Polyodon spathula sturgeon breed is successfully reared in Romania in many fishery farms for meat production and it is capitalized on domestic market as consumption fish. In the current paper were studied a number of 1400 sturgeons from Polyodon spathula breed (1200 individuals of one summer - P.s.0+ and 200 individuals of fourth summers - P.s.3+). From this flock were weighted around 10%, for each age group, and for laboratory determinations were chosen 10 fishes for each age with the corporal mass close to the group mean. After analysing the fillets gathered from the studied fishes for establishing the chemical characteristics, nutritive and biological values of proteins were drawn some interesting conclusions. So, regarding chemical composition we notice that in the meat of analysed fishes water is in a rate of 75.41% at P.s.3+ and 78.37% for P.s.0+; proteins - between 18.08% for P.s.0+ and 19.89% for P.s.3+, values which place those fishes in the group of protein fishes; lipids - between 2.45% and 3.45%, values which situated those sturgeons in category of fishes with a low content in lipids; collagen � 3.83% at P.s.0+ and 4.14% at P.s.3+ which indicate low values for proteins of weak quality in the meat of those sturgeons. Study of nutritive value for the analysed fishes indicate the fact that fishes P.s.0+ have a mediocre nutritive value, having the ratio w/p of 4.33 while sturgeons P.s.3+ were placed in the 2nd category � fishes with a good nutritive value (rate w/p = 3.79). Energetic value of the studied fillets was 97.39 kcal/100 g for P.s.0+ and 114.31 kcal/100 g for P.s.3+, which enlightened an increase of nutritive value with aging, fact especially due to accumulation of adipose tissue. Study of proteins quality, through the presence of those 8 essential amino-acids in the meat of analysed fishes, show the fact that at sturgeons P.s.0+ proportion of essential amino-acids was 20.88% from total amino-acids, while at sturgeons P.s.3+ was 26.23%, fact which enlightened an increasing of proteins� biological value with fish aging. This fact was also shown by calculation of proteins� biological value through chemical methods (EAA index); calculated value for sturgeons P.s.0+ was a little bit lower (118.73) than the one calculated for sturgeons P.s.3+ (118.79).
THE EFFECT OF HEAT UPON THE BIOLOGICAL VALUE OF CEREAL PROTEINS AND CASEIN
