Optimization of goat milk vacuum-assisted block freeze concentration using responsesurface methodology and NaCl addition i

Response Surface Methodology was applied to optimize the effects of freezing time, vacuum conditions, and time under vacuum regarding concentrated yield response, resulting from optimal parameters of the milk vacuum-assisted block freeze concentration process. Additionally, it was verified the NaCl influence, using different salt contents (0.5, 1, 1.5, and 2%) addition and freezing time of 1 day, vacuum equal to 10 kPa, and time under vacuum 60 min, in goat milk vacuum-assisted freeze concentration performance. The concentrate with 1.5 and 2% of NaCl addition showed the highest values for the total solids (35.06 and 36.21 g 100 g−1) and protein contents (10.43 and 10.70 g 100 g−1), while the concentrate without NaCl addition concentrated more lactose content (17.42 g 100 g−1). The samples with 1.5 and 2% of NaCl addition reached parameters of the process more satisfactory with a concentrate yield of 85.79 and 92.14%, concentration percentage of 28 and 32%, and efficiency of process approximately of 90%. Finally, the best performance was observed when used 1.5 and 2% NaCl addition in the goat milk submitted to the vacuum-assisted freeze concentration process.