Properties of raspberry powder obtained by a new method of fluidised-bed jet milling and drying compared to other drying methods.

Background: Among food producers, there is a need for and a great interest in obtaining powders from fruit and vegetables characterised by high nutritional values and sensory qualities at favourable prices, preferably lower than those for powders obtained by freeze-drying (FD). The present study assessed the functional properties, including bioactive ingredient contents, of the raspberry powders obtained by a new method of fluidised-bed jet milling and drying (FBJD) which has not been yet used on an industrial scale.

Results: Compared to the powders obtained by FD, the powders obtained by the new method were characterised by a comparable content of vitamin C (~2.70-2.74 mg g ), approximately 10-15% higher contents of anthocyanins and polyphenols, and higher antioxidant properties. Compared to the powders obtained by convection drying (CD) and spray drying (SD) methods, FBJD powders were characterised by approximately 40% and 80% higher polyphenol contents and 43% and 77% higher antioxidant activities, respectively. The content of vitamin C in FBJD powders was 49% higher than in CD powders, and only 4% higher than in SD powders.

Conclusion: Considering the findings outlined above, the method tested is concluded to be competitive with the methods currently used as a result of the high content of bioactive compounds in powders obtained by means of the cheaper, low-temperature process of simultaneous drying and micronisation in FBJD. © 2020 Society of Chemical Industry.