Abstract
A commercial spun soya-bean protein that had been subjected to mild alkali treatment in its manufacture, and the protein isolate from which it had been made, were evaluated in biological and microbiological tests. When diets were givenad lib. in tests with rats, growth was better on the parent protein; but with equal, restricted dietary intakes there was no difference between the two protein sources. The kidneys of all the rats appeared normal on histological examination and showed no signs of nephrocytomegalia, which has been found in the kidneys of rats given soya protein subjected to severe alkali treatment. Similarly in growth tests with chicks, there was no difference between the two proteins and it was concluded that the manufacturing process did not impair the nutritional quality of the spun protein.
In microbiological assay tests withStreptococcus zymogenes, the available methionine of the alkali-treated material was consistently lower by about 20%. But when pronase was substituted for the papain normally used in the assay procedure there was no difference between the preparations; the methionine appeared fully available. The lower values following papain predigestion probably indicated a real though small difference in rate of proteolysis but this was clearly not significant in relation to biological availability for rats and chicks.
Zusammenfassung
Ein kommerzielles versponnenes Sojabohnen-Protein—während der Fabrikation mildalkalisch behandelt—ferner das Protein—Isolat aus dem es hergestellt wurde, wurden biologisch und mikrobiologisch geprüft und bewertet. Bei ad libitum-Fütterung von Ratten war die Wachstumsrate mit dem ursprünglichen Protein grösser, jedoch bei gleicher, eingeschränkter Nahrungsaufnahme, ergab sich zwischen beiden Proteinen kein Unterschied. Die Nieren aller Tiere erschienen bei histologischer Untersuchung normal und zeigten keine Anzeichen von ‘Nephrocytomegalie’ (Nierenzellenvergrösserung), wie es der Fall bei Nieren von Ratten war, die mit Sojaprotein gefüttert wurden, das einer intensiveren Alkalibehandlung ausgesetzt war. Ähnlich gab es bei Wachstumstesten mit Kücken keine Differenzen zwischen den beiden Proteinen. Hieraus ist zu schliessen, dass der angewandte Verarbeitungsprozess die ernährungsphysiologische Qualität des Proteins nicht mindert.
In mikrobiologischen Tests mitStreptococcus zymogenes war der verfügbare Methionin-Gehalt in dem Alkalibehandelten Material beträchtlich geringer, um ca. 20%. Wenn jedoch Pronase anstelle von Papain bei dem Verfahren hinzugefügt wurde, gab es keine Unterschiede zwischen den Präparaten; das Methionin erschien voll verfügbar. Die niedrigeren Werte bei der Papain-Vorverdauung zeigen wahrscheinlich eine reale, wenn auch sehr kleine Differenz in der Proteolysegeschwindigkeit an, was aber im Hinblick auf die biologische Verfügbarkeit für Ratten und Kücken nicht signifikant war.
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Hewitt, D., Ford, J.E. & Porter, J.W.G. Nutritional quality of a spun soya-bean protein: Comparison of biological and microbiological tests. Plant Food Hum Nutr 29, 253–260 (1979). https://doi.org/10.1007/BF02590279
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DOI: https://doi.org/10.1007/BF02590279