Effect of nanofiltration on the composition of cottage cheese whey and its use in ice cream.

摘要

This study consisted of two parts: one part dealt with the effect of Nanofiltration (NF) of Cottage cheese whey (CCW) and the other with the use of hydrolyzed NF CCW retentates in ice cream products.; Nanofiltration offers a good opportunity to improve the flavor and functionality of CCW by removing most of its minerals and lactic acid. The thin polyamide composite NF membranes had a total area of 2.15 m{dollar}sp2{dollar} (200 dalton MW cut-off) in a spiral-wound configuration. The pH of the whey was adjusted to 3, 3.5, 4.35, 5.5 and 6.5. NF was continued until the retentate was concentrated to VCR 3 to achieve 15-17% total solids, and then diafiltrated against 3 volumes of distilled water at constant volume (VDF 3). There was a significant pH effect on the lactic acid and ash permeation during NF. The minerals and lactic acid % reduction ranged from 55-73%, and 80-92%, respectively. The results suggest that at pH values above 4.35, NF achieved higher levels of demineralization and deacidification than at lower pH values, but resulted in lower membrane flux and longer processing times. Despite the high levels of deacidification, NF did not significantly increase the pH (4.7) of the final retentate. The NF retentate was lactose hydrolyzed and used as an ingredient in ice cream.; Whey products can be used to replace up to 25% of milk solids non fat (MSNF) in ice cream products. Improved nutritional value and the cost reduction are important factors that favor substituting MSNF with whey solids. Ice cream mixes were formulated to contain 12% or 10% fat, 15% sucrose or 11.25% sucrose and 7.5% corn syrups solids that had 0, 25, 50 and 75% of their MSNF from nonfat dry milk (NFDM) replaced with hydrolyzed NF retentates. In general, MSNF replacement with hydrolyzed NF retentate reduced the protein content of the mixes. There was a significant increase in the viscosity during 48{dollar}spcirc{dollar}C aging. In general, 12% fat ice cream had larger emulsion droplet sizes, higher viscosity, lower melting rates and better shape retention than 10% fat products. Control (0% MSNF replacement) ice creams had higher % overrun than the test samples with NF retentate solids. The fat globules by TEM examination of the frozen ice cream ranged from 0.4-0.8 {dollar}mu{dollar}m. Replacement of MSNF with hydrolyzed NF retentate at {dollar}le{dollar}50%, gave products that were equally acceptable as the control ice cream. Replacement of 75% MSNF ice cream resulted in a too sweet, weak body and less acceptable ice cream.