title: Characterisation of viscosity, colour, 5-hydroxymethylfurfural content and diastase activity in raw rape honey (Brassica napus) at different temperatures.
abstract: The effect of heating at various temperatures (30, 40, 50, 60, 70 and 80 °C) on dynamic viscosity, colour, 5-hydroxymethylfurfural (5-HMF) concentration and diastase activity of raw rape honey were assessed. In fresh honey, moisture, ash, free acidity, pH and electrical conductivity averaged 185.3 g kg(-1), 1.2 g kg(-1), 18.71 mEq kg(-1), 4.2 and 0.25 mS cm(-1), respectively. Heating significantly (p ≤ 0.05) increased lightness (L*), yellowness (b*), chroma (C*), hue (h°) values, but decreased redness (a*). The viscosity at 20 °C (33.6 Pa s) differed significantly (p ≤ 0.01) with those at 30, 40 and 50 °C (8.2, 2.5, and 1.6 Pa s, respectively). Diastase activity decreased concomitant with heating at higher temperatures. Honey heated at 80 °C for 15 min showed the maximum increase of 5-HMF content, with an average of 1.9 mg kg(-1) (62 %), compared to unheated samples. Heating for 15 min between 50 °C and 80 °C did not significantly degrade the quality of the honey, but, slightly enhanced formation of 5-HMF and reduced the diastase activity.
authors.affiliation: Laboratory of Instrumental Analysis of Food, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin, Poland.
authors.forename: Monika
authors.initials: M
authors.lastname: Kędzierska-Matysek
authors.affiliation: Laboratory of Instrumental Analysis of Food, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin, Poland.
authors.forename: Mariusz
authors.identifier: 0000-0003-0941-1714
authors.initials: M
authors.lastname: Florek
authors.affiliation: Department of Commodity Science and Processing of Raw Animal Materials, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Wolanciuk
authors.affiliation: Department of Commodity Science and Processing of Raw Animal Materials, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Skałecki
authors.affiliation: Department of Commodity Science and Processing of Raw Animal Materials, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Litwińczuk
keywords: Colour; Diastase activity; Heat treatment; Hydroxymethylfurfural; Rape honey; Viscosity