## 3 Results and Discussion
### Physico-Chemical Properties  
#### 3.2.1 Color Characteristics  
CIELAB color characteristics (\(L^{\star}\), \(a^{\star}\), \(b^{\star}\)) and calculated color attributes Chroma (C*) and hue angle (\(l^{\star}\)) of strained yogurt and _Kurut_ samples are given in Table 5. The drying temperature and drying technique interaction were found significantly effective on color parameters of the _Kurut_ samples (\(p\) < 0.05) (Table 5). 45 \({}^{\circ}\)C resulted in a decrease in whiteness (\(p<0.05\)) (Table 5). \(L^{\star}\) is a temperature dependent parameter according to [PERSON] et al. [51] and brown pigment formation depending on heating intensity could cause a decrease in \(L^{\star}\) values according to [PERSON] et al. [52; 53]. Strained yogurt and KV35 and KV45 had negative \(a^{\star}\) values characterized by greenness. KV35 and KV45 were significantly different than K35 and K45 (\(p<0.05\)) (Table 5). No statistical difference was observed between KV35 and KV45. The temperature increase caused an increase in greenness in KV35 and KV45, which was consistent with the results found by [PERSON] [50] under vacuum conditions. In general, yogurt is characterized by negative \(a^{\star}\) and positive \(b^{\star}\) values [51; 22; 52]. Redness (positive \(a^{\star}\) values) was pronounced in K35 and K45 and increased with the rising drying temperature from 35 \({}^{\circ}\)C to 45 \({}^{\circ}\)C in the OD technique (Table 5) (\(p<0.05\)). The transfer of \(a^{\star}\) from green to the red hue may be due to the samples' exposure to more intense heat for longer periods in the OD technique to achieve the maximum possible dryness. Additionally, non-enzymatic browning reactions related to drying conditions of K35 and K45 could cause an increase in redness. The temperature of drying, and the duration that the product is exposed to, affects the degree of non-enzymatic browning reaction and also the color attributes [54]. All samples showed positive \(b^{\star}\) values, indicating yellownness in the color space (Table 5). There was a significant difference between KV45 and K45 in terms of \(b^{\star}\) related to the vacuum existence or not (\(p<0.05\)). The temperature increase from 35 \({}^{\circ}\)C to 45 \({}^{\circ}\)C was found significant only for K35 and K45 (\(p<0.05\)), (Table 5). The color intensity of the strained yogurt increased with drying, represented by higher chroma (C*) values in the Kurut samples. In the samples, C* values were close to each other except for K45 having the highest chroma value (Table 5). Higher C* describes how intensely a sample is perceived by the human eye, meaning that the stronger the color, lower values mean the grey color is paler [38; 51]. Strained yogurt, KV35 and KV45 had negative hue angles (\(h^{\star}\)) (Table 5). Hue angle (\(h^{\star}\)) defines the degree of difference of a definite color by taking the grey color as a base. From angles 0\({}^{\circ}\) to 360\({}^{\circ}\), the definition of color changes as; angels of 90\({}^{\circ}\), 180\({}^{\circ}\) and 270\({}^{\circ}\) represent yellow, green and blue hues, respectively. The angles of 0\({}^{\circ}\) and 360\({}^{\circ}\) exactly represent the red hue [38]. The VOD application did not affect the \(h^{\star}\) values of KV35 and KV45 much differently than the strained yogurt. High hue angles indicate lower yellow character in the product which is the strained yogurt, KV35 and KV45 were less yellow than K35 and K45. Values of \(h^{\star}<90^{\circ}\) calculated for K35 and K45 represent the color of the samples in the yellow/red region. In the literature, there is a lack of study describing the color properties of _Kurut_ product. In general, _Kurut_ is characterized with its slightly whitish-cream or light-yellow color. The degree of whiteness of _Kurut_ is directly related to the fat content of the raw milk, drying conditions, storage temperature and time. In Figure 2, derived color indices of _Kurut_ samples are represented.