Unlocking the Secrets of Yeast Proteases in Ham Flavoring

Biting into a slice of dry-cured ham. The rich, savory taste that bursts in your mouth is a result of complex processes. Yeast proteases, enzymes that break down proteins, play a big role in this flavor development. But how exactly do they work their magic? Scientists have been curious about this for a while. Let's talk about two types of yeast proteases: Rhodotorula mucilaginosa AUMC 9298 (RM) and Candida parapsilosis d70a (CP). These were found in Jinhua ham, a famous Chinese delicacy. Researchers wanted to see how these proteases affect the taste of dry-cured ham. First, they checked how well these proteases work under different conditions. It turns out, RM and CP proteases are quite active at a pH range of 5. 0 to 8. 0 and temperatures between 30 to 50°C. This is important because it shows they can work well in the conditions found in dry-cured ham. Now, let's talk about how these proteases break down myofibrillar proteins (MP), the main proteins in muscle. RM proteases are particularly good at degrading myosin, a type of MP. This is a key finding because myosin is a major component of meat proteins. The researchers also looked at the free amino acids released during this protein breakdown. After just 4 hours of hydrolysis, the total free amino acid content increased significantly. RM had the highest content at 33. 91 mg/100 mL, followed by CP at 25. 28 mg/100 mL, and Pichia kudriavzevii XS-5 (PK) at 18. 44 mg/100 mL. This increase in free amino acids is crucial for flavor development.To understand the flavor profile better, the researchers identified 32 metabolites using LC-MS/MS. They found that peptides and amino acid derivatives were the key components of MP hydrolysates. These compounds contribute to the overall taste of the ham. Now, let's talk about the taste parameters. The scores for umami, richness, and aftertaste were highest in RM. This suggests that RM proteases are particularly effective in enhancing these flavor aspects. To find out which compounds are responsible for these taste improvements, the researchers used PLS-DA and correlation analysis. They discovered that compounds like aspartic acid, N-Methyl-aspartic acid, Glu-Glu, γ-Glu-Cys, glutamic acid, γ-Glu-Glu, and γ-Glu-Gln were positively correlated with the improvement of umami, richness, and aftertaste. This means these compounds play a significant role in making the ham taste better. So, what does all this mean? It shows that yeast proteases, especially RM, can greatly enhance the taste of dry-cured ham. By breaking down proteins and releasing key flavor compounds, they contribute to the rich, savory taste that we all love. This knowledge could help in developing even better-tasting hams in the future.