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


Orak H. H. , Aktas T., Yagar H., Isbilir S. S. , Ekinci N., ŞAHİN F. H.

FOOD SCIENCE AND TECHNOLOGY INTERNATIONAL, vol.18, no.4, pp.391-402, 2012 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 18 Issue: 4
  • Publication Date: 2012
  • Doi Number: 10.1177/1082013211428213
  • Title of Journal : FOOD SCIENCE AND TECHNOLOGY INTERNATIONAL
  • Page Numbers: pp.391-402

Abstract

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 beta-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 mu g 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.