Demineralized Whey

Demineralized whey is whey that has had a significant proportion of minerals removed. There are various degrees of demineralization but levels of 35%, 70% and 90% are available depending on the application. Demineralized whey also has a neutral flavour which makes it suitable for baby milk formulations, specific geriatric foods, various mainstream foods and beverages.

In the process of demineralization there is not only the removal of ions but also the reduction in lactose and ash content. Lactose is a problematic sugar for those who are intolerant to it. In communities that can digest lactose, its presence is not that much of an issue but in Asia for example, lactose is not readily digested and causes severe digestion issues.

When lactose is removed the whey may often be described and called partially delactosed whey. The removal of up to 33% by weight of the lactose is enough for most formulations. The process of electrodialysis is used to reduce minerals mainly calcium salts.

The 90% demineralized whey is used for infant nutrition because it has a cation and anion content closest to human breast milk. To obtain a standard whey for baby formulations closest to human milk will often require mixing with skimmed milk.  It means that the osmolarity of any formulations using demineralized whey are as close to ‘real’ milk as possible. It reduces the load placed on delicate organs such as baby’s kidneys whilst keeping all the key proteins needed for digestion and growth.

The food industry relies on whey in all sorts of applications but demineralised whey in particular is ideal for dessert formulations because the salty flavour is removed. It also has a lower hygroscopicity which means it doesn’t clump as readily. It can also be certified still as kosher or halal.

Processing Considerations

Processing can exploit three processes which in combination produce different degrees of deionization. The three are nanofiltration or ultrafiltration, electrodialysis and ion-exchange. The type of processing used will depend on capital costs and operating costs.

Ultrafiltration is a membrane process which allows the lactose to be removed from the whey.  Nanofiltration is the process whereby using a membrane there is selective passage of small ions, mainly monovalent ones such as sodium, potassium and chlorine which pass through leaving the proteins and fats to be retained.

If only nanofiltration is used, the ion content of demineralised whey is between 30 and 35% reduction, the lactose content is less than 74% and the ash content is over 5%.

Nanofiltration is often combined with electrodialysis to reduce the ion concentration further by between 50 and 70%. The demineralised whey has a lactose content of between 73 and 77%. The final combination which is ultimately the most expensive is to combine ion-exchange with both nanofiltration and electrodialysis. This demineralises the whey by over 90%. The lactose content of the whey is the over 80% and the ash content is less than 1%.

The liquid whey is usually concentrated by evaporation which raises the concentration by almost 2/3rds. The concentrated whey liquid is usually spray dried to a fine white powder.