Benders'dictionary of nutrition and food technology

306metaphysis Growing portion of a long bone, between the epiphysisand the shaft (diaphysis).metaproteins Products of the action of dilute acid or alkali onproteins; they are no longer soluble at their isoelectric points(see isoelectric focusing) but will dissolve in weak acid oralkali.metformin See hypoglycaemic agents.methaemoglobin Oxidised haemoglobin (unlike oxyhaemoglobinin which oxygen is reversibly bound without oxidising theiron); cannot transport oxygen. Present in small quantities innormal blood, increased after certain drugs and after smoking,and in babies after consumption of food or water containingmoderately high levels of nitrates. Rarely occurs as a geneticdisease, methaemoglobinaemia.methaglen (metheglin) A traditional British wine made fromhoney (and thus a form of mead) to which herbs are addedbefore fermentation. Originally for medicinal purposes.methanogens archaea found in rumen flora that producemethane (and hydrogen) as a metabolic end-product.methanol (methyl alcohol, wood alcohol) The first member of thealcohol series, chemically CH 3 —OH. It is a highly toxic substanceand leads to mental disturbance, blindness and death when consumedover a period. See alcohol, denatured.methionine An essential amino acid, abbr Met (M), M r 149.2, pK a2.13, 9.28, codon AUG. One of the three containing sulphur.Cystine and cysteine (the other two sulphur amino acids) arenot essential, but can only be made from methionine, and thereforethe requirement for methionine is lower if there is an adequateintake of cyst(e)ine.Therefore the total sulphur amino acidcontent of foods is generally considered.methionine load test For vitamin b 6 status; measurement ofurinary excretion of homocysteine after a test dose of 3g ofmethionine; the enzyme cystathionine synthetase (EC 4.2.1.22)is pyridoxal phosphate-dependent.methionine sulphoximine Formed by reaction between nitrogentrichloride (agene) and the amino acid methionine when flouris treated with agene as a bleaching agent. Causes running fits indogs, and although it has never been shown to be toxic to humanbeings, the use of agene as a flour improver was abandoned inUK in 1955.Methocel TM Methyl cellulose.méthode champenoise Sparkling wine made by a secondfermentation in the bottle, as for champagne, but outside theChampagne region of north-eastern France.Methofas TM Methyl hydroxypropyl cellulose.