Glossary

Category: O

  • Orotic acid

    An intermediate in the biosynthesis of pyrimidines; a growth factor for some microorganisms and at one time called vitamin B13. There is no evidence that it is a human dietary requirement. Metabolic intermediate in the synthesis of prymidines. Uracil-6-carboxylic acid. It is a precursor in the formation of pyrimidine nucleotides.  

  • Ornithine-arginine cycle

    The metabolic pathway for the synthesis of urea.  

  • Organoleptic

    Sensory properties, i.e. those that can be detected by the sense organs. For foods, it is used particularly of the combination of taste, texture, and astringency (perceived in the mouth) and aroma (perceived in the nose). Affecting or making an impression upon an organ. Sometimes used as a synonym for sensory when referring to examination…

  • Orexins

    Two small peptide hormones produced by nerve cells in the lateral hypothalamus, believed to be involved in stimulation of feeding. Neuropeptides produced by the hypothalamus that influence sleep and wakefulness.  

  • Orexigenic

    Stimulating appetite. To a substance that increases appetite.  

  • Opsomania

    Craving for special food.  

  • Oncotic pressure

    That part of plasma osmotic pressure exerted by proteins. The pressure exerted by the plasma proteins on the walls of the vascular system. These proteins are too large to pass through the capillaries, hence this pressure is noted only in the large vessels. Pressure within a blood vessel exerted by the presence of colloid molecules,…

  • Omophagia

    Eating of raw or uncooked food.  

  • Oligosaccharides

    Carbohydrates composed of 3-10 monosaccharide units (with more than 10 units they are termed polysaccharides). Those composed of fructose, galactose or isomaltose have prebiotic action and encourage the growth of beneficial intestinal bacteria. Relatively short molecular chains made up to 10-100 simple sugar (saccharide) units. These sugar (i.e., carbohydrate) chains are frequently attached to protein…

  • Oligopeptides

    Polymers of 4 or more amino acids; more than about 20-50 are termed polypeptides, and more than about 100 are considered to be proteins. A relatively short chain molecule that is made up of amino acids linked by peptide bonds.