Weimer Improving the Flavour of Cheese

1. Auflage 2007
ISBN: 978-1-84569-305-3
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 600 Seiten

Reihe: Woodhead Publishing Series in Food Science, Technology and Nutrition

Flavour is key to the acceptance of cheese products among consumers and is therefore a critical issue for professionals in the dairy industry. However, the manufacture of cheeses that are consistently safe and flavourful often eludes scientists. Developments such as high throughput genome sequencing and metabolite analysis are having a significant impact on research, leading to the development of new tools to control and improve the flavour of cheese. With contributions from an international array of acclaimed authors, Improving the flavour of cheese, provides crucial reviews of recent research in the field.The book begins with a summary of cheese ripening and the compounds associated with cheese flavour. Part one discusses the metabolism of specific substrates to flavour compounds by microbes associated with milk and cheese. Part two reviews the influence of ingredients, processing and certain chemical and physical factors on cheese flavour. Part three addresses the measurement of cheese flavour. The book concludes with a selection of case studies on specific product types such as hard Italian, brined cheese, as well as low fat and soft-ripened cheeses.Improving the flavour of cheese provides a unique review of emerging techniques and ideas to control the flavour of cheese. This original book will be a standard reference for those concerned with the development and manufacture of cheese. - Discusses the wealth of research in the area of flavour development - Reviews the influence of ingredients, processing and certain chemical and physical factors on cheese flavour - Concludes with a selection of case studies on specific product types

Autoren/Hrsg.

Weimer, B C

Leseproben

2 Compounds associated with cheese flavor
B. Ganesan; B.C. Weimer    Utah State University, USA M.C. Qian; H.M. Burbank    Oregon State University, USA 2.1 Introduction
‘Say cheese’, calls the photographer in any part of the world when a photograph is to be taken. This is the extent to which the taste of cheese has influenced people such that it brings a smile upon a mention. However, cheese flavor is a very complex phenomenon. Even though there is a unique flavor for every cheese, there is a large range of specific compounds that have varying quantities in each cheese type to constitute cheese flavor. Years of research have not yielded a single unique compound that contributes to any cheese flavor in isolation (Manning, 1979a, b). Hence, the Component Balance Theory of Cheese Flavor (Mülder, 1952), that attributes cheese flavor to a delicate balance among a multitude of compounds, is widely accepted. It is commonly accepted that bacterial metabolism is the key to the development of cheese flavor for acid production in the vat and complex compound production during ripening (Law et al., 1976). Many compound classes are present in cheese, a majority of which originate from bacterial metabolism, either direct products of metabolic pathways (e.g. volatile sulfur compounds and fatty acids), or chemical combinations of different product classes such as methional and S-methyl-thioesters (Cuer et al., 1979a,b; Lamberet et al., 1997; Lee et al., 1997; Weimer and Dias, 2005). Large libraries of such compounds are extensively studied, but only generalities about the compounds and their production have been yielded (Urbach, 1993, 1995). The role of selected peptides in bitterness of cheese is widely accepted (Broadbent et al., 1998; Edwards and Kosikowski, 1983; Kai, 1996). However, the role of a specific compound or a class of compounds to dominate the preferential organoleptic properties has yet to be demonstrated beyond volatile sulfur, methyl ketones and fatty acids in Cheddar cheese (Weimer and Dias, 2005; Weimer et al., 1999). Recent research efforts have focused on the ability to understand the roles of particular substrates available in cheese to act as flavor precursors for these compounds (Avsar et al., 2004; Fox and Wallace, 1997; Gallardo-Escamilla et al., 2005; Smit et al., 2004a,b). Fat, proteins, peptides, amino acids, volatile sulfur compounds, alcohols, aldehydes, ketones and volatile fatty acids are some of the classes of compounds that contribute to cheese flavor (Urbach, 1993). Volatile sulfur compounds play a major role in many cheese types (Aston and Douglas, 1983; Ferchichi et al., 1985; Hemme et al., 1982; Law and Sharpe, 1978; Manning, 1979b; Weimer et al., 1999); but they alone do not lead to the total flavor perception of any cheese type. All attempts to simulate Cheddar cheese flavor have not been successful in producing real cheese flavor (Manning, 1979a). This suggests that the major components do not play a single-handed role and the role of minor components must be considered. Eventually, a scheme to define the chemical basis of flavor beyond the Component Balance Theory is necessary to objectively control and modify cheese flavor. This chapter attempts to assess and understand the role of some of the classes of cheese flavor compounds. The association of bacteria in generating these compounds will also be briefly discussed. 2.2 Bacteria and cheese flavor
Addition of bacteria is an essential step in cheese-making towards a good-flavored cheese. Cheese without bacteria fails to develop flavor during ripening (Aston and Douglas, 1983; Law and Sharpe, 1975). The flavor profile of cheeses depends on bacteria involved in cheese ripening and their catabolic capabilities leading to the different flavor compounds present in different cheeses (Fox and Wallace, 1997). Bacteria are involved in all steps of cheese making. In the initial stages of Cheddar cheese ripening, lactic acid bacteria (LAB) catabolize lactose to lactic acid. Lactose is reduced to undetectable levels after 30 days (Crow et al., 1993). Proteolysis by bacteria slowly degrades the casein matrix over time. The peptides and amino acids are transported and utilized by bacteria in the matrix (Christensen et al., 1999). Peptides are directly related to bitterness in Cheddar cheese (Broadbent et al., 1998). Amino acids are catabolized to flavor compounds involved in positive Cheddar flavor in culture and cheese slurries (Dias and Weimer, 1999; Harper and Wang, 1980a, b). The type of bacteria added modulates flavor production in cheese during ripening. Previous studies focused on identifying the best flora type, either singly or in combination, to produce an acceptable Cheddar cheese flavor (Aston and Creamer, 1986; Baankreis, 1992; Banks et al., 1989; Bhowmik et al., 1990; Broadbent et al., 1998; Christensen et al., 1999; Crow et al., 1993; Desmazeaud and Cogan, 1996; Dias and Weimer, 1999; Fox and Wallace, 1997; Khalid and Marth, 1990; Yvon et al., 1999). The focus is often on nonstarter lactic acid bacteria (NSLAB), predominantly lactobacilli, as the causal agents of flavor on the basis of their population in later stages of cheese ripening (Dias and Weimer, 1998; Laleye et al., 1990; Muehlenkamp-Ulate and Warthesen, 1999; Peterson and Marshall, 1990; Trepanier et al., 1991). The role of different genera in Cheddar cheese flavor continues to be elusive and the cumulative interpretations from numerous studies add to the controversy. Nonstarter lactobacilli intensify cheese flavor and have been adopted for addition as starter culture in hard cheeses (Fox et al., 1996; Laleye et al., 1990; Reiter et al., 1967). However, lactococci have a unique causative role in cheese flavor, and consequently remain the heart of the starter culture (Parra et al., 2000). Total bacterial counts are related to flavor development. The lower the number of starter lactococci, the more intense the Cheddar flavor; when lacto-coccal plate counts of cheese are >109cfu g-1, cheese is bitter (Lowrie et al., 1974). Recently, a number of authors found that lactococci enter a state of no growth, but they remain metabolically active (Kunji et al., 1993; Rallu et al., 1996; Stuart et al., 1999; Thomas and Batt, 1969). This may lead to a limited population of lactococci detected by bacterial plate counts during cheese ripening. However, lactococcal starters continue to remain metabolically active and play a causative role in cheese flavor. 2.3 Cheese flavor
Different cheese types have groups of flavor compounds that are responsible for their unique flavors (Table 2.1) (Kristoffersen, 1975; Vedamuthu et al., 1966). But the knowledge of flavor impact is limited to a few groups only (Urbach, 1993). Compounds contribute specific flavor attributes based on their physicochemical properties (Urbach, 1993). Some compounds represent typical flavors of certain cheeses, acting as impact compounds for that flavor but not for the total flavor perception (Table 2.1). Multiple lists of flavor compounds are available in the literature (Fox and Wallace, 1997; Fox et al., 1996; Urbach, 1993, 1995). Table 2.1 Flavor compounds formed during cheese ripening Type of cheese Associated flavor compounds Impact compounds Cheddar Lactic acid, acetic acid, amino acids, sulfur compounds, ammonia Methanethiol Swiss-type Lactic acid, propionic acid, acetic acid, amino acids (proline), sulfur compounds, alkyl pyrazines 3-Methyl butyric acid Blue-veined Volatile fatty acids, ketones, amino acids, lactones, aromatic hydrocarbons, methyl ketones, secondary alcohols Heptan-2-one Italian Volatile fatty acids, amino acids, alcohol, ketones n-Butyric acid Gouda Amino acids, fatty acids Tilsit Methanethiol, methyl thioacetate and thiopropionate, hydrogen sulfide (adapted from El Soda, 1993; Urbach, 1993) Flavor compounds are classified by at least four systematic schemes as organoleptic, chemical classes, cheese type, and originating substrate. While a sharp, nutty flavor is typical of aged Cheddar from some parts of the world, a similar profile in Mozzarella or Gouda cheeses is totally unacceptable. Several fractions of cheese have been analyzed for flavor dominators and all of them, neutral, basic, acidic, aqueous- or organic-partitioning, are known to contribute to the...