Mozzarella, production technology

Mozzarella is a fresh stretched-curd cheese that is not aged, originating from Campania (South-West Italy) where it was produced – and is still made, as well as recognized by a specific PDO – starting from buffalo milk.

The majority of Italian mozzarellas, including the famous PDO of Gioia del Colle (Apulia, South-East Italy), is today made with cow's milk (mozzarella fiordilatte), or with a mixture of buffalo and cow milk. In rare cases also with sheep or goat milk.

Mozzarella production technology

Pasteurization

Traditional production of mozzarella took place starting from raw milk. However, the necessary attention to microbiological risks has prevailed over tradition and the undisputed superior sensory quality. (1,2) Today only pasteurized milk is therefore used.

Coagulation

The milk is heated to 35-40°C, inside multipurpose tanks where rennet and lactic ferments are then added. Alternatively, organic acids such as citric acid or lactic acid may be used instead of the latter. However, the difference is substantial:

- lactic ferments allow a slower acidification and the development of characteristic sensory compounds that give mozzarella a superior quality

- organic acids allow a faster coagulation. Production times are thus accelerated, to the detriment of the organoleptic quality of the product. (3)

The rennet in an acidic environment allows the coagulation of caseins (milk proteins) with fats and the formation of a 'curd mass' that precipitates and separates from the whey.

Curd cutting and maturation

The next phase It is the breaking of the clot, through special 'mechanical spines' that reduce it into granules. This is followed by placement on trolleys and maturation in a chamber at a temperature of 35-40 °C and 90-99% humidity.

The crushing of the clot Allows the release of the remaining whey. The acidic environment also enables the demineralization of the curd, meaning the transfer of calcium and phosphorus from casein to the whey, thus facilitating the subsequent spinning phase.

Stretching

The spinning Is the only heat treatment in the mozzarella production process. It is carried out at the end of maturation by immersing the curd in hot water (80-90 °C), with various purposes:

– to obtain a stretching of the casein micelles and the formation of a silky and plastic dough

– to partially inactivate the rennet, slowing down its coagulating and proteolytic activity

– to inhibit spoilage and/or pathogenic microorganisms that may remain from previous processing, also due to accidental contamination during production (4,5).

At the end of spinning the mozzarella is shaped into typical ball shapes, or pulled to obtain the braid shape.

Setting and packaging

The final phase Is immersion in two solutions:

• In cold water (< 15 °C), in firming tanks, to lower the product temperature
• In brine, in special tanks of water with a salt concentration of about 20%, where salt is absorbed by osmosis.

The mozzarellas Are finally packaged, in bags or trays, in the preserving liquid (a solution of water, lactic or citric acid, whey proteins, sodium chloride and residual lactic ferments). This liquid performs important technological functions such as prolonging the product's shelf life and maintaining proper hydration to prevent the formation of surface crusts.

Nutritional characteristics

The nutritional profile of the average Italian Made cow mozzarella is characterized as follows:

– proteins (mainly caseins), about 20%

– fats, mainly saturated, about 20%

– carbohydrates, mainly lactose, almost (but not completely) absent. Lactose-free mozzarellas are also made for consumers who are intolerant

– mineral salts. Mozzarella is a good source of sodium, calcium, and phosphorus. It also contains potassium and iron, although in smaller amounts

– vitamins. Appreciable levels of riboflavin (vit B2) and vitamin A are present, as well as niacin (vit B3), thiamine (vit B1), and vitamin E. (6)

Francesco Carlini

Notes

(1) Silvia Bonardi, Dario Dongo. Mountain cheeses and fresh raw milk cheeses, the STEC risk. Food Times. 5.9.23

(2) EFSA. Drinking raw milk: what risks are involved?https://www.efsa.europa.eu/it/press/news/150113

(3) Dario Dongo, Michele Polignieri. Mozzarella, here’s why to beware of citric acid. Food Times. 6.11.20

(4) L. de Ruvo. The stretching of the curd: can it be considered a control measure  https://arclab.it/la-filatura-della-cagliata-si-puo-considerare-come-una-misura-di-controllo/

(5) G. Mucchetti and E. Neviani. Microbiology and dairy technology. Tecniche Nuove, Milan, 2006. ISBN 978-88-481-1817-0

(6) Italian Society of Human Nutrition (2014). LARN, Reference intake levels for nutrients and energy for the Italian population, 4th revision  https://sinu.it/tabelle-larn-2014/