Benders'dictionary of nutrition and food technology

355PAR See physical activity ratio.para-amino benzoic acid (PABA) Essential growth factor formicro-organisms. It forms part of the molecule of folic acid andis therefore required for the synthesis of this vitamin. Mammalscannot synthesise folic acid, and PABA has no other knownfunction; there is no evidence that it is a human dietary requirement.Sulphanilamides (sulpha drugs) are chemical analoguesof PABA, and exert their antibacterial action by antagonisingPABA utilisation.parabens Methyl, ethyl and propyl esters of p-hydroxybenzoicacid used together with their sodium salts as antimicrobials infood (E-214–219). Effective over a wide range of pH; more effectiveagainst moulds and yeast than against bacteria.paracasein Obsolete name for precipitated milk casein.paracrine Production by a cell of locally acting hormone-like substancesthat act on nearby cells.See also autocrine; endocrine glands.paraffin, medicinal (liquid) See medicinal paraffin.Paraflow TM A plate heat exchanger used for pasteurising liquids.parageusia Abnormality of the sense of taste.See also dysgeusia; gustin; hypogeusia.parakeratosis Disease of swine characterised by cessation ofgrowth, erythema, seborrhoea and hyperkeratosis of the skin;due to zinc deficiency and possibly to changes in essential fattyacid metabolism.paralactic acid See sarcolactic acid.paralytic shellfish poisoning Caused by shellfish that have accumulatedtoxins from the dinoflagellate plankton, Gonyaulax spp.parasol mushroom Macrolepiota procera, see mushrooms.paratha Indian; wholewheat unleavened bread.parathormone Commonly used as an abbreviation for theparathyroid hormone; correctly a trade name for a pharmaceuticalpreparation of the hormone.parathyroid hormone Hormone secreted by the four parathyroidglands (in the neck near the thyroid gland). The hormoneis secreted in response to a fall in plasma calcium, and actson the kidney to increase the formation of the active metaboliteof vitamin d (calcitriol), leading to an increase in plasmacalcium by increasing intestinal absorption and mobilising themineral from bones. It also reduces urinary excretion ofphosphate.paratyphoid See typhoid.parboil Partially cook. Of special interest in nutrition is the parboilingof brown rice, steaming rice in the husk before milling.The water-soluble vitamins diffuse from the husk into the grain;