Functional yeast protein concentrate

Abstract

The present invention relates to a method for preparing a yeast protein concentrate, said method comprising the lysis of yeast cells in a suspension that was adjusted to a particular pH prior to lysis, subsequently subjecting the soluble fraction obtained from lysis to filtration to reduce the content of molecules smaller than 30 kDa, and optionally drying the solution obtained from filtration. The present invention further relates to a yeast protein concentrate obtainable by the method of the invention. The yeast protein concentrate comprises a high amount of proteins which are still folded and are therefore capable of aggregation to form a solid protein matrix upon heating. In addition, the yeast protein concentrate of the invention will be of unobtrusive taste and is therefore particularly suited for use in the preparation of food items, such as meat substitute products.

1 . Method for preparing a yeast protein concentrate comprising non-denatured yeast protein molecules, said method comprising
 (a) providing a suspension comprising yeast cells;   (b) adjusting the pH of the suspension to a value between 6.5 and 8.5;   (c) lysing the yeast cells by mechanical means;   (d) subjecting the soluble fraction of the lysate to filtration to reduce the content of molecules smaller than 30 kDa; and   (e) optionally, drying the solution obtained from filtration in step (d) to obtain a protein concentrate powder.   
     
     
         2 . Method of  claim 1 , wherein method steps (a)-(d) are performed at a temperature below 40° C. 
     
     
         3 . Method of  claim 1 , wherein the suspension in step (a) has a dry matter content of between about 5-20%. 
     
     
         4 . Method of  claim 1 , wherein the suspension in step (a) is washed with a basic washing buffer prior to cell lysis. 
     
     
         5 . Method of  claim 1 , wherein the content of molecules smaller than 10 kDa is reduced in step (d). 
     
     
         6 . Method of  claim 1 , wherein lysing the yeast cells in step (c) is performed in a bead mill. 
     
     
         7 . Method of  claim 1 , wherein the pH of the lysate is re-adjusted to a value between 6.5 and 8.5 after step (c). 
     
     
         8 . Method of  claim 1 , wherein the protein solution obtained after filtration is sterilized. 
     
     
         9 . Method of  claim 1 , wherein the protein solution obtained after filtration is freeze-dried or spray-dried to provide a powder. 
     
     
         10 . Yeast protein concentrate, such as a Yeast protein concentrate powder, obtainable by a method of  claim 1 . 
     
     
         11 . Yeast protein concentrate, such as a Yeast protein concentrate powder, comprising a mixture of proteins, wherein the folded proteins included in the protein concentrate unfold at a temperature range between 45° C. and 83° C. 
     
     
         12 . Yeast protein concentrate according to  claim 11 , wherein the total amount of free amino acids, dipeptides and tripeptides is less than 20%, more preferably less than 18%. 
     
     
         13 . Yeast protein concentrate according to  claim 11 , wherein at least 40% of the proteins contained in the concentrate powder have an apparent size of more than 5 kDa. 
     
     
         14 . Yeast protein concentrate comprising at least 55% (w/w) total crude protein per dry matter, and wherein at least 40% of the proteins in the concentrate have an apparent size larger than 60 kDa. 
     
     
         15 . Yeast protein concentrate according to  claim 14 , wherein said concentrate comprises at least 60% (w/w), at least 65% (w/w), or at least 70% (w/w) total crude protein per dry matter. 
     
     
         16 . Yeast protein concentrate according to  claim 14 , wherein said concentrate comprises 30% (w/w) or less, preferably 25% (w/w) or less, and more preferably 20% (w/w) or less beta-glucans per dry matter. 
     
     
         17 . Yeast protein concentrate according to  claim 14 , wherein said concentrate comprises at least 40% (w/w), at least 45% (w/w), or at least 50% (w/w) soluble crude protein per dry matter. 
     
     
         18 . Yeast protein concentrate according to  claim 14 , wherein at least 20% (w/w) of the soluble crude protein in the concentrate can be precipitated by heating the concentrate to 90° C. for 10 minutes. 
     
     
         19 . Yeast protein concentrate according to  claim 11 , wherein said concentrate is a liquid having a dry matter content of at least 1%, at least 1.5%, at least 2%, at least 2.5%, at least 3%, at least 3.5%, at least 4%, at least 4.5%, or at least 5%. 
     
     
         20 . Yeast protein concentrate according to  claim 11 , wherein said concentrate is a powder having a dry matter content of at least 90%, at least 92%, at least 94%, or at least 96%. 
     
     
         21 . Method for preparing a protein gel, said method comprising
 (a) providing a yeast protein concentrate powder according to  claim 11 ;   (b) mixing the yeast protein concentrate powder with an aqueous carrier fluid; and   (c) heating the mixture to a temperature of at least 55° C. to provide the protein gel.   
     
     
         22 . (canceled)