Effects of hot air and freeze drying methods on antioxidant activity, colour and some nutritional characteristics of strawberry tree (Arbutus unedo L) fruit

Food Sci Technol Int. 2012 Aug;18(4):391-402. doi: 10.1177/1082013211428213. Epub 2012 Apr 20.


Antioxidant activity, colour and some nutritional properties of hot air and freeze-dried strawberry tree (Arbutus unedo L.) fruits were investigated. Additionally, the effects of two pre-treatments, namely ethyl oleate and water blanching, were compared in terms of drying characteristics. For determination of antioxidant activities in ethanol extracts, two different analytical methods were used: 1,1-diphenyl-2-picrylhydrazyl scavenging activity and β-carotene bleaching activity. As a result, the ethyl oleate pre-treatment shortened the drying time by hot air method and gave a higher 1,1-diphenyl-2-picrylhydrazyl scavenging activity (82.16 ± 0.34%), total phenolic content (7.62 ± 1.09 µg GAE/g extract), ascorbic acid content (236.93 ± 20.14 mg/100 g), besides hydromethylfurfural was not observed. Freeze-dried fruits exhibited higher ascorbic acid content (368.63 ± 17.16 mg/100 g) than those fresh fruits (231.33 ± 19.51 mg/100 g) and nearly 1,1-diphenyl-2-picrylhydrazyl activity (93.52 ± 0.41 %) to fresh fruits (94.03 ± 1.18%). Colour characteristics, sugar content and mineral contents of fruits were significantly affected by pre-treatments and drying methods (p < 0.05). It is concluded that the drying of strawberry tree fruits should bring a valuable and attractive foodstuff to food industry due to the rich nutritional components, antioxidant activity and colour. Another conclusion from this study is that the freeze-drying is the best drying method to keep the nutritional value, antioxidant activity and sensory properties of fruits.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antioxidants / analysis*
  • Ascorbic Acid / analysis
  • Dietary Carbohydrates / analysis
  • Ericaceae / chemistry*
  • Food Preservation / methods*
  • Freeze Drying
  • Fruit / chemistry*
  • Furaldehyde / analogs & derivatives
  • Furaldehyde / analysis
  • Hot Temperature / adverse effects
  • Kinetics
  • Minerals / analysis
  • Nutritive Value
  • Oleic Acids / chemistry
  • Pigmentation*
  • Plant Extracts / chemistry
  • Sensation
  • Trace Elements / analysis
  • Turkey


  • Antioxidants
  • Dietary Carbohydrates
  • Minerals
  • Oleic Acids
  • Plant Extracts
  • Trace Elements
  • 5-hydroxymethylfurfural
  • Furaldehyde
  • Ascorbic Acid
  • ethyl oleate