Benders'dictionary of nutrition and food technology

330nicotinamide adenine dinucleotide (phosphate) See nad.nicotinate, sodium Sodium salt of nicotinic acid; has been used,among other purposes, to preserve the red colour in fresh andprocessed meats.nicotinic acid (see p. 329) One of the vitamers of niacin.NIDDK National Institute of Diabetes and Digestive and KidneyDiseases; web site http://www.niddk.nih.gov/.nigella Peppery seeds of the wild onion, Nigella sativa.Nigerian berry See serendipity berry.nigerseed Or nug, Guizotia abyssinica; grown in India andEthiopia as food crop.night blindness Nyctalopia. Inability to see in dim light as a resultof vitamin a deficiency.See also dark adaptation; vision.nim leaf Sweet nim, an aromatic Indian herb with an aromaresembling that of truffles.ninhydrin test For proteins and amino acids (actually for theamino group). Pink, purple or blue colour is developed onheating the amino acid or peptide with ninhydrin (triketohydrindenehydrate).nip The gap between rollers in a mill or a moulding/formingmachine.nisatidine See histamine receptor antagonists.nisin antibiotic isolated from lactic Streptococcus group N;inhibits some but not all Clostridia; not used clinically. The onlyantibiotic permitted in the UK to preserve specified foods. It isnaturally present in cheese, being produced by a number ofstrains of cheese starter organisms. Useful to prolong storage lifeof cheese, milk, cream, soups, canned fruits and vegetables,canned fish and milk puddings. It also lowers the resistance ofmany thermophilic bacteria (see thermophiles) to heat and sopermits a reduction in the time and/or temperature of heatingwhen processing canned vegetables.nitrates The inorganic form of nitrogen used by plants; found insoils and included in inorganic fertiliser. Nitrate is a natural constituentof crops in amounts sometimes depending on the contentin the soil. Also found in drinking water as a result of excessiveuse of fertilisers. Health problems can arise because within a dayor two of harvesting some crop nitrates are converted intonitrites which can react with the haemoglobin (especially fetalhaemoglobin) to form methaemoglobin which cannot transportoxygen. An upper limit of 45–50 mg nitrate/L drinking water hasbeen recommended for infants. Also used, together with nitrite,for curing meat (see meat, curing).See also nitrosamines.