Nitrogen fixation

1. IV. TECHNOLOGY MILESTONES IN FOOD AND AGRICULTURE IV.1. Fertilizers and Soil Nutrients Nitrogenfixation Nitrogen fixation is an essential natural process in which microorganisms convert the otherwise less-reactive nitrogen into inorganic nitrogen compounds, which in turn first enter the nutritional chain as organic nitrogen compounds such as proteins in plants. Availiable soil nitrogen, especially nitrates, is normally deficient for intensive crop production. Many commercial processes have been developed to produce nitrogen fertilizers, including the best known Haber-Bosch method for ammonia synthesis. The achievability of balanced soil chemistry was also advanced by the 1956 development of the Kjeldahl method to automatically analyze the amount of existing nitrogen present in organic compounds. The nitrogen cycle Root nodules The Haber-Bosh process At the end of the nineteenth century, the limited food supply of the world’s expanding population raised growing concerns. The nitrogen content of agricultural soil had been exhausted, and the question of industrial support for nitrogen fertilizers remained unsolved. Some scientists predicteded worldwide starvation. Therefore, an urgent task was the production of nitrogen compounds utilizing nitrogen from the air. The solution came in 1908 from Germany, where Fritz Haber discovered the principles of ammonia synthesis, utilizing all physical and chemical resources available at that time. The synthesis takes place on iron catalyst at high pressure and temperature. Carl Bosch, chemist at BASF (Badische Anilin- & Soda-Fabrik) commercialized the process by establishing the first, state-of-the-art, industrial-level production in 1913. This industrial process allowed for the expansion of both agriculturul production and human population during the 20th century. Fritz Haber Advances in chemical fertilizers Beginning in 1913, synthetic fertilizers were commercially produced and dramatically improved crop yields and production. Innovations in the basic production of chemical fertilizers have been made ever since, including the 1930 marketing of granulated fertilizers and the 1965 introduction of suspension fertilizers in the American market. In the 1970s, granulation was further refined to introduce fertilizers suitable for home-use blending. The most recent innovations in commercial fertilizers include time-release encapsulation that avoids environmentally undesirable over fertilization. Green Revolution and hybrid plants Since the 1870s, hybrid plants have been created to use desirable traits to increase food production and quality. Organic chemistry identifies desirable plant qualities, translates those qualities to successive hybrids, and maximizes nitrogen uptake with chemical fertilizers. These advances led to the ‘Green Revolution’, beginning when Mexico first became self-sufficient in wheat production in 1943. By 1964, much of Asia’s population was being fed using new hybrid plants and soil nutrient chemistry. American farmers are now embracing new kinds of hybrid plants, such as maize and potatoes that secrete a pesticide in their leaves and stems.

2. IV. TECHNOLOGY MILESTONES IN FOOD AND AGRICULTURE IV.2. Crop Protection and Pest Management Bordeaux method and fungicides In 1882, French botanist Pierre M. A. Millardet employed an aqueous solution of copper sulfate and hydrated lime dissolved in water (Bordeaux mixture) to effectively combat mildew in French vineyards. The Bordeaux mixture now controls a number of fungi that attack crops. This also marked the first large-scale fungicide use and revolutionized chemical crop protection. Chemical innovations in agricultural fungicides continued with the introduction of dithiocarbamate fungicides in 1934 and strobilurin fungicides in 1996. DDT and pesticides Pesticides shield agricultural crops from harm by fungi, insects, and competition from other plants. In 1939, Paul Mueller developed the inexpensive insecticide DDT (dichlor-diphenyl-trichlorethan) to control potato beetles and other insects. DDT and similar pesticides controlled crop pests and insect-borne diseases for over twenty years. In the 1960s, public concerns about environmental damage and accumulation of DDT in the human body, combined with increasing resistance in pest species led to the evolution of new pesticides and the decline of DDT. Today’s low-application pesticides provide greater economy for farmers, added worker safety, and are more environmentally friendly than ever before. DDT in combating malaria Thinned egg- shells caused by DDT Livestock protection The treatment of animal disease, either by vaccination or medication, has increased the quality and quantity of the food supply. In 1881, Louis Pasteur successfully perfected techniques to vaccinate animals in order to induce immunity against the anthrax-causing organism. In 1981, the anti-parasitic Ivermectin was introduced to fight a wide range of mites, worms, and other internal parasites that effect animal health. Current research is attempting to prevent bovine spongiform encephalopathy (BSE), the so called `mad cow disease’ that is believed to be caused by proteins in animal feed that harbor the infectious agent. Louis Pasteur Farm mechanization In conjunction with the need for efficient application technologies for agricultural chemicals (fertilizers, pesticides) and water, agricultural chemistry and farm mechanization have developed together over the last century. They have dramatically increased farm efficiency and productivity. The Diesel-oil-powered tractor was developed by the American inventor Benjamin Holt, in 1904. Today’s tractors, cultivators, combines reapers, irrigation machines, computer-based application technology, and sophisticated GPS software are all enabled by chemical innovations such as petrochemical fuels, structural materials (metal alloys and advanced plastics), tire technology, and computing electronics. Modern combine-harvester The crawler tractor developed by Holt

3. IV. TECHNOLOGY MILESTONES IN FOOD AND AGRICULTURE IV.3. Food Processing, Handling and Safety Saccharin and sweeteners Artificial sweeteners created using chemistry aid both diabetics and dieters in controlling their sugar intake. In 1901, John F. Quenny manufactured the artificial sweetener Saccharin. In 1967, the manufacturing of high-fructose corn syrup using a patented enzyme to increase the fructose sweetness of corn syrup from 14% to 42% began and quickly became the sweetener for all major soft drinks. Aspartame was first sold in 1985 in the USA; this low-calorie intense sweetener, marketed as NutraSweet, was developed in 1955 as a possible anti-ulcer drug. Vitamin additives Understanding food biochemistry has revolutionized nutrition by offering cures for dietary deficiencies and malnutrition caused by lack of vitamins. Chemistry has made great advances in this field, as shown by examining the first vitamin to be discovered. Vitamin A (beta-catotene) was isolated in 1913 from butter and egg yolks, and is an essential nutrient for vision and the protection of epithelia. Its chemical structure was determined in 1931, and it was first synthesized in 1947. The Hungarian biochemist Albert Szent-Györgyi isolated hexuronic acid (ascorbic acid) from adrenal glands in 1928. It is now known as vitamin C. In 2001, genetically-modified ‘golden rice’ that produces pro-vitamin A arrives in Asia to fight blindness and other deficiency diseases. Preservation and manufacturing advances The roots of food chemistry go back to the German Justus Liebig, who first made meat extract at the middle of the nineteenth century. Advances in preservation and manufacturing techniques have allowed us to create processed foods. As food chemistry fueled industrial practices, many new processed foods were developed. New technologies also exten the shelf life of food, including freeze-drying (liophilisation) (1906), deep-freezing foods (1920), precooking frozen foods (1939), and making concentrates from fluids (1946). The one-time placard of Liebig’s meat extract Food safety and testing Any raw agricultural product or prepared food can become contaminated and adversely affect human health. Contamination may occur during preparation, cooking, serving or storage. Chemical advances that increase food safety include rapid test methods which enable the detection of microbial food contaminants and the control of food-borne epidemics. Illnesses from the most common food-borne pathogens have been reduced by 20% from 1997 to 1999 in the United States.

4. IV. TECHNOLOGY MILESTONES IN FOOD AND AGRICULTURE IV.4. Food Storage Food packaging Packaging food with plastics, metal, glass, and ceramic technologies helps to preserve food during sale, shipping, and preparation. Ralph Wiley invented industrial saran polymer in the 1930s, and household Saran wrap was introduced in 1953 to provide an excellent barrier to oxygen, moisture, aroma, and chemicals under extreme humidity and temperature conditions. Saran wrap is a copolymer of vinylidene chloride and vinyl chloride. Other innovations include utilization of aluminum cans for foods and beverages (1960s), and of PET (polyethylene terephthalate) as recyclable container packaging to replace glass or aluminum (1970s). Refrigerants and chlorofluorocarbons Since it was introduced for home use in 1918, refrigeration has altered food preservation by providing the ability to transport and store fresh foods safely. Early in the 1920s, refrigerators became unpopular after the sulfur dioxide coolant proved to be toxic. The solution was Freon 12, a chlorofluorocarbon (also referred to as a CFC, CCl2F2) compound made into a refrigerant gas by Thomas Midgley and Charles Kettering in 1931. Refrigerators quickly became standard in homes, restaurants, and grocery stores. Freon’s role is now being discontinued because of its role in the destruction of the earth’s ozone layer. Icebox (1890) and modern refrigerator Microwave ovens Household appliances in the 20th century have eliminated much of the everyday labor of food preparation. One such innovation fueled by chemical advances was the microwave oven. In 1945, Percy L. Spencer was reportedly standing near an operating radar transmitter at Raytheon when a candy bar in his pocket began to melt. Fascinated, he replicated this experience with popcorn, and the microwave oven was born. His Radarange debuted later that decade in industrial kitchens. Today, World War II-type microwave transmitters, called magnetrons, still form the heart of this popular appliance. Molecule of hypochlorous acid Clean water Advances in chemistry have ensured safe water supplies that are free from bacteria, viruses, and other harmful contaminants. Innovations include using carbons to remove bad taste and odor, other ingredients to soften the water and remove heavy metals, and modern technology for water treatment, supply, and distribution. Chlorine disinfection in water treatment systems was underway by 1910, and household bleach was introduced in 1913. Chlorine-based disinfectants remain an excellent method for protecting kitchens and food-processing facilities from food-borne diseases.