Guest Columns

Cheese Technology

Browning, blistering or burning of Mozzarella cheese on pizza

Dr. Mali Reddy

Dr. Mali Reddy serves as president of the American Dairy and Food Consulting Laboratories and International Media and Cultures (IMAC Inc.), Denver, Colo. He holds several degrees including M.S. and Ph.D. degrees from Iowa State University in food technology and microbiology. He is a guest columnist for this week’s issue of Cheese Market News®.

Two decades ago, the leading dishes in America were steak and hamburger. Starting from the mid-1970s, the pizza industry experienced phenomenal growth ,and by the 1980s and 1990s, Italian food — especially pizza — became the No. 1 food in America.

The pizza explosion did not stop with the United States; its influence also spread to the United Kingdom, European Economic Community, Eastern Europe, Middle East, Far East, and Pacific nations.

As a consultant to the leading pizza chains in the United States, I still remember going to Europe to promote American-type pizza. In the beginning they resisted the intrusion of the American-style pizza into those countries.

Today, wherever you go throughout the world, you can find several different U.S. pizza chains. I recently returned from a trip to China, and to my surprise the Chinese have developed a taste for the American-style pizza. Pizza chains are now expanding in China. I found similar growth patterns and lifestyle changes in India. With the advent of economic explosions in India and China, the American food industry can do extremely well, provided the quality is maintained.

The one mantra or buzz word in the food industry is quality, quality, quality. The major element that dictates quality of pizza is Mozzarella cheese. Consequently the quality of Mozzarella has to be improved and constantly maintained in order to expand the pizza business. If the quality of cheese is not maintained and proper quality pizza is not served, sooner or later pizza will no longer be the No. 1 food choice in the United States and will no longer be in as high demand internationally, hurting the U.S. dairy industry.

One area of concern, of course, is the browning or burning or blistering of Mozzarella on pizza. Slight browning of cheese upon baking is not objectionable. Excessive browning is considered a serious defect. One step beyond browning is burning. A burned or partially burned food may act as a carcinogen or a potential cancer promoting compound.

The browning of cheese on pizza is due to maillard reaction (i.e. proteins or protein breakdown products reacting with sugars when exposed to high heat). With modern food habits and time pressures, pizza must be baked at high temperatures. If the Mozzarella has more residual sugars such as galactose, glucose and lactose, it will have more of a tendency to brown or burn on pizza. Basically, milk has lactose sugar which is made of glucose and galactose. The cheese’s starter cultures break down lactose sugar to glucose and galactose so that they can consume these simple sugars to derive their energy requirements. If the proper starter cultures, fermentation techniques and cheese making parameters such as pH, temperature, aging, etc., are not maintained and followed, these simple sugars will end up in the cheese and thus cause browning or burning on the pizza.

As the pizza industry developed, several changes came in the production of Mozzarella in the United States. Traditionally this cheese is made using two types of bacteria: coccus (Streptococcus thermophilus) and rod (Lactobacillus bulgaricus). Even though Bergey’s manual has changed their names, for the sake of simplicity I have used their colloquial names and their old scientific nomenclature. These two organisms dictate the functionality of Mozzarella on pizza. The coccus culture has more of a tendency to induce the browning of cheese because of its lack of or reduced ability to utilize galactose sugar (which is a top browning sugar), compared to rod culture. Traditionally these cultures were grown in starter media at the plant level and the plant adjusted the ratio of these organisms according to the quality of milk, season and quality of cheese requested by the customers. In my opinion, this is an excellent way to manufacture the best quality cheese, and several industry experts agree with me. With today’s plant scrutiny, Mozzarella plants have the ability to safely make bulk starters and adjust the coccus to rod ratios to improve the cheese quality according to the customer’s requirements — cheese quality by choice rather than chance.

However, lately EPA has been very strict about the composition of the sewer. Consequently in the cheese industry, several changes have come in terms of conservation of water and reduction of discharge of pollutants. If the cheese curd is not washed to reduce the simple sugars, the cheese will burn on pizza. We all should obey the rules to reduce pollution. However, with the practice of reduction of washing of the curd and using more coccus direct set cultures, the browning, blistering or burned cheese defect on pizza is increasing at a dramatic rate. This defect, unless it is corrected, may lead to a drop in sales, which will hurt the dairy industry as a whole. Burned cheese in not only unappealing on pizza but also may be injurious to human health, according to the limited medical research and literature on burned food proteins. These browning or burning defects can be corrected by using proper starter and proven cheese technologies without having to wash the curd.

The industry as a whole should make an attempt to improve the quality of Mozzarella cheese, rather than taking short cuts and temporary conveniences, to go forward globally. Thus, let us stick to proper proven modern science and technology, and the proven traditional art of cheesemaking.


The views expressed by CMN’s guest columnists are their own opinions and do not necessarily reflect those of Cheese Market News®.

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