Dr.Badruddin Khan asked:
Most foods contain enzymes or natural chemicals, such as acids or alcohols that cause them to begin to lose desirable characteristics almost immediately after harvest or preparation. In addition, a host of environmental factors, such as heat and the presence of microorganisms, acts to change foodstuffs in ways that may harm the food product. Food preservation traditionally has three goals: the preservation of nutritional characteristics, the preservation of appearance, and a prolongation of the time that the food can be stored. Traditional methods of preservation usually aim to exclude air, moisture, and microorganisms, or to provide environments in which organisms that might cause spoilage cannot survive.
Ancient peoples are known to have had dried fruits, vegetables, and meats. The pemmican of Native Americans and the jerky consumed by present-day campers and hikers are both prepared by drying. The drying process can include smoking, which may actually add antibacterial agents. The processes of dehydration and freeze-drying, used today to produce such foods as powdered coffee and soup, are variations of drying. Among the earliest preservatives were sugar and salt (NaCl), which produced food environments of high osmotic pressure that denied bacteria the aqueous surroundings they needed to live and reproduce. Jams and jellies are preserved as solutions of high sugar content, and many meats (e.g., hams) and fish are still preserved by salting. Unlike other microorganisms, molds can often withstand the effects of high salt or sugar concentrations in foods. Fortunately, they seldom cause illness.
Early methods of air removal included the sealing of foods inside containers (such as jars), or the covering of food surfaces with hot paraffin. The invention of canning by Nicolas Appert enabled commercial preparations of foodstuffs. In response to a prize offered by Napoleon in 1795, Appert developed a method of canning and preserving fruits and vegetables in glass containers for sea voyages. His process was used commercially in 1910 by Peter Durand in England, using metal cans. During the earliest days of canning, some persons (including some Arctic explorers) probably died as a result of exposure to the lead that was once used to solder cans. Modern techniques of air removal include vacuum sealing and the use of plastic wrappings.
Along with cooking that kills most bacteria, freezing stops or slows bacterial growth and changes in foods brought about by enzymes present in the foods. Unlike the slower freezing of foods in homes, quick freezing in commercial processing enables foods to retain more of their natural appearance and taste. Chemical preservatives include free radical scavengers (also known as antioxidants), such as vitamin C and compounds such as BHA (butylated hydroxyanisole), and bacterial growth inhibitors, such as benzoic acid, sulfur dioxide, and sodium nitrite (NaNO2 ). Ethanol (CH3 CH 2 OH) has long been used as a preservative, both of itself (as in wine), and of other foods (e.g., fruits stored in brandy). Some chemical preservatives may be harmful: Sulfur dioxide (often used to preserve wines) is irritating to the bronchial tubes of persons who have asthma, and nitrites have been implicated as carcinogens.
After Louis Pasteur proved that it was the presence of bacteria that caused food to spoil, there was a tendency to consider all microorganisms harmful. But in fact, microbial action is responsible for the production and preservation of some foods. The action of microbes is a part of the production of cheese and some flavoring agents. Sauerkraut is both processed and preserved by lactobacilli, and yeast cells ferment sugars, producing alcohol, which may add zest to beverages as well as help to preserve them. Nitrates are a common preservative in luncheon meats.
The irradiation of foods has the advantage of enabling food packaging and preparation in which there is less person-to-food contact, thus decreasing the possibility of contamination and decreasing the need for chemical preservatives, some of which may be harmful. The ionizing radiation that is used to irradiate foods, wherein the foods are exposed to bursts of high-intensity x rays or streams of electrons, disrupts bacterial DNA. Some persons have objected to the irradiation of foods because of an (unfounded) fear of radioactivity. As pathogens such as virulent strains of coliform bacteria have caused food poisoning, the irradiation of animal carcasses and, in particular, of hamburger during its preparation has become more desirable. Irradiation currently extends the shelf lives of foods such as strawberries. Irradiation does not make foods radioactive, but may cause changes in food color or texture.
Ascorbic Acid
Ascorbic acid or vitamin C is an antiscorbutic agent. Scurvy is a disease that potentially ranks as the second most important nutritional deficiency, after protein-calorie malnutrition. Scurvy, once common in among sailors, causes bleeding and inflamed gums, loose teeth, poor wound healing, pain in the joints, muscle wasting, etc. The structure of vitamin C is simple, resembling a monosaccharide, and most animals are able to synthesize ascorbic acid. Only primates, guinea pigs, and some fruit bats have lost the ability to synthesize it. Vitamins are organic molecules that mainly function as catalysts for reactions in the body.
Vitamin C is water-soluble and very important to all humans because it is vital to the production of collagen. Inside the cell, it helps form a precursor molecule called “procollagen” that is later packaged and modified into collagen outside the cell. Collagen is a glue-like substance that binds cells together to form tissues. It is the most abundant of the fibers contained in connective tissues. Connective tissue gives the human body form and supports its organs.
Vitamin C is also important as it helps protect the fat-soluble vitamins A and E, as well as fatty acids from oxidation. It is therefore a reducing agent and scavenger of radicals (sink of radicals). Radicals, molecules with unpaired electrons, are very harmful to the body as a result of their high reactivity, which may induce mutations and possibly cancer. Vitamin C, being an excellent source of electrons, can therefore donate electrons to free radicals such as hydroxyl and superoxide and quench their reactivity.
A debate exists over the anticancer properties of vitamin C. However, current evidence suggests that the major benefit of ascorbic acid with regard to cancer may be in reducing the risk of developing cancer, rather than in therapy. Vitamin C can work inside the cells to protect DNA (deoxyribonucleic acid), the hereditary material in cells, from the damage caused by free radicals. Also, it can reduce the development of nitrosamines (amines linked to the NO group) from nitrates, chemicals that are commonly used in processed foods. Once formed, nitrosamine can become carcinogenic (cancer-causing).
Sources of vitamin C are numerous: citrus fruits such as oranges, limes, and grapefruits and vegetables including tomatoes, green peppers, potatoes, and many others. The recommended dietary allowance (RDA) of vitamin C is 60 milligrams per day. Some studies suggest higher daily doses especially for the elderly, women, and the infirm. For example, the late Linus Pauling, best known for his theory on chemical bonding and a two-time Nobel Prize winner, consumed several grams of vitamin C per day for the last forty years of his life and lived to age ninety-three.
Caffeinated Content
Most foods contain enzymes or natural chemicals, such as acids or alcohols that cause them to begin to lose desirable characteristics almost immediately after harvest or preparation. In addition, a host of environmental factors, such as heat and the presence of microorganisms, acts to change foodstuffs in ways that may harm the food product. Food preservation traditionally has three goals: the preservation of nutritional characteristics, the preservation of appearance, and a prolongation of the time that the food can be stored. Traditional methods of preservation usually aim to exclude air, moisture, and microorganisms, or to provide environments in which organisms that might cause spoilage cannot survive.
Ancient peoples are known to have had dried fruits, vegetables, and meats. The pemmican of Native Americans and the jerky consumed by present-day campers and hikers are both prepared by drying. The drying process can include smoking, which may actually add antibacterial agents. The processes of dehydration and freeze-drying, used today to produce such foods as powdered coffee and soup, are variations of drying. Among the earliest preservatives were sugar and salt (NaCl), which produced food environments of high osmotic pressure that denied bacteria the aqueous surroundings they needed to live and reproduce. Jams and jellies are preserved as solutions of high sugar content, and many meats (e.g., hams) and fish are still preserved by salting. Unlike other microorganisms, molds can often withstand the effects of high salt or sugar concentrations in foods. Fortunately, they seldom cause illness.
Early methods of air removal included the sealing of foods inside containers (such as jars), or the covering of food surfaces with hot paraffin. The invention of canning by Nicolas Appert enabled commercial preparations of foodstuffs. In response to a prize offered by Napoleon in 1795, Appert developed a method of canning and preserving fruits and vegetables in glass containers for sea voyages. His process was used commercially in 1910 by Peter Durand in England, using metal cans. During the earliest days of canning, some persons (including some Arctic explorers) probably died as a result of exposure to the lead that was once used to solder cans. Modern techniques of air removal include vacuum sealing and the use of plastic wrappings.
Along with cooking that kills most bacteria, freezing stops or slows bacterial growth and changes in foods brought about by enzymes present in the foods. Unlike the slower freezing of foods in homes, quick freezing in commercial processing enables foods to retain more of their natural appearance and taste. Chemical preservatives include free radical scavengers (also known as antioxidants), such as vitamin C and compounds such as BHA (butylated hydroxyanisole), and bacterial growth inhibitors, such as benzoic acid, sulfur dioxide, and sodium nitrite (NaNO2 ). Ethanol (CH3 CH 2 OH) has long been used as a preservative, both of itself (as in wine), and of other foods (e.g., fruits stored in brandy). Some chemical preservatives may be harmful: Sulfur dioxide (often used to preserve wines) is irritating to the bronchial tubes of persons who have asthma, and nitrites have been implicated as carcinogens.
After Louis Pasteur proved that it was the presence of bacteria that caused food to spoil, there was a tendency to consider all microorganisms harmful. But in fact, microbial action is responsible for the production and preservation of some foods. The action of microbes is a part of the production of cheese and some flavoring agents. Sauerkraut is both processed and preserved by lactobacilli, and yeast cells ferment sugars, producing alcohol, which may add zest to beverages as well as help to preserve them. Nitrates are a common preservative in luncheon meats.
The irradiation of foods has the advantage of enabling food packaging and preparation in which there is less person-to-food contact, thus decreasing the possibility of contamination and decreasing the need for chemical preservatives, some of which may be harmful. The ionizing radiation that is used to irradiate foods, wherein the foods are exposed to bursts of high-intensity x rays or streams of electrons, disrupts bacterial DNA. Some persons have objected to the irradiation of foods because of an (unfounded) fear of radioactivity. As pathogens such as virulent strains of coliform bacteria have caused food poisoning, the irradiation of animal carcasses and, in particular, of hamburger during its preparation has become more desirable. Irradiation currently extends the shelf lives of foods such as strawberries. Irradiation does not make foods radioactive, but may cause changes in food color or texture.
Ascorbic Acid
Ascorbic acid or vitamin C is an antiscorbutic agent. Scurvy is a disease that potentially ranks as the second most important nutritional deficiency, after protein-calorie malnutrition. Scurvy, once common in among sailors, causes bleeding and inflamed gums, loose teeth, poor wound healing, pain in the joints, muscle wasting, etc. The structure of vitamin C is simple, resembling a monosaccharide, and most animals are able to synthesize ascorbic acid. Only primates, guinea pigs, and some fruit bats have lost the ability to synthesize it. Vitamins are organic molecules that mainly function as catalysts for reactions in the body.
Vitamin C is water-soluble and very important to all humans because it is vital to the production of collagen. Inside the cell, it helps form a precursor molecule called “procollagen” that is later packaged and modified into collagen outside the cell. Collagen is a glue-like substance that binds cells together to form tissues. It is the most abundant of the fibers contained in connective tissues. Connective tissue gives the human body form and supports its organs.
Vitamin C is also important as it helps protect the fat-soluble vitamins A and E, as well as fatty acids from oxidation. It is therefore a reducing agent and scavenger of radicals (sink of radicals). Radicals, molecules with unpaired electrons, are very harmful to the body as a result of their high reactivity, which may induce mutations and possibly cancer. Vitamin C, being an excellent source of electrons, can therefore donate electrons to free radicals such as hydroxyl and superoxide and quench their reactivity.
A debate exists over the anticancer properties of vitamin C. However, current evidence suggests that the major benefit of ascorbic acid with regard to cancer may be in reducing the risk of developing cancer, rather than in therapy. Vitamin C can work inside the cells to protect DNA (deoxyribonucleic acid), the hereditary material in cells, from the damage caused by free radicals. Also, it can reduce the development of nitrosamines (amines linked to the NO group) from nitrates, chemicals that are commonly used in processed foods. Once formed, nitrosamine can become carcinogenic (cancer-causing).
Sources of vitamin C are numerous: citrus fruits such as oranges, limes, and grapefruits and vegetables including tomatoes, green peppers, potatoes, and many others. The recommended dietary allowance (RDA) of vitamin C is 60 milligrams per day. Some studies suggest higher daily doses especially for the elderly, women, and the infirm. For example, the late Linus Pauling, best known for his theory on chemical bonding and a two-time Nobel Prize winner, consumed several grams of vitamin C per day for the last forty years of his life and lived to age ninety-three.
Caffeinated Content
