The significance of powder breakdown during conveying within industrial milk powder plants

Abstract

Instant whole milk powder is designed to rapidly dissolve in water, which depends on the particle size distribution (PSD). The fragile powder exiting the dryer is conveyed for packing which breaks down the particles, worsening the dissolution properties. This work investigated the effect of conveying on the final functional properties using two industrial plants with differing transport systems; a pneumatic system and bucket elevator. It was expected that the plant with the bucket elevator consistently produced powder with superior dissolution due to lower breakdown during transport. This was evaluated using the change in PSD. It was found that the plant with the bucket elevator had at least as large a change in the median particle size as the plant with the pneumatic transport system, contrary to the expectation. However, the plant with the bucket elevator had an initially larger particle size, and so the percentage of fine particles that negatively impact dissolution, remained low post transport. When quantified using the change in bulk density, having an initially low bulk density compensated for large increases in bulk density during conveying and powder with lower bulk density pre-transport showed better wettability post transport. Thus in order to produce powder with the desired functionalities the focus should be on improving the initial agglomeration and generating larger particles and lower bulk density pre-transport, as opposed to optimizing the powder transport.

Breakage of infant milk formula through three different processing methods and its influence on powder properties

“…Boiarkina et al investigated the breakage of instant whole milk powder in two different industrial plants with different transport systems, i.e. a pneumatic conveying system, and a bucket elevator (Boiarkina et al, 2016).…”

“…There are three breakage mechanisms based on the resulting size distribution of child particles: fragmentation/damage, chipping/attrition, and fracture (Aarseth, 2004;Ghadiri and Zhang, 2002;Lawn and Swain, 1975). If the breakage is excessive, it can lead to a number of serious consequences including but not limited to an increase in dust generation (Kalman and Goder, 1998;Oveisi et al, 2013;Salman et al, 2002;Wu and Wu, 2017) and loss in functionality and product performance (Bemrose and Bridgwater, 1987;Boiarkina et al, 2016;Zumaeta et al, 2005). Specifically, fine dust produced may lead to air pollution and plugging of processing equipment, increased possibility of dust explosions, loss of product through the production of undersized particles.…”

Near‐infrared spectroscopy and data analysis for predicting milk powder quality attributes

“…The metallic bearing at the inlet to the Mastersizer was removed to minimise particle breakdown due to attrition. These conditions and parameters during the Mastersizer operation were selected based on preliminary experimentation and previous studies of Boiarkina et al (2016). It is worth mentioning that the cumulative particle size distribution was also produced for all the samples to find out the cumulative percentage of fine particles, that is particles with a diameter of 180 µm or less, or the fine particle distribution (X f ).…”

Effects of Morphology on the Bulk Density of Instant Whole Milk Powder

“…It is worth mentioning that the milk powder samples that were measured came from a packer and had already gone through significant dense phase vacuum transport. Therefore, only the most robust powder is left behind at this point, as everything else is crushed during transport [15]. Finally, the milk powders from different particle size fractions were remixed following a simplex centroid design, discussed in Section 2.1.5.…”