Method for optimising the production efficiency, organoleptic quality and stability over time of a protein-rich microalgae biomass

Abstract

The present invention relates to a method for optimising the downstream processing of a protein-rich microalgac biomass of the Chlorella genus previously prepared by fermentation in heterotrophic conditions and in the absence of light, comprising: 1) providing biomass comprising more than 50% protein by dry weight of biomass; next, at low temperature, carrying out the following steps: 2) harvesting the biomass at the end of fermentation, 3) washing and concentrating the biomass, 4) optionally, lysing the biomass, next, without low temperature stress, 5) optionally, concentrating the biomass slurry, 6) applying heat treatment, 7) drying the biomass obtained in this way in order to obtain the product, a step of adjusting the pH to 7 being applied before or after the heat treatment step 6).

1 - 10  (canceled). 
     
     
         11 . A method for optimizing the downstream processing of a protein-rich biomass of microalgae of the  Chlorella  genus which has been prepared beforehand by fermentation in heterotrophic conditions and in the absence of light, comprising:
 1) providing a biomass comprising more than 50% proteins by dry weight of biomass;   then, at low temperature:   2) recovering the biomass at the end of fermentation,   3) washing and concentrating the biomass,   4) optionally lysing the biomass,   then, with no low temperature constraints:   5) optionally concentrating the biomass suspension,   6) applying a heat treatment, and   7) drying the resulting biomass to obtain the product,   a step of adjusting the pH to  7  being applied before or after step  6 ) of heat treatment.   
     
     
         12 . The method as claimed in  claim 11 , characterized in that the protein comprises more than 60% by dry weight of the biomass. 
     
     
         13 . The method as claimed in  claim 11 , characterized in that the heat treatment is a high temperature/short time (HTST) heat treatment for 30 seconds to 5 minutes at a temperature lower than 100° C. 
     
     
         14 . The method as claimed in  claim 11 , characterized in that the heat treatment is an ultra-high temperature (UHT) heat treatment at a temperature of between 100° C. and 150° C. for 5 to 30 seconds. 
     
     
         15 . The method as claimed in  claim 11 , characterized in that the biomass is washed with at most 6 volumes of water per 1 volume of biomass. 
     
     
         16 . The method as claimed in  claim 11 , characterized in that the biomass suspension is neutralized to pH 7 by adding KOH or NaOH. 
     
     
         17 . The method as claimed in  claim 11 , characterized in that the cells of the biomass are lysed by milling. 
     
     
         18 . The method as claimed in  claim 11 , characterized in that the biomass is concentrated by centrifugation or evaporation. 
     
     
         19 . The method as claimed in  claim 11 , characterized in that the effects of the steps of processing the microalgal biomass on the quality of the product are also determined by one or more of the following parameters:
 measuring the dry cell weight in the biomass;   measuring the sugar content;   determining the amount of proteins;   analyzing the volatile organic compounds;   measuring enzyme activities, in particular lipoxygenase activity;   measuring the coloration or the pigment content;   measuring the content of metals, in particular iron, copper or nickel; and/or   determining the degree of oxidation.   
     
     
         20 . The method as claimed in  claim 11 , characterized in that the microalgae of the  Chlorella  genus are selected from the group consisting of  Chlorella vulgaris, Chlorella sorokiniana  and  Chlorella protothecoides.    
     
     
         21 . The method as claimed in  claim 20 , characterized in that the microalgae of the  Chlorella  genus is  Chlorella protothecoides.    
     
     
         22 . The method as claimed in  claim 17 , characterized in that the cells of the biomass are lysed by bead milling. 
     
     
         23 . The method as claimed in  claim 15 , characterized in that the biomass is washed with at most 3 volumes of water per 1 volume of biomass. 
     
     
         24 . The method as claimed in  claim 12 , characterized in that the protein comprises more than 65% by dry weight of the biomass. 
     
     
         25 . The method as claimed in  claim 12 , characterized in that the protein comprises more than 70% by dry weight of the biomass.