11 Flashcards
What are the essential features of an ideal fermentation system?
It should have an appropriate design for the type of substrate and product, efficient yeast/substrate separation, capacity matched to facility needs, hygienic design, efficient CIP system, and effective control and monitoring systems.
How is vessel type selection crucial for an ideal fermentation system?
Vessel type and facility design should consider efficient volume gauging, attemperation systems, gas control, foaming control, and CO2 collection.
What materials are commonly used in fermentation system construction and why?
Stainless steel is favored for its durability, corrosion resistance, high thermal conductivity, and its smooth, easily cleanable surface.
What are the benefits of using top cropping systems in brewing?
Used with top fermenting ale strains, typically unsophisticated attemperation systems, can be made from traditional materials, suitable for 50 – 500 hl capacities.
What are the advantages of cylindroconical fermenters?
Closed design ensures excellent hygiene, suitable for large batch sizes, excellent draining properties, suitable for pressurization and CO2 collection, and allows efficient waste material removal.
What are the disadvantages of cylindroconical fermenters?
Potential yeast crop contamination with non-yeast solids, high hydrostatic pressures can stress yeast, possible flavor effects, and difficulties in post-fermentation additions.
Describe the design and function of vertical cylindrical fermentation vessels.
These have a capacity of 300 – 1500hL, are relatively inexpensive, have good cleaning and draining properties, but cropping is less efficient.
Describe the design and function of horizontal cylindrical fermentation vessels.
Typically 150 –1000 hL capacity, avoids high hydrostatic pressures, built on a slight incline to facilitate emptying, but yeast crop removal and CIP efficiency can be challenging.
What is the design significance of spheroconical fermenters?
Designed to enclose maximum volume within minimum surface area, excellent mixing, cleaning, and cooling characteristics, but expensive to manufacture and transport.
What are the stages involved in second-generation bioethanol production?
Involves Separate Hydrolysis and Fermentation (SHF), Simultaneous Saccharification and Fermentation (SSF), and Consolidated BioProcessing (CBP).
Explain the SHF method in lignocellulosic ethanol production.
Separate hydrolysis and fermentation offer good process control but are time-consuming.
Explain the SSF method in lignocellulosic ethanol production.
Combines hydrolysis and fermentation into a single process for faster fermentation and more efficient enzyme activity, though harder to control.
Explain the CBP method in lignocellulosic ethanol production.
Aims to simplify the process by removing the requirement for enzyme additions, significant research and GMO are necessary.
What are the benefits of continuous fermentation systems?
Provides a continuous supply of product, reduces downtime, and should allow high-efficiency fermentation and consistent product if operated correctly.
What are the challenges associated with continuous fermentation systems?
Technically complex, inflexible, requires continuous substrate supply, high risk of microbial contamination, and selection of variant yeast strains.
How do batch and continuous fermentation systems compare?
Batch cultures are more flexible, suit varying product streams, and fit well with other batch processes in the plant, whereas continuous systems require careful control to mimic batch-like nutrient assimilation.
What are immobilized yeast reactors and their benefits?
Yeast is attached to an inert support medium, allowing high concentration and rapid reaction times in small, high-efficiency units, suited to bespoke tasks like flavor maturation or partial fermentation.
What are the considerations for choosing between several small vessels or one large vessel in a fermentation facility?
Several small vessels offer flexibility for multiple product types but have higher capital costs and poor space utilization. One large vessel provides efficient space use and simpler pipework but is less flexible.
How is fermentation progress typically monitored in industrial settings?
Typically done via offline sampling for substrate concentration, pH, and key flavor compounds; in-line systems provide continuous monitoring and can be integrated with control systems.
Summarize the factors to consider when choosing a fermentation system.
Fermentation system choice depends on the scale, product type, capital expenditure, and desired process control; cylindroconical vessels are globally popular due to their versatility and efficiency.
