Milk clotting for cheese producing is usually performed using enzymes from animal sources and the most common, chymosin, is obtained from the stomach of newborn calves. Some researches have identified new sources of enzymes that have the ability of coagulating the milk like proteases from vegetal. The objective of this study was to evaluate the concentration by microfiltration of a vegetal proteolytic enzymatic extract obtained from sunflower seed. The raw material utilized was sunflower seed from Embrapa's experimental station. Enzyme extraction was performed according to the following procedure: sunflower seed disintegration in a pilot plant mill, homogenization in an industrial blender and aqueous extraction in brine solution during 18 hours under refrigeration. The extract was centrifuged and conducted to microfiltration system composed by three ceramic membranes with 1.0 μm pore size. Permeate flux was determined along the process and samples were collected from feed, permeate and retentate, for determination of total proteins, proteolytic activity and coagulation unit. Average permeate flux was 33 L/hm~2 and concentration factor was equal to 5.0. As expected the coagulation unit was lower in retentate fraction (4.72 CU/mL) than in feed (10.93 CU/mL) and no milk coagulation was verified with the permeate sample. No proteolytic activity was detected in permeate fraction and total protein content was 0.29 mg/mL. Proteolytic activity increased from 1.43 U/mL in raw extract to 2.18 U/mL in retentate and protein content has increased from 1.69 mg/mL to 6.21 mg/mL. Both total protein and proteolytic activity were concentrated in retentate fraction although they were not in the same range of the concentration factor, probably due to the protein denaturing and loss of enzymatic activity. The obtained results suggest a potentiality for the concentration of the sunflower seed protease by microfiltration, although it is needed further studies to optimize the process.
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