Figure 1. Cheeses today have a wide range of quality traits. Photo copyright © iStockphoto.com/Kcline pg 66 BY DIANE L. VAN HEKKEN Quality Aspects of RAW MILK CHEESES The microflora of the raw milk contributes to a greater diversity of cultures and enzymes, which ripens the cheese faster and produces stronger flavors and aromas. heese has been a part of the human Milk Pasteurization diet for thousands of years (Fox and Throughout the centuries, the sanitation pro- McSweeney, 2004). Over the centu- tocols for milk collection, processing, and ries, cheesemakers have relied on the cheesemaking were minimal or nonexistent indigenous microflora and enzymes by current standards. Cheesemakers occasion- naturally found in raw milk from ally had to contend with cheese of inconsistent Cdomesticated animals to help develop the very or poor quality or short shelf life. The start specific signature quality traits of the hun- of the industrial age led to larger pooled milk dreds of different types, styles, and varieties sources, larger scale cheese plants, and wider of cheese found around the world (Figure 1). distribution of the product. Subsequently, food Quality traits such as appearance, aroma, fla- safety became a major concern as bovine tuber- vor, and texture are critical to the value that culosis, brucellosis, and typhoid fever were consumers place on the raw milk cheeses. linked to consumption of raw milk (Holsinger With the transition to pasteurized milk et al., 1997). After the introduction of Louis by most of the cheese industry, raw milk Pasteur’s germ theory in the 1860s, milk pro- cheeses manufactured in the United States ducers began to heat treat their milk and, by have survived as a niche market with very loyal the 1940s, most cheesemakers in the U.S. were customers. Today, the growing numbers of using pasteurized milk to make their cheese. artisan and farmstead raw milk cheese oper- Government regulations (FDA, 2012a, b) ations are in response to consumer interest are now in place concerning heat processing of in locally produced and sustainable agricul- milk intended for human consumption and the tural products (Figure 2), although the bulk of mandatory sanitation protocols required for on the raw milk cheeses continue to be manufac- the farm and in the cheese plant. Today’s dairy tured by a few large-scale cheese companies. industry is focused on keeping Campylobacter Of the 10.61 billion lb of cheese manufactured jejuni, Escherichia coli O157:H7, Listeria monocyto- in the U.S. in 2011 (NASS, 2012), it is esti- genes, Salmonella, and enteroxin producing Bacillus mated that less than 1% was made from raw cereus and Staphylococcus aureus from contaminat- milk (Goddik, 2012). This article focuses on ing dairy products (Holsinger et al., 1997). the quality traits of raw milk cheese and how The current legal definition of milk pasteur- and why they differ from pasteurized versions. ization in the U.S. requires that every particle 06.12 • www.ift.org 67 pg About 30 of the 72 cheeses defined by the Food and Drug Figure 2. Specialty raw milk cheeses, such as the Administration (FDA) can be award-winning Rogue River Blue shown here, appeal to made legally from raw milk and the consumer visually and through the palate. sold throughout the U.S. (see Photo courtesy Rogue Creamery, Central Point, Ore. Table 1; ACS, 2012b). The Centers for Disease Control (CDC, 2012) and FDA (FDA, 2012c) currently recommend that persons at risk, such as children under 5-years old, pregnant women, and persons with chronic diseases or sup- pressed immune systems, should not consume raw milk products. Raw Milk Cheeses To prevent pathogenic contami- nation, raw milk cheesemakers ensure that high quality milk from healthy animals is collected and processed under hygienic condi- tions. The main argument against pasteurization, as it relates to qual- ity traits, is that the prolonged heating of milk destroys the advan- tageous enzymes and bacteria (and their associated enzymes) that impart the essential nuances of milk is heated to a specific tem- In the 1950s, standard of to the texture, aroma, and fla- perature and held continuously identity for many cheeses was vor of cheese. Manufacturers of at or above that temperature for modified to include the state- raw milk cheeses may heat shock the specified time; i.e., 63°C ment that any cheese made from their raw milk (60–65°C for 15 for 30 min, 72°C for 15 sec, or milk that was not pasteurized sec) to ensure that pathogens are 89°C for 1 sec (FDA 2012b). This must be held at temperatures destroyed but not long enough to heat treatment destroys all non- above 1.6°C for a minimum of 60 kill all of the beneficial bacteria or spore forming organisms in the days before it could be sold in the inactivate the enzymes. However, milk, including pathogenic bac- U.S. (FDA 2012b). Therefore, this milk does not meet the legal teria and most of the indigenous fresh and young raw milk cheeses requirements for pasteurization. bacteria, yeasts, and molds. cannot be sold in the U.S. Reactions in Cheese Table 1. Styles of cheeses found in the U.S. and the type of milk used in their manufacture (ACS, 2012c). Only varieties that will be aged for a minimum of 60days can be made from raw milk. There are numerous components found in milk that are critical to Style Cheese Milk the final quality of the cheese. The Blue Roquefort, Gorgonzola, Danish blue Raw* and pasteurized proteins, lipids, and carbohydrates Firm-hard Gouda, Cheddar, Dry Jack, Swiss/ Raw* and pasteurized are substrates for the biochemi- Emmenthaler, Gruyere, Parmesan cal and chemical reactions and Fresh Chevre, cottage cheese, cream cheese, Feta, Pasteurized only microbiological activity that quark, Queso Fresco and other fresh Hispanic- occur to produce the final cheese. style cheeses, mascarpone, ricotta These processes are driven by the Rind Tomme de Savoie, Mimolette, Stilton, Raw* and pasteurized enzymes in the milk, originating Lancashire, Epoisses, Livarot, Taleggio from either the mammary gland Pasta filata Mozzarella, provolone, scamorza Raw* and pasteurized or the indigenous microflora, or are added during cheesemaking as Soft ripened Brie, Camembert Usually pasteurized coagulant or inoculated cultures. Semi-soft Blues, Colby, Fontina, Havarti, Monterey Jack Raw* and pasteurized Only one-third of the 60 esti- * cheese must be aged for a minimum of 60 days mated indigenous enzymes present pg 68 06.12 • www.ift.org in milk have been characterized, lysis. The enzymes include prote- dairy industry (Cornell, 2008). and only plasmin, cathepsin D, and ases, peptidases, lipases, esterases, A recent study of Vermont lipoprotein lipase have been stud- lactases, decarboxylases, dehy- farmstead raw milk cheese opera- ied in cheese (Fox, 2003). Limited drogenases, and synthases among tions found that 86% of the milk information on the other enzymes others (Beuvier and Buchin, samples had <10,000 SPC with and whether they are inactivated 2004; McSweeney and Fox, 42% <1,000 SPC (D’Amico and during pasteurization makes it dif- 2004; Upadhyay et al., 2004). Donnelly, 2010). The American ficult to estimate their influence Cheese Society (ACS, 2012a) in cheese. Pasteurization is known Start with High-Quality Cheesemilk reports that about two-thirds of to completely inactivate alkaline The essential step in making any their members exceed federal reg- phosphatase, partially inactivate cheese is to begin with high-quality ulatory standards, follow a Hazard cathepsin D (Hayes et al., 2001) milk. The 2007 grade ‘A’ pasteur- Analysis & Critical Control Points and lipoprotein lipase (Hickey et ized milk ordinance (FDA, 2012a) (HACCP) plan, and adhere to al., 2007), and disrupts the com- sets maximum limits for pre-pas- ACS-recommended best practices. plex system of inhibitors and teurized milk at 100,000 standard activators for plasmin, essentially plate count g-1 (SPC) or 750,000 Microflora in Cheese increasing its activity in pasteur- somatic cell counts mL-1 (SCC). Extensive research has been con- ized milk (Prado et al., 2006). California has stricter require- ducted since the early 1900s The indigenous microflora ments for certified raw milk for to identify the bacteria that are found in raw milk brings an abun- direct human consumption at responsible for imparting the dance of enzymes into cheesemilk <50,000 SPC and <600,000 quality traits for specific cheeses. that can be used by the bacterial SCC (CDFA, 2012). Values as low Today’s culture supply companies metabolic pathways, secreted into as <10,000 SPC and <200,000 have extensive inventories of lac- the cheese, or released upon cell SCC have been suggested by the tic acid bacteria (LAB), nonstarter pg 025670 Buchi_IFT_March_NIR Kjeldahl_Jun.indd06.12 • www.ift.org 1 5/18/2012 3:32:48 PM in raw milk Queso Chihuahua and only five in the pasteurized milk cheeses. Ogier et al. (2002) reports eight bands in DNA pro- files from Camembert cheese made from raw milk and only five bands in a pasteurized version. A raw milk Greek cheese, Avenato, has 12 different species of LAB, three Lactococcus, three Leuconostoc, and six Lactobacillus (Hatzikamari et al., 1999). Raw milk Comté was found to have 13–15 differ- ent strains of Lactobacillus paracasei and rhamnosus (Berthier et al., 2001). The wider selection of bac- Figure 3. The aging process assists in the development of teria contributes a wider array of the desired quality traits of the cheese. enzymes available to degrade milk Photo copyright © iStockphoto.com/matejmm components, thus affecting tex- tural and sensorial attributes. Texture of Raw Milk Cheeses lactic acid bacteria (NSLAB), aging while NSLAB and adjuncts Cheesemakers carefully select and adjunct cultures for making start off at lower numbers, 103–104 protocols and control vat condi- many different types, styles, and cfu g-1, and increase during aging.