The estimation of ?available lysine? in human foods by three chemical procedures

Abstract

Seventeen test foods were each analyzed by four methods. Total lysine was measured by conventional amino acid analysis. Reactive lysine was measured with either fluorodinitrobenzene, o-phthalaldehyde or a differential dye-binding procedure. The results were then compared with another group's results from rat growth assays of the same samples for availably lysine. A sample of deliberately heat-damaged milk powder gave a rat assay value corresponding to 64% of its total lysine content; other values were all higher and on average 99% for 7 animal products, and 87% for 9 vegetable products. The correlation coefficient between the two sets of values was 0.95. The 'reactive lysine' procedures failed to give a better prediction of the rat values.

Farinha integral de trigo germinado: 3. Características nutricionais e estabilidade ao armazenamento

“…Contudo, TAVERNER & FARREL [31,32] encontraram para trigo valores de lisina disponível na faixa de 0,79 a 0,94%. CARPENTER et al [6] encontraram para o grão de trigo 2,23 a 2,57g de lisina disponível/ 16g de N (100g de proteína).…”

“…É uma alternativa adequada para diminuição de fatores antinutricionais, como os fitatos, inibidores da protease e taninos, presentes originalmente nestes grãos. Além de converter proteínas vegetais de baixa qualidade nutricional em proteínas de melhor qualidade, também provoca mudanças na composição centesimal, aumento nos teores de certos aminoácidos essenciais e vitaminas do complexo B, degradação parcial de proteínas e amido e melhora na digestibilidade [6].…”

Fluorometric determination of chemically available lysine: Adaptation, validation and application to different milk products

“…Different chemical methods (guanidation, reduction with sodium borhydride, fluorodinitrobenzene direct method and indirect difference method, dye-binding lysine) have been compared [8,20,21], the conclusion being that the determination of furosine and the Carpenter method (1960) are the most appropriate for estimating reactive lysine in milk. However, direct application of the spectrophotometric Carpenter method (1960) to foods having high carbohydrate or reducing sugar contents is not possible, because interfering compounds can be formed with the subsequent overestimation of reactive lysine.…”

Development of a novel bioassay for determining the available lysine contents of foods and feedstuffs

“…The most wellknown method is the FDNB method 60 which uses the Sanger reaction to convert lysine to dinitrophenyl-lysine which is extracted and measured spectrophotometrically or by HPLC. This method has been applied to animal feedstuffs 34,57 , breakfast cereals 24,25,31,61 , meat 61,62 and milk 61 . However, the method underestimates the reactive lysine content of foods since some of the dinitrophenyllysine may be destroyed during the acid-hydrolysis step used to liberate the dinitrophenyl-lysine from the protein 63 , necessitating the use of correction factors.…”