The skinny on apple polyphenols
Apple skin polyphenols incorporated in edible films were highly effective at inhibiting the growth of Listeria monocytogenes in a concentration-dependent manner, with a minimum concentration of 1.5% needed, according to researchers with the U.S. Dept. of Agriculture’s Agricultural Research Service and the University of California, Davis.
The researchers measured the antimicrobial effects of the films made from apple puree and with apple skin polyphenols [at concentrations 0–10% (w/w)] against L. monocytogenes, Salmonella enterica, and Escherichia coli O157:H7. The control sample (film without apple skin polyphenols) did not inhibit the growth of the three bacteria. While the polyphenols showed antimicrobial effect against L. monocytogenes, the compounds did not inhibit the growth of the other two bacteria regardless of the concentration used. Citing previous studies, the researchers attributed the results to phenolics from plants being less effective against preventing the growth of Gram-negative bacteria than Gram-positive bacteria. They also suggested that the films could be used as a wrap or coating for cheese to prevent the growth of L. monocytogenes.
The results showed that the polyphenols decreased the water vapor permeability, increased the tensile strength and elongation, and darkened the color of the films. The researchers said that more studies are needed on the formulation of edible films with apple skin polyphenols such as adding apple juice concentrate or sweeteners to overcome the bitter taste of the films.
The study, “Physical and Antibacterial Properties of Edible Films Formulated with Apple Skin Polyphenols,” appeared in the March 2011 issue of Journal of Food Science.
Nanoparticles fight bacteria
A newly developed paper coated with silver nanoparticles helps to fight foodborne pathogens and shows promise as a food packaging material.
By using ultrasound, the researchers were able to coat the paper with silver nanoparticles to achieve uniform coatings from 90 nm to 150 nm in thickness and a penetration depth of more than 1 μm. They tested the effectiveness of the paper at killing Escherichia coli and Staphylococcus aureus and found that the coated paper killed the bacteria in three hours, which suggests that this paper can be incorporated into food packaging material to help promote longer shelf life, they reported. The study, “Sonochemical Coating of Paper by Microbiocidal Silver Nanoparticle,” appeared in the Jan. 18, 2011, issue of Langmuir.
Growth for gluten-free products
As more consumers adopt a gluten-free diet, food formulators are responding by developing gluten-free products and reformulating popular products. As a result, the U.S. gluten-free foods and beverages market in 2010 grew to $2.6 billion in retail sales, with predicted growth to $6 billion in 2015, according to Packaged Facts, which compiles and publishes market research.
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Once available in specialty stores, gluten-free food and beverage products now share shelf space at supermarkets and chain stores and are manufactured by companies both small and large.
Packaged Facts added that as an example of a company working to deliver more gluten-free food offerings, General Mills claims to offer 250 gluten-free products, including five varieties of Chex cereal and products marketed under its Betty Crocker and Bisquick brands.
New test traces outbreak source
Scientists at the U.S. Food and Drug Administration used a new genome sequencing test to trace the sources of a 2009–2010 foodborne illness outbreak as part of its traceback investigation.
The outbreak was caused by Salmonella enterica serotype Montevideo. The FDA scientists used next-generation sequencing to test 35 contaminated samples that came from suppliers, people who became sick, and food sources that originated from different places and were produced at different times.
They found that the origin of the outbreak strain was a single food facility and that the outbreak was linked to red and black pepper used in salami.
The letter, “Identification of a Salmonellosis Outbreak by Means of Molecular Sequencing,” was published Feb. 23, 2011, in The New England Journal of Medicine, doi: 10.1056/NEJMc1100443.
Feeding the mission to Mars
While NASA food technologists have made many advances in developing food for short-duration space missions over the years, new research and development approaches are needed to formulate foods for the crews of space missions to Mars and beyond, reports a team of scientists from NASA Advanced Food Technology.
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Space missions such as these could last years, and scientists need to develop nutrient-dense food that has at least a 5-year shelf life, partial gravity cooking processes, ways to deliver nutrients over time, and food packaging that meets mass, barrier, and processing requirements of NASA. Three NASA scientists reviewed the research in each of these areas and discussed the gaps in developing the next-generation food and packaging for long-duration space missions. Some of the challenges include developing cooking processes to mitigate foodborne illnesses, improving the nutritional quality of food to meet the micronutrient requirements for 5 years, and more.
The article, “Developing the NASA Food System for Long-Duration Missions,” appeared in the March 2011 issue of Journal of Food Science.
IR kills pathogens on almonds
Subjecting almonds to an infrared pasteurization treatment of 90°C for 10–15 minutes reduced Pediococcus by more than 5-log, according to research published in Journal of Food Engineering.
Additionally, the researchers with the U.S. Dept. of Agriculture’s Agricultural Research Service, University of California, Davis, and Northwest Agricultural and Forestry University, Yangling, Shaanxi, China, reported that holding the almonds at 80°C for more than 22 minutes resulted in a more than 4-log reduction, which is the target reduction that the almond industry requires.
The researchers heated whole raw almonds using infrared pasteurization to 100°C, 110°C, and 120°C, cooled the samples at ambient temperature to holding temperatures of 70°C, 80°C, or 90°C, and then held the samples at the temperatures for different time periods up to 60 minutes.
The study, “Infrared Pasteurization of Raw Almonds,” appeared online early in Journal of Food Engineering, doi: 10.1016/j.jfoodeng.2010.12.034.
FDA approves preservation process
The Food and Drug Administration has given second approval to a new microwave-based technology for food preservation.
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More specifically, the approval is for preserving “non-homogeneous” food, in this case, salmon filets in sauce. This follows an FDA approval in October 2009 for the technology’s use for preserving “homogeneous materials,” specifically, mashed potatoes. The approvals speed up efforts to commercialize the technology.
A team of researchers at Washington State University developed the technology to extend the shelf life of food and improve food quality and nutrition. It involves heating packaged food with microwaves at 915 MHz while the food is immersed in pressurized hot water to eliminate food pathogens and spoilage microorganisms in just five to eight minutes. The Washington State University Research Foundation in late 2010 licensed the technology to Food Chain Safety, a private firm dedicated to commercializing microwave-assisted thermal sterilization.
A variety of organizations, including Kraft Foods, Hormel Foods, Ocean Beauty Seafoods, Rexam Containers, Ferrite Components, Graphic Packaging, Pinprick, and the Washington State University Agricultural Research Center, provided funding for the project.
What’s new with food companies
• The National Science Foundation has awarded ChromaDex Corp. a $500,000 Phase II Small Business Innovation Research Grant.
• FONA International Inc. has won the 2010 Best of Business Award in the Flavoring Extracts category from the Small Business Commerce Association.
• GLG Life Tech Corp. reported that two stevia-related patent applications were granted by the State Intellectual Property Bureau of the People’s Republic of China.
• International Flavors & Fragrances Inc. plans to build a flavor production plant in Guangzhou, China, and a flavor and fragrance production plant in Singapore.
• Maxx Performance will build an R&D and manufacturing facility in Roanoke, Va.
• Solae has opened a food application center focused on beverage, bakery, confectionery, and meat products in Shanghai, China.
• Symrise has redesigned its website at www.symrise.com to include more information about sustainability, naturalness, and consumer insights.
• True Source Honey™ has launched a certified honey traceability program to certify the origin of honey being distributed and consumed within North America.