Classification and Functional Properties of Processed Cheese

Transcription

1 농업생명과학연구 47(6) pp Journal of Agriculture & Life Science 47(6) pp Classification and Functional Properties of Processed Cheese Ho-Kyung Ha 1 Mee-Ryung Lee 2 Chi-Won Noh 3 Jin-Wook Kim 1 Won-Jae Lee 1* 1 Dept. of Animal Bioscience (Insti. of Agric. & Life Sci.), Gyeongsang National Univ., Jinju , Korea 2 Dept. of Food and Nutrition, Daegu University, Gyeongsan , Korea 3 Gyeongsangnam-do Agricultural Research & Extension Services, Jinju , Korea Received: NOV , Revised: NOV , Accepted: NOV ABSTRACT Processed cheese is manufactured by mixing natural cheeses with emulsifying salts and other ingredients and heating under agitation to produce a homogeneous product. Processed cheese, processed cheese food, and processed cheese spread are classified in the US standards for processed cheese. The functional properties of processed cheese, such as firmness and meltability, are regarded as a quality indicator assessing overall cheese quality and consumer preference. Various analytical methods have been developed to determine the functional properties of processed cheese. In this review, the classification and functional properties of processed cheeses are described and analytical tools for evaluating the functional properties of processed cheese are discussed. Key words - Processed cheese, Classification, Functional property, Analytical method * Corresponding author: Won-Jae Lee Tel: Fax: wjleewisc@gnu.ac.kr

2 220 Journal of Agriculture & Life Science 47(6) I. Introduction Processed cheese is manufactured by mixing various types of natural cheeses, emulsifying salts, and dairy and non-dairy ingredients including whey protein powder and salts. The cheese mixtures are then heated under a partial vacuum with a constant stirring to obtain homogeneous products, such as slices, shreds, and sauces (Piska & Štĕtina, 2004; Kapoor et al., 2007). The first processed cheese was developed by Gerber and Stettler (Gerber and Co., 1911) and was initially made to prolong the shelf life of natural cheese (Kapoor & Metzger, 2008). To prepare a smooth, homogeneous processed cheese, they mixed melted Swiss cheese with emulsifying salt (sodium citrate). There are three major categories of processed cheeses: i) processed cheese, ii) processed cheese food, and iii) processed cheese spread. The functional properties of processed cheese including firmness and meltability are important factors affecting cheese quality and consumer preference (Blazquez et al., 2006; Lee & Lee, 2013). To produce processed cheese with good quality and consumer acceptability, it is necessary to understand how processeed cheeses are classified and what analytical methods are used to determine the functional properties of processed cheese. II. Classification of processed cheese The US standards for processed cheeses are defined in the code of Federal Regulations, Title 21, Part 133 (FDA, 2013) as pasteurized processed cheese, pasteurized processed cheese food, and pasteurized processed cheese spread. The fat content of pasteurized processed cheeses is expressed as percent fat on a dry weight basis while other constituents are expressed on a wet weight basis (Zehren & Nusbaum, 1992). Characteristics of processed cheese, processed cheese food, and processed cheese spread are presented in Table Processed cheese Processed cheese is a dairy product resulting from blending and heating one or more types of natural cheese with emulsifying salts into a homogeneous plastic mass (Kosikowski, 1977). The moisture and fat content of processed cheese are regulated according to the legal definitions, which apply to the natural cheese. For the processed cheese made with Cheddar cheese, the regulatory requirement for the moisture content and fat content of processed Cheddar cheese is no more than 40% moisture on a wet weight basis and no less than 43% fat on a dry weight basis (FDA, 2013). Emulsifying salts commonly selected for processed cheeses are disodium phosphate, trisodium phosphate, and tetrasodium pyrophosphate (Shimp, 1985). Emulsifying salts in processed cheese are used to supplement the emulsifying capabilities of cheese proteins such as casein by sequestering calcium and solubilizing cheese proteins (Caric & Kalab, 1999). The amount of emulsifying salts is not more than 3% of the weight of the processed cheese on a wet weight basis (FDA, 2013). Acidulents such as lactic acid or citric acid are limited to concentrations such that the ph of the processed cheese is not less than 5.3 (FDA, 2013). Water added to processed cheese is used to solubilize emulsifying salts. The amount of water added to processed cheese is controlled to conform to the legal moisture requirements. Preservatives include sorbic acid, potassium sorbate, sodium sorbate, sodium propionate, or calcium propionate (Zehren & Nusbaum, 1992). Processed cheese in consumer size packages may

3 Ha et al : Classification and functional properties of processed cheese 221 contain preservatives consisting of not more than 0.2% by weight of sorbic acid, potassium sorbate, sodium sorbate, or any combination of two or more of these, or consisting of not more than 0.3% by weight of sodium propionate, calcium propionate, or a combination of sodium propionate and calcium propionate (FDA, 2013). Colors such as annato or carotene derivatives are utilized to standardize the processed cheese color to a uniform hue and intensity. Cream, anhydrous milk fat, or butter oil may be used to compensate for fat reduction resulting from the addition of nonfat solids to processed cheese (Zehren & Nusbaum, 1992). 2.2 Processed cheese food Processed cheese food is a dairy product requiring the selection, grinding, heating, and emulsification principles equivalent to processed cheese (Kosikowski, 1977). However, optional dairy ingredients such as milk, nonfat dry milk (NFDM), cheese whey, and whey powder which are not permitted for processed cheese are approved for addition to the processed cheese food (Kosikowski, 1977; Zehren & Nusbaum, 1992; FDA, 2013). The moisture content of processed cheese food is not greater than 44% on a wet weight basis and the fat content is not less than 23% on a dry weight basis (FDA, 2013). Acidulents such as acetic, citric, or lactic acid may be added to increase acidity and microbiological stability (Zehren & Nusbaum, 1992). The ph of processed cheese food is not less than 5.0 (FDA, 2013). Plotka (1997) successfully produced low fat processed cheese food using a cheese base prepared from reconstituted NFDM. The use of NFDM as an ingredient of processed cheese food improves the spreadability and stability of processed cheese food (Caric & Kalab, 1999). Gupta and Reuter (1993) produced processed cheese foods from Cheddar cheese and whey protein concentrate (WPC). 2.3 Processed cheese spread Processed cheese spread is prepared from ingredients that are approved for use in processed cheese food (Kosikowski, 1977). Food grade stabilizers such as guar gum, xanthan gums, gelatin, or carageenan are permitted in processed cheese spread at concentrations not more than 0.8% (w/w) of the weight of processed cheese spread (FDA, 2013). The stabilizers are used to improve the consistency and stability of processed cheese spread (Zehren & Nusbaum, 1992). The moisture content of processed cheese spread is between 44 and 60% on a wet weight basis (FDA, 2013). The incorporation of excess moisture is approved to give a spreading quality to the processed cheese spread (Kosikowski, 1977). The fat content of processed cheese spread is not less than 20% on a dry weight basis (FDA, 2013). The ph of processed cheese spread is not below 4.0. (FDA, 2013). III. Functional properties of processed cheese and processed cheese food For food application, functional properties of cheese play an important role in the performance of cheese during the preparation and consumption of cheese (Guinee, 2002; Kapoor & Metzger, 2008). Firmness and meltability, which are the functional properties of processed cheese, are major parameters to affect the overall quality of processed cheeses (Shirashoji et al., 2006). 3.1 Firmness Firmness is a measure of the degree of cheese hardness and is a key factor affecting the consistency

4 222 Journal of Agriculture & Life Science 47(6) of cheese during shredding and slicing for food preparation (Guinee, 2002; Kapoor & Metzger, 2008). Firmness is affected by the moisture content of processed cheese and the type and concentration of emulsifying salts (Shimp, 1985; Gupta & Reuter, 1993). The firmness of processed cheese foods decreases with an increase in moisture content (Gupta & Reuter, 1993). Emulsifying salts selectively sequester calcium. The calcium bound to the casein reduces the water solubility and emulsifying properties of casein. Since emulsifying salts selectively chelate calcium, emulsifying salts enhance the emulsifying properties of casein. Emulsifying salts, such as tetrasodium pyrophosphate and sodium tripolyphosphate, strongly chelate calcium, and lead to the formation of firm processed cheese. On the other hand, emulsifying salts, such as disodium phosphate and trisodium phosphate, weakly chelate calcium resulting in the formation of soft processed cheese (Shimp, 1985). The firmness of processed cheese increased with an increase in the concentration of emulsifying salts, such as trisodium citrate (Shirashoji et al., 2006) and sodium hexametaphosphate (Shirashoji et al., 2010), from 0.25 to 2.75%. 3.2 Meltability Meltability is the capacity of cheese to form a uniform continuous melt (Kindstedt, 1999). Meltability of processed cheeses is an important quality parameter when the processed cheeses are used in soups or casserole recipes at schools or fast food restaurants (Zehren & Nusbaum, 1992). The meltability of processed cheeses is affected by the cooking time of processed cheese, the type and concentration of emulsifying salts, moisture content, and the amount of WPC added (Harvey et al., 1982; Shimp, 1985; Savello et al., 1989; Gupta & Reuter, 1993). An increase in the cooking time of processed cheese from 5 min to 15 min greatly decreases the meltability of processed cheese (Harvey et al., 1982). Similar results were reported by Shirashoji et al. (2006; 2010), who found that the meltability of processed cheese slightly reduced as cooking time increased from 0 min to 20 min. An increase of moisture content in processed cheese results in an increase in meltability (Gupta & Reuter, 1993). The meltability of processed cheese decreases as the amount of WPC added to processed cheese increases (Savello et al., 1989; Gupta & Reuter, 1993). A decrease in the concentration of emulsifying salts, such as trisodium citrate (Shirashoji et al., 2006) and sodium hexametaphosphate (Shirashoji et al., 2010), from 2.75 to 0.25% resulted in a decrease in the meltability of processed cheese. IV. Analytical methods for the determination of functional properties of processed cheese 4.1 Firmness Various empirical, imitative, and fundamental instrumental assess have been developed to determine the firmness of processed cheese (Templeton & Sommer, 1930; Thomas et al., 1970; Gupta et al., 1984; Kapoor & Metzger, 2008). In penetrometric methods, which is the empirical method, the firmness of processed cheese was determined by measuring force (expressed as grams of weight) needed to deform a cube of processed cheese (Templeton & Sommer, 1930; Kapoor & Metzger, 2008). Texture profile analysis (TPA) has been widely used in dairy industry and is an imitative instrumental analysis to measure the firmness of processed cheese (Kapoor & Metzger, 2008). TPA test is developed to mimic human mastication. A flat pate in TPA breaks down processed cheese generating two consecutive

5 Ha et al : Classification and functional properties of processed cheese 223 compression cycles (Steffe, 1996; Rosenthal, 1999). There are several instrumental methods to perform TPA in processed cheese, such as the Instron Universal Testing machine (Harvey et al., 1982; Gupta et al., 1984), General Foods Texturometer, and the TA.XT2i texture analyzer (Texture Technologies Corp., Scarsdale, N.Y., U.S.A.) (Drake et al., 1999; Awad et al., 2002; Kapoor & Metzger, 2004, 2005; Prow & Metzger, 2005). 4.2 Meltability The first method to evaluate the meltability of processed cheese was the Arnott Test (Arnott et al., 1957). This test is based on the measurement of changes in the height of processed cheese cylinders heat-treated in an oven at 100 C for 15 min. Meltability of processed cheese was quantified as the percent reduction in the height of cheese cylinder after heat treatment (Arnott et al., 1957; Kapoor & Metzger, 2008). The most frequently used meltability test for processed cheese is the Schreiber test (Kosikowski, 1977). In this test, the thick disks of cheese samples are placed in a petri dish and then heated at 232 C for 5 min in an oven, followed by cooling melted cheese for 30 min. The meltability of processed cheese was assessed with the Schreiber melt test score sheet, which has 11 concentric rings (Muthukumarappan et al., 1999; Kapoor & Metzger, 2008). Squeeze flow rheometry, named UW Meltmeter, has been developed to determine the meltability of processed cheese (Lucey et al., 2003; Kapoor & Metzger, 2008). In this method, squeeze-flow device with circular pate attached to an linear variable differential transformer generates melt profile from melted cheese. Squeeze flow rheometry can be used to objectively investigate the flow properties of melted processed cheese at various temperatures (Wang et al., 1998; Kapoor & Metzger, 2008) V. Conclusions Processed cheese can be classified into processed cheese, processed cheese food and processed cheese spread depending on the cheese composition, such as fat, moisture content, final ph, and optional ingredients. The firmness and meltability of cheeses are the crucial functionalities to affect the overall quality of processed cheese. The moisture content and emulsifying salt of cheeses are key-factors affecting the Table 1. Classification of processed cheese Type Ingredients 1,2 Composition 1,2 Min ph 1 Processed cheese food spread 1 Natural cheeses Emulsifying salt Acidifying agents Water, Colors Preservatives Cream 1,2 Same as processed cheese but milk, skim milk, cheese whey, and whey powder are permitted 1,2 Same as processed cheese food but stabilizers such as guar gum, oat gum and carrageenan are permitted 1 FDA (2013); 2 Kosikowski (1977) a For processed Cheddar cheese; b wet weight basis; c dry weight basis. 2 Not more than 40% moisture a on wwb b or not less than 43% fat a on dwb c Not more than 44% moisture on wwb or not less than 23% fat on dwb 1 Not less than 44% and not more than 60% moisture on wwb or not less than 20% fat on dwb

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