# Production of Vegan Ice Cream: Enrichment with Fermented Hazelnut Cake
## 3 Results and Discussions
### Enzyme Inhibition Profiles of Ice Cream Products Before and After In Vitro Digestion
The highest inhibition was observed in HIC, whereas FHIC exhibited the lowest inhibition. Notably, DIC, which lacked ACE inhibition before digestion, displayed substantial inhibitory activity post-digestion, likely due to the release of bioactive peptides from hydrolyzed milk proteins--a well-documented source of ACE-inhibitory peptides [65; 66]. Despite expectations of enhanced bioactivity in FHIC due to fermentation, its ACE inhibition was only 65% of HIC's activity, suggesting that inhibitory potency depends more on peptide sequence and amino acid composition than on peptide abundance. No AChE inhibition was detected in any ice cream sample before digestion. However, post-digestion, inhibition levels ranged from 51.56 \(\pm\) 0.23% to 74.37 \(\pm\) 1.56% at a concentration of 1 mg/mL. The lowest inhibition was observed in digested DIC, with a slight increase in digested HIC. Consistent with ACE inhibition trends, fermentation-derived peptides in FHIC may contribute to higher AChE inhibition. In contrast to the observed increase in AChE inhibition following the digestion of ice cream-derived peptides, gastrointestinal digestion has been shown to significantly reduce (\(p\) < 0.05) the AChE-inhibitory activity of plant phenolic-rich extracts (e.g., carob, grape pomace, and chestnut shell). This is likely due to the structural degradation of labile phenolic compounds (e.g., gallotannins and anthocyanins) under digestive pH conditions, altered bioavailability from interactions with digestive enzymes and bile salts, and depolymerization of high-molecular-weight polyphenols into inactive monomers [67; 68]. Unlike other enzymes, lipase inhibition was observable in undigested ice cream samples (39.40 \(\pm\) 2.98% to 45.12 \(\pm\) 0.34% at 0.0025 g/mL) but was not present after digestion, indicating the degradation of lipase-inhibitory components by digestive enzymes or interactions with other gastrointestinal elements. Notably, the digestion medium itself exhibited \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Ice Cream** & **\(\alpha\)-Amylase/\(\alpha\)-Glucosidase** & **ACE Inhibition** & **AChE Inhibition** & **Lipase Inhibition** \\  & **Inhibition (\%)** & **(mg captopril/g)** & **(\%)** & **(\%)** \\ \hline DIC & N.D. & N.D. & N.D. & 45.12 \(\pm\) 0.34  \\ HIC & N.D. & 0.76 \(\pm\) 0.01  & N.D. & 39.40 \(\pm\) 2.98  \\ FHIC & N.D. & N.D. & N.D. & 39.94 \(\pm\) 2.23  \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Enzyme inhibition activities of ice cream products. 32.12% lipase inhibition, indicating potential interference from digestive components. This pattern diverges from trends observed with phenolic-rich plant extracts. The lipase inhibition increased post-digestion due to the release of bioactive phenolics (e.g., gallic acid and epigallocatechin gallate in green tea) because digestive enzymes hydrolyze polyphenol complexes, thus enhancing their activity [69; 70]. A similar loss of lipase inhibition post-digestion was reported for milk phospholipids due to bile salt displacement of inhibitors at lipid-water interfaces [71].