Non-protein nitrogen in infant cereals affected by industrial processing

Abstract

The effects of industrial processing on non-protein content in four varieties of infant cereals, so-called `Multicereal' and `Wheat' as gluten infant cereals, and `Growth' and `Rice and carrot' as gluten-free infant cereals were determined. Samples were classified according to their industrial stage of treatment: (1) mixture of raw flours; (2) mixture of roasted flours; (3) mixture of enzymatically hydrolysed and drum-dried flours (film); (4) commercial infant cereals. Total nitrogen (TN), protein nitrogen (PN) and non-protein nitrogen (NPN) contents were higher in gluten infant cereals than in gluten-free infant cereals. NPN content was always higher than PN content in all cereals. Industrial processing led to a significant increase in NPN ( P<0.01) and free amino acid contents ( P<0.001), whereas TN and PN contents decreased significantly ( P<0.05). Although non-amino acid nitrogen components remained stable with the industrial processing, a high content of ammonium was found in gluten-free infant cereals as a consequence of taurine and asparagine degradation.