Moulds Flashcards
Are moulds eukaryotes and prokaryotes?
Eukaryotes
How are the filaments of moulds called?
Hypae
What is ragi used for in fermentation?
In uncooked rice as starter culture
What is the name of the mould used in blue veined cheeses?
Penicillium roqueforti
Can fungi produce B12 vitamin?
No, vitamin B12 is a bacterial metabolite
If one wanted to create a meat alternative which is fortified in vitamin B12 how could he do it?
Develop a lupine tempeh by fermentation with mixed culture between:
Rhizopus sp + B12 producing bacterium, for e.g., P. freudenreichii. As the fungi consumes oxygen, the anaerobic bacteria can grow and produce vitamin b12
Aspergillus oryzae describe the fungi.
It is an ascomycetes, has vegetative reproduction, the vegetative spores are situated at the conidia on swollen vesicles.
Penicillium roqueforti describe the fungi.
It is an ascomycetes, has vegetative reproduction, the vegetative spores are situated at the conidia on branched structures.
Rhizopus oligosporus describe the fungi.
It is a zygomycetes has vegetative and sexual reproduction, the vegetative spores are situated in the sporangiospores in the sporangia.
Does R. oligosporus grow on nitrate? What are good nitrogen sources for this fungi?
No. Good nitrogen source are ammonia and some amino acids.
In which sugars can R. olgiosporus grow?
Simple sugars not in complex ones such as raffinose, sucrose and stachynose.
Is soybean oil a good source for r. olgiosporus?
It is excellent. Will use the carbons in oil as source.
What is water activity and how is it determined?
The free water in the food product, not bound. It is determined by the vapor pressure of the solution over the water vapor pressure of pure water.
What is the general aw requirement for bacteria and fungi?
0.91 and 0.7
How is growth of aerobic mould affected by reduction of oxygen?
Relatively unaffected, O2 concentration can decrease down to 1%.
What is the effect of CO2 concentration on the growth of aerobic moulds. What is the optimal concentration?
Heavily reduce growth at high CO2. Optimal concentration is around 5% CO2. Above this, mould growth is inhibited.
Are lipids a good basis for production of flavours in moulds?
Yes
Which are the 4 groups of secondary metabolites produced by moulds?
- Antimicrobial compounds
- Texturizing agents
- Flavour -aromatic compounds
- Taste enhancers
How can esters amount be maintained or increased?
Promote alcohol conversion through acetyl CoA to ester or inhibit esterase which converts esters to alcohol +acid.
What is the difference between homologous and heterologous expression?
If the origin and the host mould are the same then it is homologous. But if the host is for example, A. oryzae and the origin is Thaumatoccocus danielli (plant) then this is a heterologous expression.
Do moulds work well in liquid fermentation?
No. They work good in solid fermentation.
