tailieunhanh - THE CHEMISTRY OF MILK

The chosen gait of the one-humped camel on free range is a leisurely but almost a continuous walk. When walking the camel covers about 4 km/hour. They have often been tracked to cover 50 km during a day’s feeding, but 30 km is very common. Very young camels exhibit vigorous, spontaneous play, including some running and jumping. By 2 to 3 weeks age they are involved in playgroups similar to those formed by lambs, kids and buffalo/cow calves. These groups remain almost together between feeds. Mature camels will hasten towards a feed supply, usually at a jog, but. | The chemistry of milk The principal constituents of milk are water fat proteins lactose milk sugar and minerals salts . Milk also contains trace amounts of other substances such as pigments enzymes vitamins phospholipids substances with fatlike properties and gases. The residue left when water and gases are removed is called the dry matter DM or total solids content of the milk. Milk is a very complex product. In order to describe the various constituents of milk and how they are affected by the various stages of treatment in the dairy it is necessary to resort to chemical terminology. This chapter on the chemistry of milk therefore begins with a brief review of some basic chemical concepts. Dairy Processing Handbook chapter 2 13 Chemical symbols of some common elements in organic matter C Carbon Cl Chlorine H Hydrogen I Iodine K Potassium N Nitrogen Na Sodium O Oxygen P Phosphorus S Sulphur Fig. The nucleus of the atom consists of protons and neutrons. Electrons orbit the nucleus. . _ Diameter 1 . ---- ------ 1 Atomic nucleus Electron Diameter 10 000 Fig The nucleus is so small in relation to the atom that if it were enlarged to the size of a tennis ball the outer electron shell would be 325 metres from the centre. Basic chemical concepts Atoms The atom is the smallest building block of all matter in nature and cannot be divided chemically. A substance in which all the atoms are of the same kind is called an element. More than 100 elements are known today. Examples are oxygen carbon copper hydrogen and iron. However most naturally occurring substances are composed of several different elements. Air for example is a mixture of oxygen nitrogen carbon dioxide and rare gases while water is a chemical compound of the elements hydrogen and oxygen. The nucleus of the atom consists of protons and neutrons figure . The protons carry a positive unit charge while the neutrons are electrically neutral. The electrons which orbit the nucleus carry a negative charge .