Production of single cell protein concentrates from lactic acid bacteria cultures and determination of technological characteristics

In this study, suitable fermentation conditions for single cell protein (SCP) production were determined using Lb. plantarum MF4 and Lb. brevis MF343 strains, and the chemical and technological properties of protein concentrates obtained by extracting and purifying proteins from single cells were determined. Accordingly, the highest biomass production in fermentations performed at different media (MR, SS, MS, SM), pH value (pH 6.0, 6.5, 7.0), temperature (25, 30, 35oC) and agitation speeds (50, 200 rpm) is obtained in MS medium, as 2.57 g / L (35oC, pH 7.0, 12. hour) by Lb. plantarum MF4 strain and 2.27g / L (35oC, pH 6.5, 24. hour) by Lb. brevis MF343 strain. There was no increase in biomass production under shaking fermentation conditions. Specific growth rate and volumetric productivity values obtained in fermentations were calculated as 0.405 h-1, 0.212 g / L.h for Lb. plantarum MF4 and 0.384 h-1, 0.094 g / L.h. for Lb. brevis MF343. After LAB cells and commercial yeast cells produced by fermentation performed under optimum THP production conditions were disrupted with the help of sonication, enzymes and homogenizer for an efficient extraction; the effects of factors such as pH, dilution rates and NaCl on the extraction of proteins were determined. In extractions, the highest extraction yields of MF4, MF343 and yeast cell homogenates were 69.84%, 85.14%55.42, respectively, at dilution rates of 2.25 at pH 12. In the purification stage, alcohol and isoelectric precipitation techniques were used to recover proteins from cell extraction fluids. In the precipitation processes performed with alcohol, at 80 % alcohol concentration, protein recovery rates were obtained as 79.73%for MF4 extracts, 77.81%for MF343 extracts and 86.75%for yeast extracts. In the purifications performed by isoelectric precipitation, the highest protein recovery rates were calculated at pH 3.5 (86.64%) for MF4 extract, pH 2.5 (94.77%) for MF343 and pH 3.0 (88.77%) for yeast. The protein contents in dry matter of THP concentrates produced by isolectric precipitation under suitable conditions were calculated as 72.47%in MF4 sample, 73.09%in MF343 sample and 62.79%in yeast sample. It has been determined that the aspartic, glutamic and lysine amino acid contents of THP concentrates are higher than other amino acids. Some technological properties of THP concentrates produced were also investigated and the protein solubility rates of samples were calculated as 79%for MF4, 98%for MF343; oil absorption capacities were calculated as 16%for MF4, 17%for MF343; foam capacities were calculated as 220%for MF4, 260%MF343; emulsion activity indices and emulsion stability indices were calculated as 122.65 m2 / g - 18.61 min for MF4 and 104.66 m2 / g - 35.12 min for MF343. By determining the chemical and technological properties of the protein concentrates produced by optimizing the fermentation conditions for THP production from lactic acid bacteria; their usability for the food industry has been revealed.