Abstract: The invention relates to a process of treating squeezing juice having a high protein and sugar content, obtained by squeezing vegetable matter to be used as foodstuff. This process comprises the following steps:submitting said squeezing juice issuing from a squeezing press to a first inoculation with a first mesophile homofermentative lactic bacteria in a proportion of at least 10.sup.4 bacteria per milliliter;maintaining the thus inoculated juice at a temperature comprised between 28.degree. and 35.degree. C., preferably 30.degree. C., during 15 to 20 hours, under slow agitation and without aeration, so as to obtain a suspension constituted by an insoluble fraction of vegetable and microbial proteins, and a residual liquid phase, said suspension having a pH comprised between 4.2 and 4.5;separating said soluble fraction from said liquid fraction; andseparately treating the residual liquid and said insoluble fraction.