INFLUENCE OF κ-CARRAGEENAN, AGAR-AGAR AND STARCH ON THE RHEOLOGICAL PROPERTIES OF BLUEBERRIES YOGURT Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel MareUniversity - Suceava Volume XI, Issue 2 – 2012 29 HON EY CLA SSI FI CATION US ING CO LOUR ME ASU REME N T *Mircea OROIAN1, Ana LEAHU 2, Cristina DAMIAN 3, Amelia BUCULEI4 1-4Food Engineering Faculty, Stefan cel Mare University of Suceava, Romania 1m.oroian@fia.usv.ro, 2analeahu@fia.usv.ro, 3cristina.damian@fia.usv.ro, 4ameliab@fia.usv.ro *Corresponding author Received 15 March 2012, accepted 2 May 2012 Abstract: The purpose of this work is to classify honey to their floral source based on their colour. For this study were chosen 15 samples of honey from different floral sources (5 samples of acacia, 5 samples of tilia and 5 samples of sun flower honey). The colour of honey is influenced by the floral source, due to the minerals and other minor components presented; exposure to heat and storage time may affect honey’s colour. One of the easiest way to determine the honey colour is using the reflectance measurement in CIELab coordinates. The coordinates in CIELab dimension are L*, a* and b* values, which explain a 3-dimensional colour space. The L* value is the vertical axis and defines the lightness, and a* and b* values are perpendicular horizontal axes and define red-to-green and blue-to-yellow, respectively. In addition, hue angle (H) and colour intensity (C*) can be calculated from a* and b*. The honeys with the greatest purity of colour were the sun flower and tilia samples; the acacia samples exhibited the least purity of colour. The colour intensity of the samples is different from a floral source to another one. The sun flower sample had the highest colour intensity, followed by tilia and acacia honeys. All the colour parameters were significantly different. Keywords: luminosity, colour intensity, hue angle 1. Introduction The colour of honey is one of its most variable features. Honeys show very different colours, varying from white or pale yellow to dark red or even black [1]. The colour of honey is characteristic of its floral source due to minerals and other minor components. Exposure to heat and storage time may affect honey’s colour. Honey appears lighter in colour after it has granulated. The colour of a specific sample of honey, after it granulates depends on the crystal size. The final crystals give the lightest appearance. For this reason, most cremed honeys are opaque and light in colour. Honey can become darker as a result of storage, although at widely differing rates. This depends upon the composition of the honey (acidity, nitrogen, and fructose contents) and its initial colour. Generally, the darkening of honey is temperature sensitive and occurs more rapidly when honey is stored at high temperatures [2]. Many studies have dealt with the relation of honey colour to the floral origin, industrial processing methods, and the temperature and/or time of storage [3, 4, 5, 6]. In other study, the influence of the pollen grains, their morphology and colour, on the honeycolour has been considered [7]. However, in spite of the great importance of the colour of honey as an indicator of its origin and quality, there is no official method for its determination. Thus, as for other foods, the method proposed by Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel MareUniversity - Suceava Volume XI, Issue 2 – 2012 30 the Organisation Internationale de la Vigne et du Vin [8] for the colourimetric analysis of grape-derived products, which is a simplification of the CIEYxy [9] with the CIE 1931 Standard Observer (2° visual field) based on the consideration of the whole visible spectrum, is used. The L*, a*, and b* values explain a 3- dimensional colour space. The L* value is the vertical axis and defines the lightness, and a* and b* values are perpendicular horizontal axes and define red-to-green and blue-to-yellow, respectively. In addition, hue angle (H) and chroma (C*) can be calculated from a* and b*. H is distributed in the 4 quadrants of the a* and b* plane, and C* is higher the further it is from the origin of the coordinate [10]. The purpose of this work is to classify the honey (from different unifloral sources) based on the colour profile in CieLab coordinates. 2. Materials and methods 2.1. Materials 15 samples of honeys (5 samples of acacia, 5 samples of tilia and 5 samples of sun flower) were purchased from the local market of Suceava county. Before being used they were warmed up to 55 °C to dissolve any crystals, and kept in flasks at 30 °C to remove air bubbles that could interfere the colour studies. 2.3. Colour measurement The colour measurement was achieved with using spectrometer Ocean Optics (USA). The samples were fitted in plastic flask with 3.8 cm height and 6 cm diameter. To measure the reflected light is opened a diagram of 8 mm. The reflection specters are registered and are calculated the CIELab parameters are calculated at a 100 angle, using the D65 light: L*(luminosity, between 0[black], at 100 [white]), a*(+a*[red], -a* [green]), b*(+b*[yellow], -b*[blue]) and h* [tone]. In figure 1 is presented the L*, h and C*. The colour intensity C* (eq.1) is calculated as: (1) The hue angle (eq. 2) is computed as: (2) In figure 1 is presented the L*, h and C*. Fig.1. L*, C*, h* colour space [11] 2.7. Statistical analysis An analysis of variance (ANOVA) (α=0.05) with least significant difference (LSD) test using Statgraphics Plus 5.1 were performed on the data colour parameters. The variables were weighted with the inverse of the standard deviation of all objects in order to compensate for the different scales of the variables. 3. Results and discussion The colour of honey is different from a floral source to another one. To characterize the honey samples in terms of colour, they were plotted in their corresponding positions Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel MareUniversity - Suceava Volume XI, Issue 2 – 2012 31 on the a*-b* and a*-L* colour spaces (Fig. 2 and 3). On the a*-b* colour space, the nearer a honey is to the origin, the less purity of colour it has, and the further away it from the origin it is, the greater its purity is. The honeys with the greatest purity of colour were the sun flower and tilia samples; the acacia samples exhibited the least purity of colour. Sun flower and tilia samples had the greatest yellow component (highest b* values). Sun flower and tilia samples had a high red component (a*), while the tilia sample had weak green component (-0.43, tab. 1).The diference between honeys in function of the components a* and b* are statistical semnificative (P<0.001). Figure 2 shows tilia and acacia honeys were clearer (higher L* value) than the other varieties. Sunflower honey is not so clear then the other ones (L* values are much smaller than in the case of acacia and tilia). The luminosity of honey samples was significantly different (P<0.001). Tab.1. Colour parameter of honey Colour Parameter Honey type F-value Acacia Sun Flower Tilia L* 56.61a 44.88b 50.01b 7.13*** a* -0.43c 6.13a 3.33b 18.66*** b* 17.76b 23.07ab 24.43a 3.39* C* 17.89b 24.10a 24.88a 4.53* h -1.15b -2.57b 3.36a 7.34** The colour intensity of the samples is different from a floral source to another one. The sun flower sample had the highest colour intensity, followed by tilia and acacia honeys. The colour intensity could be influenced by the presence of the pigments from the floral source into the sun flower honeys. The colour intensity was significantly different (P<0.05). The hue angle is significantly different (P<0.05) from a floral source to another one. The highest hue angle is achieved in the case of tilia honeys, while the acacia and sun flower had a negative hue angle. Fig.2. a*-b* colour components of honeys – blue circle acacia, red rhombus – tilia, green triangle - sunflower The colour values obtained were within the expected ranges for each of the honeys studied. The most colour values reported in the literature generally correspond to measurements made by the Pfund scale (mm; [12, 13]). Although only a few studies had used CIELAB (L*, a*, b*) to measure colour in nectar and honeydew honey [14, 15] their results were similar to this study. Fig.3. a*-b* colour components of honeys– blue circle acacia, red rhombus – tilia, green triangle – sunflower Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel MareUniversity - Suceava Volume XI, Issue 2 – 2012 32 4. Conclusion The colour of honey could be chosen as reliable indicator of its floral origin. The honeys with the greatest purity of colour were the sun flower and tilia samples; the acacia samples exhibited the least purity of colour. Sun flower and tilia samples had the greatest yellow component (highest b* values). The sun flower sample had the highest colour intensity, followed by tilia and acacia honeys. The colour intensity could be influenced by the presence of the pigments from the floral source into the sun flower honeys. The highest hue angle is achieved in the case of tilia honeys, while the acacia and sun flower had a negative hue angle. All the colour parameter were significantly different. 5. References [1] Gonzalez-Miert, M.L., Ayala, F., Terrab, A., Echavarri, J. F., Negueruela, A.I. Heredia, F. J., 2007, Simplified method for calculating colour of honey by application of the characteristics vector method, Food Research International, 40, 1080-1086 [2] USA National Honey Board (303) 776-2337 [3] Crane, E. (1984). Bees, honey and pollen as indicators of metals in the environment. Bee World, 65, 47–49. [4] Fe´ller-Demalsy, M. J., Vincent, B., & Beaulieu, F. (1989). Mineral content and geographical origin of Canadian honeys. Apidologie, 20, 77–91. [5] Free, J. B., Williams, I. H., Pinsent, R. J. F. H., Townshend, A., Basi, M. S., & Graham, C. L. (1983). Using foraging honeybees to sample an area for trace- metals. Environmental Entomology, 9, 9–12 [6] Pereyra, A. G., Burin, L., & Buera, M. P. (1999). Colour changes during storage of honeys in relation to their composition and initial colour. Food Research International, 32, 185–191. [7] Terrab, A., Gonza´lez-Miret, M. L., & Heredia, F. J. (2004). Colour characterisation of thyme and avocado honeys by diffuse reflectance spectrophotometry and spectroradiometry. European Food Research and Technology, 218, 488–492. [8] OIV (1979). Recopilacion de los metodos internacionales de analisis de vinos. Madrid: Publicaciones del Ministerio de Agricultura. [9] CIE 15:2004, Technical report colourimetry, 3rd ed. Commission Internationale de l’Eclairage Central Bureau. [10] Bakker J, Bridle P, Timerlake F. 1986. Tristimulus measurements (CIELAB 76) of port wine colour. Vitis 25:67–78. [11]www.konicaminolta.com/about/research/core_tec hnology/optical/instrument_001.html [12] Corbella, E., & Cozzolino, D. (2006). Classification of the floral origin of Uruguayan honeys by chemical and physical characteristics combined with chemometics. LWT- Food Science and Technology, 39, 534–539. [13] Persano-Oddo, L., Gioia-Piazza, M., & Zellini, G. (1995). Caratteristiche cromatiche dei mieli uniflorali. Apicoltura, 10, 109–120. [14] Terrab, A., Gonzalez, G. A., Diez, M. J., & Heredia, F. J. (2003a). Mineral content and electrical conductivity of honeysproduced in Northewet Morocco and their contribution to the characterisation of unifloral honeys. Journal of the Science of Food and Agriculture, 83, 637–643. [15] Lazaridou, A., Biliaderis, C. G., Bacandritsos, N., & Sabatini, A. G. (2004). Composition, thermal and rheological behaviour of selected Greek honeys. Journal of Food Engineering, 64(1), 9–21. 15 samples of honeys (5 samples of acacia, 5 samples of tilia and 5 samples of sun flower) were purchased from the local market of Suceava county. Before being used they were warmed up to 55 °C to dissolve any crystals, and kept in flasks at 30 °C to remove air bubbles that could interfere the colour studies. 15 samples of honeys (5 samples of acacia, 5 samples of tilia and 5 samples of sun flower) were purchased from the local market of Suceava county. Before being used they were warmed up to 55 °C to dissolve any crystals, and kept in flasks at 30 °C to remove air bubbles that could interfere the colour studies. 15 samples of honeys (5 samples of acacia, 5 samples of tilia and 5 samples of sun flower) were purchased from the local market of Suceava county. Before being used they were warmed up to 55 °C to dissolve any crystals, and kept in flasks at 30 °C to remove air bubbles that could interfere the colour studies.