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I had observed tiny oil spots in my reconstituted spray dried creamer powder. What is the cause of oil spots?

October 10, 2017
ANSWER

Spray drying is a well-established and widely used method for transforming a wide range of liquid foods into powder form. However, there are few factors that we need to consider to minimize the product quality issues (Muzaffar et al., 2015; Tan et al., 2011):-

  • Types of carrier agent and their concentration
  • Air flow rate
  • Feed flow rate
  • Atomizer speed
  • Hygroscopicity of substances
  • Processing temperature
  • Blending components
  • Particle sizes

Loading of high edible oil such as Vitamin E could be the culprit that contribute to the oil spot (US Patent US 6020003 A, 1998). According to European Patent Office EP 1 071 464 B1 (1999), end products are prone to be oil spotted if the oil is not well encapsulated.  Thus, microencapsulated is potentially offer numerous benefits to the food ingredients being encapsulated where it protects materials from moisture and maintain the stability of ingredients that are volatile or sensitive to heat, light or oxidation (Fernandes et al., 2013).

Besides that, feed flow rate is another aspect to be concerned. As feed flow rate is increased, more molecules was atomized into the drying chamber and produced larger liquid droplets. Thus, larger droplets have smaller surface area and may reduce the outlet air temperature causing outlet air humidity becoming higher. Larger droplets increased the distance to travel the heat to the center of the droplets as well as increasing the distance to travel moisture from the center of the droplets the surface. As a consequence, the moisture is difficult to evaporate and causing the powder cannot dry thoroughly (Tan et al., 2011).

Stickiness is another frequent phenomenon encountered during spray drying of sugar and acid rich food materials. The hygroscopicity and processing temperature contribute to the stickiness problem. The low glass transition temperature, high hygroscopic, low melting point and high water solubility of dry solids tend to produce the highly sticky products (Phisut, 2012). Thus, addition of high molecular weight drying aids, process based approaches like use of low humidity and low temperature conditions, cooling of dryer chamber wall and surface modification by proteins are the possible ways to solve the stickiness problem and hence to increase the product recovery (Muzaffar et al., 2015).

In a nutshell, the quality of spray dry powder is dependent on the operating parameters that affecting the end product properties. Additionally, microencapsulation provides a physical barrier between the core compound and the other components of the product which helps to increase stability and to improve the properties of end products.

 

References

Fernandes, R. V. de B., Borges, S. V., & Botrel, D. A. (2013). Influence of spray drying operating conditions on microencapsulated rosemary essential oil properties. Food Science and Technology, 33(1), 171-178. https://doi.org/10.1590/S0101-20612013000500025

Gharsallaoui, A., Roudaut, G., Chambin, O., Voilley, A. & Saurel, R. (2007). Applications of spray-drying in microencapsulation of food ingredients: An overview. Food Research International, 40(9), 1107-1121. https://doi.org/10.1016/j.foodres.2007.07.004

Muzaffar, K., Nayik, G. A. & Kumar, P. (2015). Stickiness Problem Associated with Spray Drying of Sugar and Acid Rich Foods: A Mini Review. Journal of Nutrition & Food Sciences, S12, 003. https://doi.org/10.4172/2155-9600.S12-003

Phisut, N. (2012). Spray drying technique of fruit juice powder: some factors influencing the properties of product. International Food Research Journal, 19(4), 1297-1306.

Stroh, F., Bower, D. K., Chaundy, F. K., Finnan, J. L., Soblesky, T. B., (1999). Spray-Dried Powders With High Edible-Oil Loadings Based On Non-Hydrolyzed Gelatin And A Method Of Making Such Spray-Dried Tablettable Powders. European Patent Office EP 1 071 464 B1.

Stroh, F., Bower, D., Chaundy, F., Finnan, J. & Soblesky, T. (1998). Method of making spray-dried powders with high edible-oil loadings based on non-hydrolyzed gelatin. US Patent US 6020003 A.

Tan, L. W., Ibrahim, M. N., Kamil, R. & Taip, F. S. (2011). Empirical modeling for spray drying process of sticky and non-sticky products. Procedia Food Science, 1, 690-697. https://doi.org/10.1016/j.profoo.2011.09.104

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