Enzymes Flashcards
What are enzymes?
Proteins that act as biological catalysts, accelerating reactions without being consumed in the process.
All enzymes are proteins; they act as biological catalysts.
What does enzyme specificity refer to?
Each enzyme performs a specific function on a particular substrate to produce a specific product.
Each enzyme only does one job.
What factors affect enzyme activity?
Temperature, pH, and the presence of inhibitors like ethanol, glucose, polyphenols, and SO2.
List the classes of enzymes.
- Oxidoreductases
- Transferases
- Hydrolases
- Lyases
- Isomerases
- Ligases
- Translocases
What are pectinases and their role in winemaking?
Enzymes that break down pectins, increasing juice yield, decreasing turbidity, and improving lees compaction.
What are the different types of pectinases?
- Pectin Lyase
- Pectate Lyase
- Pectin methyl esterase
- Polygalacturonase
What do cellulases and hemicellulases do?
Degrade cellulose and hemicellulose, enhancing cell wall degradation and improving extraction of aroma/flavour compounds.
What are glycosidases and their function?
Enzymes that liberate bound aroma and flavour compounds by breaking down glycosidic bonds.
What can inhibit the activity of glycosidases?
Glucose, alcohol, and SO2.
What are glucanases used for in winemaking?
Degrade β-glucans to improve filterability and accelerate the development of autolysis characters during ageing.
What is the role of lysozyme in winemaking?
Hydrolyzes glycosidic bonds in gram-positive bacteria, inhibiting or delaying malolactic fermentation.
Where are commercial enzymes typically derived from?
Aspergillus niger and Trichoderma.
What is one potential disadvantage of glycosidase activity?
Some glycosidases can degrade anthocyanins, leading to colour loss.
What does cinnamyl esterase do?
Hydrolyzes the ester link on hydroxycinnamic acids, forming vinyl-phenols that can lead to medicinal/clove-like characters.
What is enzyme contamination in winemaking?
Can result in POF+ (Phenol off aroma positive) yeast strains.
Why should enzymes be used before bentonite fining?
Enzymes are proteins and can react with bentonite fining agents.
True or False: Enzymes always enhance wine quality.
False.
Fill in the blank: Enzymes can significantly improve winemaking and _______.
[wine quality]
