3.2. Colour of fractions of the glucan isolation process
The result for colour of fractions obtained from the glucan isolation process was recorded using CIE lab colour space and is presented in Table 1. Fraction F4 obtained by hot water and enzymatic extraction steps contained significantly (p < 0.01) higher values of lightness (L∗). A high degree of brightness could have a technologically favourable advantage when the raw ingredient (β-glucan) has to be added to light or transparent food products, since their incorporation would be unlikely give these food products a spoilt or darker appearance ( Ahmad et al., 2009 and Ahmad et al., 2010). A relatively lower value of redness (a∗) was observed (p < 0.01) in yeast cell wall fraction (F1), whereas the a∗ value of fraction F2, when hot water treatment was applied, was higher and statistically significant (p < 0.01). With regard to the b∗ values, these varied significantly (p < 0.01) in all fractions. Higher b∗ values in fractions F3 and F4 can be explained by the fact that glucan extracted by enzymatic steps (savinase and lipolase enzymes) has a slightly yellowish appearance that affects the suitability of extracted glucan in food products. Maillard reaction products are possibly the molecules that contribute to the yellowish colour. In fact, fraction F3 and F4 contained the highest β-glucan content (Borchani et al., 2014) and consequently the most glucose, which contributes to Maillard reactions.