The Effect of Low-Temperature Spray Drying with Dehumidified Air on Phenolic Compounds, Antioxidant Activity, and Aroma Compounds of Rapeseed Honey Powders

Abstract

The influence of low-temperature spray drying (inlet/outlet air, 75/50°C) with the use of dehumidified air on rapeseed honey phenolics, antioxidant activity, and aroma compounds was investigated. Maltodextrin and NUTRIOSE® were used as carriers. Additionally, skimmed milk was tested as water substitute for feed solution preparation. Honey powders obtained by this method were characterized by high antioxidant activity and rich aroma. Changes in aroma profile during drying at low temperature were recognized as favorable and creating desirable fragrance of the product. In the case of 80% honey powders (20% of carrier), the investigated properties were not deteriorated comparing to pure honey before drying. Thus, this level of carrier addition can be treated as optimal from the point of view of bioactive properties retention during low-temperature spray drying. Such low carrier addition was not presented before in case of honey spray drying, and is favorable due to the perception of such product as natural. If used as food component, the dose of such honey-rich powder can be reduced comparing to traditional products containing higher amount of carrier (usually not lower than 50%).

Advances in spray drying of sugar-rich products

“…The dehumidified air spray drying may be optimized by reduction of inlet and outlet drying air temperatures to about 75 C and 50 C respectively, which substantially increase the product yield up to 84-95%, [25] keeping high juice/honey solids to carrier solids content ratio up to 80:20. Application of low drying air temperature enable the increase in retention in bioactive compounds [37] and reduction of energy consumption during the drying process. The disadvantages of application of low temperature spray drying combined with air dehumidification are additional investment and energy cost required to remove the moisture from the drying air as well as limited range of process parameters.…”

“…The flowability may be evaluated by Carr Index (CI) or Hausner Ratio (HR). Based on the Carr Index powders flowability might be classified as very good (< 15), good (15)(16)(17)(18)(19)(20), fair (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35), bad (35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45), and very bad (>45). [60] According to Hausner ratio powder cohesiveness may be classified as low (high flowability) for HR <1.2, medium 1.2-1.4 and high for HR >1.4 (low flowability).…”

“…Spray drying at low drying temperatures can be performed only at limited range of process parameters: the moisture content in the feed and the feed rate have to be decreased to reduce the amount of water supplied to the drier for evaporation, because it is difficult to remove large amounts of water at low drying temperatures [37] .…”

“…The same research group found that low temperature spray drying by dehumidified air has favorable effect on retention of bioactive compounds in rapeseed honey. [37] For instance, retention of phenolic compounds in rapeseed honey powder dried with a "Nutriose" carrier (product solids to carrier solids content 80:20) was about 86.3% and antioxidant activity decreased only by ca. 22.1% after low temperature spray drying.…”

“…22.1% after low temperature spray drying. [37] In the standard high-temperature spray drying process in order to obtain acceptable product yields of fruit or honey powder, concentration of the drying carrier in the final product might exceed 50% (product solids to carrier solids content ratio 1.00). For example, Arag€ uez-Fortes et al obtained spray dried guava powder (Psidium guajava L.) with product yield 42.6-70.2% applying inlet/outlet air temperatures 130-170 C/75 C and adding maltodextrin as a carrier in the amount 50:50, 37.5:62.5 and 25:75 juice solids to carrier solids content ratio.…”