The chemical composition and the amount of phenylalanine in 13 types of breakfast cereals produced in Brazil and marketed in São Paulo were studied. All products showed high amounts of carbohydrates, higher than 77%, supplying a minimum of 345 kcal/100g. The protein contents (Nx5.7) ranged from 3.8 to 7.3%. The phenylalanine levels varied between 224 and 451 mg/100g of the products and the lowest levels were detected in cereals with a reduced protein content, corresponding to cereal flakes with high sugar contents. The amino acid analysis revealed that phenylalanine accounted for 5.96±0.12 g/100g recovered amino acids, with no significant statistical differences among the 13 products studied and showed to be independent of the cereal type. It was possible to establish a linear correlation between the micro-Kjeldahl nitrogen and the phenylalanine level of the samples (correl. coeff. 0.9887) and consequently estimate the phenylalanine contents based only on a simple nitrogen analysis and multiplying the protein content by 5.96. The calculated phenylalanine contents in the 13 products did not differ statistically from the data obtained by amino acid analysis.
cereal flakes; chemical composition; phenylalanine
