Analysis of change of the colour parameters of paprika powder with different added oleoresin

Abstract

The instrumental colour measurement isn’t used in course of the making and the qualification of the paprika powder, although the colour is the most important sense property of its. Paprika is also used as a natural food colour. The colour of paprika powder is very important too, because the consumer concludes its colouring power based on its colour. The colouring power is determined by quality and quantity of colouring agent of paprika squarely. The colour of the powder is influenced by its particle size, oil content and moisture content and first of all the colour agent content.We investigated how the colour agent content increasing influences the colour characteristics of paprika powders. The L*, a*, b* colour coordinates defined in the CIELab colour space were applied for the colour characterization. The measurements were carried out using a Minolta CR-300 tristimulus colour analyser.We loosed the colour agent from the paprika powder samples using acetone. The colour agent content of obtained samples was less than 10 ASTA units. After different quantity of oleoresin ( 0.0186 g, 0.0461 g, 0.0626 g, 0.0953 g, 0.3500 g, 0.6399 g) was added to samples of 10 g of powder. The colour characteristics and colour agent content of these samples were determined. The relation between colour agent content and colour coordinates was analysed using regression analysis and the colour differences ΔE*_ab were determined between samples with different colour agent content.The results depicted that L* lightness coordinate decreased with increasing colour agent content, the points fitted on a reciprocal function with a significant correlation ( p=0.01). In the case of a* redness coordinate the points fitted on a saturation function (0.01), the redness coordinate didn’t change above 129 ASTA units. The b* yellowness coordinate increased to 97 ASTA units, then decreased, the points fitted on a second degree function with a significant correlation (p=0.01). The function has maximum at 97.17 ASTA units; the maximum value was 25.22 coordinate units. The value of hue angle (h^o_ab) progressively decreased while the colour agent content was added. The C*_ab chroma increased to 121 ASTA units, then decreased, the points fitted on a second degree function with a significant correlation (p=0.01). It depicts, that the colour of powder became more red and darker as the colour agent content increased. The colour differences ΔE*_abcalculated between samples with different colour agent content were smaller above 130 ASTA units. It shows that the rate of the change of the paprika powders colour was smaller while the colour agent content increased.