Jumaat, 8 Mac 2013

Genetically modified foods


Genetically modified foods

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Genetically modified foods (GM foods, or biotech foods) are foods derived from genetically modified organisms (GMOs), specifically, genetically modified crops. GMOs have had specific changes introduced into their DNA by genetic engineering techniques. These techniques are much more precise[1] than mutagenesis (mutation breeding) where an organism is exposed to radiation or chemicals to create a non-specific but stable change. Other techniques by which humans modify food organisms include selective breeding and somaclonal variation.

Commercial sale of genetically modified foods began in 1994, when Calgene first marketed its Flavr Savr delayed ripening tomato.[2] Typically, genetically modified foods are transgenic plant products: soybean, corn, canola, and cotton seed oil. These may have been engineered for faster growth, resistance to pathogens, production of extra nutrients, or any other beneficial purpose. GM livestock have also been experimentally developed, although as of July 2010 none are currently on the market.[3]

While there is broad scientific consensus that food on the market derived from GM crops pose no greater risk to human health than conventional food,[4][5][6][7][8][9][10][11] critics have objected to GM foods on several grounds, including safety issues,[7] ecological concerns, and economic concerns raised by the fact GM plants (and potentially animals) that are food sources are subject to intellectual property law.

Genetically engineered plants are generated in a laboratory by altering their genetic makeup and are tested in the laboratory for desired qualities. This is usually done by adding one or more genes to a plant's genome using genetic engineering techniques. Most genetically modified plants are generated by the biolistic method (particle gun) or by Agrobacterium tumefaciens mediated transformation.

Once satisfactory plants are produced, sufficient seeds are gathered, and the companies producing the seed need to apply for regulatory approval to field-test the seeds. If these field tests are successful, the company must seek regulatory approval for the crop to be marketed (see Regulation of the release of genetic modified organisms). Once that approval is obtained, the seeds are mass-produced, and sold to farmers. The farmers produce genetically modified crops, which also contain the inserted gene and its protein product. The farmers then sell their crops as commodities into the food supply market, in countries where such sales are permitted.
Scientists first discovered that DNA can transfer between organisms in 1946.[12] The first genetically modified plant was produced in 1983, using an antibiotic-resistant tobacco plant. 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.[2] In the early 1990s, recombinant chymosin was approved for use in several countries, replacing rennet in cheese-making.[13] 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), soybeans resistant to the herbicide glyphosate (Monsanto), virus-resistant squash (Asgrow), and additional delayed ripening tomatoes (DNAP, Zeneca/Peto, and Monsanto).[2] 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 U.S. leads a list of multiple countries in the production of GM crops, and 25 GM crops had received regulatory approval to be grown commercially.

Fruits and vegetables

3 views of the Sunset papaya cultivar, which was genetically modified to create the SunUp cultivar, resistant to PRV.[15]
Papaya has been genetically modified to resist the ringspot virus. 'SunUp' is a transgenic red-fleshed Sunset cultivar that is homozygous for the coat protein gene of PRV; 'Rainbow' is a yellow-fleshed F1 hybrid developed by crossing 'SunUp' and nontransgenic yellow-fleshed 'Kapoho'.[15] The New York Times stated that "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."[16]
The New Leaf potato, brought to market by Monsanto in the late 1990s, was developed for the fast food market, but was withdrawn from the market in 2001[17] after fast food retailers did not pick it up and food processors ran into export problems.[18] There are currently no transgenic potatoes marketed for human consumption.[18] However, in October 2011 BASF requested cultivation and marketing approval as a feed and food from the EFSA for its Fortuna potato, which was made resistant to late blight by adding two resistance genes, blb1 and blb2, which originate from the Mexican wild potato Solanum bulbocastanum.[19][20]
As of 2005, about 13% of the zucchini grown in the US was genetically modified to resist three viruses; the zucchini is also grown in Canada.[21]
As of 2012, an apple that has been genetically modified to resist browning, known as the Nonbrowning Arctic apple produced by Okanagan Specialty Fruits, is awaiting regulatory approval in the US and Canada. A gene in the fruit has been modified such that the apple produces less polyphenol oxidase, a chemical that manifests the browning.[22]

Milled corn products

Human-grade corn can be processed into grits, meal, and flour.
Grits are the coarsest product from the corn dry milling process. Grits vary in texture and are generally used in corn flakes, breakfast cereals, and snack foods. Brewers’ grits are used in the beer manufacturing process.
Corn meal is an ingredient in several products including cornbread, muffins, fritters, cereals, bakery mixes, pancake mixes, and snacks. The finest grade corn meal is often used to coat English muffins and pizzas. Cornmeal is also sold as a packaged good.
Corn flour is one of the finest textured corn products generated in the dry milling process. Some of the products containing corn flour include mixes for pancakes, muffins, doughnuts, breadings, and batters, as well as baby foods, meat products, cereals, and some fermented products. Masa flour is another finely textured corn product. It 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.[23]

Milled soy products

Soybean seed contains about 19% oil. To extract soybean oil from seed, the soybeans are cracked, adjusted for moisture content, rolled into flakes and solvent-extracted with commercial hexane. The remaining soybean 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 U.S. soybean crop is used for livestock feed. Part of the remaining 2% of soybean meal 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.[24][25]

Soy protein isolates

Food-grade soy protein isolate first became available on October 2, 1959 with the dedication of Central Soya's edible soy isolate, Promine D, production facility on the Glidden Company industrial site in Chicago. Soy protein isolate is a highly refined or purified form of soy protein with a minimum protein content of 90% on a moisture-free basis. It is made from soybean meal which has had most of the nonprotein components, fats and carbohydrates removed. Soy isolates are mainly used to improve the texture of processed meat products, but are also used to increase protein content, to enhance moisture retention, and are used as an emulsifier.[26][27]

Soy protein concentrates

Soy protein concentrate is about 70% soy protein and is basically soybean meal without the water-soluble carbohydrates. Soy protein concentrate retains most of the fiber of the original soybean. It is widely 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).[26][28]

Flours

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.[26][29]

Textured soy protein

Textured soy protein (TSP) is made by forming a dough from soybean meal with water in a screw-type extruder, and heating with or without steam. The dough is extruded through a die into various possible 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.[26][30]

Highly processed derivatives containing little to no DNA or protein

Lecithin

An example of a phosphatidylcholine, a type of phospholipid in lecithin. Red - choline and phosphate group; Black - glycerol; Green - unsaturated fatty acid; Blue - saturated fatty acid
Corn oil and soy oil, already free of protein and DNA, are sources of lecithin, which is widely used in processed food as an emulsifier.[31][32] Lecithin is highly processed. Therefore, GM protein or DNA from the original GM crop from which it is derived is often undetectable - in other words, it is not substantially different from lecithin derived from non-GM crops.[11][33] Nonetheless, consumer concerns about genetically modified food have extended to highly purified derivatives from GM food, like lecithin.[34] This concern led to policy and regulatory changes in Europe in 2000, when Regulation (EC) 50/2000 was passed[35] which required labelling of food containing additives derived from GMOs, including lecithin. Because it is nearly impossible to detect the origin of derivatives like lecithin, the European regulations require those who wish to sell lecithin in Europe to use a meticulous system of Identity preservation (IP).[33][36]

Vegetable oil

Most vegetable oil used in the US is produced from several crops, including the GM crops canola,[37] corn,[31][38] cotton,[39] and soybeans.[40] Vegetable oil is sold directly to consumers as cooking oil, shortening, and margarine,[41] and is used in prepared foods.
There is no, or a vanishingly small amount of, protein or DNA from the original GM crop in vegetable oil.[11][42] 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[43] removes all, or nearly all non-triglyceride ingredients.[44]

Corn starch and starch sugars, including syrups


Structure of the amylose molecule

Structure of the amylopectin molecule
Starch or amylum is a carbohydrate consisting of a large number of glucose units joined by glycosidic bonds. This 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.[11]
Starch can further modified to create modified starch for specific purposes,[45] 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.[46][47]
  • Sugar alcohols, such as maltitol, erythritol, sorbitol, mannitol and hydrogenated starch hydrolysate, are sweeteners made by reducing sugars.

Sugar


Structure of sucrose
The United States imports 10% of its sugar from other countries, while the remaining 90% is extracted from domestically grown sugar beet and sugarcane. Of the domestically grown sugar crops, half of the extracted sugar is derived from sugar beet, and the other half is from sugarcane.
After deregulation in 2005, glyphosate-resistant sugar beet was extensively adopted in the United States. 95% of sugar beet acres in the US were planted with glyphosate-resistant seed in 2011.[14] Sugar beets that are herbicide-tolerant have been approved in Australia, Canada, Colombia, EU, Japan, Korea, Mexico, New Zealand, Philippines, Russian Federation, Singapore, and USA.[48]
The food products of sugar beets are refined sugar and molasses. Pulp remaining from the refining process is used as animal feed. The sugar produced from GM sugarbeets is highly refined and contains no DNA or protein—it is just sucrose, the same as sugar produced from non-GM sugarbeets.[11][49]

Foods processed using genetically engineered products

Cheese

Rennet is a mixture of enzymes used to coagulate 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 suffered from bad tastes. With the development of genetic engineering, it became possible to extract rennet-producing genes from animal stomach and insert them into certain bacteria, fungi or yeasts to make them produce chymosin, the key enzyme in rennet.[50][51] The genetically-modified microorganism is killed after fermentation and chymosin isolated from the fermentation broth, so that the Fermentation-Produced Chymosin (FPC) used by cheese producers is identical in amino acid sequence to the animal source.[52] The majority of the applied chymosin is retained in the whey and, at most, may be present in cheese in trace quantities.[11] In ripe cheese, the type and provenance of chymosin used in production cannot be determined.[52]
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 the ideal milk-clotting enzyme.[53] In 1999, about 60% of US hard cheese was made with FPC[54] and it has up to 80% of the global market share for rennet.[55] By 2008, approximately 80% to 90% of commercially made cheeses in the US and Britain were made using FPC.[52] Today, the most widely used Fermentation-Produced Chymosin (FPC) is produced either by the fungus Aspergillus niger and commercialized under the trademark CHY-MAX®[56] by the Danish company Chr. Hansen, or produced by Kluyveromyces lactis and commercialized under the trademark MAXIREN®[57] by the Dutch company DSM.

Foods made from animals fed with GM crops or treated with bovine growth hormone

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 is a canola meal that is used as an ingredient in animal feed and contains protein from the canola.[58] Likewise, the bulk of the soybean crop is grown for oil production and soy meal, with the high-protein defatted and toasted soy meal used as livestock feed and dog food. 98% of the U.S. soybean crop is used for livestock feed.[59][60] As for corn, In 2011, 49% of the total maize harvest was used for livestock feed (including the percentage of waste from distillers grains).[61] "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."[62]
In some countries, recombinant bovine somatotropin (also called rBST, or bovine growth hormone or BGH) is approved for administration to dairy cows in order 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, has no direct affect on humans.[63][64] The Food and Drug Administration, World Health Organization, American Medical Association, American Dietetic Association, and the National Institute of Health have independently stated that dairy products and meat from BST treated cows are safe for human consumption.[65] However, on 30 September 2010, the United States Court of Appeals, Sixth Circuit, analyzing evidence submitted in briefs, found that there is a "compositional difference" between milk from rBGH-treated cows and milk from untreated cows.[66][67] 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."[67]

Foods made from GM animals

As of December 2012 there were no genetically modified animals approved for use as food, but a GM salmon was near FDA approval at that time.[68][69]
Animals (e.g. goat,) usually used for food production (e.g. milk,) have already been genetically modified and approved by the FDA and EMA to produce non-food products (for example, recombinant antithrombin, an anticoagulant protein drug.)[70][71]

Detection

Testing on GMOs in food and feed is routinely done using molecular techniques like DNA microarrays or qPCR. These tests can be based on screening genetic elements (like p35S, tNos, pat, or bar) or event-specific markers for the official GMOs (like Mon810, Bt11, or GT73). The array-based method combines multiplex PCR and array technology to screen samples for different potential GMOs,[72] combining different approaches (screening elements, plant-specific markers, and event-specific markers).
The qPCR is used to detect specific GMO events by usage of specific primers for screening elements or event-specific markers. Controls are necessary to avoid false positive or false negative results. For example, a test for CaMV is used to avoid a false positive in the event of a virus contaminated sample.
In a January 2010 paper,[73] 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."

Regulation

The regulation of genetic engineering concerns the approaches taken by governments to assess and manage the risks associated with the use of genetic engineering technology and the development and release of genetically modified organisms (GMO). There are differences in the regulation of GMOs between countries, with some of the most marked differences occurring between the USA and Europe. Regulation varies in a given country depending on the intended use of the products of the genetic engineering. For example, a crop not intended for food use is generally not reviewed by authorities responsible for food safety,[18] while GM crops intended for use in human or animal food are reviewed by such authorities. Additionally, various govern the importation of GM commodities, as well as food made using GM commodities.

Controversy

The genetically modified foods controversy is a dispute over the relative advantages and disadvantages of food derived from GMOs, genetically modified crops used to produce food and other goods, and other uses of genetically modified organisms in food production. The dispute involves consumers, biotechnology companies, governmental regulators, non-governmental organizations and scientists. The key areas of controversy related to genetically modified (GM) food are: risk of harm from GM food, whether GM food should be labeled, the role of government regulators, the effect of GM crops on the environment, the impact of GM crops for farmers, including farmers in developing countries, the role of GM crops in feeding the growing world population, and GM crops as part of the industrial agriculture system.
There is broad scientific consensus that food on the market derived from GM crops pose no greater risk than conventional food.[4][5][6][7][8][9][10] No reports of ill effects have been documented in the human population from GM food.[7][74][75] Supporters of food derived from GMOs hold that food is as safe as other foods and that labels send a message to consumers that GM food is somehow dangerous. They trust that regulators and the regulatory process are sufficiently objective and rigorous, and that risks of contamination of the non-GM food supply and of the environment can be managed. They trust that there is sufficient law and regulation to maintain competition in the market for seeds, believe that GM technology is key to feeding a growing world population, and view GM technology as a continuation of the manipulation of plants that humans have conducted for millennia.
Advocacy groups such as Greenpeace and World Wildlife Fund have concerns that risks of GM food have not been adequately identified and managed, and have questioned the objectivity of regulatory authorities. Opponents of food derived from GMOs are concerned about the safety of the food itself and wish it banned, or at least labeled. They have concerns about the objectivity of regulators and rigor of the regulatory process, about contamination of the non-GM food supply, about effects of GMOs on the environment, about industrial agriculture in general, and about the consolidation of control of the food supply in companies that make and sell GMOs, especially in the developing world. Some are concerned that GM technology tampers too deeply with nature.

See also


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