High pressure homogenization of dairy products is today state of the art but limited by the fat content (max 17 vol.-%). This article describes the development of a novel simultaneous homogenization and mixing (SHM) valve which allows homogenization of dairy products with a fat content of up to 42 vol.-%. The challenging task of homogenizing dairy products with high fat content is to stabilize disrupted fat droplets especially against extensive aggregation. Aggregation and coalescence rates could be significantly reduced by a new microstructured valve allowing the emulsifier-containing phase to be injected directly into the zone of droplet disruption.

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Partial homogenization using a microstructured SHM (Simultaneous Homogenizing and Mixing) valve (as presented in part I) significantly reduces aggregation of fat globules during their homogenization by feeding the continuous phase directly into the droplet disruption zone. It allows homogenizing cream up to at least 42 vol.-% of fat, thus reducing processing costs significantly without loss in product quality (process intensification). In contrary to conventional milk technology, droplet sizes can be reduced at high fat contents with increasing pressure or increasing temperature of the homogenized stream (as presented in part II). This breaks new ground in dairy product design. In part III our focus is set on the influence of the SHM valve geometry on the homogenization results. No significant influence was found for the shape of the flow channels. In contrast, the distance at which the mixing streams enter has a significant impact on the homogenization results. For standard SHM valves with a T-shaped mixing unit we found an optimal distance at around 5 mm behind the valve outlet. In order to separate the tasks of implying a counter-pressure and instant diluting, an SHM2 double-valve configuration is suggested combining a double homogenization valve with a mixing unit. This offers the possibility to profit from counter-pressure just as well as in full-stream homogenization and gives more freedom in the mixing inlet design. Optimal distances for the mixing stream inlet are between 0 and 5 mm.

Partial homogenization using a microstructured SHM (Simultaneous Homogenizing and Mixing) valve significantly reduces aggregation of fat globules within their homogenization by feeding the continuous phase directly into the droplet disruption zone (as discussed in part I of this work). It allows homogenization of cream containing up to at least 42 vol.-% fat, and thus, significantly reduces processing costs without loss in product quality, i.e., overall process intensification. The present article details current results on the influence of material parameters, i.e., emulsifier system and fat content, and process parameters, i.e., homogenizing pressure and the temperature of both streams, on the fat globule size distribution. In contrast to conventional technology, SHM valve technology generates decreasing droplet sizes with increasing pressure or with increasing temperature of the homogenizing stream. This novel technique breaks new ground in dairy product design.