Cheese Classification, Characterization, and Categorization: AGlobalPerspective MONTSERRAT ALMENA-ALISTE1 and BERNARD MIETTON2 1Department of Nutrition and Food Sciences, University of Vermont, Burlington, VT 05405-0086, and Green Mountain Coffee Roasters, Waterbury, VT 05676; 2Expertise Agroalimentaire, 39800 Poligny, France ABSTRACT Cheese is one of the most fascinating, complex, and differentiation of cheese include the variability among diverse foods enjoyed today. Three elements constitute the fundamental processing and aging characteristics that cheese ecosystem: ripening agents, consisting of enzymes and influence both the chemical composition of the fresh microorganisms; the composition of the fresh cheese; and the cheese and its enzymatic potential during ripening. The environmental conditions during aging. These factors determine and define not only the sensory quality of the final cheese fundamental cheesemaking factors include (i) method of product but also the vast diversity of cheeses produced coagulation used to transform the original cheesemaking worldwide. How we define and categorize cheese is a milk into a gel or coagulum (e.g., acid versus rennet); complicated matter. There are various approaches to cheese (ii) acidification characteristics (both rate and time), classification, and a global approach for classification and from the point of setting the milk up through the man- characterization is needed. We review current cheese ufacture of the young or fresh cheese, which define the fi classi cation schemes and the limitations inherent in each of mineralization level of the casein but also moisture loss; the schemes described. While some classification schemes are based on microbiological criteria, others rely on descriptions of and (iii) additional steps during the cheesemaking pro- the technologies used for cheese production. The goal of this cess controlling moisture levels of the young cheese (e.g., review is to present an overview of comprehensive and practical cooking temperature and pressing and salting condi- integrative classification models in order to better describe tions). Also, in the case of ripened cheeses, it is important cheese diversity and the fundamental differences within to consider the characteristics of the ripening conditions cheeses, as well as to connect fundamental technological, (temperature, relative humidity, and rates of O2,CO2, microbiological, chemical, and sensory characteristics to and NH3) that ultimately influence the character and contribute to an overall characterization of the main families fl of cheese, including the expanding world of American diversity of cheese micro oras. artisanal cheeses. Received: 10 August 2011, Accepted: 27 April 2012, Published: 24 January 2014 INTRODUCTION Editor: Catherine W. Donnelly, University of Vermont, Burlington, VT Cheese is one of the most complex, fascinating, and di- Citation: Almena-Aliste M, Mietton B. 2014. The microbiology of traditional hard and semihard cooked mountain cheeses. Microbiol verse foods enjoyed today. Certainly, the characteristics Spectrum 2(1):CM-0003-2012. doi:10.1128/microbiolspec.CM- and activity of the specific starters and adjunct cultures 0003-2012. selected for each variety contribute to the complexity Correspondence: Montserrat Almena-Aliste, montse.almena@ and diversity of cheeses. In addition to the microbio- gmail.com © 2014 American Society for Microbiology. All rights reserved. logical aspects, features contributing to the diversity and ASMscience.org/MicrobiolSpectrum 1 Downloaded from www.asmscience.org by IP: 200.55.51.2 On: Wed, 25 Feb 2015 20:03:27 Almena-Aliste and Mietton The diversity and complexity of cheese varieties create TOWARDS A GLOBAL difficulties with respect to classification and character- CLASSIFICATION SYSTEM ization of cheeses. Most of the classical classification Multiple cheese classification models exist, and broad systems are based exclusively on one of the following studies have previously analyzed the majority of the criteria: textural properties (firmness), milk type, co- schemes developed to classify cheese varieties into agulation method, cooking temperature, cheese com- meaningful groups of families (1, 2). However, very few position, and characteristic ripening agent. However, studies have analyzed and highlighted the interest in and few classification models are based on integrative ap- importance of using a global approach for classification proaches that show a more accurate picture of the di- and characterization of different cheeses (3, 4). In her versity of cheese and the differentiation among the many work towards the global approach for the characteriza- varieties. Furthermore, an international assessment of tion of cheeses, Noël (3) introduces the classification of the classification systems by families also indicates two Lenoir et al. (5) as a model to achieve this purpose. major but different approaches, which in some cases can The classification proposed by Lenoir et al. (Fig. 1) be a source of confusion. The “European” approach shows how the diversity of French cheeses is mainly due (mainly used in France and in southern Europe) uses the to differences in three key processing steps (coagulation, technological processes as the criteria for classification, draining, and ripening) that define the type of technol- while the “Anglo-Saxon” classification model is mainly ogy and major chemical characteristics of each cheese based on textural properties (firmness). Later in this re- variety. These three key processing steps define the basis view, we discuss how the polarity between these two for the diversity and differentiation of cheeses but also methods of classification associated with the linguistic indirectly influence each other. For instance, the type of factors can be a source of technical confusion regarding coagulation used to coagulate the milk (e.g., lactic type some cheeses. versus enzymatic or rennet type) shapes the char- The majority of the published literature addressing the acteristics of the gel in terms of structure, firmness, and classification and diversity of cheese is mainly based on cohesion. To drain off the moisture from the resulting European cheeses—such as French appellation d’origine gel, specific techniques may include mechanical actions contrôlée (AOC) cheeses—with very few data describ- (e.g., cutting and stirring of the curds and pressing ing the innovative technologies or the rich diversity of conditions) which may be more or less vigorous and American artisanal cheeses. intense and, as in the case of rennet-coagulated cheese The goal of this review is to present an overview of varieties, also may include different cooking temper- comprehensive and practical integrative classification atures of the whey-and-curds mixture (e.g., uncooked if models in order to better describe cheese diversity and <40°C, semicooked if <50°C, and cooked if >50°C) to the fundamental differences within cheeses and connect contribute to the expulsion of more water from the fundamental technological, microbiological, chemical curds. The young, fresh cheese resulting from these steps and sensory characteristics to contribute to an overall will be more or less moist and indirectly more or less characterization of the main families of cheese, all while acidic and mineralized. Moisture and mineralization including the expanding world of American artisanal levels affect cheese size and aging ability of the product. cheeses. Cheeses with a large format (rennet-coagulated and The review is organized into three main sections. The cooked varieties) have the lowest moisture and highest first section introduces different interdisciplinary clas- calcium contents and can be aged for several months or sification models that will help to explain the diversity even years. In contrast, small acid-coagulated varie- of cheese from a comprehensive and practical view. The ties are mainly consumed fresh and have high moisture second part offers a concise but practical character- levels (more than 70% water) and a very demineralized ization of the main families of cheese, including tech- structure (only 0.2 to 0.5% calcium), associated with nical, chemical, microbiological, and sensory aspects. the levels of acidification at coagulation and draining The last section presents and analyzes the categoriza- (Fig. 1). During ripening, the resulting young cheeses tion system used by the American Cheese Society (ACS; having different formats and physicochemical charac- http://www.cheesesociety.org). The ACS is the most teristics may have been modified by the action (or not) prestigious and influential cheese organization in the of molds (internal or external) or other microorga- United States and provides an original and practical nisms. Special applications during ripening lead to the model to categorize the unique diversity of American development of a natural rind, including a more or less cheeses. complex microflora consisting of yeasts, micrococci, 2 ASMscience.org/MicrobiolSpectrum Downloaded from www.asmscience.org by IP: 200.55.51.2 On: Wed, 25 Feb 2015 20:03:27 Cheese Classification, Characterization, and Categorization: A Global Perspective MILK LACTIC ACIDIFICATION RENNET ACTION COAGULATION (with or without rennet (with lactic acidification) action) DRAINING SLOW DRAINING DRAINING FAVORED DRAINING by CENTRIFUGATION with only cutting by : or FILTRATION cutting cutting cutting stirring stirring stirring pressing pressing heating grinding pressing TYPES OF FRESH SOFT SOFT & SEMISOFT* HARD HARD CHEESES