Benders'dictionary of nutrition and food technology

409renal threshold Concentration of a compound in the blood abovewhich it is not reabsorbed in the kidney, and so is excreted in theurine.rendering Liberation of fat from adipose tissue. Dry rendering,heating the fat dry; wet rendering may use steam or hot water,either in open vessels or sealed under a pressure of 280–490 kPa(40–70psi).renin Proteolytic enzyme (angiotensin-forming enzyme,angiotensinogenase, EC 3.4.23.15) secreted by the kidney; specificfor the leucine–leucine bond in angiotensinogen, yieldingangiotensin i.This is then cleaved to yield active angiotensin IIby the angiotensin converting enzyme (ace, EC 3.4.15.1), a peptidasein the blood vessels of the lungs and other tissues.rennet Extract of calf stomach; contains the enzyme chymosin(rennin) which clots milk. Used in cheese-making and forjunket.rennet, fungal A mixture of proteolytic enzymes from Mucorpusillus, M. michei and Endothia parasitica, used as substitutesfor rennet.rennet, vegetable The name given to proteolytic enzymes derivedfrom plants, such as bromelain (from the pineapple) and ficin(from the fig), as well as biosynthetic chymosin. Used for thepreparation of vegetarian cheeses.rennin See chymosin.rentschlerising Sterilising by treatment with ultraviolet light,named after Dr H.C. Rentschler, who developed the lamp.reovirus One of a small group of RNA-containing viruses thatinfect the intestinal and respiratory tracts without causing specificor serious disease.See also echovirus; enterovirus.REPFED Ready to eat products for extended durability, orrefrigerated pasteurised foods for extended durability.reporter gene A readily detectable gene (e.g. that for β-glucuronidase, firefly luciferase or green fluorescent protein)transferred into a transgenic organism together with the geneof interest, to permit ready identification of those cells in whichthe gene transfer has been achieved. Unlike a marker gene, itdoes not confer a survival advantage on the transfected cellsunder laboratory conditions, but leads to the expression of areadily measured protein.repression Inhibition of gene expression leading to a decrease inthe rate of synthesis of a protein.See also induction.resazurin test See methylene blue dye-reduction test.resins, ion-exchange See ion-exchange resins.