Issue Date: June 27, 2011
Maximizing the Benefits of Food
Opportunities are greater than ever before for cutting-edge science to improve food and agriculture. Chemistry, in particular, can help provide a safe, healthful, and sustainable food supply to meet a growing worldwide population.
In this International Year of Chemistry, the central science should be acknowledged for its necessity in growing, developing, improving, processing, and protecting our foods. Analytical chemistry, biotechnology, and food technology join forces to help feed both developing nations and more advanced economies.
Chemistry has already helped ensure that today’s food is the safest, most affordable, and most nourishing in history. Detailed understanding of the chemical structures, stabilities, and reactivities of the essential nutrients has guided agricultural breeding, processing, and food formulations to optimize seed stability, commodities, and food products, virtually eliminating essential nutrient deficiencies. Analytical chemistry allows detection of trace contaminants in food from deliberate or accidental adulteration, helping reduce people’s exposure to dangerous levels of pesticides, industrial chemicals, and heavy metals, and dramatically improving response to the rare exposure incidents when they occur.
However, new dangers will inevitably emerge in foods, and chemists are vital to discovering and eliminating them. For example, acrylamide, a possible human carcinogen, can form when starchy foods are fried or baked. It forms when asparagine reacts with a reducing sugar in a variant of the Maillard browning reaction. The chemical sleuthing that identified acrylamide as a widespread toxicant in foods is a story unto itself (J. Agric. Food Chem.,DOI: 10.1021/jf020302f).
Detection of acrylamide with parts-per-billion sensitivity has allowed scientists to understand its formation and to develop technologies to prevent its formation (J. Agric. Food Chem.,DOI: 10.1021/jf0730486). Food chemists and biochemists are working with plant scientists to breed new potato varieties with low free-asparagine content that will produce less acrylamide during browning.
Scientists analyze not only produce, but the carnivore’s intake, too. During last year’s Deepwater Horizon oil spill crisis, a small army of chemists assessed the possible contamination of seafood. The oil leaking into the Gulf of Mexico contained polycyclic aromatic hydrocarbons, some of which are potential carcinogens. To date, over 300,000 animals in the Gulf have been tested, and none of the shrimp, finfish, or crabs contain the hazardous hydrocarbons at levels of concern set by the Food & Drug Administration. In fact, according to FDA, the levels fell below detection limits in the vast majority of the samples.
The rapid results from analytical laboratories allowed most fishing areas in the Gulf to reopen within four months; within a year all areas were opened. Gulf seafood is now the most tested seafood in the world. Testing continues to search for any significant residual toxicants and exposures.
Analytical food chemistry is also contributing tools for detecting the illegal contamination of food with adulterants such as melamine. In 2007 and 2008, pet foods, milk, and infant formula were illegally spiked with melamine to provide increased levels of nitrogen, making the products appear to contain more protein than was actually present. The tainted products caused kidney and urinary tract problems in domesticated animals and thousands of people. In response to the crises, regulatory agencies in many countries quickly established maximum allowable melamine levels and developed laboratory methods to measure melamine cyanurate.
Analytical chemists worldwide have been busy improving the food safety surveillance systems that protect global food supplies from melamine. Recently, researchers have developed methods suitable for rapid automated screening of a large number of samples (Anal. Chem., DOI: 10.1021/ac200926e). They have also developed methods to detect contamination in nonlaboratory settings (J. Agric. Food Chem., DOI: 10.1021/jf2008327).
Microbial contamination of food can also cause outbreaks of food-borne illness. Here, too, chemists play an important role. The chemistry-based tools of biotechnology enable rapid, accurate detection and identification of pathogenic bacteria.
A vivid example of the combination of biology and chemistry in the analysis of food is the polymerase chain reaction (PCR). Along with pulsed-field gel electrophoresis, PCR has brought speed and precision to researchers identifying the precise organisms that cause contamination. With these chemical tools, scientists can discover within hours whether a single microbial strain has caused multiple outbreaks that might otherwise have been viewed as an isolated incident. For instance, scientists used a sophisticated form of PCR to pinpoint a source of Escherichia coli O157:H7 in spinach originating from a single farm during a 2006 outbreak that caused product recalls in several states.
Biotechnology can do more than identify problems in the food supply: It also has the potential to be a valuable tool in ensuring sustainability. Even as the world’s population grows, land for agriculture is limited. Transforming rain forest or other ecosystems to produce food is not acceptable. Conventional agriculture cannot meet the increasing demand for food.
Biotechnology, in the form of transgenic crops, cloned animals, and engineered microbes, can help. Chemistry sits at the core of biotech solutions. Future biotech crops will tolerate drought, salt, floods, pests, and other environmental stresses. These crops will be particularly important in regions where irrigation water is limited or uncertain. Scientists are also developing biotech crops to address dietary needs for micronutrients and for proteins, lipids, and complex carbohydrates.
Microscopic algae have also emerged as major targets in biotechnology because they are inexpensive to grow and may be able to produce large quantities of oils suitable for biodiesel, special oils for industrial and food applications, and a protein-carbohydrate mixture useful as animal feed or as a food ingredient. Expansion and development of microbial technology could also lead to low-cost food oils that require little landmass to produce. Chemistry has already provided the tools to manipulate microalgae to produce food oils rich in omega-3 fatty acids—“healthy fat.”
A leader in healthy food research was John E. Kinsella (1938–93). During his prolific career at Cornell University and the University of California, Davis, he studied how compounds that we now know as phytochemicals and nutraceuticals contribute to functional foods—foods that include disease-preventing or health-promoting ingredients other than basic nutrients. He espoused a central role for the consumer, as well as the concepts of sustainability and health in food production, processing, delivery, and consumer choice.
More recently, chemistry has solved a long-standing mystery about the good-for-your-health antioxidants, such as flavonoids, phenolics, and anthocyanins, in plant extracts. Many compounds act as chemical antioxidants, yet this simple chemical property cannot explain the epidemiological evidence suggesting that foods rich in these materials reduce the risk of some cancers and cardiovascular disease (J. Agric. Food Chem.,DOI: 10.1021/jf2013875).
Improved analytical techniques and tools of molecular biology are now demonstrating that specific plant, animal, and microbial metabolites consumed by humans exhibit unique bioactivities, from inhibiting enzymes to regulating the expression of genes. As research identifies the pathways involved in disease, the bioactivities of these naturally occurring compounds may prove therapeutic.
The tools of molecular biology—genomics, proteomics, metabolomics, glycomics—are being applied to diets and to populations. They are helping unravel the tantalizing good health enjoyed by people who eat the so-called Mediterranean diet. The diet is characterized by infrequent consumption of red meat; weekly servings of eggs, poultry, and fish; and frequent consumption of cheese and yogurt, olive oil, fruits, vegetables, beans and other legumes, nuts, wine (particularly red wine), whole grains, and potatoes. Hypotheses for the effect of the Mediterranean diet revolve around plant-based nutrients with health-promoting, disease-preventing, or medicinal properties.
Now the tools of high-field nuclear magnetic resonance spectroscopy and mass spectrometry, once used to identify individual chemicals, are being expanded to examine hundreds of compounds simultaneously, allowing scientists to follow the ever-changing mix of chemicals within living systems, known as the metabolome (J. Agric. Food Chem.,DOI: 10.1021/jf061218t). Researchers can monitor changes in entire pathways of metabolites in response to disease or to subtle alterations in diet. As a result, recent studies are providing remarkable detail of the temporal processes of digestion, metabolism, and excretion of specific food components.
By understanding the digestion rates and pharmacokinetics of food components, research has transformed simple vitamins and lipids such as niacin and omega-3 fatty acids into successful therapeutic drugs, for instance Niaspan and Lovaza. Human nutritional evaluation tools promise the ability to connect specific foods, food preparation, and consumption patterns to personal disease risk or predisposition. The result may transform impersonal diets for populations into personal food choices for preventive measures.
The tools of biotechnology are also leading to a better understanding of the influence on human health of microbes in our gastrointestinal tracts. Research published last year details how human milk oligosaccharides interact with babies’ developing gut microflora (J. Agric. Food Chem.,DOI: 10.1021/jf9044205). Scientists have shown how unique sets of complex oligosaccharides help shape the intestinal microbial communities of breast-fed infants by functioning as decoys for pathogens and by selectively stimulating the growth of beneficial bacteria.
In a series of studies, David A. Mills and a team of researchers at UC Davis tested strains representing 10 different genera of bacteria for their ability to survive and grow on isolated oligosaccharides chemically separated from human milk. They found that some strains of good bacteria grew well with only oligosaccharides as a carbon source, while E. coli and other pathogens did not. Related studies at UC Davis Medical Center are examining how “healthy” gut microbes protect premature infants against pathogens.
These are new insights into the ways dietary components support health. This understanding may lead to improvements in bovine and other milk and agricultural products. Combining the efforts of several disciplines will enable scientists to tackle complex questions at the molecular level related to bioactivity and health benefits of food components that just a few years ago were out of reach. Combining efforts also allows researchers to face new challenges in producing healthy foods with reduced input of scarce resources—water and energy—as well as low quantities of synthetic chemicals, and low emissions of greenhouse gases.
Food processing, often a key step in making healthy food available, also relies heavily on chemistry. Food processing is carried out for several reasons, including the following:
To improve the safety of foods. Processing is often the key step in preventing spoilage or the growth of unsafe microorganisms. Proper processing can involve pasteurization with irradiation, packaging under hygienic conditions, and incorporation of shelf-life-enhancing natural antimicrobial agents. Such steps can help reduce consumer exposure to pathogenic or toxin-producing strains of E. coli, Salmonella, Campylobacter, Listeria, Aspergillus, and other microorganisms.
To improve the healthiness of foods. Processing can increase the content of chemicals in foods that are beneficial to health. For example, ultraviolet irradiation of milk or mushrooms increases both foods’ concentration of vitamin D (J. Agric. Food Chem., DOI: 10.1021/jf073398s). Biotechnology may yet identify health-promoting bioactives that processing can exploit in other widely consumed foods such as rice and wheat.
To improve the quality and consumer appeal of foods. Processing can increase consumption of produce that is inherently healthy but underutilized, such as sweet potatoes, black beans, and grain bran. Examples in the U.S. involve production of snack chips from sweet potatoes, and crackers and chips from several varieties of seasoned beans, alone or paired with grains.
Processing that can extend shelf life, improve appeal, and deliver health benefits can improve the nutrition of people at all levels of the socioeconomic spectrum. Tomatoes illustrate how food processing improves food—and that scientists still have much to learn about processing’s potential.
Tomatoes are a primary source of the antioxidant lycopene in the diet and are one of the most consumed vegetables in the U.S. Scientists think they play a role in the Mediterranean diet’s health benefits and have begun studying the potential role of lycopene in preventing prostate cancer. In processed food such as ketchup, tomato sauce, and tomato soup, tomato products are available year-round.
Food technologists are exploring new methods of peeling tomatoes that eliminate the use of caustic chemicals, in addition to exploring conditions for cooking and canning tomatoes that maintain their health benefits. Research has shown that proper processing conditions can maintain, and even enhance, the amount and bioavailability of lycopene and other antioxidants in tomato products (J. Med. Food, DOI: 10.1089/10966200152053668). Scientists are working to find health-enhancing processing methods for tomatoes and other agricultural commodities that are efficient in the use of water and energy, and minimize emissions of greenhouse gases and waste.
Food processing, safety, sustainability, and healthfulness have already made great strides but still offer scientific challenges. These challenges can benefit from multidisciplinary research involving chemists along with food technologists, microbiologists, sensory scientists, agricultural engineers, and other scientists and engineers. The benefits of such cooperative efforts may appear in affordable, healthy, delicious, and sustainable foods far surpassing what the average consumer puts on the dinner plate in wholesomeness and overall sensory appeal.
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