Instant Whole Milk Powder Research Articles

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

The chemical and physical properties of instant whole milk powder (IWMP), such as morphology, protein content, and particle size, can affect its functionality and performance. Bulk density, which directly determines the packing cost and transportation cost of milk powder, is one of the most important functional properties of IWMP, and it is mainly affected by physical properties, e.g., morphology and particle size. This work quantified the relationship between morphology and bulk density of IWMP and developed a predictive model of bulk density for IWMP. To obtain milk powder samples with different particle size fractions, IWMP samples of four different brands were sieved into three different particle size range groups, before using the simplex-centroid design (SCD) method to remix the milk powder samples. The bulk densities of these remixed milk powder samples were then measured by tap testing, and the particles’ shape factors were extracted by light microscopy and image processing. The number of variables was decreased by principal component analysis and partial least squares models and artificial neural network models were built to predict the bulk density of IWMP. It was found that different brands of IWMP have different morphology, and the bulk density trends versus the shape factor changes were similar for the different particle size range groups. Finally, prediction models for bulk density were developed by using the shape factors and particle size range fractions of the IWMP samples. The good results of these models proved that predicting the bulk density of IWMP by using shape factors and particle size range fractions is achievable and could be used as a model for online model-based process monitoring.

Effects of morphology on the dispersibility of instant whole milk powder

The functionality and performance of instant whole milk powder (IWMP) can be related to its physical and chemical properties; i.e. particle size, morphology and fat distribution. Dispersibility, a measure of rehydration, has become one of the most important quality characteristics of IWMP. Many milk powder properties may affect the dispersibility. Based on literature and our own experience, particle size and morphology may be the two most important factors. This work investigated the quantitative relationship between particle size, morphology and dispersibility. Samples of different brands of IWMPs were fractionated using sieving and then remixed. The powder dispersibility was then measured, and the particle morphology characteristics obtained using light microscopy combined with image processing. Principal component analysis (PCA), partial least squares (PLS) and artificial neural network (ANN) methods were used to process the data. It was found that IWMP produced by different plants have different shape factors (circularity, convexity, and area) and the trends of the dispersibility versus the changes in the shape factors (circularity, convexity and area) for different particle size groups are different. Then, by the use of the size fractions and shape factors, prediction models for dispersibility were developed. A further experiment addressed the validity of the ANN model.

Rapid particle size measurements used as a proxy to control instant whole milk powder dispersibility

Dispersibility is a key quality variable for instant whole milk powder (IWMP) measured manually using a complex and laborious dissolution method post-production. Consequently, the lack of timely feedback means that the functional quality cannot be controlled in real time. This work proposes the idea of applying a simpler, surrogate measurement that can be implemented in the plant in order to have useful real-time information regarding the quality of the product being produced. This, we term, is a proxy measurement. The functional property dispersibility was used as a case study, with particle size being investigated as a proxy at an industrial IWMP plant. It was found that particle sizing could be used to provide useful information regarding the powder, with the proxy measurement being able to predict in-specification powder 97% of the time. Although the test was not as effective for predicting out-of-specification results, with a false-positive rate of 50%, the fact that out-of-specification events are rare in the industry setting means that the overall proxy measurement is still between 78 and 87% accurate and thus useful for predicting the dispersibility quality of the IWMP. Furthermore, these proxy measurements can then be combined with on-line plant information using multivariate techniques to further improve their accuracy and understand how the quality can be controlled by changing the plant processing conditions.