The study, published in Food Hydrocolloids, suggests using fungal or microbial enzymes to link the milk protein beta-casein could change its physical properties, so enhancing its functional characteristics.
“The results demonstrated that enzymatically cross-linked beta-casein was stable under acidic conditions and was more resistant to pepsin digestion when compared to non cross-linked b-casein,” wrote the researchers, led by Dr. Maija-Liisa Mattinen, from VTT Technical Research Centre of Finland.
The authors stated that their findings could have “high impact on the development of novel food structures with improved properties such as good satiety, controlled energy intake and digestibility.”
As appreciation of the mechanisms behind controlling food intake and satiety improve, the potential for developing foods with improved nutrient delivery and controlled energy intake are of high importance, report the researchers.
The structure and properties of proteins can be modified using cross-linking enzymes. With previous research suggesting foods with higher satiety could be produced via enzymatic cross-linking.
Protein cross-linking has also been shown to have several technological advantages including aiding the formation of more stable foams and emulsions.
Milk proteins like beta-casein are rich in nutritional and functional properties, but are also linked withincreasing occurrence of allergies, obesity, and other undesired health effects.
The aim of the new study was to investigate the effects of fungal tyrosinase (TrTyr) and microbial transglutaminase (Tgase) on the cross-linking of beta-casein.
The researchers used tests mimicking gastric conditions to analyze the stability of the cross-linked beta-casein, finding that cross-linking by TrTyr and Tgase decreased digestibility.
“The cross-linked beta-caseins, were found to be resistant to pepsin proteolysis when compared to the digestibility of the native b-casein,” reported the authors.
Composition of digested protein fragments and peptides varied depending on the cross-linking and the digestion reaction conditions used.
For beta-casein cross-linked by Tgase, large protein particles were found remaining in the reaction mixture after digestion.
In the case of beta-casein cross-linked by TrTyr, many small protein fragments remained in the reaction mixture at the end point of the digestion.
“The research results have an impact on the understanding of how food structure can affect digestibility and gastric emptying time and hence the hormone responses of the gut and subsequent food intake,” noted the authors.
The researchers added that their results can be “exploited in tailoring novel food matrices with improved functional properties such as decreased digestibility, controlled energy intake and low allerginicity.”
Source: Food Hydrocolloids
Published online ahead of print, doi: 10.1016/j.foodhyd.2010.05.007
“Effect of enzymatic cross-linking of b-casein on proteolysis by pepsin”
Authors: E. Monogioudi, G. Faccio, M. Lille, K. Poutanen, J. Buchert, M.L. Mattinen