A comparison of reverse osmosis, nanofiltration and ultrafiltration as concentration processes for skim milk prior to drying

Abstract

Skim milk was concentrated by reverse osmosis (RO), nanofiltration (NF) and ultrafiltration (UF) and the retentates were spray‐dried. The resulting powders were reconstituted to 25% TS and sterilised to evaluate their heat stability. Reverse osmosis led to maximum retention of calcium, a fall in pH for its retentate and its reconstituted powder. All RO powders produced a weak gel on heating. Some calcium was lost during NF and a greater amount during UF. Their resulting reconstituted powders had a higher pH than those produced by RO. Powders produced by UF showed poor heat stability. Only one powder produced by NF showed good heat stability. This could be improved by addition of stabilisers at appropriate addition rates.

Lower ultrafiltration temperature improves membrane performance and emulsifying properties of milk protein concentrates

“…On an average, UF removed 24.9% of the calcium from skim milk into permeate at 15°C compared to 20.2% at 30°C and 16.6% at 50°C, indicating that higher UF temperature coincides with less efficient calcium removal. Syrios et al (2011) also indicated that increased UF temperature resulted in reduced ionic calcium in the permeate when heating the skim milk to 50°C prior to UF. Similar observations have been made by Chandrapala et al (2010a, b), Lewis (2011), On-Nom et al (2010, Premaratne and Cousin (1991), Rose and Tessier (1959) and Vasiljevic and Jelen (1999).…”

“…During UF, about 10 mM soluble calcium (30% of total calcium), which is in the diffusible form, can pass through the membrane and accumulate in the permeate (Holt 1981). Removal of calcium during UF would result in some modifications in the salt system of milk such as solubilisation of colloidal calcium phosphate and migration of calcium from the micelles (Syrios et al 2011). These changes in the salt system could also have affected the structure of casein micelles in milk (ST-Gelais et al 1992).…”

“…The change of the casein micelle size induced by different heating conditions was reported by using centrifuged skim milk (Ono et al 1999). The production of MPC at 10 and 50°C has been reported by Havea (2006) and Syrios et al (2011) but the effect on the properties of MPC has not been studied. Consequently, comprehensive information on the effect of temperature of UF processing on MPC functional performance is scarce.…”

Changes in the volatile profile of skim milk powder prepared under different processing conditions and the effect on the volatile flavor profile of model white chocolate

“…Other concentration methods include membrane separation techniques such as reverse osmosis (RO; Glover, 1985), which operates at high pressure and temperatures below those reached during EV. Comparison of RO, nanofiltration, and UF was discussed by Syrios et al (2011) with regard to stability, pH, calcium content, and gel formation. showed that concentration by RO, compared with concentration by EV, retained far more of the sweet character of the milk, driven by a greater retention of most volatiles, particularly lactones and furaneol.…”

Lactose crystallisation in concentrated whey: the influence of vat type

“…Although many studies have investigated lactose crystallisation and the drying of dairy products (Guerra-Hern andez et al 2002;Kelly 2006;Syrios et al 2011;Gernigon et al 2013;Li et al 2016), no studies exist that probe whether the type of vat affects lactose crystallisation. The aim of this study was to describe the rate of lactose crystallisation in concentrated whey using two different vats.…”