Questions about the value and safety of different categories of food are especially difficult to answer because people have been modifying foods almost since the dawn of civilization. Vprašanja o vrednosti in varnosti različnih vrst hrane, še posebej težko odgovoriti, ker ljudje so bili spreminjanje hrane skoraj od začetka civilizacije. In fact, without certain types of food modification, the human species might never have survived on Earth. Dejstvo je, ne da bi nekatere vrste hrane spremembe, človeške vrste, nikoli ne bi preživela na Zemlji.
By far the most common and oldest type of food modification used by humans is food preservation. Daleč najpogostejša in najstarejša vrsta spremembe hrane, ki jo je hrana ljudi, ohranjanje. Imagine, for instance, a community of early humans in northern Europe trying to survive a long, cold winter with no method for preserving food. Predstavljajte si, na primer, skupnost zgodnjih ljudi v severni Evropi poskuša preživeti dolgo in mrzlo zimo brez metode za konzerviranje živil. Or picture a group of hunters in tropical Africa who have just killed a huge animal that could provide them with meals for weeks. Ali slika je skupina lovcev v tropski Afriki, ki so pravkar ubil veliko žival, ki bi jim lahko posredoval obroke za tednih. In both cases, men and women faced the problem of preserving food that has become available at one time for use at a later time—often, much later. V obeh primerih, moški in ženske se soočajo s problemom konzerviranje živil, ki so postale dostopne naenkrat za uporabo na kasnejši čas, pogosto, mnogo kasneje.
Over the millennia, people have discovered a variety of methods for keeping food from "going bad"—in other words, decaying. V tisočletjih so ljudje odkrili različne metode za vodenje hrano iz "gre slabo", z drugimi besedami, razpada. Cooking, smoking, freezing, and drying were among the earliest food preservation techniques. Kuhanje, kajenje, zamrzovanje in sušenje so bili med prvih tehnik konzerviranja. The use of a broad range of spices, the most important of which was salt, also proved effective as a way of preserving foods. Uporaba številnih začimb, najpomembnejši, ki je bila sol, prav tako izkazali za učinkovite kot način ohranjanja živil.
Although early humans developed a variety of methods for preserving food, it is doubtful that they knew anything about the mechanisms by which such techniques preserved foods; they simply knew that they worked. Čeprav zgodnji ljudje razvili različne metode za konzerviranje hrane, pa dvomim, da so vedele, kaj o mehanizmih, s katerimi te tehnike konzervirane hrane, ki jih preprosto vedeli, da so delali. Deeper understanding did not come about until the 19th century, when researchers such as the French chemist Louis Pasteur (1822-95) and the German bacteriologist Robert Koch (1843-1910) discovered the role of microorganisms in the decay of organic material and the spread of disease. Globlje razumevanje ni prišlo do 19. stoletja, ko so raziskovalci, kot so francoski kemik Louis Pasteur (1822-1895) in nemški bakteriolog Robert Koch (1843-1910) je odkril vlogo mikroorganizmov pri razpadu organskih snovi in širjenje bolezni. These scientists were able to show that certain environmental conditions favored the growth of bacteria (heat and moisture), while others discouraged their survival (cool temperatures and a dry environment). Ti znanstveniki uspeli dokazati, da so nekatere okoljske razmere prednost rast bakterij (toplote in vlage), drugi pa odsvetuje njihovo preživetje (cool temperature in suho okolje).
This information helped explain the success of various food preservation techniques. Ta informacija je pomagal razložiti uspeh različnih tehnik konzerviranja. For example, drying preserves foods because it removes much of the moisture that bacteria need to grow. Na primer, sušenje ohranja hrano, saj odpravlja veliko vlage, ki bakterije potrebujejo za rast. Freezing works because it lowers the temperature of food to the point that the growth of bacteria is severely inhibited. Zamrzovanje deluje, saj znižuje temperaturo hrane do te mere, da bo rast bakterije je močno inhibirana. Spices are effective for a variety of reasons, one being that they may release chemical compounds that are toxic to bacteria; cloves, for example, release a compound called eugenol that slows the growth of bacteria. Začimbe so učinkoviti pri različnih razlogov, eden je, da lahko sproščajo kemične spojine, ki so strupeni za bakterije, nageljnove žbice, na primer, javnost spojino imenovano eugenol, ki zavira rast bakterij. And smoking food preserves it because smoke, like spices, contains a number of chemicals that inhibit the growth of bacteria. In kajenje hrane jo ohranja zaradi dima, kot so začimbe, vsebuje številne kemikalije, ki zavirajo rast bakterij. One of the most widely used of modern synthetic preservatives, butylated hy-droxyanisole (BHA), is a natural component of smoke. Ena izmed najbolj razširjenih sodobnih sintetičnih konzervansov, butil HY-droxyanisole (BHA) je naravna sestavina dima.
Introduction Predstavitev 
The History Of Food Modification Pretekle spremembe hrane 
Food Additives Aditivi za živila 
Synthetic Foods Sintetična Živila Genetically Modified Foods Gensko spremenjena hrana Food-Borne Illnesses And Irradiation Of Foods Hrana, ki se prenašajo bolezni in obsevanje živil Organic And Natural Foods Organske in naravne Živila 
