Genetically modified foods (or GM foods) are foods produced from organisms that have had specific changes introduced into their DNA using the methods of genetic engineering. These techniques allow for the introduction of new traits as well as greater control over traits than previous methods such as selective breeding and mutation breeding.
Commercial sale of genetically modified foods began in 1994, when Calgene first marketed its Flavr Savr delayed-ripening tomato. Most food modifications have primarily focused on cash crops in high demand by farmers such as soybean, corn, canola, and cotton seed oil. These have been engineered for resistance to pathogens and herbicides and for better nutrient profiles. GM livestock have been developed, although as of November 2013 none were on the market.
There is broad scientific consensus that food on the market derived from GM crops poses no greater risk to human health than conventional food. However, opponents have objected to GM foods on grounds including safety, environmental impact and the fact that some GM seeds that are food sources are subject to intellectual property rights and owned by corporations.
History
Food biotechnology is a branch of food science that seeks to improve foods and food production. Biotechnological processes include industrial fermentation, plant cultures and genetic engineering.
Food biotechnology dates back to the time of the Sumerians and Babylonians who used yeast to make fermented beverages such as beer. Plant enzymes such as malts were also used millennia ago. The invention of the microscope by Anton van Leeuwenhoek allowed humans to discover microorganisms that came to be used in food production. In 1871 Louis Pasteur discovered that heating juices to a certain temperature kills dangerous bacteria, affecting wine and fermentation. The eponymous pasteurization was applied to milk, to improve food safety.
The discovery of enzymes and their role in fermentation and digestion of foods led to the use of genetically modified microbes to make enzymes such as the protease chymosin for cheese production. Cheese had typically been made using the enzyme complex rennet that had extracted from cows' stomach lining. Scientists modified bacteria to produce chymosin, which was also able to clot milk, resulting in cheese curds. Microbial enzymes became the first application of genetically modified organisms in food production and were approved in 1988 by the US Food and Drug Administration.
Scientists discovered in 1946 that DNA can transfer between organisms. The first genetically modified plant was produced in 1983, using antibiotic-resistant tobacco. In 1994, the transgenic Flavr Savr tomato was approved by the FDA for marketing in the US. The modification allowed the tomato to delay ripening after picking. In the early 1990s, recombinant chymosin was approved for use in several countries.
In the US in 1995, the following transgenic crops received marketing approval: canola with modified oil composition (Calgene), Bacillus thuringiensis (Bt) corn/maize (Ciba-Geigy), cotton resistant to the herbicide bromoxynil (Calgene), Bt cotton (Monsanto), Bt potatoes (Monsanto), glyphosate-tolerant soybeans (Monsanto), virus-resistant squash (Monsanto-Asgrow), and additional delayed ripening tomatoes (DNAP, Zeneca/Peto, and Monsanto). In 2000, with the creation of golden rice, scientists genetically modified food to increase its nutrient value for the first time. As of 2011, the US is the leading country in the production of GM foods. Twenty-five GM crops had received regulatory approval. As of 2013, roughly 85% of corn, 91% of soybeans, and 88% of cotton produced in the US are genetically modified.
Process
Genetically engineered plants are generated in a laboratory by altering their genetic makeup and are tested in the laboratory for desired qualities. The most common modification is to add one or more genes to a plant's genome. Less commonly, genes are removed or silenced.
Once satisfactory plants are produced, the producer applies for regulatory approval to field-test them. Field-testing involves cultivating the plants on farm fields. If these field tests are successful, the producer applies for regulatory approval to grow and market the crop. (see Regulation of the release of genetic modified organisms). Once approved (which can take years) seeds (or cuttings, etc.) are cultivated and sold to farmers. The farmers plant, cultivate and harvest the new strain, which contains the modification. The farmers then sell their crops as commodities in countries where such sales are permitted. In some cases, the approval covers marketing but not cultivation.
Relation to food
GMOs have varying relationships to food. Some are consumed unprocessed, while others are processed in ways that remove DNA and its immediate products (proteins). Other are used to produce unmodified foods. Plant and animal relationship differ.
DNA/protein
GM foods that include modified DNA and/or protein include fruits, vegetables, corn and soy. Corn and soy are also consumed after modifications that remove most/all DNA/protein.
Fruits and vegetables
Papaya was genetically modified to resist the ringspot virus. 'SunUp' is a transgenic red-fleshed Sunset cultivar that is homozygous for the coat protein gene of PRSV; 'Rainbow' is a yellow-fleshed F1 hybrid developed by crossing 'SunUp' and nontransgenic yellow-fleshed 'Kapoho'. The New York Times stated, "in the early 1990s, Hawaii’s papaya industry was facing disaster because of the deadly papaya ringspot virus. Its single-handed savior was a breed engineered to be resistant to the virus. Without it, the state’s papaya industry would have collapsed. Today, 80% of Hawaiian papaya is genetically engineered, and there is still no conventional or organic method to control ringspot virus." The GM cultivar was approved in 1998. In China, a transgenic PRSV-resistant papaya was developed by South China Agricultural University and was first approved for commercial planting in 2006; as of 2012 95% of the papaya grown in Guangdong province and 40% of the papaya grown in Hainan province was genetically modified.
The New Leaf potato, brought to market by Monsanto in the late 1990s, was developed for the fast food market, but was withdrawn in 2001 after fast food retailers rejected it and food processors ran into export problems.
As of 2005, about 13% of the Zucchini (a form of squash) grown in the US was genetically modified to resist three viruses; that strain is also grown in Canada.
In 2011, BASF requested the European Union Food Safety Authority's approval for cultivation and marketing of its Fortuna potato as a feed and food. The potato was made resistant to late blight by adding resistant genes blb1 and blb2 that originate from the Mexican wild potato Solanum bulbocastanum. In February 2013, BASF withdrew its application.
In 2013, the USDA approved the import of a GM pineapple that is pink in color and that "overexpresses" a gene derived from tangerines and suppress other genes, increasing production of lycopene. The plant's flowering cycle was changed to provide for more uniform growth and quality. The fruit "does not have the ability to propagate and persist in the environment once they have been harvested," according to USDA APHIS. According to Del Monte's submission, the pineapples are commercially grown in a "monoculture" that prevents seed production, as the plant's flowers aren't exposed to compatible pollen sources. Importation into Hawaii is banned for plant sanitation reasons.
In 2014, the USDA approved a genetically modified potato developed by J.R. Simplot Company, which contains 10 genetic modifications that prevent bruising and produce less acrylamide when fried than conventional potatoes; the modifications do not cause new proteins to be made, but rather prevent proteins from being made, via RNA interference.
In February 2015 Arctic Apples were approved by the USDA, becoming the first genetically modified apple approved for sale in the United States. Gene silencing is used to reduce the expression of polyphenol oxidase (PPO), thus preventing the fruit from browning.
Corn
Corn used for food has been genetically modified to tolerate various herbicides and to express a protein from Bacillus thuringiensis (Bt) that kills certain insects. About 90% of the corn grown in the US has been genetically modified.
Corn can be processed into grits, meal and flour as an ingredient in pancakes, muffins, doughnuts, breadings and batters, as well as baby foods, meat products, cereals, and some fermented products. Masa flour is variety of flour that is produced using the alkaline-cooked process. A related product, masa dough, can be made using corn flour and water. Masa flour and masa dough are used in the production of taco shells, corn chips, and tortillas.
Soy
Genetically modified soybean has been modified to tolerate herbicides, express Bt, and produce healthier oils. About 90% of soybeans in the US are genetically modified.
Soybeans contain about 20% oil. In the most common method used to extract the oil, the soybeans are cracked, adjusted for moisture content, rolled into flakes and solvent-extracted with commercial hexane. The remaining soy meal has a 50% soy protein content. The meal is 'toasted' (a misnomer because the heat treatment is with moist steam) and ground in a hammer mill.
Ninety-eight percent of the US soybean crop is used for livestock feed. Part of the balance is processed further into high protein soy products that are used in a variety of foods, such as salad dressings, soups, meat analogues, beverage powders, cheeses, nondairy creamer, frozen desserts, whipped topping, infant formulas, breads, breakfast cereals, pastas, and pet foods. Processed soy protein appears in foods mainly in three forms: soy flour, soy protein isolates and soy protein concentrates.
Protein isolate
Food-grade soy protein isolate first became available on October 2, 1959 with the opening of Central Soya's edible soy isolate production facility on the Glidden Company industrial site in Chicago. Soy protein isolate is a highly refined form of soy protein with a minimum protein content of 90% on a moisture-free basis. It is made from soy meal that has had most of the fats and carbohydrates removed. Soy isolates are mainly used to improve the texture of processed meat products and to increase protein content, enhance moisture retention, and as an emulsifier.
Protein concentrate
Soy protein concentrate is about 70% soy protein and is basically soybean meal without carbohydrates. Soy protein concentrate retains most of the bean fiber. It is used as a functional or nutritional ingredient in a wide variety of food products, mainly in baked foods, breakfast cereals and in some meat products. Soy protein concentrate is used in meat and poultry products to increase water and fat retention and to improve nutritional values (more protein, less fat).
Flour
Soy flour is made by grinding soybeans into a fine powder. It comes in three forms: natural or full-fat (contains natural oils); defatted (oils removed) with 50% protein content and with either high water solubility or low water solubility; and lecithinated (lecithin added). As soy flour is gluten-free, yeast-raised breads made with soy flour are dense in texture. Soy grits are similar to soy flour except the soybeans have been toasted and cracked into coarse pieces. Kinako is a soy flour used in Japanese cuisine.
Textured protein
Textured soy protein (TSP) is made by forming a dough from meal with water in a screw-type extruder, and heating with or without steam. The dough is extruded through a die into various shapes and dried in an oven. The extrusion technology changes the structure of the soy protein, resulting in a fibrous, spongy matrix similar in texture to meat. TSP is used as a low-cost substitute in meat and poultry products.
Derivative products
Corn starch and starch sugars, including syrups
Starch or amylum is a polysaccharide is produced by all green plants as an energy store. Pure starch is a white, tasteless and odourless powder that is insoluble in cold water or alcohol. It consists of two types of molecules: the linear and helical amylose and the branched amylopectin. Depending on the plant, starch generally contains 20 to 25% amylose and 75 to 80% amylopectin by weight.
To make corn starch, corn is steeped for 30 to 48 hours, which ferments it slightly. The germ is separated from the endosperm and those two components are ground separately (still soaked). Next the starch is removed from each by washing. The starch is separated from the corn steep liquor, the cereal germ, the fibers and the corn gluten mostly in hydrocyclones and centrifuges, and then dried. This process is called wet milling and results in pure starch. The products of that pure starch contain no GM DNA or protein.
Starch can be further modified to create modified starch for specific purposes, including creation of many of the sugars in processed foods. They include:
- Maltodextrin, a lightly hydrolyzed starch product used as a bland-tasting filler and thickener.
- Various glucose syrups, also called corn syrups in the US, viscous solutions used as sweeteners and thickeners in many kinds of processed foods.
- Dextrose, commercial glucose, prepared by the complete hydrolysis of starch.
- High fructose syrup, made by treating dextrose solutions with the enzyme glucose isomerase, until a substantial fraction of the glucose has been converted to fructose. In the United States, high fructose corn syrup is the principal sweetener used in sweetened beverages because fructose has better handling characteristics, such as microbiological stability, and more consistent sweetness/flavor. One kind of high fructose corn syrup, HFCS-55, is typically sweeter than regular sucrose because it is made with more fructose, while the sweetness of HFCS-42 is on par with sucrose.
- Sugar alcohols, such as maltitol, erythritol, sorbitol, mannitol and hydrogenated starch hydrolysate, are sweeteners made by reducing sugars.
Lecithin
Corn oil and soy oil, already free of protein and DNA, are sources of lecithin, which is widely used in processed foods as an emulsifier. Lecithin is sufficiently processed that protein or DNA from the original crop from which it is derived is often undetectable with standard testing practices. Nonetheless, consumer concerns about GM food extend to such products. This concern led to policy and regulatory changes in Europe in 2000, when Regulation (EC) 50/2000 was passed which required labelling of food containing additives derived from GMOs, including lecithin. Because of the difficulty of detecting the origin of derivatives like lecithin with current testing practices, European regulations require those who wish to sell lecithin in Europe to employ a comprehensive system of Identity preservation (IP).
Sugar
The US imports 10% of its sugar from other countries, while the remaining 90% is extracted from domestically grown sugar beet and sugarcane. Domestically grown sugar crops come half from beet, and the other half from cane.
After deregulation in 2005, glyphosate-resistant sugar beet was extensively adopted in the United States. 95% of beet acres in the US were planted with glyphosate-resistant seed in 2011. Herbicide-tolerant beets are also approved in Australia, Canada, Colombia, EU, Japan, Korea, Mexico, New Zealand, Philippines, Russian Federation and Singapore.
The food products of sugar beets are refined sugar and molasses. Pulp from the refining process is used as animal feed. The sugar produced from GM sugarbeets contains no DNA or proteinâ€"it is just sucrose, chemically indistinguishable from sugar produced from non-GM sugarbeets.
Vegetable oil
Most vegetable oil used in the US is produced from GM crops canola, corn, cotton and soybeans. Vegetable oil is sold directly to consumers as cooking oil, shortening and margarine and is used in prepared foods.
There is a vanishingly small amount of protein or DNA from the original crop in vegetable oil. Vegetable oil is made of triglycerides extracted from plants or seeds and then refined and may be further processed via hydrogenation to turn liquid oils into solids. The refining process removes all, or nearly all non-triglyceride ingredients.
Unmodified foods created using GMOs
Cheese
Rennet is a mixture of enzymes used to coagulate milk into cheese. Originally it was available only from the fourth stomach of calves, and was scarce and expensive, or was available from microbial sources, which often produced unpleasant tastes. Genetic engineering made it possible to extract rennet-producing genes from animal stomachs and insert them into bacteria, fungi or yeasts to make them produce chymosin, the key enzyme in rennet. The modified microorganism is killed after fermentation. Chymosin is isolated from the fermentation broth, so that the Fermentation-Produced Chymosin (FPC) used by cheese producers has an amino acid sequence that is identical to bovine rennet. The majority of the applied chymosin is retained in the whey. Some chymosin may remain in cheese in trace quantities.
FPC was the first artificially produced enzyme to be registered and allowed by the US Food and Drug Administration. FPC products have been on the market since 1990 and have been considered in the last 20 years to be the ideal milk-clotting enzyme. In 1999, about 60% of US hard cheese was made with FPC. Its global market share approaches 80%. By 2008, approximately 80% to 90% of commercially made cheeses in the US and Britain were made using FPC. The most widely used FPC is produced either by the fungus Aspergillus niger (CHY-MAX®) by Danish company Chr. Hansen, or produced by Kluyveromyces lactis (MAXIREN®) by Dutch company DSM.
Animals fed GMOs
Livestock and poultry are raised on animal feed, much of which is composed of the leftovers from processing crops, including GM crops. For example, approximately 43% of a canola seed is oil. What remains after oil extraction is a meal that becomes an ingredient in animal feed and contains canola protein. Likewise, the bulk of the soybean crop is grown for oil and meal. The high-protein defatted and toasted soy meal becomes livestock feed and dog food. 98% of the US soybean crop goes for livestock feed. In 2011, 49% of the US maize harvest was used for livestock feed (including the percentage of waste from distillers grains). "Despite methods that are becoming more and more sensitive, tests have not yet been able to establish a difference in the meat, milk, or eggs of animals depending on the type of feed they are fed. It is impossible to tell if an animal was fed GM soy just by looking at the resulting meat, dairy, or egg products. The only way to verify the presence of GMOs in animal feed is to analyze the origin of the feed itself."
GM hormone
In some countries, recombinant (GM) bovine somatotropin (also called rBST, or bovine growth hormone or BGH) is approved for administration to increase milk production. rBST may be present in milk from rBST treated cows, but it is destroyed in the digestive system and even if directly injected into the human bloodstream, has no direct effect on humans. The Food and Drug Administration, World Health Organization, American Medical Association, American Dietetic Association and the National Institutes of Health have independently stated that dairy products and meat from rBST-treated cows are safe for human consumption. However, on 30 September 2010, the United States Court of Appeals, Sixth Circuit, analyzing submitted evidence, found that there is a "compositional difference" between milk from rBGH-treated cows and milk from untreated cows. The court stated that milk from rBGH-treated cows has: increased levels of the hormone Insulin-like growth factor 1 (IGF-1); higher fat content and lower protein content when produced at certain points in the cow's lactation cycle; and more somatic cell counts, which may "make the milk turn sour more quickly."
GM animals
As of November 2013 no genetically modified animals approved had been for use as food, but a GM salmon had been awaiting regulatory approval since 1997.
Some mammals typically used for food production have been modified to produce non-food products, a practice sometimes called Pharming. Genetically modified goats have been approved by the FDA and EMA to produce recombinant antithrombin, an anticoagulant protein drug.
Research and experiments have gone into adding promoter genes into animals to accelerate growth and to increase disease resistance (e.g., injection of a-lactalbumin gene into pigs.)
Controversies
The genetically modified foods controversy is a dispute over the use of food and other goods derived from genetically modified crops and other uses of genetic engineering in food production. The dispute involves consumers, farmers, biotechnology companies, governmental regulators, non-governmental organizations, activists and scientists. The key areas of controversy are whether GM food should be labeled, the role of government regulators, objectivity of scientific research and publication, and the effects on health, the environment, pesticide resistance, farmers and on feeding the world population. Other concerns include contamination of the conventional food supply, rigor of the regulatory process, and control of the food supply by GM seed companies.
There is broad scientific consensus that food on the market derived from GM crops poses no greater risk than conventional food. No reports of ill effects have been documented in the human population from GM food. The starting point for assessing GM food safety is to evaluate its similarity to the non-modified version. Further testing is then done on a case-by-case basis to ensure that concerns over potential toxicity and allergenicity are satisfied. Although labeling of GMO products in the marketplace is required in 64 countries, the US does not require this. The FDA's policy is to require a label given significant differences in composition or health impacts. They have not identified such differences in any food currently approved for sale.
Opponents such as the advocacy groups Organic Consumers Association, the Union of Concerned Scientists, and Greenpeace claim risks have not been adequately identified and managed, and they have questioned the objectivity of regulatory authorities. Some health groups claim that the potential long-term impact on human health have not been adequately assessed and propose mandatory labeling or a moratorium on such products.
Regulation
Governments invoke varied processes to assess and manage the use of genetic engineering technology and GMO development and release, including crops and fish. Marked differences separate the US and Europe. Regulation varies idepending on the intended product use. For example, a crop not intended for food use is generally not reviewed by authorities responsible for food safety.
In the United States, three different government organizations are responsible for regulating GMOs. The Food and Drug Administration (FDA) checks the chemical composition of the organism for any potential allergens. The United States Department of Agriculture (USDA) supervises field testing and monitors the distribution of GM seeds. The United States Environmental Protection Agency (EPA) is responsible for monitoring pesticide usage, including plants modified to contain proteins toxic to insects. Like the USDA, the EPA also oversees field testing and the distribution of crops that have had contact with pesticides to ensure the GMOs are safe for the environment.
One of the key issues concerning regulators is whether GM products should be labeled. Labeling can be mandatory when a product exceeds a threshold content level (which varies between countries) or voluntary. A study that investigated voluntary labeling in South Africa, found that 31% of products labeled as GMO-free had a GM content above 1.0%. In Canada and the USA labeling is voluntary, while in Europe all food (including processed food) or feed that contains greater than 0.9% of GMOs must be labelled.
As of 2015, 64 countries require GMO labeling; more than a third of these in compliance with a single EU ruling.
Detection
Testing on GMOs in food and feed is routinely done using molecular techniques such as PCR and bioinformatics.
In a January 2010 paper, the extraction and detection of DNA along a complete industrial soybean oil processing chain was described to monitor the presence of Roundup Ready (RR) soybean: "The amplification of soybean lectin gene by end-point polymerase chain reaction (PCR) was successfully achieved in all the steps of extraction and refining processes, until the fully refined soybean oil. The amplification of RR soybean by PCR assays using event-specific primers was also achieved for all the extraction and refining steps, except for the intermediate steps of refining (neutralisation, washing and bleaching) possibly due to sample instability. The real-time PCR assays using specific probes confirmed all the results and proved that it is possible to detect and quantify genetically modified organisms in the fully refined soybean oil. To our knowledge, this has never been reported before and represents an important accomplishment regarding the traceability of genetically modified organisms in refined oils."
See also
- California Proposition 37 (2012)
- Chemophobia
- Genetic engineering
- Genetically modified crops
- Genetically modified food controversies
- Genetically modified organisms
- Regulation of the release of genetic modified organisms
- Starlink corn recall
References
External links
- Documentary on YouTube
- Library resources in your library and in other libraries about Genetically modified food
- Media related to Genetically modified organisms at Wikimedia Commons