# Evaluation of Hazelnut Cake Flour for Use as a Milk Powder Replacer in Ice Cream
## 3 Results and Discussion
### Colour Properties  
Colour is an important parameter, first noticed during the food evaluation. Indeed, this attribute is considered the most important in terms of food appearance. There are a few systems for colour describing, such as RGB (red, green, and blue), Hunter \(L\)\(a\)\(b\), CIE \(L^{*}\)\(a^{*}\)\(b^{*}\), CIE \(X\)YZ, CIE \(L^{*}\)\(u^{*}\)\(v^{*}\), etc. [41]. This research utilized the CIELAB model, which enables colour comparison by measuring the difference in \(\Delta E^{*}\) value, thus enhancing the assessment of variations among samples. The incorporation of HPCF resulted in significant (\(p<0.05\)) changes in terms of \(L^{*}\), \(a^{*}\), and \(b^{*}\) values (Table 5). The \(L^{*}\) value (indicating lightness) of the control sample was significantly higher than that of the ice cream samples with HPCF. More precisely, \(L^{*}\) values decreased gradually along with increased HPCF concentration, from 91.03 to 71.40 for C-HN4. [PERSON] et al. [50] also reported that yoghurt supplementing with hazelnut skin decreased their \(L^{*}\) values. In addition, other studies that examined the incorporation of various materials with functional properties into ice cream have confirmed a trend of decreasing lightness [4; 36; 79]. The whitening index (_WI_) was also significantly (\(p<0.05\)) decreased because of the HPCF addition. These changes were expected since hazelnuts contain pigmented compounds such as carotenoids, flavonoids, and proanthocyanidins [80]. Regarding parameter \(a^{*}\), which indicates green (\(-a^{*}\)) and red (\(+a^{*}\)) shades, ice cream samples with replaced SMP showed positive values in the red domain (0.98-4.33), with an evident increase in these values. An increase in redness due to the incorporation of hazelnut milk in ice cream was previously reported [42]. In addition, [PERSON] and [PERSON] [18]  
Figure 4: Melting behaviour of ice cream samples: (**a**) pictures taken during the melting and (**b**) melting curves. The results are expressed as mean \(\pm\) SD. C—control ice cream; HN1, HN2, HN3, HN4—samples with 25%, 50%, 75%, and 100% replacements of SMP with HPCF. observed that increasing the level of hazelnut meal protein in functional beverages causes the rise of \(a^{*}\) values. A \(b^{*}\) values differed across samples so the clear trend for \(b^{*}\) was not noticed, but all samples with HPCF had significantly lower values (10.04-12.12) compared to the control sample (12.90). Furthermore, a clear trend of a significant increase in the browning index (\(BI\)) was observed as the ratio of HPCF increased. As a result, the samples containing hazelnut flour exhibit a \(BI\) ranging from 0.009 to 0.044, whereas the \(BI\) value for the control sample is recorded as negative, specifically \(-\)0.015. It was determined that \(h^{*}\) was significantly influenced by the level of SMP replacement. The highest hue value was found in the control sample (98.49) and it was reduced by increasing the HPCF concentration, resulting in the lowest value recorded for HN4 (70.37). The measure of chroma, reflecting the intensity or purity of colour, is observed to be decreased in samples that include hazelnut flour. This indicates that HPCF-enriched ice cream may have a more subdued or less brilliant colouration. The observed decline in the hue and chroma value of ice cream after the incorporation of HPCF in place of SMP could be a result of the darker pigmentation associated with hazelnut flour relative to milk powder, as well as potential interactions that may alter the light absorption characteristics of the blend. The largest total colour difference (\(\Delta E\)) was noticed in a sample with a 100% replacement of SMP, which indicates an impact of HPCF addition on the ice cream's colour. In addition, values for colour differences were in the range of 8.84 to 20.63, meaning there was a change in the colour properties of ice cream samples visible to the human eye, regarding the scale of visible differences.