title: Effects of hot air and freeze drying methods on antioxidant activity, colour and some nutritional characteristics of strawberry tree (Arbutus unedo L) fruit.
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 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.
authors.affiliation: Food Technology, Vocational School of Technical Sciences, Namik Kemal University, Tekirdag, Turkey. horak@nku.edu.tr
authors.forename: H H
authors.initials: HH
authors.lastname: Orak
authors.forename: T
authors.initials: T
authors.lastname: Aktas
authors.forename: H
authors.initials: H
authors.lastname: Yagar
authors.forename: S Selen
authors.initials: SS
authors.lastname: İsbilir
authors.forename: N
authors.initials: N
authors.lastname: Ekinci
authors.forename: F Hasturk
authors.initials: FH
authors.lastname: Sahin
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D001205:Ascorbic Acid / Q000032:analysis; D004040:Dietary Carbohydrates / Q000032:analysis; D029791:Ericaceae / Q000737:chemistry*; D005519:Food Preservation / Q000379:methods*; D005612:Freeze Drying; D005638:Fruit / Q000737:chemistry*; D005662:Furaldehyde / Q000031:analogs & derivatives / Q000032:analysis; D006358:Hot Temperature / Q000009:adverse effects; D007700:Kinetics; D008903:Minerals / Q000032:analysis; D009753:Nutritive Value; D009829:Oleic Acids / Q000737:chemistry; D010858:Pigmentation; D010936:Plant Extracts / Q000737:chemistry; D012677:Sensation; D014131:Trace Elements / Q000032:analysis; D014421:Turkey
chemical_list: D000975:Antioxidants; D004040:Dietary Carbohydrates; D008903:Minerals; D009829:Oleic Acids; D010936:Plant Extracts; D014131:Trace Elements; C008046:5-hydroxymethylfurfural; D005662:Furaldehyde; D001205:Ascorbic Acid; C033180:ethyl oleate