Physical characterization of whole and skim dried milk powders

Abstract

The lack of updated knowledge about the physical properties of milk powders aimed us to evaluate selected physical properties (water activity, particle size, density, flowability, solubility and colour) of eleven skim and whole milk powders produced in Europe. These physical properties are crucial both for the management of milk powder during the final steps of the drying process, and for their use as food ingredients. In general, except for the values of water activity, the physical properties of skim and whole milk powders are very different. Particle sizes of the spray-dried skim milk powders, measured as volume and surface mean diameter were significantly lower than that of the whole milk powders, while the roller dried sample showed the largest particle size. For all the samples the size distribution was quite narrow, with a span value less than 2. The loose density of skim milk powders was significantly higher than whole milk powders (541.36 vs 449.75 kg/m). Flowability, measured by Hausner ratio and Carr's index indicators, ranged from passable to poor when evaluated according to pharmaceutical criteria. The insolubility index of the spray-dried skim and whole milk powders, measured as weight of the sediment (from 0.5 to 34.8 mg), allowed a good discrimination of the samples. Colour analysis underlined the relevant contribution of fat content and particle size, resulted in higher lightness (*) for skim milk powder than whole milk powder, which, on the other hand, showed higher yellowness (*) and lower greenness (-*). In conclusion a detailed knowledge of functional properties of milk powders may allow the dairy to tailor the products to the user and help the food processor to perform a targeted choice according to the intended use.

Correlating Volatile Lipid Oxidation Compounds with Consumer Sensory Data in Dairy Based Powders during Storage

“…The a* values were negative across all samples with significantly (p ≤ 0.001) higher values observed for SMP than FFWMP and IMF samples across all treatments with the highest a* value observed in the SMP stored at 37 • C (-5.83). As expected, significantly (p ≤ 0.001) higher b* (yellowness) values were observed in FFWMP samples, due to the increased fat content [27]. Increased b* values (blue-to-yellow colour) in dairy products as observed in the FFWMP powder samples have previously been associated with β-carotene content [18], which has been linked with dairy products produced from pasture [28].…”

Process optimization of polyphenol‐rich milk powder using bee pollen based on physicochemical and functional properties

“…It is usually considered that powders containing particles of more than 200 μm are free‐flowing while fine powders (<100 μm) due to cohesion offer the greater resistance to flow thus affecting the flowability (Kim, Chen, & Pearce, ). In the present study, the particle size were higher than the spray‐dried milk powder varying from 10 to 250 μm (Schuck & Ouest, ), however, lower than the particles of roller‐dried powder (108.89–168.14 μm) as reported by Pugliese et al (). This may be due to the dependency of particles shape and size on drying systems and further grinding operations.…”

Physical characterization of spray-dried milk powders and their agglomerates with the addition of carob, cinnamon, and ginger powders

“…The color values of milk powders.The brightness value of WMP were found to be as 90.98. Similar findings were reported by Pugliese et al[34] (L*=96.06-96.49, a*= (-)1.78-(-)1.43, b*=13.70-14.59 for whole milk powder. The oxidation or browning reaction may be prevented during the spray drying due to the antioxidant activity of the CNP and GP.…”

“…The bulk and tapped density values of the WMP were found to be as 216.92±8.79 kg/m 3 and 442.50±11.59 kg/m 3 . Pugliese et al [34] reported that the bulk and tapped density values of the spray-dried four whole and seven skim milk powders varied between 396-480kg/m 3 and 553-662kg/m 3 and 407-666kg/m 3 and 578-87kg/m 3 , respectively. The different density values may be due to the different process conditions (inlet/outlet temperature, feed flow rate, atomization pressure etc.)…”