Development of an in vitro assay to adequately assess plant protein digestibility

摘要

Background/Aims: Plant protein digestibility is affected by the presence ofstarch and the plant cell wall (PCW) as well as physiological changesduring upper gastrointestinal (GI) digestion. Hsu’s (1977) multi-enzymemethod is commonly used to assess plant protein digestibility. However, itdoes not take into consideration the physiological changes that occurduring oral and upper GI digestion phases, and therefore may simplifyplant protein digestibility. This study aims to develop an in vitro plantprotein digestibility assay that represents human digestion adequately bytaking into consideration the presence of starch and the physiologicalchanges that occur in the oral cavity to the small intestine (SI).Methods: Sorghum was used to assess differences in protein digestionbetween the multi-enzyme method and the proposed enhanced in vitroassay. Released protein and peptides were characterised by protein contentdetermination and sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE) analysis.Results: Taking into account the changes that occur with oral and SIdigestion improved sorghum protein digestibility to ~25%. Polymericproteins were able to be further hydrolysed to oligomers and monomersduring SI digestion, demonstrating improved digestion.Conclusions: The increased protein digestibility by including an oralprocessing indicates that physical breakdown of the PCW and starch isimportant in enhancing protein digestibility and absorption in the SI. Thisnew enhanced method may be more accurate in determining plant proteindigestibility than the commonly used multi-enzyme assay as it takes intoconsideration bioaccessibility and physiological considerations.