Assessment of the flowability of spray-dried milk powders for chocolate manufacture

Abstract

-This work reports on the flowability of novel milk powders that have potential for application in the manufacture of chocolate. Many milk powders are cohesive which can give rise to powder flow problems. Shear cell techniques were used to measure the following powder flow properties: powder flowfunction, effective angle of internal friction and angle of wall friction. These measurements were used in assessing cohesion developed within the powders under compaction and adhesion to a stainless steel surface. The work investigated how fat content, free-fat content, particle size, moisture content, lactose content, amorphous lactose content and storage conditions influenced the flowability of the milk powders. Increased fat content reduced powder flowability especially when comparing 1% and 26% fat powders. Varying free-fat content showed no effect on flowability. Particle size had a major influence on flowability, as increasing the particle size significantly improved the flowability of powders with 1% and 26% fat content. The concentration of amorphous lactose present increased the susceptibility of powders for sorbing moisture, resulting in reduced flowability and caking. Finally, powder flow property measurements can be applied in the design of hoppers and silos that give consistent reliable flow, which is essential in powder handling and processing operations. milk powder / flowability / shear testing / chocolate manufacture Résumé -Évaluation de l'aptitude à l'écoulement de poudres de lait séché par atomisation utilisables en chocolaterie. Cet article présente les propriétés d'écoulement de nouvelles poudres de lait utilisables dans la fabrication de chocolat. De nombreuses poudres de lait sont collantes, ce qui peut conduire à des problèmes d'écoulement. Des techniques de cisaillement ont été utilisées pour mesurer sur ces poudres les propriétés d'écoulement suivantes : fonction d'écoulement, angle effectif de friction interne et angle de friction à la paroi. Ces mesures ont été utilisées pour évaluer la cohésion à l'intérieur de poudres agglomérées et leur adhésion à une surface en acier inoxydable. Ce travail a montré comment les teneurs en matière grasse et en matière grasse libre, la taille des particules, l'humidité, les teneurs en lactose et en lactose amorphe et les conditions de stockage influencent la coulabilité des poudres de lait. L'augmentation de la teneur en matière grasse conduisait à une diminution de la coulabilité, en particulier en comparant des poudres à 1 % et à 26 % de matière grasse. La variation de la teneur en matière grasse libre n'avait pas d'effet sur la coulabilité. Par contre, la taille des particules avait un effet majeur puisque l'accroissement de la taille des particules améliorait de façon significative la coulabilité des poudres contenant 1 % ou 26 % de matière grasse. La concentration en lactose amorphe présent augmentait la susceptibilité des poudres à la sorption d'eau, entraînant une coulabilité réduite et un mottage. Finalement, les mesures des propriétés d'éc...

The Influence of Composition and Manufacturing Approach on the Physical and Rehydration Properties of Milk Protein Concentrate Powders

“…The increase in particle density with a decrease in the protein content could be accounted for by the concomitant increase in lactose in the powders. Furthermore, the MPC40 in the current study had a loose bulk density value of 0.40 g/cm 3 , which is lower than the value of 0.65 g/cm 3 recorded by Fitzpatrick [28] for a commercial skim milk powder. This difference in bulk density may be due to the difference in the total solids content of the concentrate between the MPC40 sample (21.7%) and a typical commercial skim milk concentrate (e.g., 50%).…”

“…A FF graph was obtained by plotting major principal consolidating stress (MPCS) as a function of unconfined failure strength (UFS). This corresponds to the strength that develops within a powder when consolidated, which must be overcome to enable powder flow [28]. Flow index (i) values were calculated from the inverse of the slope of the FF curve.…”

“…The poor flowability of the low-protein MPC sample (i.e., MPC40) is possibly related to the use of a two-fluid nozzle during spray drying, or the drying of this concentrate at a relatively lower total solids content than would be used for a typical commercial product with a similar protein content (e.g., skim milk). Crowley [34] reported that the flow index was reduced from 13.4 for MPC35 to 3.5 for MPC85, while Fitzpatrick [28] reported a flow index value of 6.1 for a commercial skim milk powder. The Hausner ratio (HR) values correlated with the flowability results, which demonstrated that high protein powders had poorer flowability than low protein powders.…”

Profile of Spray-Dried Emulsions Stabilised by Milk Proteins

“…Sypkość proszków zmnierjsza się wraz ze zmniejszeniem wymiarów cząstek poniżej 200 µm [43]. To, że wymiar cząstek ma istotny wpływ na zdolność do płynięcia potwierdzono w testach bezpośredniego ścinania według procedury Jenike odnoszącej się do śmietanki w proszku [20]. Indeks płynięcia nie zmieniał się wraz ze zwiększaniem się zawartości tłuszczu na powierzchni i proszki o wielkości cząstek <100 μm charakteryzowane były jako bardzo kohezyjne.…”

Study of Polyphenol Content and Antioxidant Properties of Various Mix of Chocolate Milk Masses with Different Protein Content

“…Powder dried on a cylinder has a high content of free fat (at the level of about 90%), while spray-dried powder has below 10%. Powder dried on rolls usually has a larger average particle size of about 150 µm and a small vacuole volume, while spray-dried powder has a smaller particle size-about 70 µm-and a high vacuole volume [26].…”