October 2011
Bringing industry the latest technical insights and research on dairy nutrition, products and sustainability.
 
Featured Event

Dairy Research Institute Proudly Supports New Institute for Dairy Ingredient Processing at Midwest Dairy Foods Research Center

Driving dairy innovation is highlighted with the grand opening this month of the Institute for Dairy Ingredient Processing (IDIP), a component of the new Davis Dairy Plant at South Dakota State University. IDIP provides dairy ingredient manufacturers with an efficient, valuable and improved way to research and develop and test new dairy-based ingredients and processes. IDIP is the only resource of its kind developed to facilitate the commercialization of manufacturing processes that expand the product portfolio of dairy-based ingredients produced for domestic and international markets. Learn more.

Introducing the Dairy Research Institute New Product Competition

As part of the dairy checkoff funders' commitment to dairy research and innovation, the Dairy Research Institute launched a new product competition to recognize outstanding student teams who develop an innovative dairy beverage that  is on trend with current industry insights. This opportunity supports the importance of dairy research and provides a platform for students to bring their knowledge and expertise to dairy beverage innovation. Learn more.

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Research from the Dairy Research Institute

Study Reinforces That 3-4 Daily Dairy Servings Can Be Part of an Effective Weight Loss Plan

A 15-week controlled feeding study among 71 overweight and obese men and women found that those who consumed 3-4 daily servings of dairy lost the same amount of weight, body fat and intra-abdominal fat as those who consumed one serving or less. This study reinforces that adequate dairy consumption can be a part of an effective weight loss plan.

Participants in the study were between the ages of 20 and 50 and were on a fully controlled diet that reduced total caloric intake by 500 calories per day. Participants were randomly assigned to consume either an adequate dairy diet that included 3-4 servings or a low dairy diet that included one serving or less. Those in the adequate dairy group consumed a variety of products, including low- or reduced-fat milk, low-fat yogurt and full-fat cheese.

Results:

  • Subjects in both the adequate dairy and control groups lost similar amounts of body weight, body fat and intra-abdominal fat.
  • There were no differences between the two groups in lean body mass, total cholesterol, LDL cholesterol or fasting glucose levels.
  • There was a trend toward greater reduction in fat-cell size in the adequate dairy group. Changes at the cellular level may occur before whole-body changes in fat mass can be seen. These results indicate a higher amount of fat lost from fat cells in those consuming adequate dairy.
  • Consumption of the adequate dairy diet significantly improved blood levels of vitamin D, with an average increase from baseline of nearly 17 percent. Vitamin D levels in the low-dairy group did not significantly change.

Some previously published clinical trials with overweight and obese adults found that those who followed reduced-calorie diets and increased their dairy intake to three servings a day lost more body weight and fat than those who reduced their caloric intake and consumed inadequate amounts of dairy foods. Overall, observational and clinical research continues to indicate that the consumption of three servings of milk, cheese or yogurt each day as part of a nutrient-rich, balanced diet helps maintain a healthy weight.

In clinical studies examining the role of dairy in weight loss where caloric restriction was induced, weight loss was achieved. Therefore, the inclusion of three servings of dairy in a weight-loss diet does not preclude weight loss and, in some studies, has been shown to enhance weight loss. The Dietary Guidelines for Americans recommends individuals 9 years and older consume three daily servings of low-fat or fat-free milk and milk products to help build a healthy diet.

Van Loan MD, Keim NL, Adams SH, et al. Dairy foods in a moderate energy restricted diet do not enhance central fat, weight, and intra-abdominal adipose tissue losses nor reduce adipocyte size or inflammatory markers in overweight and obese adults: A controlled feeding study. J Obes. [Epub ahead of print]. 2011 Sep 14

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Review Concludes That Natural Trans Fat From Dairy Foods and Beef Are Different From Industrial Trans Fats and May Show Positive Health Effects

A comprehensive review of research reveals that natural trans fats produced by ruminant animals such as dairy and beef cattle are not detrimental to health in amounts commonly consumed, and in fact experimental models have shown they may be linked to reduced risk of cardiovascular disease and cancer.

The review states that consuming natural trans fats produced by ruminant animals, such as conjugated linoleic acid (CLA) and vaccenic acid, has different health effects than consuming industrially produced trans fats, such as partially hydrogenated vegetable oils. Industrially produced trans fats have been associated with elevated cholesterol levels and coronary heart disease.

According to the review, the naturally occurring trans fat has a different fatty acid profile than industrial trans fat, which contributes to its different physiological effects. Also, the amount of natural trans fat consumed has been relatively stable and much lower than the amounts consumed from partially hydrogenated oils that have been associated with adverse effects. For example, in the U.S., intake of ruminant trans fatty acids represents only about 20 percent of total trans fatty acid intake.

The authors of this comprehensive review say additional studies are needed on the health effects of ruminant trans fat in amounts that are commonly consumed in the diet. Although experimental data from animal studies suggest that ruminant trans fatty acids may beneficially affect risk of cardiovascular disease and cancer, controlled clinical trials in humans are needed to determine the effects of vaccenic acid and the specific forms of CLA on markers of cardiovascular risk and cancer.

Recommendations to reduce trans fats in the diet are based on studies of industrially produced trans fats. Therefore, it’s important for the dairy industry to clarify the distinction between naturally occurring trans fats that exist in very small amounts in dairy products and those produced industrially.

Gebauer SK, Chardigny J-M, Jakobsen MU, et al. Effects of Ruminant trans Fatty Acids on Cardiovascular Disease and Cancer: A Comprehensive Review of Epidemiological, Clinical, and Mechanistic studies. Adv Nutr. 2011;2:332-354.

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Chocolate Milk and Other Beverages Containing Protein and Carbohydrate Help Improve Recovery After Endurance Exercise

A recent review paper reports, “Present evidence suggests that chocolate milk is a good choice as a recovery beverage for endurance athletes.” The author stated that beverages containing both carbohydrate and protein, such as chocolate milk, can improve recovery under some exercise conditions. Nutrition for improved recovery following endurance exercise must replenish spent fuel, repair muscle and rehydrate the athlete. This may allow for more intense training for an event or better performance during competitions such as soccer or tennis tournaments, track or swim meets that include multiple heats, or bicycle stage races.

Carbohydrate supplies most of the calories in chocolate milk — provided by the natural sugar lactose and other added sugars. Research shows the carbohydrate in chocolate milk quickly replenishes muscle glycogen, a fuel used during endurance exercise. High-quality proteins in chocolate milk, such as casein and whey, contain a substantial proportion of branched-chain amino acids such as leucine, which play an important role in muscle protein synthesis. In addition, the electrolyte content of milk or chocolate milk may aid rehydration.

Of the few studies looking specifically at chocolate milk, most have shown a favorable influence on post-exercise recovery. Although more research is needed before specific recommendations can be made, the author concluded that chocolate milk is a good choice for recovery by endurance athletes — particularly since it is widely available at a relatively low cost and is very palatable. Lactose-free chocolate milk is an option for those athletes who might be lactose intolerant.

A related article by Ferguson-Stegall, et al., was summarized in the June issue of this newsletter. For more information on chocolate milk and exercise recovery, click here.

Saunders MJ. Carbohydrate-Protein Intake and Recovery from Endurance Exercise: Is Chocolate Milk the Answer? Curr Sports Med Rep. 2011;10(4):203-210.

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Higher Dietary Intakes of Calcium and Vitamin D Associated with Lower Percent Body Fat in Premenopausal African-American Women

A new study provides additional evidence that consuming low-fat and fat-free dairy products may be an effective strategy for those who are struggling with obesity. A cross-sectional study of 100 healthy, premenopausal African-American women found that those who consumed the recommended amount of calcium for their age group had an average body mass index (BMI) within the normal range and a relatively low percent body fat. However, 80 percent of participants did not meet their calcium recommendation; they were obese with an average BMI of 31.7 and a high average percent body fat of 39.4. A 37.9 or higher percent body fat was associated with significantly lower intakes of dietary calcium (none of the participants took calcium supplements) and vitamin D.

Only about a third of the women consumed the amount of vitamin D recommended at the time of this study; none consumed amounts higher than currently recommended (600 IU/day). Those women who did not meet their vitamin D intake recommendations also had a low average calcium intake of 605.3 mg/day, were classified as obese and had 40 percent body fat.

Overall, say the authors, previous studies support the contention that inadequate calcium intake may increase the risk of overweight. They discussed several physiological mechanisms that may explain how dietary calcium influences body weight in humans and how it interacts with vitamin D in a complex system. For example, it has been shown that a higher intake of dietary calcium signals fat cells (through the active form of vitamin D) to reduce the rate of fat cell formation and increase the rate of breakdown. In addition, higher intakes of calcium may reduce fat absorption from the gut and increase fat oxidation (use of fat as fuel).

Several components of dairy products, such as calcium, protein and vitamin D may work together to help reduce body fat. For example, there is evidence that leucine, an essential amino acid found in abundance in whey protein, can decrease energy storage in fat cells and increase fat utilization in muscle. In addition, dairy proteins — when part of a higher protein diet — have been shown to suppress short-term food intake and promote satiety. Therefore, the authors said increasing the consumption of low-fat dairy products may be a good strategy for increasing calcium and vitamin D intakes in populations struggling with obesity.

Tidwell DK, Valliant MW. Higher amounts of body fat are associated with inadequate intakes of calcium and vitamin D in African American women. Nutr Res. 2011;31(7):527-536.

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Consumption of Leucine, an Amino Acid Present in Whey Protein, Enhances Post-exercise Muscle Protein Synthesis

Whey protein is one of the best sources of leucine, an amino acid that has been shown to have post-exercise benefits. In a randomized crossover study in eight military adults, muscle protein synthesis following exercise was 33 percent greater after consuming a leucine-enriched amino acid supplement during one hour of moderate cycling than when a similar amino acid supplement lower in leucine was consumed. The authors said these findings support their hypothesis that consuming a small amount of essential amino acids enriched with leucine during steady state exercise limits the body’s dependence on its protein stores and enhances muscle protein synthesis in exercise recovery.

On day 8 and 13 of the study, volunteers engaged in 60 minutes of moderate steady state exercise (e.g., endurance exercise on a stationary cycle). Throughout the exercise, volunteers consumed an equal volume of either a leucine-enriched (3.5 grams leucine) essential amino acid supplement dissolved in water with artificial sweetener every 20 minutes or a control essential amino acid supplement that was lower in leucine (1.87 g leucine). The total amount of essential amino acids consumed in each trial was 10 g (2.5 g every 20 minutes for an hour), with an amino acid profile consistent with the amount of essential amino acids in 20 g of high-quality protein, such as whey protein.

Previous studies have established the benefit of essential amino acid supplementation (particularly leucine) for enhancing muscle protein synthesis after resistance exercise. This is the first study to assess whether dietary supplementation of leucine during endurance-type exercise enhances muscle protein synthesis in recovery. Future studies might explore how enhancing the leucine content of protein supplements may benefit other populations susceptible to muscle loss, such as the elderly or chronically ill.

As noted in an article in the March issue of Nutritional Outlook, “Whey protein is one of the best sources of naturally occurring branched chain amino acids, including leucine, which is unique compared with other amino acids in its ability to stimulate muscle protein synthesis.” Whey protein provides a great opportunity for the food and beverage industry to reach consumers who want protein-rich foods high in leucine for muscle recovery benefits.

Pasiakos SM, McClung HL, McClung JP, et al. Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances post-exercise muscle protein synthesis. Am J Clin Nutr. 2011;94(3):809-818.

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Whey Protein Supplementation While Maintaining a Usual Diet Reduces Fatty Liver in Obese Women

A new study indicates whey protein may be beneficial for fatty liver in obese women. The incidence of nonalcoholic fatty liver disease, characterized by an elevated concentration of fats within the liver, is often increased in obese individuals and is strongly associated with other metabolic complications of obesity, such as insulin resistance, impaired glucose tolerance and abnormal blood lipids. A study in Switzerland among 11 obese nondiabetic females found that a four-week supplementation with 60 grams/day whey protein, when incorporated into the usual diet, significantly decreased liver fat by 21 percent, fasting blood levels of total trigylcerides by 15 percent and total cholesterol by 8 percent.

The average age of the study participants was 38 years. The researchers instructed the women to consume 20 g of commercially available whey protein dissolved in water 30 minutes before breakfast, lunch and dinner. Otherwise, they were allowed to eat and drink whatever they wanted.

After four weeks of whey protein supplementation, body weight remained unchanged, while body fat mass was slightly, but significantly, reduced and lean body mass was increased. Visceral (intrabdominal) fat volume, liver volume, fasting and two-hour plasma glucose and insulin concentrations were not changed. Since body weight did not change even though 250 calories/day were provided by the whey protein supplement, the authors speculated that the whey may have had a satiating effect, leading to a spontaneous decrease in food intake. A lower intake of carbohydrate or fat, for example, could potentially be responsible for the observed reductions in liver fat and plasma triglyceride.

Previous studies have indicated that whey protein supplementation may be beneficial for weight maintenance and muscle protein synthesis when part of a higher protein diet. Further studies are needed to confirm its benefit for nonalcoholic fatty liver disease — and determine whether consumption of whey protein long-term by obese individuals may be an effective strategy for improving metabolic health.

Bortolotti M, Maiolo E, Corazza M, et al. Effects of a whey protein supplementation on intrahepatocellular lipids in obese female patients. Clin Nutr. 2011;30(4):494-498.

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A 25-gram Whey Protein Drink After Resistance Exercise Stimulates Muscle Protein Synthesis More Effectively Than Smaller Amounts Consumed Over Time

Previous studies have established that consumption of the dairy protein whey (rapidly digested protein) enhanced the effect of exercise on muscle protein synthesis more effectively than the dairy protein casein (slowly digested protein). In order to study the effect of different protein absorption rates on muscle protein synthesis after resistance exercise, whey protein was given to eight healthy, physically active men post-exercise either as a single 25-gram drink or in smaller, 2.5-g drinks consumed every 20 minutes 10 times. Consuming smaller amounts of whey protein more frequently was meant to simulate amino acid delivery to the blood stream of a more slowly digested protein. Results showed that consuming 25 g of whey protein all at once post-exercise rapidly delivered amino acids to the bloodstream and stimulated muscle protein synthesis to a significantly greater extent than an identical amount of protein consumed in smaller amounts over time.

The authors speculated that habitually consuming rapidly digested proteins, such as whey protein, after resistance exercise provides a muscle-building advantage. These findings have important implications for refining recommendations for eating patterns and protein choice after exercise in order to maximize muscle growth over the long term. The results also may have application to elderly populations, who need improved strategies for minimizing age-related reductions in muscle mass.

West DW, Burd NA, Coffey VG, et al. Rapid aminoacidemia enhances myofibrillar protein synthesis and anabolic intramuscular signaling responses after resistance exercise. Am J Clin Nutr. 2011;94(3):795-803.

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Consumption of High Amounts of Milk Fat Shown to Not Increase Markers of Inflammation After a Meal

This study demonstrates that milk fat does not adversely affect post-meal markers of inflammation and those that can lead to atherosclerosis. Prior research has indicated that cardiovascular disease risk can be partially predicted by the presence of biomarkers of inflammation after a meal abnormally high in fat. The results of a study in 12 overweight Australian adults aged 55-69 years indicated that consumption of high amounts (45 grams) of milk fat provided by butter, cream, yogurt or cheese within a single breakfast meal did not increase markers of inflammation. In fact, the high-fat cream breakfast containing nearly half a cup of cream, the high-fat butter breakfast containing about 3 tablespoons of butter and the low-fat control breakfast containing over 1½ cups of low-fat milk significantly lowered levels of some inflammatory markers at three hours after the meal. In addition, markers of inflammation were not affected by whether the food was fermented or not.

The study was conducted in two parts — a single-meal study and a four-week intervention. In the single-meal study, five meals — one containing low-fat milk (control) and four containing full-fat dairy foods (45 g of fat provided by Cheddar cheese, cream, butter and yogurt) — were tested on different days over a 2-3 week period for their effect on eight markers of inflammation and atherosclerosis in the blood at three and six hours after the meal. A four-week intervention, conducted about nine weeks after completion of the single-meal study, tested whether the effect on biomarkers differed depending on whether the full-fat dairy food was fermented or not. Participants ate higher-fat diets containing approximately 50 g of fat, either from nonfermented sources such as butter plus cream and full-fat ice cream or from fermented sources such as Cheddar cheese and full-cream yogurt.

In the four-week intervention, there were no differences in inflammatory markers between diets containing full-fat fermented or non-fermented dairy foods. There were also no differences in average plasma glucose, triglyceride, total cholesterol, LDL cholesterol or HDL cholesterol.

Additional work is necessary to determine the mechanism by which milk fat may differ from other sources of saturated fat. The milk fat research program of the Dairy Research Institute® is further assessing potential beneficial attributes associated with milk fat and cheese consumption.

Nestel PJ, Pally S, Macintosh GL, et al. Circulating inflammatory and atherogenic biomarkers are not increased following single meals of dairy foods. Eur J Clin Nutr. [Epub ahead of print]. 2011 Aug 3.

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Higher Intake of Potassium Associated with Significantly Lower Risk of Stroke

Milk is the No. 1 dietary source of potassium in the American diet, and a new study shows that this nutrient may significantly lower risk of stroke. A meta-analysis of 10 independent prospective studies found that for every 1,000 milligrams/day increase in potassium intake, the risk of stroke decreased by 11 percent. When specific subtypes of stroke were analyzed as reported in five studies, a higher potassium intake was associated with a significant reduction in risk of ischemic stroke. The relationship was not as strong for other types of stroke.

The association between potassium intake and risk of stroke was similar in both men and women and was shown in studies with both less than and greater than 10 years of follow-up. The association was also similar in studies conducted in the United States, Europe or Asia.

Many Americans do not consume enough potassium — a nutrient listed among the nutrients of public health concern by the 2010 Dietary Guidelines. Food sources of potassium include fruits, vegetables, root vegetables, legumes, milk and yogurt. An eight-ounce serving of fat-free milk provides about 382 mg of potassium. One way increased potassium intake may help reduce risk of stroke is by reducing blood pressure.

According to the authors, a meta-analysis of randomized controlled trials indicates that potassium alone or in combination with calcium and magnesium — all nutrients provided by dairy foods — is associated with a reduction in blood pressure. Eating according to the DASH dietary pattern, rich in fruits and vegetables and containing the recommended three servings of dairy foods (rich in potassium, calcium and magnesium) is a recommended way to help maintain a healthy blood pressure and potentially reduce the risk of stroke.

Larsson SC, Orsini N, Wolk A. Dietary Potassium Intake and Risk of Stroke: A Dose-Response Meta-Analysis of Prospective Studies. Stroke. [Epub ahead of print]. 2011 July 28.

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Higher Intake of Probiotic Milk Products Associated With Lower Risk of Preeclampsia in Pregnant Women

Researchers in Norway found that pregnant women who were the highest consumers of probiotic milk products had a 20 percent lower risk of preeclampsia than did nonconsumers. A daily average intake of at least 140 mL of probiotic milk products — equivalent to about 5 ounces of probiotic-containing yogurt — was associated with a lower risk of preeclampsia. Preeclampsia is a serious condition in pregnancy characterized by elevated blood pressure and protein in the urine. This condition is associated with poor pregnancy outcome and is one of the leading causes of maternal death worldwide.

Compared to no intake, moderate and high intakes of probiotic milk products were associated with reduced risk of severe preeclampsia, with the high intake group having a 40 percent lower risk. Severe preeclampsia often leads to medically indicated preterm delivery.

The study participants were part of a large prospective study of 33,000 pregnant women in Norway bearing their first child. Previous studies have found that probiotics can favorably modify inflammation of placental cells that function in the nourishment and implantation of the embryo. This inflammatory response seems to play a prominent role in early-onset and severe preeclampsia. The authors also speculated that probiotic milk products may influence the risk of preeclampsia more indirectly by reducing blood pressure.

The investigators said these results warrant future randomized controlled trials investigating specific strains/species of probiotics for their effectiveness in reducing the risk of preeclampsia during pregnancy.

Prior research indicates that dairy foods may beneficially influence blood pressure. The Dairy Research Institute continues to explore the unique ability of dairy, including cultured dairy products, to improve blood pressure in at-risk populations.  

Brantsaeter AL, Myhre R, Haugen M, et al. Intake of probiotic food and risk of preeclampsia in primiparous women: the Norwegian Mother and Child Cohort Study. Am J Epidemiol. [Epub ahead of print]. 2011 Aug 5.

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Many Americans Not Meeting Recommended Intakes of Calcium, Vitamin D and Potassium Even When Enriched/Fortified Foods and Dietary Supplements Are Included

An analysis of current data from the National Health and Nutrition Examination Survey (NHANES) 2003-2006 assessed usual intakes of 19 micronutrients for U.S. residents aged 2 years and older. Nutrient intakes were assessed from all sources, including nutrients naturally occurring in food, nutrients contributed by enrichment/fortification of foods and nutrients supplied by dietary supplements. This is the first analysis to separately determine intakes of micronutrients naturally occurring in foods and those contributed by enrichment and/or fortification. When only naturally occurring food sources were considered, substantial percentages of children and adults did not consume enough of several micronutrients. Enrichment and/or fortification of foods contributed significant percentages of vitamins A, B6, B12, C and D as well as thiamin, riboflavin, niacin, folate and iron. When intakes from dietary supplements were considered, the percentages of those underconsuming these nutrients were further reduced.

According to the analysis, the percentage of individuals with total usual nutrient intake from foods and dietary supplements below the Estimated Average Requirement (EAR) for the population was considerable for vitamin D (70 percent), vitamin E (60 percent), calcium (38 percent), vitamin A (34 percent), vitamin C (25 percent) and magnesium (45 percent). Less than 3 percent of the population had total usual intakes of potassium that exceeded the EAR. The EAR is used by experts to identify nutrient inadequacies in groups or populations, but not individuals. The Recommended Dietary Allowance, or RDA, is the target for individuals and dietary patterns in the 2010 Dietary Guidelines for Americans (DGA).

The DGA recommends individuals achieve recommended nutrient intakes from food sources, without over-consuming calories, by consuming nutrient-dense foods such as fruits and vegetables, whole grains, lean meats and low-fat or fat-free dairy foods. Americans 9 years and older are currently consuming 1.6 of the recommended three dairy servings per day on average. Adding just one more serving of dairy can help fill some of America’s nutrient gaps, including calcium, vitamin D and potassium — under-consumed nutrients identified by the DGA to be of public health concern.  

Fulgoni III VL, Keast DR, Bailey RL, Dwyer J. Foods, fortificants, and supplements: Where do Americans get their nutrients? J Nutr. [Epub ahead of print]. 2011 Aug 24.

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Evidence Emerging That Low Vitamin D Status Is Associated with Obesity, Type 2 Diabetes and Cardiovascular Disease in Ethnic Minorities

The authors of a systematic review of 20 primarily cross-sectional studies say emerging evidence indicates that low-vitamin D levels are associated with obesity, type 2 diabetes, cardiovascular disease and metabolic syndrome — and ethnic minorities are the most affected. According to the paper, ethnic minorities had significantly higher rates of vitamin D insufficiency, defined as a blood level of less than 50 nmol/L 25 hydroxyvitamin D, than their white counterparts. Ethnic groups included African-Americans, Pacific Islanders, Hispanic-/Mexican-Americans, Asian-American, Maori and migrants.

Because most of the studies reviewed were cross-sectional and not randomized controlled trials, it was not possible to establish a causal relationship between vitamin D status and these chronic diseases. Establishing such causal links and understanding the mechanisms behind them will be crucial to determining whether additional food fortification with vitamin D will help reduce their risk. Currently milk, many yogurts and some cheeses in the U.S. are fortified with vitamin D — with milk being the number one dietary source of this vitamin.

Renzaho AM, Halliday JA, Nowson C. Vitamin D, obesity, and obesity-related chronic disease among ethnic minorities: systematic review. Nutr. 2011;27(9):868-879.

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Consuming Yogurt and Regular Milk Is Associated with Reduced Risk of All Invasive Breast Cancer in Swedish Women

Researchers in Sweden hypothesized that high-fat diets may have different effects on the development of breast tumors depending on the sex hormone (estrogen and progesterone) receptor status of the tumor. In the first study of its kind, the researchers prospectively tested this hypothesis in more than 15,000 women, ages 45-73 years, enrolled in the Malmo Diet and Cancer cohort; they also determined if associations with fat depended on the type of fat or its specific food source. “Energy-adjusted intakes of yogurt and regular milk (3 percent fat) were associated with protective linear risk trends across food group categories for all invasive breast cancer and estrogen receptor-positive (ER+) and progesterone receptor-positive (PR+) tumors,” the authors reported. In contrast, vegetable-oil-based margarine and dried soups/sauces were associated with trends of increased risk for all invasive breast cancer and ER-PR- tumors.

Classifying breast tumors on the basis of hormone receptor status is used to guide treatment strategy, since each type of tumor is biologically different. For example, elevated blood levels of steroid sex hormones, estrogen and progesterone, are associated with increased risk of receptor-positive, hormone-dependent tumors, which have a more favorable prognosis. Receptor-negative breast tumors are not hormone-dependent and tend to have a poorer prognosis within 5 years of diagnosis. The researchers combined estrogen receptor (ER) and progesterone receptor (PR) status when defining receptor status categories. In this study, breast cancer risk was examined for the following three categories: ER+PR+; ER+PR-; and ER-PR-.

The researchers point out that yogurt and regular milks associated with reduced risk in this study are fresh foods commonly used in the traditional Swedish diet. These associations warrant further investigation.

Although not noted in this paper, several studies in animal models of breast cancer have demonstrated that conjugated linoleic acid (CLA), a component of milk fat, effectively deters several aspects of the disease process. A review of the effects of ruminant (dairy and beef) trans-fatty acids on cardiovascular disease and cancer by Gebauer, et al., summarized in this newsletter, further discusses the evidence evaluating ruminant trans fat and breast cancer. 

Wirfält E, Li C, Manjer J, et al. Food sources of fat and sex hormone receptor status of invasive breast tumors in women of the Malmö Diet and Cancer cohort. Nutr Cancer. 2011;63(5):722-733.

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Benzoyl Peroxide Is More Effective Bleaching Agent for Whey Protein Concentrate Than Hydrogen Peroxide

Benzoyl peroxide was found to be more effective and cause fewer off-flavors than hydrogen peroxide when added as a bleaching agent in whey processing. This valuable insight can be used for the continued improvement in whey product quality. Bleaching agents have been used in whey products for many years to remove residual annatto cheese color. Previous studies have shown that bleaching agents have a negative impact on taste and flavor of 70 percent whey protein concentrate (WPC70). This is the first study to focus on the impact of bleaching on lower-protein whey products.

Investigators at the Southeast Dairy Foods Research Center at North Carolina State University compared the effectiveness of hydrogen peroxide (HP) with two concentrations of benzoyl peroxide (BP). The investigators concluded that both concentrations of BP more effectively bleached the whey proteins than HP at the highest concentration (500 mg/kg) allowed in fluid whey. The differences in color were not significant in spray-dried 34 percent whey protein concentrate (WPC34) made from the whey but were different in solutions made with them. The research also showed that the HP-bleached WPC34 product had the highest flavor defect, followed by 100 mg of BP/kg, 50 mg of BP/kg and unbleached WPC34. The differences between the BP bleached whey and the unbleached whey were not statistically significant in this study. The flavor defects included loss of cooked, milky flavor and sweet aromatic flavor as well as an increase in “cardboard flavor” due primarily to lipid oxidation. The research indicated that lower levels of benzoyl peroxide are more effective for bleaching whey compared with hydrogen peroxide.

It should be noted that benzoyl peroxide is not allowed to be used in whey products that might be exported for use in infant products (Codex Alimentarius) or for export to certain countries, such as China.

Listiyani MA, Campbell RE, Miracle RE, Dean LO, Drake MA. Influence of bleaching on flavor of 34% whey protein concentrate and residual benzoic acid concentration in dried whey proteins. J Dairy Sci. 2011;94(9):4347-4359.

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Model System Predicts Required Amount of Salt Replacer Prior to Production of Cheese

Utilizing a model system prior to manufacturing Cheddar cheese can aid in predicting the amount of salt replacer required to achieve a target water activity in the final cheese. Substituting salt replacers for salt on a weight basis does not achieve the same water activity in cheese and therefore may result in growth of undesirable organisms or differences in the ripened flavor of the cheese. Researchers at the Midwest Dairy Foods Research Center at the University of Minnesota identified a method of forecasting the proper amount of salt replacer required not only for simple replacers such as potassium chloride, but also for those where the chemical composition is more complex, such as sea salt. Past research has required manufacturing many cheeses in sample vats to measure the required amount of replacement salt, a time-consuming and costly process.

Excessive sodium intake has been linked to the development of hypertension in certain at-risk groups of people. Food manufacturers, including dairy processors, are exploring lowering salt content and finding replacement salts to maintain taste and other attributes. In cheese making, the salt-to-moisture ratio is considered critical for overall cheese quality and identifying the right balance of replacement salts in natural cheese making is important in maintaining a high-quality end product.

The research concluded that manufacturers could use a model system to determine the appropriate salt and salt replacer concentrations prior to cheese making. This new process will reduce the need for manufacturing experimental batches of cheese, which should help expedite sodium replacement research.

Grummer J, Schoenfuss TC. Determining salt concentrations for equivalent water activity in reduced-sodium cheese by use of a model system. J Dairy Sci. 2011;94(9):4360-4365.

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Listeria Survival Similar in Low- and Regular-Salted Cheddar Cheese

Survival of Listeria monocytogenes in low-salt Cheddar cheese is not significantly different from its survival in regular Cheddar cheese. Salt, pH and lactic acid content represent some of the multiple hurdles contributing to the microbiological safety of traditional cheeses. Public health officials’ desire to reduce sodium in the diet has resulted in concern about the possible effect on the microbiological safety of low-sodium cheese.

To address this concern, researchers at the Western Dairy Center at Utah State University have conducted a study to determine the survival of L. monocytogenes in low-salt Cheddar cheese compared with regular-salt Cheddar. Research was conducted using Cheddars made at two different pH levels and two salt levels (traditional and low salt). The researchers monitored the survival of Listeria at 4, 10 and 21 degrees C for various storage times up to 90 days. In all cases, Listeria was not able to grow on the inoculated cheeses. In fact, there was a limited reduction in the number of bacteria in the cheese during storage but none of the treatments demonstrated more than a 95 percent reduction. At 4 and 10 degrees there was slightly less, but not statistically less, reduction of Listeria in the low-salt cheese than in the full-salt controls. The survival of the Listeria during storage of all cheeses reinforces the requirement for good sanitation practices during manufacturing, distribution and use of all cheeses.

Shrestha S, Grieder JA, McMahon DJ, Nummer BA. Survival of Listeria monocytogenes introduced as a post-aging contaminant during storage of low-salt Cheddar cheese at 4, 10, and 21°C. J Dairy Sci. 2011;94(9):4329-4335.

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Investigating the Influence of Calcium Binding Salts on Casein in Non-fat Cheese and Milk Protein Solutions

The interactions between casein, free calcium and calcium bound into the casein micelle are critical to the textural properties of all milk products, especially cheese. Two papers by a research team at the Wisconsin Center for Dairy Research at the University of Wisconsin-Madison reported on fundamental research to more fully understand the nature of these interactions. These studies aimed to increase understanding of the very complex interactions between the proteins in milk and cheese products so that more industrially relevant approaches to development of non-fat cheese will be more successful.

In the study by Kaliappan, the researchers examined how different phosphate and citrate compounds bound calcium in milk protein concentrate solutions. They found that the differences in binding the calcium controlled thickness and gelation of the milk solutions.

In the report by Stankey, different compounds (sodium sulfate, sodium chloride and sodium thiocyanate) were added to fat-free cheese. These salts change the way casein proteins in cheese react with water and with each other. For example, fat-free cheese often is very firm and rubbery due to the strong binding between casein proteins, whereas in full-fat cheese, the fat separates the protein molecules and helps control their interactions. As with altering the amount of fat, adding different sodium salts to the cheese impacted the way the proteins interacted. The changes in sodium caused the cheese to soften earlier and/or melt at a different temperature.

The information derived from these fundamental studies will help guide future applied research and product development.

Kaliappan S, Lucey JA. Influence of mixtures of calcium-chelating salts on the physicochemical properties of casein micelles. J Dairy Sci. 2011;94(9):4255-4263.

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Stankey JA, Johnson ME, Lucey JA. Effect of selected Hofmeister salts on textural and rheological properties of nonfat cheese. J Dairy Sci. 2011;94(9):4264-4276.

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Microfiltration May Improve Quality of Dairy Products

Spores in milk are resistant to pasteurization and reduce the quality and shelf life of products such as cheese, milk powders and bottled fluid milks. Microfiltration, when done before pasteurization, was confirmed to be more effective than pasteurization alone in preserving milk quality in this study conducted by the U.S. Department of Agriculture’s Eastern Regional Research Center.

The study optimized the operation of the two filtration systems, and then compared the efficacy of removal of Bacillus spores using ceramic membranes with two different pore sizes (0.8 µ vs. 1.4 µ). Both filters removed essentially all of the spores, with the 0.8µ filter reducing the spore count to less than 1/10th of that from the 1.4µ filter. The shelf life of the pasteurized control was between seven and 14 days at refrigeration temperatures. The shelf life of the milk that had been filtered before pasteurization was 28 days. Filtered, pasteurized milk has recently been introduced into the United States.

Tomasula PM, Mukhopadhyay S, Datta N, et al. Pilot-scale crossflow-microfiltration and pasteurization to remove spores of Bacillus anthracis (Sterne) from milk. J Dairy Sci. 2011:94(9);4277-4291.

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Sustainability
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Promising Advances Made Toward Developing Biodegradable Packaging with Antimicrobial Properties

Increasing consumer demand for nutritious and environmentally friendly products has presented challenges to the food industry to develop biodegradable packaging that can maintain the safety and quality of packaged foods from point of production to point of consumption. Meanwhile, outbreaks of foodborne pathogens continue to drive the search for innovative ways to inhibit microbial growth in foods while maintaining quality, freshness and safety.

Antimicrobial packaging can play an important role in reducing the risk of pathogen contamination as well as extending the shelf life of minimally processed foods. Packaging based on polylactic acid can have the added benefit of offering a biodegradable packaging option, which can be combined with antimicrobial functionality.

The results of this study indicate that the incorporation of bacteriocins like nisin into polylactic acid (PLA) could provide a possible delivery system for improving the efficacy of bacteriocins in food applications. The study confirmed the retention of nisin activity when incorporated into the PLA polymer and its antimicrobial effectiveness against the foodborne pathogens tested, namely Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella Enteritidis.   

While this is a preliminary study in which only films were evaluated, it provides a starting point to determine whether PLA/nisin has potential for biodegradable antimicrobial packaging. PLA/nisin polymer could potentially be used to make bottles or could be coated on the bottle surface for use in liquid food packaging. Further research will be required to establish the parameters for optimal antimicrobial efficiency.

Jin T, Zhang H. Biodegradable Polylactic Acid Polymer with Nisin for Use in Antimicrobial Food Packaging. J Food Sci. 2008;73(3):M127-M134.

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Methane-producing Organisms From Rumen of Holstein and Jersey Cows Different

Enteric methane emissions from dairy cattle account for approximately 25 percent of the carbon footprint for fluid milk. (Thoma, et al. “Greenhouse Gas Emissions of Fluid Milk in the U.S.”, University of Arkansas, 2010.) For this reason, identifying existing research that could help the dairy industry reduce enteric methane emissions is a priority for the Innovation Center for U.S. Dairy®. This study is the first to compare the ruminal methanogen composition of lactating Holstein and Jersey cows under similar environmental and dietary conditions. The findings provide a better understanding of the structure and composition of ruminal methane-producing microbes across breeds; they can potentially unveil novel enteric methane mitigation strategies for the future.

The researchers examined the rumen fluid from 19 cows in a single herd that included animals from both breeds that were fed the same diet. The researchers constructed Holstein- and Jersey-specific gene clone libraries using rumen methanogen 16S rRNA polymerase chain reaction (PCR) products. Sequence analysis of the libraries resulted in a total of 55 species-level operational taxonomic units (OTU). An OTU represents an organism in a genetically-based classification scheme. The researchers found significant differences in DNA-sequence representation and diversity in the methanogen community structures from Holstein and Jersey cows, with Holstein cows exhibiting more diversity in their ruminal methanogen composition. Twenty OTU were common to both breeds, 23 were only found in Holstein cows and 12 were exclusive to the Jersey clone library. Sequences related to Methanobrevibacter millerae were almost twice as abundant in the Jersey than in the Holstein library, while Methanosphaera-related sequences and novel uncultured clones were more frequent in the Holstein library. Finally, sequences associated to Methanobrevibacter ruminantium were equally represented in both breed libraries.

The differences in ruminal methanogen composition between Holstein and Jersey cows may be a function of potential differences in animal anatomy and physiology associated with breed. Further research is needed to improve industry understanding on the factors that contribute to breed and individual animal differences in ruminal methanogen composition.

King EE, Smith RP, St-Pierre B, Wright AD. Differences in the rumen methanogen populations of lactating Jersey and Holstein dairy cows under the same diet regimen. Appl Environ Microbiol. 2011;77(16):5682-5687.

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Other Publications

Vitamin D-Fortified Milk Achieves the Targeted Serum 25-Hydroxyvitamin D Concentration without Affecting That of Parathyroid Hormone in New Zealand Toddlers

Houghton LA, Gray AR, Szymlek-Gay EA, Heath A-LM, Ferguson EL. J Nutr. [Epub ahead of print]. 2011 Aug 10.
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Following federal guidelines to increase nutrient consumption may lead to higher food costs for consumers

Monsivais P, Aggarwal A, Drewnowski A. Health Aff (Milwood). 2011;30(8):1471-1477.
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Effects of dairy products on Crohn’s disease symptoms are influenced by fat content and disease location but not lactose content or disease activity status in a New Zealand population

Nolan-Clark D, Tapsell LC, Hu R, Han DY, Ferguson LR. J Am Diet Assoc. 2011;111(8):1165-1172.
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Dietary intake of α-linolenic acid and low ratio of n-6:n-3 PUFA are associated with decreased exhaled NO and improved asthma control

Barros R, Moreira A, Fonseca J, et al. Br J Nutr. 2011;106(3):441-450.
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Dietary fat and breast cancer: comparison of results from food diaries and food-frequency questionnaires in the UK Dietary Cohort Consortium

Key TJ, Appleby PN, Cairns BJ, et al., Am J Clin Nutr. [Epub ahead of print]. 2011 Aug 24.
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Classification of Swiss cheese starter and adjunct cultures using Fourier transform infrared microspectroscopy

Prabhakar V, Kocaoglu-Vurma N, Harper J, Rodriguez-Saona L. J Dairy Sci. 2011:94(9);4374-4382.
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UHT Milk Processing and Effect of Plasmin Activity on Shelf Life: A Review

Chavan RS, Chavan SR, Khedkar CD, Jana AH. Comp Rev Food Sci Food Safety. 2011;10(5):251-268.
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Key Dates
Research from the Dairy Research Institute being presented at key industry meetings.

2011 Net Impact Conference
Oct. 27-29, 2011
Oregon Convention Center, Portland, Ore.


Farm to Table: Sustainability in the Milk Industry’s Supply Chain
Sandra Vijn, Innovation Center for U.S. Dairy®

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Dairy Research Institute publishes its own scientific insights in this newsletter as well as research and other items of interest of other organizations. Methodologies, conclusions or findings of third party studies do not necessarily reflect the views or carry the endorsement of Dairy Research Institute.