened pastafilata cheeses such as Caciocavallo Silano, Ragusano, Provolone Valpadana, and Kashkaval. Proteolysis and lipolysis are considered as the two primary biochemical processes of long-ripened pasta-filata cheeses, which involve many chemical, physical, and microbiological changes under controlled environmental conditions. During ripening, the distribution pattern of FAAs and FFAs changes due to the complexity of the maturation process, resulting in the formation of the characteristic flavor of long-ripened pasta-filata cheeses (Tables 2 and 3). Proteolysis of long-ripened pasta-filata cheeses is influenced by chymosin, plasmin, and peptidases from starters and NSLAB, pH, moisture of curds, temperature and time of storage, salt, and humidity. Urea-polyacrylamide gel electrophoresis (urea-PAGE)
cheese) of individual and total free amino acids in some pasta-filata cheeses
Amino acid
Caciocavallo Silano
Caciocavallo Pugliese
Ragusano
Kashkaval
Provolone Valpadana
Aspartic acid Cysteic acid Threonine Serine Glutamic acid Glycine Alanine Cysteine Valine Methionine Isoleucine Leucine Tyrosine Phenylalanine Histidine Lysine Arginine Proline Total free amino acids
660 530 670 1790 3860 430 690 140 1500 460 1200 2430 680 1100 160 2560 0 2320 21 180
646 43 449 612 1969 410 640 109 991 395 992 1552 458 1286 267 1414 53 1632 13 918
800 0 800 1100 6000 500 540 120 210 650 156 2800 430 1900 850 3000 0 2000 21 856
182 0 109 41 401 67 191 0 104 66 81 260 130 295 62 126 80 173 2368
1000 0 30 700 2000 300 800 0 1000 200 0 3000 0 0 30 3000 0 0 12 060
The values indicated represent the average of several determinations made by different authors in cheeses that had a slightly different ripening time.
Table 3 Concentration (mg kg Butyric (C4:0) Caciocavallo Silano Caciocavallo Pugliese Ragusano Kashkaval Provolone Valpadana a
1
cheese) of individual and total free fatty acids in some pasta-filata cheeses
Caproic (C6:0)
Caprylic (C8:0)
Capric (C10:0)
Lauric (C12:0)
Myristic (C14:0)
Palmitic (C16:0)
Stearic (C18:0)
Oleic (C18:1)
Linoleic (C18:2)
Linolenic (C18:3)
Total free fatty acids
4
2
540
985
875
924
11 650
300
2600
680
170
18 730
320
100
35
70
50
95
160
20
145
25
18
1038
1093 5 782
437 5 308
161 3 81
309 5 172
317 17 122
597 168 120
123 554 199
1285 180 334a
371 456
1232 45
40 16
5965 1454 2118
C18 congeners refer to stearic (C18:0), oleic (C18:1), linoleic (C18:2), and linolenic (C18:3) acids. The values indicated represent the average of several determinations made by different authors in cheeses that had a slightly different ripening time.
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2
3
4
5
6
7
8
751
9 10 11 12 13
γ-Casein β-Casein β-Casein (f1–192) αs1-Casein αs1-Casein (f24–199)
Figure 1 Urea-PAGE of pH 4.6-insoluble nitrogen fraction from different sections of Caciocavallo Pugliese cheese during ripening. Lane 1, sodium caseinate standard; lanes 2–5, outer section at 1, 21, 42, and 60 days; lanes 6–9, middle section at 1, 21, 42, and 60 days; and lanes 10–13, inner section at 1, 21, 42, and 60 days.
indicated that both s1- and -casein are hydrolyzed during ripening. Owing to the large size of most of the longripened pasta-filata cheeses, persistence of gradients of temperature, and especially of NaCl between the center and rind of the curd, may influence proteolysis during cheese ripening (Figure 1). The action of both plasmin and chymosin on s1- and -casein is clearly evident from their characteristic proteolytic products. Chymosin readily hydrolyzes s1-casein with the concomitant formation of a peptide identified as s1-casein (f24–199). The primary cleavage site of chymosin in -casein is Leu192–Tyr193. In solution, chymosin cleaves -casein at seven sites. The resulting large peptides are -casein f1–192, f1–189, f1–163/4/5, and f1–139. Plasmin has been shown to be active in long-ripened pasta-filata cheeses since it is heat stable and not inactivated under the time, temperature, and pH conditions that occur during stretching. Evidence of plasmin activity in Caciocavallo Pugliese cheese is shown by the degradation of -casein with the concomitant formation of -caseins. The primary proteolysis may also differ for different pasta-filata varieties depending on the stretching temperature. For instance, the high stretching temperature used during the manufacture of Provolone cheese results in limited residual coagulant activity and, therefore, proteolysis proceeds slowly. On the contrary, Kashkaval is stretched at a lower temperature, which results in higher residual coagulant activity and greater primary and further secondary proteolysis during ripening. The same is generally found in Ragusano and Caciocavallo Pugliese cheeses. The ratio of water-soluble N/total N may vary from 13 to 37% in long-ripened pasta-filata
cheeses (Caciocavallo Silano, Caciocavallo Pugliese, Ragusano, Kashkaval, and Provolone Valpadana), depending on the specifics of manufacture (Table 1). The concentration of FAAs in the water-soluble extract of cheeses may vary from 2368 to 21 856 mg kg 1, indicating a very different level of secondary proteolysis among the different cheeses (Table 2). At the end of ripening, the average concentration of FAAs in Caciocavallo Silano and Ragusano cheeses is 21 180 mg kg 1 (corresponding to 6.6% of the total protein content), which may be considered relatively high compared to Caciocavallo Pugliese (13 918 mg kg 1), Provolone Valpadana (12 060 mg kg 1), and especially Kashkaval, which typically has 2368 mg kg 1 (corresponding to 1% of the total protein content). Glutamic acid, valine, leucine, and lysine are the FAAs commonly present at high concentrations in all long-ripened pasta-filata cheeses. The other FAAs are present at different concentrations among the cheeses. Long-ripened pasta-filata cheeses are characterized by a different level of lipolysis. The concentration of total FFAs may vary from 1388 to 18 730 mg kg 1 (Table 3). Probably also due to the use of calf rennet paste, Caciocavallo Silano contains high concentrations of FFAs (18 730 mg kg 1), the principal of which are caprylic, capric, lauric, palmitic, myristic, and oleic acids. During the ripening of Ragusano cheese, lipolysis by lamb or kid rennet paste liberates 5965 mg kg 1 of free FFAs. Compared to proteolysis, lipolysis seems to proceed at higher rates on the exterior portion of the curd blocks. The opposite characterizes ripening of Caciocavallo Pugliese where the main liberation of FFAs
752 Cheese | Pasta-Filata Cheeses: Traditional Pasta-Filata Cheese
(e.g., butyric, caproic, palmitic, and oleic) decreases from the middle and inner to outer sections of the cheese. See also: Cheese: Cheese Flavor; Hard Italian Cheeses; Pasta-Filata Cheeses: Low-Moisture Part-Skim Mozzarella (Pizza Cheese). Lactic Acid Bacteria: Lactobacillus spp.: General Characteristics.
Further Reading Collins YF, McSweeney PLH, and Wilkinson MG (2004) Lypolysis and catabolism of fatty acids in cheese. In: Fox PF, McSweeney PLH, Cogan TM, and Guinee TP (eds.) Cheese:
Chemistry, Physics and Microbiology, Vol. 2, pp. 373–389. London, UK. Beresford: Elsevier Ltd. Kindstedt P, Caric M, and Milanovic S (2004) Pasta-filata cheeses. In: Fox PF, McSweeney PLH, Cogan TM, and Guinee TP (eds.) Cheese: Chemistry, Physics and Microbiology, Vol. 2, pp. 251–277. Beresford: Elsevier Ltd. Lucey JA, Johnson ME, and Horne DS (2003) Perspectives on the basis of the rheology and texture properties of cheese. Journal of Dairy Science 86: 2725–2743. McSweeney PLH (2004) Biochemistry of cheese ripening: Introduction and overview. In: Fox PF, McSweeney PLH, Cogan TM, and Guinee TP (eds.) Cheese: Chemistry, Physics and Microbiology, Vol. 2, pp. 347–360. Beresford: Elsevier Ltd. Piraino P, Zotta T, Ricciardi A, Parente E, and Salzano G (2008) Acid production, proteolysis, autolytic and inhibitory properties of lactic acid bacteria isolated from pasta-filata cheeses: A multivariate screening study. International Dairy Journal 18: 81–92.