Pasta brownness: An assessment

Pasta colour is an essential factor in assessing pasta quality. It results from a desirable yellow component, an undesirable brown component and, unde r some drying conditions. a red component. The cause of pasta brownness is complex and its biochemical and technological basis is still a matter of co ntroversy. This paper is a comprehensive review of the literature data in t he light of results which have been recently obtained in our laboratory. Pa sta brightness (L) is an indicator of the attenuation of the light reflecte d by pasta samples. Brownness is usually defined as 100-L, and brownish pas ta is characterised by a low L value and a dominant wavelength in the 578 n m region. The contributions of cultivar and location to the variance of L a re about 15% and 65%, respectively. Within the same cultivar, L decreases w hen the protein and ash contents increase but the basis of these relations ari not known. Pasta brownness is the result of an inherent brownness of th e endosperm (the dominant parameter in the case of semolina scarcely contam inated by the peripheral parts of the grain), of the degree of purity of th e semolina and of Maillard reactions when pasta are dried at high temperatu re. Inherent brownness of semolina could be due to a water-soluble copper p rotein (Matsuo's brown protein) and/or to the action of oxidising enzymes w hich would take place during grain maturation. The brown colour of spaghett i increases sharply with the ash content of the milling streams. Whether su ch brownness results from the inherent brownness of milling streams or from the action of polyphenol oxidase is not known. Kneading and extrusion of p asta have no significant effect on brownness. The formation of brown 'melan oidin' pigments due to the development of Maillard reactions is related to the reducing-sugar content of pasta and the drying parameters. Recommendati ons for future research are given, which include further genetic and physic ochemical investigations of Matsuo's brown protein, the evolution of polyph enoloxidase activity during durum wheat grain maturation and the relationsh ip between pasta brownness and the PPO activity of milling streams. (C) 200 0 Academic Press.