Studies lead to safer produce
A group of researchers at the U.S. Dept. of Agriculture’s Agricultural Research Service are developing new technologies to remove or inactivate microbial contaminants from fresh and minimally processed fruit and produce.
Bacteria attach to the surface of fruits and vegetables and form biofilms, which are masses of microbes attached to surfaces and to each other by bacterial polymers. Scientists believe that this polymer coating may help protect bacterial cells from harm when the surface is cleaned using a conventional washing method, such as using chlorine to sanitize produce.
Salmonella attach to inaccessible regions, like crevices, and form biofilms on the surface of cantaloupe rind, allowing the pathogen to avoid contact with the cleaning or sanitizing solution. The health of the consumer can be compromised when these protected Salmonella cells on the surface are transferred to the internal fruit during cutting and that fruit is eaten by the consumer.
To help attach and thrive on the surface of cantaloupe, Salmonella cells produce fimbriae, which are hair-like structures, and cellulose. ARS scientists and scientists at the University of Navarra in Spain have collaborated to examine how the cells form fimbriae and how fimbriae attach to different surfaces.
The studies have already produced results. A commercial-scale surface-pasteurization method recently developed by ARS scientists results in a 5-log (99.999%) reduction in a population of Salmonella poona on the surface of cantaloupe that had been artificially contaminated. Melons are immersed in water at 169°F for 3 min to kill pathogens, then sealed in a plastic bag to prevent recontamination before being cooled in an ice water bath. According to ARS, the method makes the fruit more safe to consume, extends its shelf life, and does not harm its quality.
Monell grows taste cells
Researchers from the Monell Chemical Senses Center, Philadelphia, Pa., have successfully grown mature taste receptor cells outside the body and kept the cells alive for a prolonged period of time. This development may help scientists understand the sense of taste and how it affects nutrition, health, and disease.
Taste receptor cells are located in taste buds on the tongue and in the throat, and they detect sweet, sour, salty, bitter, and umami taste stimuli. The receptor cells have a short life—about 10–14 days—and are replaced when new taste cells develop from a population of basal cells. Scientists have had difficulties understanding the process of taste-cell differentiation, growth, and turnover because they have been unable to keep taste cells alive outside of the body.
Addressing this problem, Monell researchers took a new approach. Instead of using mature taste cells, the researchers used basal cells from the taste buds of rats. After culturing in a medium of nutrients and growth factors, the cells divided and differentiated into functional taste cells, which were kept alive for up to two months.
The researchers explained that the cultured cells were similar to mature taste cells. The cultured cells have unique marker proteins characteristic of mature taste cells. Just like mature taste cells, the cultured cells responded to either bitter or sweet taste stimuli with increases of intracellular calcium.
One thing researchers hope to gain from studying these cultured cells is insight into how the function of taste cells changes across people’s lifespan. They also hope to help people who have lost their sense of taste.
For information on how ingredients affect taste perception, see "A Changing Perception of Taste Perception" in the November 2004 issue of Food Technology.
Chip can improve citrus
A newly developed chip shows promise in improving citrus varieties. Designed by researchers at University of California at Riverside, the GeneChip® Citrus Genome Array is said to help determine which genes, such as those associated with taste, acid content, and disease, are active in citrus tissue. This information can be used to make improvements to the fruit by allowing researchers to study traits such as nutritional characteristics, flavor components, seedlessness, and easy peeling.
"For a trait posing a problem for the consumer, such as an undesirable flavor, we can identify genes associated with the trait and target these for correction to improve the flavor," said Mikeal Roose, Professor of Genetics, Dept. of Botany and Plant Sciences. "And with this chip we can better understand what happens at the cellular level when oranges are put in cold storage after they are harvested, leading eventually to better methods of storage that improves fruit flavor."
The array consists of a glass wafer onto which about one million pieces of citrus DNA are deposited on a grid or microarray. The glass wafer is encased in a plastic container that is slightly smaller than a credit card.
Researchers using the chip first purify total RNA from plant tissue, make a copy of these molecules with a chemical tag added, and then "wash" the chip with the RNA. When a gene’s corresponding RNA is present and binds to the complementary DNA sequence on the chip, it indicates that the gene is being expressed.
The University of California researchers developed the array in partnership with Affymetrix Inc., Santa Clara, Calif.
U.S. House passes food bill
The U.S. House of Representatives has passed the National Uniformity for Food Act (NUFA), which, if it becomes law, could have significant implications on state and local food safety and food protection laws.
The act amends the Federal Food, Drug, and Cosmetic Act (FFDCA) and will not allow states to continue to enforce or establish labeling requirements that are not identical to federal standards. In the past, states have been allowed to develop labeling requirements that exceed federal standards.
NUFA allows states to petition the federal government for an exemption or to establish a national standard as it pertains to the FFDCA or the Fair Packaging and Labeling Act and to establish a labeling requirement that would differ from the federal standards if the requirement is needed to address an "imminent hazard to health".
The bill passed the House by a vote of 283 to 139 and now moves to the U.S. Senate. For more information about H.R. 4167, visit www.house.gov.
In favor of a single food agency
In the United States, do you think there should be a single government agency in charge of food safety versus the current system involving both the U.S. Dept. of Agriculture (USDA) and the Food and Drug Administration (FDA)? About 78% of the 144 respondents who participated in a December 2005 Food Technology/IFT poll said "Yes, there should be a single agency." The remainder—about 22%—said "No, keep the current USDA and FDA agencies."
One respondent, who favored a single food agency, stated, "While cooperation has increased between the two agencies, the American public and the food industry could benefit from a combined food regulation body. The public simply doesn’t understand that there are differences and they are confused about proper nutrition and food labeling and food law as it is. As an ingredient manufacturer that makes products that are FDA regulated and other products that are USDA regulated, it is challenging to keep up with the differences between laws of the two agencies. We must also remember, though, that we need to keep the functionalities of both agencies—to move to one agency should not be a consolidation process, but a best practices and combining process."
Another theme expressed by several respondents was to put "drugs" under a separate governing body.
USDA initiative to reduce Salmonella
The U.S. Dept. of Agriculture’s Food Safety and Inspection Service recently announced a comprehensive initiative to reduce the presence of Salmonella in raw meat and poultry products.
The initiative includes concentrating resources at establishments with higher levels of Salmonella and changes the reporting and utilization of FSIS Salmonella verification test results. It is patterned after the FSIS initiative to reduce the presence of Escherichia coli O157:H7 in ground beef, which led to a 40% reduction in human illnesses associated with the pathogen, according to the Centers for Disease Control and Prevention.
Comments on the initiative must be received on or before May 30, 2006. Contact Daniel Engeljohn, Deputy Assistant Administrator for the Office of Policy, Programs, and Employee Development at 202-205-0495 or visit www.fsis.usda.gov for more information about the initiative and how to submit a comment.
Tetra Pak improves package
Tetra Pak, Lund, Sweden, recently completed the worldwide rollout of a packaging material that it says will help reduce the use of non-renewable resources and energy.
The company states that its Wide packaging material is 30% thinner than previous packaging material, requires fewer polymers to produce, and will help reduce its global consumption of polymers by 50,000 tons/year or about 2,500 shipping containers/year.
"We have already produced over 50 billion packages around the globe with Australia, Brazil, and Japan leading the way," said Günther Lanzinger, Project Director. "And both manufacturers and retailers are reporting better product performance and more cost-effective operations. For instance, a transportation damage test in Brazil showed zero defects out of 9,000 packages transported on rough roads for 1,200 km."
The new packaging material is the standard for carton packages, and all Tetra Pak factories will begin to use it.
Q: What is IFT’s greatest accomplishment?
Q: What is IFT’s biggest shortcoming? The survey will be posted on www.ift.org for several weeks after the issue is distributed. The poll results will appear on our Web site and be published in a future issue of Food Technology.
by Karen Banasiak,