FACTOR AFFECTING QUALITY OF MOZZARELLA CHEESETay, W.C., Nur Mariya Ulfa, Nurul Ain Khirul Salleh

weiching.pn@gmail.com, bluelavender_90@yahoo.com, nurulainkhirulsalleh@gmail.com

INTRODUCTIONMozzarella cheese was originally manufactured from Italy. Traditionally, Mozzarella

cheese was made from buffalo milk. Now in European countries and USA it is also being made from cow milk. Mozzarella cheese is belongs to the cheese classified as “pasta filata” which refer to principle of skillfully stretching the curd in hot water in order to get a smooth texture and grain in cheese. It is a white, soft with a glossy surface, and unripened cheese which may be consumed shortly after manufacture. It is valued for its melting and stretching characteristics especially in the Pizza preparation.

Preparation of Mozzarella Cheese from Buffalo Milk Using CultureAccording to Weckx and Delbeke (1971), briefly, at 33OC, the pasteurized buffalo milk is

incubated with rennet and a starter containing S. thermophilus and L. bulgaricus. Next, in water at 80OC, the separate curd with pH 5.2 is heated, kneaded, and cut before it is cooled under running water at 10-12OC for half an hour. This followed by immersion of the cheese in chilled (5OC) brine for 30 minutes for salting. The flow chart for preparation of Mozzarella cheese by starter culture method is showed in Fig. 1.

Milk

Standardization (casein/fat ratio or only fat content)

Pasteurization

Cooling to 37OC

Addition of starter culture(S. thermophilus + L.bulgaricus, 1:1 @ 2.0% w/v)

Renneting(1.5g/100kg milk)

40 min

Cutting of curd

Cooking of cheese curd(37OC to 42OC in 40 min)

Draining of whey

Cheddaring of curd

Desired activity at which curd will stretch in hot water

Plasticizing(80-85OC/2-3 min)

Moulding into shapes

Immersion in chilled (8-10OC) brine (~20% strength)

Packaging and storage

Fig. 1: Flow chart for preparation of Mozzarella cheese using culture

Preparation of Mozzarella Cheese by Direct Acidification

The preparation of Mozzarella cheese by direct acidification involves the lowering of pH by different acids. This technique helps to eliminate variability of acid production by bacteria and avoid problems created by bacteriophages, slow starters and other contaminants. In addition, this technique allow the manufacturer to have better control over pH variations and significantly able to reduce manufacturing times. It has been reported that pizza cheese manufactured using citric acid as pH regulator had the highest calcium concentration and good meltability and stretchability. However, the type of acid had no effect with regard to fat and free oil content (Jian-Qiang, Hui-Fang, & Li-Qin, 2011). Fig. 2 shows the flow chart for preparation of Mozzarella cheese by direct acidification.

Milk

Standardization (casein/fat ratio or only fat content)

Pasteurization

Chilling to 4-8OC

Acidifying (to pH 5.4-5.6 with 25-50% HCl @ 2.0-3.5 ml/ 1 L milk)

Heating(28-30OC)

Renneting(0.5-0.75 g/ 100 kg milk)

Cutting of curd

Cooking of cheese curd(37OC to 39OC)

Draining of whey

Plasticizing/stretching under hot water(80-85OC/2-3 min)

Moulding into shapes

Immersion in chilled (8-10OC) brine (~20% strength)

Packaging and storage

Fig. 2: Flow chart for preparation of Mozzarella cheese using direct acidification

FACTORS AFFECTING QUALITY OF CHEESEAny variable changes in manufacturing of Mozzarella cheese might affect its quality in

term of functionality properties, chemical composition and proteolysis (Yun, Barbano, & Kindstedt, 1995). The major influences of Mozzarella cheese’s quality are draining pH (Yun et al., 1995), temperature (Osman & El Owni, 2009) and amount of sodium content (Agarwal, McCoy, Graves, Gerard, & Clark, 2011).

Draining pHAccording to Yun et al. (1995), draining pH is very important to be monitored as it really

affect on quality of Mozzarella cheese. Based on his research of study, calcium content might be lower (from 0.83 to 0.75%) as pH at draining is decreased, while it also cause increasing of cheese moisture content (from 45.7 to 46.3%). The moisture content increased on cheese is because of draining process is delayed as low draining pH. On top of that, the draining pH also can influence the retention of minerals where it is affected on cheese texture. However, for Mozzarella cheese, its functionality properties will change as its texture is being affected such as shredding and melting property. Not only that, Yun et al. (1995) highlighted the retention of coagulant in curd will occur as draining pH vary. These changes indirectly tend to cause fluctuation of proteolysis. Moreover, he states that with lower draining pH of 4.6 and 12% TCA soluble nitrogen, more proteolysis occurs. He also claims that Mozzarella cheese’s texture and its functionality characteristic would affect during storage as proteolysis keep continuing.

TemperatureTemperature must be monitored well during cooking process (Jana & Mandal, 2011) and

storage (Osman & El Owni, 2009). According to Jana and Mandal (2011), if temperature high (38oC-44oC) while cook milk used will produce cheese with lower moisture and decreased proteolysis during 50 days storage at 4oC. It is also may affect the firmness of melted cheese. While for storage temperature, Mozzarella cheese is stored at low temperature of 7-10oC for seven days to prevent bacteria and mold growth (Osman & El Owni). On top of that, weight of cheese will reduce as reduction of moisture content due to curd contraction and water expulsion. Besides, Mozzarella cheese can be kept at frozen degree celcius and has greater meltability than unfrozen one. However, frozen Mozzarella cheese showed poor characteristics after thawing, yet it may regain its normal characteristics after the thawed cheese was aged for 1 to 3 weeks (Bertola, Califano, Bevilacqua, & Zaritzky, 1996).

Sodium LevelAccording to Agarwal (2011), sodium used in cheese making influences the activity of

enzyme and microorganism, thus it is maintained texture, flavor, shelf life and overall acceptability of cheese. At high sodium level, its produce very firm of cheese structure and promote lower proteolysis with lower degree of casein hydration. In addition, high sodium level tends to produce cheese with less bitterness compare to low level of sodium. However, due to health conscious, salt level being reduce at the result shows that cheeses with 1.8% salt and above have an acceptable level of saltiness. If less than that, it would influence customer preference.

CHARACTERISTICS

StretchabilityStretchability of the Mozzarella cheese is a unique functional characteristic in making

pizza topping that leads to customer acceptance. It can be defined as the ability to form a continuous fibrous strand formation that extended when it is subjected to heat or tension. This characteristic of the cheese is due to the concentration of calcium phosphate and its protein network structure whereby a higher calcium content would lead to tough and grainy structure.

However, stretchability of the melted Mozzarella cheese is one the most difficult property to be tested although there are three different tests implemented to evaluate this property.

MeltabilityCustomer satisfaction on the consumption of pizza and other food products made from

Mozzarella cheese and perception towards their quality are greatly dependent on the meltability of the cheese. Meltability can be defined as the extent to the spreadability and flowability of cheese when melted under heat. Meltability of cheese is higher with the higher fat content of cheese (McMahon et al., 1996). When Mozzarella cheese is subjected to different melting temperature, it displays different type of charateristics. A study done by Kuo et al. (2001) on the effects of holding temperature on the meltability of aged cheese has found that meltability is reduced sharply with increased holding time.

BrowningBrowning of the cheese is an important contribution factor to the overall appearance of

pizzas made of Mozzarella cheese due to the Maillard reaction. This is due to the fact that the pizza making process would involve heat up above 260 degrees Celcius whereby cheese makers desire cheese that do not look burnt when baked at high temperatures (Brown, 2010). The degree of browning up to a certain extent would only produce pizzas of desirable colour, however, excess browning would occur when there are an excess of sugars, lactose or amino acids. One of the steps in cheese making would lead to the browning effect of the cheese which is the replacement of lactose with water in the cheese vat so that fresh cheese can be made for pizzas and fresh consumptions (Baskaran and Sivakumar, 2010).

RECENT CONSUMER NEEDSNowadays, health awareness keeping increasing among consumer as there is various

ailments and diseases spread all over the world. Thus, some revolution has been done in production of Mozzarella cheese which new products are introduced such as low-fat and fat-free Mozzarella cheese. According to Jana and Mandal (2011), low-fat Mozzarella cheese contain only 6.0% fat and it is made by pre-acidifyingof milk (pH6.1) with citric acid. Pre-acidifying helps in reducing the hardness and increasing meltability characteristic. Basically, low-fat Mozzarella contain EPS (exopolysacharide) which improved shred fusion, meltability and reduced surface scorching upon baking. In addition, National Salt Reduction Initiative (NSRI) has been implemented in New York as an alternative to control the level of salt in cheese (Agarwal et al., 2011). Other consumer preference toward Mozzarella cheese product is its convenience characteristics. Consumer prefers dried cheese as it is convenience and can be used for flavouring certain food items (Jana & Mandal, 2011).

CONCLUSIONProcessing of Mozzarella cheese

Jian-Qiang, Z., Hui-Fang S. and Li-Qin Z., (2011). Effects of acidifying agent on the functional

properties of pizza cheese. Packaging Food Mach., 29, 1-4.

Weckx, A.H. and Lindsay, R.C., (1971). The manufacture of Mozzarella and Pizza cheese. Journal Agriculture, 24, 1327-1329.

McMahon, D. J., Alleyne, M. C., Fife, R. L., & Oberg, C. J. (1996). Use of fat replacers in low fat mozzarella cheese. Journal of Dairy Science, 79(11), 1911-1921.

Wang, H.-H, and Sun, D.-W (2002). Correlation between cheese meltability determined with a computer vision method and with arnott and schreiber tests. Journal of Food Science, 67(2), 745-749.

Kosikowski, F. (1982). Cheese and fermented milk foods. (2nd ed., pp. 404-406). Kosikowski and Associates.

Kuo, M. –I., Wang, Y. C-., Gunasekaran, S., & Olson, N. F. (2001). Effect of heat treatments on the meltability of cheeses. J. Dairy Sci., 84, 1937–1943.

Brown, A.C. (2010). Understanding Food: Principles and Preparation. Cengage Learning.

Baskaran, D., & Sivakumar, S. (2003). Galactose concentration in pizza cheese prepared by three different culture techniques. International Journal of Dairy Technology, 56(4), 229-232. doi:10.1046/j.1471-0307.2003.00109.x

Osman, E., & El Owni, O. A. O. (2009). Evaluation of Chemical Composition and Yield of

Mozzarella Cheese using Two Different Methods of Processing. Pakistan Journal of Nutrition 8(5): 684-687.

Bertola, N. C., Califano, A. N., Bevilacqua, A. E., & Zaritzky, N. E. (1996). Effect of

Freezing Conditions on Functional Properties of Low Moisture Mozzarella Cheese. Journal Dairy Science. 79: 185-190.

Agarwal, A., McCoy, D., Graves, W., Gerard, P. D., & Clark, S. (2011). Sodium Content in

Retail Cheddar, Mozzarella, and Process Cheeses Varies Considerably in United States. Journal Dairy Science. 94: 1605-1615.

Yun, J. J., Barbano, D. M., & Kindstedt, P. S. (1995). Mozzarella Cheese: Impact of Whey

pH at Draining on Chemical Composition, Preteolysis and Functional Properties. Journal Dairy Science. 78:1-7.

Jana, A. H., & Mandal, P. K. (2011). Manufacturing and Quality of Mozzarella Cheese: A

Review. International Journal of Dairy Science 6(4): 199-226.