Recovery of milk based products

Dairy sites employ various methods to effect product recovery; instruments that detect changes in turbidity, conductivity, suspended solids or temperature. Often product recovery is determined solely by 'time', e.g. product to travel along pipe work, say from pasteuriser to finished milk tank or to a product recovery tank.

The In-Site system is very effective in identifying milk-based product. We associate 4-5 separate parameters, thus we are very accurate during analysis in determining 'milk' and this expertise enables us to accurately amend cycle times.

In-Site can differentiate between water and milk and if milk, whether it is whole milk, skim milk or cream.

Conductivity measurement is widely used as the method of determining product recovery. However, the conductivity values of the two prime mediums (milk and water) are not constant and both values can vary, day-on-day.

Did you know that the conductivity value of 100% whole milk can be the same as 80% skim milk and that 80% whole milk can have the same value as 55% skim milk.

How effective product recovery is, when using conductivity measurement, will depend upon which type of milk the instrument was calibrated against. Conductivity probes should be re-calibrated at frequent intervals.

Assume a site has a weekly milk intake of 4 million litres (£0.19/litre) and a product wastage level of 1.0%.

This equates to £395,200 per annum. Assume 10% of this loss impacts upon the effluent system, this represents a COD loading of 1,100 kgs/day.

Even if In-Site only improved the wastage level from 1.0% to 0.9% this still represents a saving of £40k/annum (milk only).

In-Site would expect to reduce wastage levels by >10%.

If this was your site, would you do anything to improve product recovery?

Poor 'product recovery' can become very expensive, not just in terms of the basic cost per litre of lost milk or cream.

If product is discharged to effluent, it may well cause the COD consent level to be exceeded, this can be very costly to the site.

Poor product recovery can cause the CIP detergent tank to become contaminated (saponified fats), these can cause the detergent tank to foam excessively wasting chemical, water and energy (and possibly impacting on effluent loading).

A CIP tank contaminated with milk fats may affect cleaning standards, leading potentially to quality issues.