What you should know about Functional Food powders
A plethora of drying techniques are employed to produce the powdered supplement you pick up off the health store shelves. The manner in which the powder is produced is vitally important to the quality and integrity of the nutrients that remain after the processing is complete.
So that broccoli powder you just brought…what exactly does it contain and how was it processed? That is a good question…
What are the different methods employed in the production of fruit and vegetable powders?
Spray drying is probably the most common technique used however this method incurs some nutrient degradation. The ingredient may also be subject to treatment with something before processing and then sprayed onto a carrier such as maltodextrin and dried.
The process: spray drying typically involves processing the fruit or vegetable into a juice, spraying onto a carrier (such as maltodextrin) and lastly drying with high heat. In the first drying step moisture rapidly evaporates from the surface, and capillary action draws moisture from within the particle. In the second period, diffusion of water to the surface controls the drying rate. As moisture content drops, diffusion rate also decreases. Removing the last few percent of moisture in a single-stage dryer is responsible for most of the residence time in the dryer.
Drum drying is another common technique employed however this method incurs nutrient degradation. The process also utilises a carrier such as maltodextrin, giving less actual ingredient as it isn’t 100% pure.
The process: Drum dryers use pureed fruits and vegetables and have one or two drums heated with hot water or steam as heating elements. Feeding is continuous between the two drums which are rotating in reverse direction. Once the product is dried it is removed by mechanical means during rotation.
Freeze drying is becoming common as it boasts high nutrient retention and superior retention of natural flavour, colour, aroma and phytonutrients, typical to what is seen in their fresh counterparts. Freeze dried powders require no carrier (no maltodextrin etc.) so is not usually added unlike spray dried fruit powders.
The process: Freeze dried is first frozen and then the water is removed by sublimation. It dries products by spraying liquids into refrigerated storage tanks. The liquids are removed by freezing and sublimation, or changing directly from a solid to a gas without melting. This technique uses no heat and is considered raw making it most useful for creating powdered products that are heat sensitive.
Refractance window drying uses infrared energy to accomplish a high quality product with high nutrient retention and superior retention of natural flavour, colour, aroma and phytonutrients, typical to what is seen in their fresh counterparts. There is no carrier required for this process.
The process: Refractance Window drying uses a proprietary heat transfer technology to gently remove moisture from delicate products. When a moisture-laden material is placed on the drying surface, a “window” for passage of energy is created at the point where the material contacts the drying substrate. This creates an excellent heat transfer point to gently dry the product but once the material is dry the “window” closes and the product is no longer subject to the heat transfer and therefore the nutrients and flavour volatiles are not damaged or driven off due to overheating. The maximum temperature of the product reaches 39-49 degrees Celsius.
As you can see a vegetable powder is not just a vegetable powder, there is a gap between the quality of each processing technique. As well as variations in processing temperatures, colour and flavour of the resulting product.
What to do? You can check the label to see if it tells you which process is used or contact the company and simply ask the question.