Mozzarella Cheese Manufacture

Mozzarella Cheese Manufacture

Provided by ADPI Center of Excellence member Dr. Nana Farkye, this article takes a look at the market information, standards and manufacturing methods, yield, shelf-life and freezing and functionality of mozzarella cheese.

Market Information

Mozzarella cheese is the largest single cheese produced by volume in the U.S.  Current USDAUS Department of Agriculture statistics show that it accounts for over 30% of the total cheese produced in the U.S. (Table 1). (https://usda.library.cornell.edu/concern/publications/m326m1757).

In 2021, the per capita consumption of Mozzarella cheese was 12.28 lb – growing steadily since 2009 when the per capita consumption of Mozzarella cheese overtook that of Cheddar (Fig. 1) (https://www.ers.usda.gov/data-products/dairy-data/) possibly due to increased growth in the popularity and consumption of Mozzarella as a pizza topping and snacking on string cheese.

The global market of Pasta filataItalian for “spun pasta”. Process where curds are heated and then stretched before being molded into the desired shape. Mozzarella can be made by the pasta filata process. cheese is about US$55 billion with the U.S. accounting for about the 57% of the global cheese).  Pasta filataItalian for “spun pasta”. Process where curds are heated and then stretched before being molded into the desired shape. Mozzarella can be made by the pasta filata process. cheese sales have risen approximately 2% per year worldwide and are projected to increase to $65.01 billion by 2028.  The global market for Mozzarella cheese estimated at US$37.3 billion in 2022, is projected to reach US$60.5 billion by 2030, growing at a rate of 6.2% over the analysis period 2022-2030.

Standards and Manufacturing Methods

Mozzarella (or Scarmoza) cheese belongs to the group of pasta filataItalian for “spun pasta”. Process where curds are heated and then stretched before being molded into the desired shape. Mozzarella can be made by the pasta filata process. cheeses.  Pasta filataItalian for “spun pasta”. Process where curds are heated and then stretched before being molded into the desired shape. Mozzarella can be made by the pasta filata process. is derived from an Italian phrase that literally means “spun paste” or “stretched curd”.  Mozzarella cheese is a soft or semisoft cheese that is consumed fresh or after a short period of ripeningChanges during the aging of a cheese.  U.S. standards of identity (SOI) describes four principal types of Mozzarella cheese based on the moisture and fat-on-dry basis (FDBFat on a dry basis) contents as tabulated in Table 2 (21 CFRThe Code of Federal Regulations (CFR) codifies the general and permanent rules published in the Federal Register by the departments and agencies of the Federal Government.  Title 21 of the CFR is reserved for rules of the Food and Drug Administration.  It can be accessed at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm Part 133.155 to 133.158).

There are other forms of Mozzarella cheese, e.g., reduced-fat Mozzarella, shredded Mozzarella, Mexican Oaxaca (pronounced Wa-ha-ka) cheese and fresh Mozzarella (shaped as a ball and packed in weak brine).  Fresh Mozzarella cheese is sold in different size balls/shapes (e.g., ciliengini and bocconcini).  Mozzarella-type cheeses are also commercially available as string cheese and pizza cheese. 

Mozzarella is a fresh soft cheese.  USDAUS Department of Agriculture specifies that Mozzarella cheeses shall be aged no less than 5 days at 38°F to 42°F (3.5°CCarbon to 5.5°CCarbon) prior to inspection unless the cheese is shredded or diced and frozen. If the shredded or diced cheese is not frozen immediately after manufacture, the cheese shall be stored at 38°F to 42°F (3.5°CCarbon to 5.5°CCarbon) until frozen.

The manufacture of SOI Mozzarella cheeses involves standardization of cheese milk to caseinProtein in milk that precipitates at pH 4.6. to fat ratios (CCarbon/F) between 0.7 (for WMM) to 1.2 (for LMPS).  The standardized cheese milk is pasteurized prior to Mozzarella cheese making using direct acidification (DA) or culture acidification (CACalcium) methods. 

For Mozzarella cheese made by DA, cold and dilute organicRegulations that refers to the way agricultural products are grown and processed. Regulations vary from country to country but in the U.S., organic crops must be grown without the use of synthetic herbicides, pesticides and fertilizers or bioengineered genes. acid is slowly metered and rapidly mixed into the milk to prevent localized coagulation of milk.  Although the CFRThe Code of Federal Regulations (CFR) codifies the general and permanent rules published in the Federal Register by the departments and agencies of the Federal Government.  Title 21 of the CFR is reserved for rules of the Food and Drug Administration.  It can be accessed at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm specifies vinegar (5% acetic acid), other acids (e.g., citric and lactic), acid esters (glucono-delta-lactone, GDL) or carbonation with CO₂ are used for pHA measure of the acidity or alkalinity of a material. The pH scale ranges from 0 (acid) to 14 (alkaline) with 7 considered neutral. pH is a measure of the concentration of hydrogen ions and is defined as the negative log of the hydrogen ion concentration. adjustment of the pasteurized milk to pHA measure of the acidity or alkalinity of a material. The pH scale ranges from 0 (acid) to 14 (alkaline) with 7 considered neutral. pH is a measure of the concentration of hydrogen ions and is defined as the negative log of the hydrogen ion concentration. 5.6-5.8 prior to rennet coagulation at ~95°F and cheesemaking.  Acidification with CO₂ has added benefits of enhancing milk qualityFocus on doing things well and producing a product acceptable to consumers by suppressing spoilage bacteria and no negative effects on wheyLiquid obtained from cheese manufacture. qualityFocus on doing things well and producing a product acceptable to consumers.  Rennet (chymosinProtease found in rennet. Produced by newborn ruminant animals to aid digestion of milk. See rennet) is added after pHA measure of the acidity or alkalinity of a material. The pH scale ranges from 0 (acid) to 14 (alkaline) with 7 considered neutral. pH is a measure of the concentration of hydrogen ions and is defined as the negative log of the hydrogen ion concentration. adjustment of milk for rapid coagulation.

The type of acid used, and the acidification pHA measure of the acidity or alkalinity of a material. The pH scale ranges from 0 (acid) to 14 (alkaline) with 7 considered neutral. pH is a measure of the concentration of hydrogen ions and is defined as the negative log of the hydrogen ion concentration. of milk before coagulation influences solubilization of calcium, cheese moisture content, yield, and cheese functionality. Decreasing acidification pHA measure of the acidity or alkalinity of a material. The pH scale ranges from 0 (acid) to 14 (alkaline) with 7 considered neutral. pH is a measure of the concentration of hydrogen ions and is defined as the negative log of the hydrogen ion concentration. causes increased solubilization of calcium, increased hydration and higher moisture cheese.  After acidification and renneting, the curd is cut and allowed to settle, heal and firm up for about 30 min before wheyLiquid obtained from cheese manufacture. drainage.  The curd is kneaded and stretched in hot water, hot salt (~6%) water, or by steam injection until it is smooth and free of lumps. The molten curd is cut, molded, and firmed by immersing in cold water or brine.   

Cultured Mozzarella cheese is manufactured from milk standardized to a CCarbon/F ratio of 0.9 to 1.2 depending on the FDBFat on a dry basis target.  The standardized milk is pasteurized and cooled to 88-90°F prior to cheesemaking.  Cheese starterBacteria added to milk to produce lactic acid in cheese, yogurt and cultured buttermilk. comprising primarily of thermophilic Streptococcus salivarius ssp. thermophilus (cocci) and Lactobacillus delbrueckii ssp. bulgaricus and/or Lactobacillus helveticus) are added. The cultured milk is coagulated with chymosinProtease found in rennet. Produced by newborn ruminant animals to aid digestion of milk. See rennet. The coagulum is cut, healed, cooked to the desired firmness.  The wheyLiquid obtained from cheese manufacture. is drained, and the curd “cheddared” to the desired pHA measure of the acidity or alkalinity of a material. The pH scale ranges from 0 (acid) to 14 (alkaline) with 7 considered neutral. pH is a measure of the concentration of hydrogen ions and is defined as the negative log of the hydrogen ion concentration. of 5.2-5.4 before melting, kneading and stretching in hot water (with or without salt) or by steam injection.  Typical stretching water temperature is ~167°F with curd temperature of ~ 125 – 140°F.  When the free-flowing molten cheese is pulled and stretched under the hot water, the proteins align resulting in a stringy chicken breast-like, fibrous texture of Mozzarella cheese.

The operational conditions of Mozzarella cheese mixer/molder influence cheese yield efficiency.  Cheese yield efficiency increases with increasing stretching temperature and decreasing screw speed due primarily to changes in fat recovery in cheese.   Increasing screw speed of the mixer/molder (5 to 19 rpm) decreases cheese moisture and increases fat loss.  Fat loss decreases with decreasing mixer temperature (130 – 150°F). 

Although low cooking temperature is desirable for Mozzarella cheese, food safetyFocus on avoiding bad events and harm to consumers. reasons necessitate operating cooker/stretcher machines at high temperatures.  Stretching for 5 min at 150.8°F or at 170.6°F for 1 min decreases the cell densityAn indication of compactness or concentration of a material. Density is given as a mass (weight) per unit volume. Mathematically density is mass divided by volume with units such as kg/m3 , g/cm3 , pounds/ft3 , etc. of L. monocytogenes by about 7 log cycles suggesting that the stretching process is an important biological control point during Mozzarella cheese manufacture. 

Yield

Cheese yields depend on the efficient recovery of milk solids (fat and protein), the amount of salt added to the cheese and the moisture retained during cheesemaking.  Fat content in milk significantly affects fat recovery, but not the percentage of nitrogen recovery, in the cheese and wheyLiquid obtained from cheese manufacture.. The lowest and highest fat cheeses (5 and 25% fat, respectively) retained a lower percentage of total fat in the cheese and, therefore, lost a higher percentage of total fat to wheyLiquid obtained from cheese manufacture. than did the medium fat cheeses (10 and 15% fat). 

The percentage of total fat loss in the stretching water decreased as the fat content of the cheese decreased. The target fat recovery in the cheese for Mozzarella cheese yields is 85% compared to 93% for Cheddar cheese.

The typical yield of Mozzarella cheese made from milk standardized to caseinProtein in milk that precipitates at pH 4.6. to fat ratio of 1.1 (without solids fortification) is about 9.5%.  However, to improve cheese throughput in a plant, manufacturers use high solids milk fortified with milk UFUltrafiltration skim milk or UFUltrafiltration whole milk while maintaining the desired CCarbon/F ratio. Click here to view the Federal register on rules for using UFUltrafiltration milk in cheesemaking.

Shelf-life and Freezing

The shelf life for optimal functionality is about 30 days for fresh (high moisture) Mozzarella packed in preserving fluid or about ≥45 days for LMPS Mozzarella used for pizza topping.  Extended storage (e.g., >60 d at 39.2°F) of LMPS mozzarella impairs functionality because the shredded cheese tends to clump together and ball up.  When Mozzarella cheese past its optimal shelf life is used on pizza, the baked cheese exudes excess free oil with a “soupy” consistency resulting from proteolysis.

Because Mozzarella cheese has a relatively short shelf life and must be transported from where it is manufactured to the destination of use, the cheese is often frozen to extend shelf life to about 12 months.  However, the frozen cheese must be used within 7 days after it is defrosted for optimal performance.  The freezing point for Mozzarella cheese ranges from 23°F to 29.8°F, depending on the moisture, solutes in cheese, added salt and age of the cheese.  Freezing affects cheese structure because not all the moisture in Mozzarella freezes.  The free water in the cheese undergoes phase change and thermal expansion causing dehydration of the protein network.  The rate at which the cheese is cooled to the freezing point and the time to completely freeze the core influences the extent of structural damage. Hence, it is best to completely freeze Mozzarella cheese in less than four hours suggesting the importance of the size of the size of cheese to be frozen.  Individual quick freeze (IQF) technology using cryogenic fluids such as liquid NNitrogen₂ or CO₂ is used to freeze Mozzarella cheese comminuted into small sizes in 10 minutes or less.

Freezing influences proteolysis of Mozzarella cheese during thawing and affects the functionality of thawed cheese. Frozen Mozzarella must be thawed in a refrigerator for 72 hours at 35 °F (best) to 41 °F (maximum) in its original package to prevent moisture loss. Slow thawing of the cheese is best. Tempering of previously frozen and thawed Mozzarella cheese for about two weeks is desired to improve its meltability and stretchability.

Functionality

Traditionally, LMPS Mozzarella requires 7-21 days storage at refrigeration temperatures for optimal functionality and baking qualityFocus on doing things well and producing a product acceptable to consumers.  For pizza baking, LMPS and LMWM mozzarella perform best when the age of the cheese is between 14 days and less than 60 days of age. After this time, the uncooked cheese will start to soften and will be difficult to cut and shred, and the cooked cheese will start to break down and tend to flow excessively and suffer from weak body and lack of stretch.   

Factors that affect cheese functionality include heat treatment given to milk, cheese chemistry – moisture, lactose content, pHA measure of the acidity or alkalinity of a material. The pH scale ranges from 0 (acid) to 14 (alkaline) with 7 considered neutral. pH is a measure of the concentration of hydrogen ions and is defined as the negative log of the hydrogen ion concentration.) and fat globule size.  The use of highly heated milk reduces cheese melt and stretch.  Mozzarella cheese with high fat content and large fat globule size have higher meltability than cheese with small fat globules and lower fat content. Hence, homogenized milk cheeses have poor meltability.  The pHA measure of the acidity or alkalinity of a material. The pH scale ranges from 0 (acid) to 14 (alkaline) with 7 considered neutral. pH is a measure of the concentration of hydrogen ions and is defined as the negative log of the hydrogen ion concentration. of curd at stretching affects cheese functionality.  Optimum stretching pHA measure of the acidity or alkalinity of a material. The pH scale ranges from 0 (acid) to 14 (alkaline) with 7 considered neutral. pH is a measure of the concentration of hydrogen ions and is defined as the negative log of the hydrogen ion concentration. is 5.2 – 5.4 for curd made by CACalcium whereas optimal stretching pHA measure of the acidity or alkalinity of a material. The pH scale ranges from 0 (acid) to 14 (alkaline) with 7 considered neutral. pH is a measure of the concentration of hydrogen ions and is defined as the negative log of the hydrogen ion concentration. of Mozzarella cheese made by DA is about 5.7.   This is related to the level of demineralization of calcium from the curd.  Mozzarella cheese curds stretched at 149°F has a higher meltability than curds stretched at 185°F.  Oiling-off of Mozzarella cheese in pizza is an important attribute.  However, excessive oiling-off is undesirable. High oiling-off is associated with larger fat globules and a higher degree of proteolysis.  Excessive levels of reducing sugar (i.e., residual lactose and galactose) affect browning on baked cheese.  Galactose accumulates in cheese made with S. thermophilus because this organism does not metabolize galactose.  Therefore, Lb. helveticus is used to instead of S. thermophilus to control the level of galactose in cheese.   

Salt content affects Mozzarella cheese functionality.  During Mozzarella cheese making, the hot cheese from the cooker/stretcher is molded and placed in a cold brine solution where it cools down and takes up salt. After brining, the salt is concentrated on the outside of the block.  Depending on the size of the block, it takes about 7 to 10 days for the salt to become evenly distributed throughout the cheese. Hence it is important to not use Mozzarella cheese that is too fresh (i.e., less than 10 days old).

With the continuous growth in the consumption of pizza, other convenient foods like quesadillas and dishes that require melted cheese functionality, the demand for Mozzarella cheese production and consumption will continue to grow.

Selected References

Barbano, D.M., A. Renda, J.J. Yun, and P.S. Kindstedt. 1994.  Influence of cheese temperature and screw speed on Mozzarella cheese yield.  Proceedings from the 31st Annual Italian and Specialty Cheese Seminar. Sept 18 & 19, 1994.

Dairy Products. ISSN: 1949-0399.  Released February 3, 2023, by the National Agricultural Statistics Service (NASS), Agricultural Statistics Board, United States Department of Agriculture (USDAUS Department of Agriculture).  Accessed May 2023.

Francolino S., F. Locci, R. Ghiglietti, R. Iezzi, G. Mucchetti.  2010. Use of milk protein concentrate to standardize milk composition in Italian citric Mozzarella cheese making.  LWT – Food Science and Technology 43:310–314.

Fusco V.,   D. Chieffi and M. De Angelis. 2022.  Invited review: Fresh pasta filataItalian for “spun pasta”. Process where curds are heated and then stretched before being molded into the desired shape. Mozzarella can be made by the pasta filata process. cheeses: Composition, role, and evolution of the microbiota in their qualityFocus on doing things well and producing a product acceptable to consumers and safetyFocus on avoiding bad events and harm to consumers.. J. Dairy Sci. 105:9347–9366.

Global Industry Analysts, Inc.  2023. Mozzarella Cheese: Global Strategic Business Report.  https://www.researchandmarkets.com/reports/5301624/mozzarella-cheese-global-strategic-business.  Accessed May 2023.

Kim J., KPotassium. A. Schmidt, R. KPotassium. Phebus, and I.J. Jeon. 1988.  Time and temperature of stretching as critical control points for ListeriaGram positive, aerobic rod that is able to grow at refrigeration temperatures. Listeria moncytogenes is a pathogen monocytogenes during production of Mozzarella cheese. J. Food Protec. 61: 116-118.