# Production of Vegan Ice Cream: Enrichment with Fermented Hazelnut Cake
## 3 Results and Discussions
### Flow Behavior of Ice Cream Products  
The rheological properties of ice cream mixes were analyzed at 25 \(\mathrm{\SIUnitSymbolMicro C}\) and 35 \(\mathrm{\SIUnitSymbolMicro C}\) using shear rate versus shear stress measurements (Table 5). The fluids exhibited non-Newtonian behavior, necessitating logarithmic transformation (In) of shear rate and shear stress values for graphical representation. The flow behavior index (n) and consistency coefficient (k) were derived from these plots (Supplementary Table S1). All ice cream formulations demonstrated shear-thinning (pseudoplastic) behavior, as evidenced by \"n\" values < 1.0, consistent with prior studies on both dairy and vegan ice creams. Shear-thinning is typical in ice cream due to the disruption of colloidal structures (e.g., fat globules and protein networks) under shear stress [41]. The lower \"n\" values (higher pseudoplasticity) in DIC align with [PERSON] et al. (2025) [1], who attributed this behavior to casein micelles and fat globule interactions in dairy systems. Temperature dependence varied by formulation in DIC and HIC, and pseudoplasticity increased with temperature (reflected by a decrease in \"n\"), whereas FHIC exhibited the opposite trend. At 25 \(\mathrm{\SIUnitSymbolMicro C}\), significant differences (\(p\) < 0.05) in flow behavior were observed among formulations, \begin{table}
\begin{tabular}{c c c c c} \hline
**LRI * & **Compound** & **DIC** & **HIC** & **FHIC** \\ \hline
1210 & Limonene & - & 46.0 \(\pm\) 2.2 & - \\
1215 & 3-Methyl-1-butanol & - & - & 13.2 \(\pm\) 0.2 \\
1445 & Acetic acid & 15.3 \(\pm\) 0.2 & 13.7 \(\pm\) 0.6 & 14.5 \(\pm\) 0.4 \\
1506 & Pyrol & - & - & 39.2 \(\pm\) 1.4 \\
1525 & Benzaldehyde & - & - & 182.3 \(\pm\) 2.7 \\
1571 & 2-Methyl Propanoic acid & & - & 32.2 \(\pm\) 0.1 \\
1843 & Hexanoic acid & 15.5 \(\pm\) 1.1 & 6.0 \(\pm\) 0.1 & - \\
1958 & \(\mathrm{\SIUnitSymbolMicro\delta}\)-Octalactone & - & 108.3 \(\pm\) 0.9 & 172.2 \(\pm\) 2.6 \\
2072 & Octanoic acid & 116.0 \(\pm\) 4.9 & 43.0 \(\pm\) 3.4 & 50.2 \(\pm\) 3.0 \\
2079 & p-Cresol & - & - & 9.1 \(\pm\) 0.2 \\
2180 & \(\mathrm{\SIUnitSymbolMicro\delta}\)-Decalactone & - & 49.2 \(\pm\) 1.6 & 94.8 \(\pm\) 2.1 \\
2413 & Benzoic acid & - & - & 7.5 \(\pm\) 0.1 \\ \hline \end{tabular} Values are given as mean \(\pm\) standard deviation. * Linear retention index (LRI) values calculated for the D8-Wax column.  
\end{table} 
Table 4: Volatile compound composition of ice cream products (\(\mathrm{\SIUnitSymbolMicro g}\)/kg sample). with DIC showing the lowest n values and HIC the highest. At 35 \({}^{\circ}\)C, DIC retained the lowest \"n\" values, but the difference from HIC became statistically insignificant (\(p>0.05\)). The temperature-dependent augmentation of pseudoplasticity (reduced \"n\" at 35 \({}^{\circ}\)C) aligns with the observations of [PERSON] et al. (2000), who reported improved fat coalescence at elevated temperatures [42]. The shear-thinning behavior of HIC parallels the report by [PERSON] et al. (2009) on fiber-enriched ice creams, where coconut oil and hazelnut cake proteins might form shear-sensitive networks [43]. The anomalous trend in FHIC (increase in \"n\" with temperature) may reflect fermentation-induced protein hydrolysis, reducing structural integrity, a phenomenon observed in fermented plant protein matrices by [PERSON] et al. (2019) [4]. The analysis of \"k\" values revealed pronounced differences in consistency. Fermented hazelnut ice cream exhibited markedly lower k values (1.9-2.6) compared to plain (26.9-80.9) and hazelnut pulp ice creams. At 25 \({}^{\circ}\)C, the highest k values were observed in plain ice cream, followed by hazelnut pulp ice cream; both increased with temperature. In contrast, fermented hazelnut ice cream displayed negligible temperature-dependent changes in consistency. The significantly lower \"k\" values in FHIC (1.9-2.6 vs. 26.9-80.9 in DIC/HIC) suggest reduced viscosity, likely due to fermentation effects.