Examining the science of umami
Umami, one of five basic tastes, is typically referred to as “savory” and “yummy.” Often associated with the flavor of soy sauce, it is also a taste characteristic of tomatoes, cheese, meat, broths, and mushrooms.
For decades, scientists have studied the mechanisms behind umami, particularly the interactions between amino acids and other compounds. Researchers in Southeast Asia surveyed many of these studies conducted on how the umami taste in Japanese soy sauce is perceived by humans. Early research concluded that a certain small peptide contributed to the umami taste. But it was not until the use of techniques like ultrafiltration, gel filtration chromatography, high performance liquid chromatography, and taste dilution analysis that some researchers were able to determine that the interactions of free amino acids and sodium may contribute to the umami taste of soy sauce.
The article, “Soy Sauce and Its Umami Taste: A Link From the Past to Current Situation,” appeared online early in Journal of Food Science, doi: 10.1111/j.1750-3841.2010.01529.x.
Nanopackaging minimizes spoilage
Nanomaterials incorporated into packaging of fresh produce helped to reduce undesirable physiochemical and physiological changes during storage, according to a new study published in Journal of Food Science.
Researchers at Nanjing Agricultural University in China combined polyethylene with nanopowder (nanosilver, kaolin, anatase titanium dioxide, and rutile titanium dioxide) to create a novel nanopackaging material with lower relative humidity, oxygen transmission rate, and high longitudinal strength. They stored strawberries in this packaging and a control (polyethylene bags) at 4°C for 12 days. The results showed that the strawberries stored in the nanopackaging had higher levels of total soluble solids, titratable acidity, and ascorbic acid and lower levels of polyphenoloxidase and pyrogallol peroxidase, which are enzymes involved in enzymatic browning.
While the results show promise for this type of nanopackaging to minimize food spoilage, the researchers caution that more studies are needed to determine the exact mechanism of nanopackaging in increasing the shelf life of food.
The study, “Effect of Nano-Packing on Preservation Quality of Fresh Strawberry (Fragaria ananassa Duch.cv Fengxiang) During Storage at 4°C,” appeared online early in Journal of Food Science, doi 10.1111/j.1750-3841.2010.01520.x.
FDA warns of labeling violations
The Food and Drug Administration has sent Warning Letters to 17 food manufacturers notifying them that package labeling for 22 of their products violates the Federal Food, Drug, and Cosmetic Act.
FDA cited violations such as unauthorized health claims, unauthorized nutrient content claims, unauthorized use of “healthy” claims, unauthorized claims that a food or ingredient can treat or mitigate disease, and others.
In a statement made in October 2009, Commissioner of Food and Drugs Margaret Hamburg expressed concern about front-of-package labels being false or misleading and urged food manufacturers to review their labeling to make sure that they complied with FDA regulations. While some manufacturers have revised their labeling since that time, FDA continues to find labels that are not in compliance, and has thus issued the Warning Letters, according to Hamburg’s Open Letter to Industry dated March 3, 2010.
“While the warning letters that convey our regulatory intentions do not attempt to cover all products with “While the warning letters that convey our regulatory intentions do not attempt to cover all products with violative labels, they do cover a range of concerns about how false or misleading labels can undermine the intention of Congress to provide consumers with labeling information that enables consumers to make informed and healthy food choices,” she wrote.
FDA plans to release draft guidance about front-of-pack calorie and nutrient labeling as well as recommend nutritional criteria for foods that make “dietary guidance” statements in their labeling, said Hamburg.
For more information, visit www.fda.gov/Food/LabelingNutrition/ucm202726.htm.
Milk affects antioxidant levels
Tea is enjoyed around the world for its flavor and health benefits. Rich in antioxidants, tea may help to decrease the risk of developing diseases like cardiovascular disease and certain cancers, studies show. But adding milk to black tea decreases the antioxidant levels, according to researchers at Oxford Brookes University, Oxford, UK.
The researchers measured the antioxidant capacity of five brands of tea and then added 10, 15, and 20 mL of whole, semi-skimmed, and skimmed cow milk to 200-mL tea infusions. The antioxidant capacity decreased in all brands of tea. More specifically, the antioxidant capacity of the tea with skimmed milk decreased significantly more than either the tea with milk or semi-skimmed milk.
“Milk is known to contain a number of fat-soluble antioxidants—tocopherols, carotenoids, and retinols,” wrote the researchers. “Therefore, decreasing the fat content of the milk may eliminate a number of the fat soluble antioxidant components and therefore decrease its antioxidant potential.”
The study, “Addition of Whole, Semi-skimmed, and Skimmed Bovine Milk Reduces the Total Antioxidant Capacity of Black Tea,” appeared in the January 2010 issue of Nutrition Research.
Investigating new bread ingredients
Whole wheat bread is a food product familiar to consumers. Now, scientists have ramped up efforts to develop breads made exclusively from oats or barley that provide antioxidants, fiber, and protein as well as other ingredients not found in whole wheat bread.
One of these ingredients is a plant-derived carbohydrate called hydroxypropyl methylcellulose (HPMC) that is used as a substitute for gluten but is also being investigated for potential cholesterol-lowering effects. Preliminary experiments conducted by researchers with the U.S. Dept. of Agriculture’s Agricultural Research Service showed that whole oat and whole barley breads formulated with HPMC have demonstrated this effect.
For more information, visit www.ars.usda.gov/is/AR/archive/feb10/breads0210.htm.
Spider enzymes as food ingredients?
Several food companies and research institutions will conduct studies on the potential use in foods of enzymes derived from snakes, spiders, and carnivorous plants thanks to a grant from the Danish Council for Strategic Research.
“When a spider catches a fly in its web, it injects digestive enzymes into its prey to liquefy it,” said Charlotte Poulsen, Genencor Enzyme Development, Danisco. “This makes it easy for the spider to devour the fly. The digestive enzymes are highly effective and we are very keen on looking into the dynamics of these enzymes.”
The group, which consists of Danisco, Novozymes, Arla Foods, and research institutions in Denmark, Finland, Poland, Brazil, and China, will work on the project for four years and then determine the commercial applications of the enzymes.
Boiling may reduce shrimp allergen
Boiling shrimp for 10 minutes may reduce allergenic properties of total shrimp extracts, according to researchers with the U.S. Dept. of Agriculture’s Agricultural Research Service and Jimei University in Fujian, China.
The protein tropomyosin is a major allergen in shrimp, lobster, crab, oysters, and squid. The researchers prepared extracts from both raw and boiled shrimp and also purified tropomyosin from both raw and boiled shrimp.
The results showed that the boiled shrimp extracts have lower IgE binding than the raw shrimp extracts. The researchers said that boiling may alter shrimp extracts in a way that may allow masking of allergenic epitopes, thereby reducing allergen recognition and altering allergenicity of the shrimp. The results from the tests conducted on tropomyosin show that the IgE binding activity of boiled tropomyosin was stronger than that of raw tropomyosin. The boiled tropomyosin may have undergone protein–protein interactions (especially aggregation) during thermal treatment to cause enhanced IgE binding, according to the researchers.
The study, “Effects of Boiling on the IgEBinding Properties of Tropomyosin of Shrimp (Litopenaeus vannamei),” appeared in the January/February 2010 issue of Journal of Food Science.
• DSM in 2011 will open its Nutrition Innovation Center in Parsippany, N.J. The center will house dedicated customer application suites, sensory services, and customer application pilot facilities.
• Firmenich has opened a new office and laboratory in Dubai, United Arab Emirates.
• Gadot Biochemical Industries recently announced its commitment to the global Responsible Care program for chemical product manufacturing. This voluntary initiative focuses on improving communication and accountability and is coordinated by the International Council of Chemical Associations.
• Glanbia Nutritionals has launched a new Web site, www.TruCalMilkCalcium.com, which discusses calcium fortification.
• PureCircle Ltd. and Imperial Sugar Co. have formed Natural Sweet Ventures LLC, a joint venture to develop blends of stevia and sugar.
• Silliker has opened a nutritional chemistry and food safety laboratory in Mhape, Navi Mumbai, India.
• Sunnyland Mills is celebrating its 75th year as a producer of whole-grain bulgur wheat products.
by Karen Nachay,