Bulei Sheng

Ph.d.-studerende

Bulei Sheng

Profil

PhD project: Effect of natural variations in milk proteins on its digestibility

University: Aarhus University

Department: Department of Food Science

Supervisor: Lotte Bach Larsen, Professor, Department of Food Science, AU

Co-supervisor: Nina Aagaard Poulsen, Associate Professor, Department of Food Science, AU

Project term: 01.09.18 – 31.08.2021

Master’s degree: MSc in Saccharide Science and Technology, South China University of Technology, China.

 

Background:

Currently, there is considerable attention towards the effect of intake of bovine milk on human digestion disorders or discomfort. Apart from lactose, milk proteins are key targets of the ongoing discussions. This is both in relation to lactose intolerants, but also in relation to potential effects of milk protein genetic variants. Upon digestion, these variants could potentially result in the generation of different bioactive peptides, and contribute to the complexity of the digestion picture. Different genetic variants have also been found to be glycosylated to varying degree, and both genetic variants and glycosylation degree may affect macromolecular structures in the milk, like organization within the casein micelles. By ingestion, dairy proteins are exposed to a complex array of digestive proteases, and when hydrolyzed the proteins provide a source of peptides with biological functions. Yet, little work has explored how this natural variation, including dietary milk glycoproteins and genetic variants are digested within the gut to release glycopeptides and bioactive peptides.

 

Aim:

The project aims to provide a molecular basis for the understanding of the contribution of natural variation in bovine milk proteins (isoforms, posttranslational and process-induced modifications) to the digestibility of milk proteins, as well as to provide a background for understanding potential diversity in opioid peptide release. By this, we aim to provide a basis for the evaluation of the possibilities of producing milk with enhanced digestibility for humans exploiting the inherent natural variation of bovine milk proteins.

 

Research outline:

Based on the extensive milk bank collected at Department of Food Science, Aarhus University, milk proteins representing different genetic variants and glyco-variants can be isolated and used in model studies, using in vitro (using e.g. porcine digestive enzymes) and ex vivo (using human derived digestive cocktails from stomach and small intestine) digestibility strategies. This is combined with sampling and analysis of milk representing different genetic variants of major milk proteins and milk characteristics of fresh and eventually heat treated milk. Tests of effects of processing, incl heat treatments on both isolated proteins and on intact milk representing different genetic variants will be included. Parameters will include determination of Maillard products and other molecular markers of processing (e.g. lysinoalanine, formation of aggregates etc) in connection with digestability studies of the processed proteins, in model systems and in milk.

 

Partners of collaboration

iFOOD – Aarhus Univeraity Centre for Innovative Food Research 

ID: 131573842