Public health concerns about the amount of sodium in the American diet and the associated risk of high blood pressure have pushed sodium into the spotlight. Find out the latest research on cheese and sodium, which was presented by Dairy Management Inc. at a symposium at the 2010 American Dairy Science Association (ADSA) meeting in Denver.

Working Together to Address the Sodium Challenge
Bill Graves, senior vice president of product research, Dairy Research Institute
Public health concerns about the amount of sodium in the American diet and the associated risk of high blood pressure have pushed sodium into the spotlight. Many government and health professionals have made public calls for voluntary reduction of salt in packaged and restaurant foods.   

The dairy industry recognizes the importance of the challenge to reduce the amount of sodium in Americans’ diets and supports public health initiatives to work with food manufacturers and all stakeholders to educate the public about healthy eating options. This effort includes product development and consumer research as well as identifying and sharing best practices to provide solutions to address public health concerns while maintaining taste, functionality and food safety.

The Innovation Center for U.S. Dairy is working with the Dairy Research Institute and other experts across the industry to share the most current consumer, sensory, nutrition and product analytical research that addresses emerging issues and opportunities for cheese. Through this pre-competitive industry collaboration, best practices for reducing salt in the cheesemaking process are being defined.

The Innovation Center recently completed a comprehensive audit of cheese products in the market, which identified significant variability in the amount of sodium content in commercially available cheeses. Reducing this variability can lead to more effective efforts to reduce the sodium content of cheeses in the market. With the increased attention on sodium, today’s consumers are more closely examining product nutrition labels for sodium content. According to Mintel International, more Americans are becoming concerned about sodium intake and are taking steps to monitor this intake by paying closer attention to package labeling. Reducing the variability of sodium content could help manufacturers improve label accuracy to better reflect the sodium content of their cheese.

At a symposium sponsored by Dairy Management Inc. at the 2010 American Dairy Science Association (ADSA) meeting in Colorado, industry experts shared the latest advancements toward reducing sodium in cheese, including the role salt plays in cheese microbiology, the important dietary nutrients of cheese, and flavor development and processes for making reduced-sodium cheese.

The 2005 Dietary Guidelines for Americans recommends limiting dietary sodium intake to 2,300 mg per day for middle-aged and older adults, African-Americans and those with hypertension; the recommended limit is 1,500 mg per day. On average, U.S. consumers ingest about 3,400 mg per day of sodium-50% higher than the current recommended intake. A report from the 2010 Dietary Guidelines Advisory Committee released in June recommends gradually lowering the current sodium intakes of adults and children to an eventual goal of 1500 mg per day. The 2010 Dietary Guidelines for Americans is expected to be released by the end of 2010.

“While cheese represents 7.8% of sodium consumption in our country, we know that cheese has multiple nutritional benefits and can play a vital role as part of a healthy diet,” said Greg Miller, president, Dairy Research Institute. “Not only does cheese taste great - it also contributes 21% of the calcium, 11% of the phosphorus, 9% of the protein, 9% of the Vitamin A and 8% of the zinc in the American diet. We are working closely with the Innovation Center for U.S. Dairy to take a leadership role in partnering with academic, science and health professionals to map out a plan to address sodium concerns.”

Diligent monitoring of the regulatory and public health environments and consumer marketplace will continue to be important. Upcoming Innovation Center work includes the release of a white paper, “Sodium: Insights for the Dairy Industry,” which provides a snapshot of the regulatory environment and also examines consumer insights and challenges as well as opportunities for reducing sodium in cheese. 

“Millions of adults have grown up eating, cooking with and enjoying the many benefits of cheese,” Miller said. “In order to stay relevant to consumers, ongoing research will help ensure that they will continue to appreciate cheese and cheese products as a satisfying, healthy and nutritious food for generations to come.”

Information and tools for the dairy industry are available at usdairy.com. Additional information on dairy product research and nutrition research can be found at www.innovatewithdairy.com.

The latest research on cheese and sodium was presented by Dairy Management Inc. at a symposium at the 2010 American Dairy Science Association (ADSA) meeting in Denver. Highlights of the presentations are outlined below:

Model Cheese Composition, Texture and Structure Can Influence Aroma, and Salt Mobility, Release and Perception
Clément de Loubens, INRA-AgroParisTech, Thiverval-Grignon, France 

To limit the impact of food on health issues such as obesity, hypertension or coronary diseases, the reduction of salt or fat content in food products without modifications to color, odor and taste remains a challenge. Researchers have found that a better understanding of the mechanisms involved in release and perception could lead to a better formulation of diet dairy products.

Researchers at INRA-AgroParisTech in France studied model dairy products with different contents of ultrafiltration retentate milk powder, milk fat and rennet to better understand and quantify the role of texture and structure on physicochemical and sensory properties. The characterization of dairy products was performed by sensory methods (profile, time intensity and temporal dominance of sensations) and by rheological (small amplitude oscillation tests, compression and texture-profile analysis), structural (confocal microscopy) and physicochemical methods (determination of aroma- and salt-partition properties and diffusion coefficients). Salt and aroma releases in the mouth were also followed respectively by in-nose measurement or by measuring the evolution of saliva conductivity during consumption.

A dominant effect of fat on aroma and salty perceptions was observed, in agreement with aroma compounds and salt behavior during in vivo and in vitro measurement. However, relating sensory perception and food product properties is a complex issue because of the variety of phenomena occurring in the mouth during consumption, such as dilution with saliva, break-down during mastication, etc. To identify main mechanisms explaining release in mouth, mechanistic models, based on the description of mass transfer of salt and aroma compounds in the mouth and taking both physiological and physicochemical parameters into account, have been developed. From the predicted release kinetics of stimuli (in agreement with experimental data), the respective roles of physiological parameters such as the masticatory performance and of product properties such as its breakdown properties can be established on salt release kinetics and salty perception. The identification of these parameters has to help to reduce salt and fat in dairy products. This ongoing research will allow for developing predictive model, which will help to tailor dairy products with specific sensorial and nutritional properties.

The Effect of Intrinsic and Extrinsic Factors on the Fate of Microbial Activity in Specialty and Lower-fat/Reduced- sodium Cheese
John B. Luchansky, Eastern Regional Research Center, United States Department of Agriculture, Wyndmoor, Pa.

Although the United States maintains one of the most abundant and wholesome food supplies in the world, the country should continue to review and improve its ability to recover, characterize and control microbial activity in foods, including specialty/ethnic products such as lower-fat/reduced-salt cheese. Various intrinsic and extrinsic factors can determine whether or not specific microbes die, grow or merely survive in cheese. A variety of biological (e.g., bacteriophage, bacteriocins), physical (e.g., high pressure processing, pasteurization) and chemical (e.g., organic acids, smoke, oxidizing agents) interventions have been used to better manage these microbes in cheese. However, salt, moisture and fat content, as well as temperature, quite arguably have the most significant effect on the fate of microbial activity in foods. Research on the ability to optimize salt and fat levels to maintain product safety/quality without causing adverse effects on the attendant sensory properties of lower-fat/reduced-salt cheese continues to emerge. With a trend toward consumption of cheeses that are more convenient, as well as lower in salt, fat and preservatives, the sole barriers against microbial activity may be adherence to Good Manufacturing Practices, formulation and refrigeration, coupled with enhanced awareness.

Influence of Salt in Moisture on Starter and Non-starter Lactic Acid Bacteria
Jeff Broadbent, Western Dairy Center, Utah State University, Logan, Utah; Jim Steele, University of Wisconsin-Madison, Madison, Wis.

The micro biota of ripening Cheddar cheese consists of the starter lactic acid bacteria (LAB) and non-starter LAB (NSLAB). Starter LAB is intentionally added to milk at the beginning of cheese manufacturing, while non-starter LAB (NSLAB) are adventitious microorganisms. These organisms have primary roles in the development of cheese flavor. Unfortunately, the mechanisms by which these organisms influence cheese flavor remain, in large part, unknown. This has made the development of cheeses with non-traditional compositions challenging, as it has not been possible to predict how changes in cheese composition would influence cheese flavor development. It is interesting to note that in both of these cheeses with non-traditional compositions, the salt-in-moisture level is significantly reduced compared to Cheddar cheese with traditional composition.

There are two primary hypotheses for how cheese composition can influence the development of cheese flavor: 1) that the microbiota of cheeses with non-traditional composition differs from that of cheeses with traditional composition; 2) that the microbiota is similar in both the traditional and non-traditional cheeses, but that the physiology of the SLAB and/or NSLAB is significantly different and hence they produced significant flavor compounds. Previous research in our groups and other groups worldwide have demonstrated that cheeses with intrinsic properties less restrictive to microbial growth accommodate a wider diversity of NSLAB, thus supporting the first hypothesis. Research recently completed has demonstrated that the physiology of SLAB and NSLAB is altered under conditions present in non-traditional Cheddar cheeses resulting in changes in the accumulation of beneficial and detrimental flavor compounds. This research has shown that the cheese microenvironment influences the composition and the metabolism of the microbiota. Strain selection is key to enhancing the flavor of Cheddar cheeses with altered compositions. Consistent control of cheese flavor will require a greater understanding of the metabolic processes which determine flavor development.

Combination of Approaches Required to Optimize Low-sodium and Low-fat Cheese Flavors
MaryAnne Drake, Southeast Dairy Foods Research Center, North Carolina State University

Flavor is a defining aspect of cheese consumption. Renewed interest in dietary fat and sodium reduction has increased interest in lowering fat and sodium in cheeses. Research conducted at the Southeast Dairy Foods Research Center at North Carolina State University sought to determine the impact of fat reduction and flavor of Cheddar cheese and determine the source of flavor differences with lower salt-in-moisture. 

Flavor and flavor development in Cheddar cheeses with a fat reduction greater than 50% are markedly altered from full-fat cheese. Similar alterations in flavor are noted with sodium reductions below 20%. Both lack of flavor and the presence of off-flavors are due to differences in flavor release as well as changes in the biochemistry of flavor development. Recent studies have highlighted homofuraneol and phenyl compounds (phenylacetic acid and phenylacetaldehyde) as sources of meaty/burnt/brothy and rosy off-flavors in low-fat and reduced-sodium cheeses. Concentrations and odor activity values of these compounds increased in Cheddar cheese with increased fat reduction. Addition of sodium gluconate to low-fat cheeses decreased levels of these compounds up to 50% but did not impact sensory perception.

Decreasing sodium in low-fat Cheddar cheeses increased bitterness and aromatic off-flavors but interactions were noted between starter culture and salt concentration, suggesting that strain selection would be beneficial for sodium reduction. Changes in salt in moisture influence starter bacteria, and are at least one source of altered flavor chemistry and off flavors. The addition of sodium gluconate helped decrease bitter taste and provided minimal impact to the cheese sensory profiles. In addition, ripening the cheese at a lower temperature (38°F compared to 45°F) past nine months provided lower rosy and decreased burnt/brothy flavors in the cheese. 

Cheesemaking Processes and Strategies for Manufacture of Low-fat and Reduced-sodium Cheeses
Tim Guinee and Kieran Kilcawley, Teagasc Food Research Centre Moorepark, Fermoy, Co., Cork, Ireland

Cheese is a concentrated gelled product that structurally consists of a calcium-phosphate casein/para-casein matrix, enclosing fat and moisture. Both the concentration of the matrix and the level of interaction between the casein aggregates making up the matrix are key determinants of the physical properties. The quality of low-fat cheese variants is not as acceptable as that of their conventional full-fat counterparts owing to their higher concentration of protein in the cheese moisture, removal of the dilution effect of fat globules, higher degree of fusion and jamming of the casein particles and unbalanced flavor.

A key strategy in the manufacture of low-fat (< 3%) cheese is to reduce the volume fraction of the casein matrix and to reduce the extent of casein aggregation. This may be achieved by dilution of the protein matrix on increasing moisture via manipulation of a range of process variables, including inter alia, heat treatment of milk, reduction in pH at rennet addition, gel firmness at cut, curd particle size, scalding rate, scald temperature, length of time in vat, pH at whey drainage, salting and milling (Cheddar) and pre-salting prior to plasticization (pasta-filata cheese). The degree of aggregation is particularly influenced by the ratio of denatured whey protein-to-casein, calcium phosphate-to-casein, the ionic strength (affected by the level of NaCl and time of salting), and pH. Reducing the contents of fat and salt in cheese adversely affects the development and release of key compounds associated with cheese flavor. Moreover, it is important to ensure that the ratios of degradation products of protein and fat per gram of protein or fat, respectively, in low-fat, low-salt cheese are altered to convey flavor perception similar to that of cheeses of normal fat and salt content. The regulation of these factors and lactate-to-protein ratio, a key factor in controlling cheese pH, are critically influenced by the type of starter culture, the level and proteolytic activity of the rennet, curd washing, ripening conditions and rate of curd cooling.