Compositional changes - Copy

Compositional changes - Copy - PLB 172 1 of 10 COMPOSITION...

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PLB 172 1 of 10 COMPOSITION AND COMPOSITIONAL CHANGES Adel A. Kader, Mikal Saltveit Department of Plant Sciences, University of California, Davis 95616 TABLE OF CONTENTS TOPIC Page 1. Introduction ························································· 1 2. Carbohydrates······················································ 2 Sugars, organic acids, polysaccharides, starch 3. Proteins································································ 2 4. Lipids ··································································· 2 5. Vitamins······························································· 2 6. Minerals······························································· 2 7. Pigments ······························································ 2 8. Aroma &flavor····················································· 2 9. References ························································· 10 INTRODUCTION Although all food is made up of the same elemen- tary constituents (e.g., carbon, hydrogen, oxygen, nitrogen, potassium, sulfur, etc.), the atoms they contain are arranged into molecules of diverse size, shape and function. The idea that foods dif- fered in molecular structure developed in the 1830’s as food was found to contain the three ma- jor components of carbohydrates, proteins and fats. Since then, the discovery of minerals, vita- mins, and amino acids have increased to more than 50, the essential nutrients found in food. Edible horticultural commodities are comprised of carbohydrates, proteins, lipids, vitamins, minerals, and characteristic aroma and flavor compounds. Their individual and combined attributes (e.g., color, texture, aroma, taste, etc) contribute to product quality. Animals are incapable of the elementary synthesis performed by plants, and therefore rely on plants for many complex molecules such as vitamin C and essential amino acids. Many foods are con- sumed because of their pleasant aroma, taste, or texture, or because of their presumed medicinal properties. Studies of the various compositional changes in plant organs during their developmental are essen- tial to determining their optimum horticultural (harvest) maturity that would produce the best quality. Such information is also important in relating sensory characteristics to composition of the commodity and in developing means of con- trolling the rate of compositional changes. Quan- tifying differences in compositional changes as influenced by the postharvest environment is im-
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Compositional changes - Copy - PLB 172 1 of 10 COMPOSITION...

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