Bread cereals and crackers are normally kept in closed containers at room temperature. Cereals like other foods made from grains, should be stored in a dark place because they will lose riboflavin if they are exposed to light. Yeast breads will keep for a few days if wrapped in plastic or foil and stored in a cool dark place, such as a bread box. In hot weather refrigeration may be required to prevent mold. Unshelled nuts can be kept at room temperature for 3 to 6 months; shelled nuts may become rancid unless frozen. Discard any that smells musty or moldy. Baking powder generally lasts 12 to 18 months. Baking soda should be stored tightly covered in a dry place I f using as a odor catcher, change it four times a year.
Grains, flours, and other foods packed in materials easily penetrated by insects for example, cardboard boxes, paper bags, and cellophane packages should be transferred to plastic, metal or glass containers with tight fitting lids. Under normal storage conditions, the shelf life of wheat flour is about one year from the time it is milled. Flour can be frozen for long term storage if carefully wrapped in moisture and vapor proof material. Whole grain flour spoil within a few weeks because their fats turn rancid. Storing them in freezer extends their life. Cake mixes last about one year at room temperature, after which the quality starts to decline.
Adolescents need more of everything to keep up with the massive teenage growth sprut: calories and protein for growth and to build muscles; and protein calcium and phosphorus, and vitamin D for bone formation. For many the demands of school and social life mean that they eat meals away from home; suddenly they are responsible for choosing the major part of their diet. Some may not make the best choices. Others may use the foods to establish an identity, such as becoming a vegetarian, without knowing how to maintain proper nutrition. Both obesity and eating disorders can plague adolescents. A sensitive approach is necessary in order to help an adolescent maintain a positive self image and professional help may be necessary.
Water is essential to virtually every body function, including digestion, absorption, and transport of nutrients, elimination of body waste and regulation of body temperature, as well as many other chemical processes. It provides a proactive cushion for body cells, and in the form of amniotic protects a developing fetus. Water is needed to build all body tissues and is the base of all body and fluid secretions such as tears, saliva and gastric juices as well as the fluids that lubricate our organs and joints. It also keeps our skin soft and smooth. As our body ages, it becomes dryer. The body of a new born infant is 75 to 80 percent water compared to 50 percent after 65 to 70. The drying out is reflected in the wrinkled skin, stiffened joints that occur naturally with aging.
The liver located in the upper right abdomen and protected by its ribs, performs thousands of vital chemical and metabolic functions among them ,the storage of fat soluble vitamins, iron and other minerals , and glycogen for future needs. It manufactures cholesterol, amino acids and other essential compounds, removes waste substances from the blood, detoxifies alcohol and environmental chemicals and metabolizes most medications. Amazingly our bodies can still function when only one quarter of the liver is healthy enough to operate. Unlike most other organs even after severe damage, the liver can regenerate itself by growing new cells. When severely diseased or subjected to excessive abuse, however the liver will fail, often with fatal results.
Foods of animal origin are the most susceptible to contamination. The muscles of healthy animals are free of bacteria, but they provide a rich culture medium for the growth of bacteria picked up in handling and processing. The skin prevents bacteria from penetrating the flesh of a living animal, but microorganisms can be transferred from the skin to the muscle when the carcass is cut up. Meats that are dressed with skin, such as poultry, are the most prone to spoilage because bacteria remain on the skin despite thorough washing after slaughter. We need to be careful while handling meat, fish, shell fish and especially poultry.
One of our most popular and versatile foods, cheese is used for everything from snacks and appetizers to main courses and deserts. Its an ancient food that can be made from the milk of almost any animal namely cow, sheep, goats, yaks, and camels. Most cheese are made by adding a mixture of enzymes, known as rennet, to milk to curdle it. The main enzyme in rennet ehich traditionaly has been isolated from the stomach lining of calves, is chymosin. Today it can also be produced by inserting the gene that codes for its production into bacteria. This allows for a more ready production of chymosin and can also cater to consumers who do not favor to the idea of an animal extract in their cheese.
Some 10,000 substances make their way into food during growing, processing and packaging. some of these accidental additives can pose more of a health threat than preservatives and other direct additives. Some foods for example contain traces of pesticides sprayed on crops or applied to the soil. Environmental pollutants in food such as PCB’s, mercury and lead are harmful when ingested with large quantities.
Sometimes allergic reactions that are blamed on foods or additives are actually triggered by an unintended one. For example a person who has never had a food allergy may inexplicably develop a rash after drinking milk. Allergists have traced the symptoms in some cases to penicillin used to treat mastitis in cows. The resulting small amounts of penicillin in the milk would not be harmful for most people, only to those who are allergic to the drug.
Additives can be safe even though they sound to be distasteful. Shellac for example resinous secretion of the female Indian lac bug is often referred to in trade as confectioner’s glaze. It can be used to give protective glossy coating to candies, jelly beans and ice cream cones. Since it is insoluble in water, it can prevent the food product from drying out by forming a moisture impermeable layer. That’s the reason citrus fruits and avocados are sometimes treated with shellac. The substance has long been used as a food additive without any problem and animal tests have shown no adverse reactions.
In all the food processors may use any of about 2800 additives although many people question the safety of these additives, the fact is that their use is governed by stringent regulations. Authorities require extensive studies before an additive is allowed on the market. In spite of this rare reductions to certain additives are possible. The appropriate use of additives, though, allows us to enjoy history’s safest and most abundant assortment of foods. The most common food additives are sugar, corn syrup and other sweeteners and salt. they are used both to enhance flavor and to retard spoilage. Other additives offer their unique health benefits.