Partial demineralization and deacidification of Greek yogurt acid whey by nanofiltration for improving the drying characteristics of Greek yogurt acid whey

Document Type


Publication Date



2019 American Dairy Science Association Annual Meeting: Cincinnati, Ohio


American Dairy Science Association


Journal of Dairy Science










Greek yogurt acid whey, nanofiltration, demineralization


Greek yogurt acid whey (GYW) contains high concentrations of lactic acid (LA) and minerals as compared with cheese whey. LA and the minerals, particularly the calcium (Ca) in GYW cause stickiness during spray drying thus limiting the processing and utilization of GYW. Nanofiltration (NF) has been in use to for partial removal of minerals from cheese whey and milk to produce high value added dairy ingredients. Similarly, NF can potentially be applied for partial demineralization and deacidification of GYW to improve spray drying and powder properties. The aim of this study was to evaluate the effectiveness of NF to remove minerals and LA from GYW for improving the spray drying ability of GYW and thus the drying characteristics of the powder. GYW (5.52 ± 0.2% total solids) obtained from a Greek yogurt manufacturer was pasteurized at 72°C for 15 s followed by cooling to 4°C before concentrating to 22.35 ± 0.8% using semi-industrial scale Nanofiltration (Molecular Weight Cutoff – 300 to 500Da) plant. GYW feed, NF retentate and NF permeate compositions in terms of total protein nitrogen, non protein nitrogen, total ash, minerals (sodium, potassium and calcium) and Lactic acid were analyzed. The corresponding percent reduction of each component was calculated and expressed on a dry matter basis. The lactic acid and total ash concentrations were reduced significantly (P < 0.05) by 34.3 ± 0.2 and 37.8 ± 0.7 respectively. The reduction of monovalent ions i.e., sodium and potassium was observed to be higher (66% and 62%) than calcium (41%). There was no significant difference (P > 0.05) in the total protein content and pH of GYW feed (4.13 ± 0.2, 4.44) and NF GYW retentate (3.95 ± 0.2, 4.38). The results show it is feasible to reduce the mineral content and lactic acid in GYW by approximately 38% and 34% respectively using NF. In subsequent studies, the NF retentate (treatment) and GYW (control) will be spray dried and the powder properties characterized.