The global yeast autolysates and extracts industry is expanding dynamically, with annual market growth rates projected at 5.8% between 2024 and 2034. Market drivers include the rapid growth of the processed food market. One of the primary uses of yeast extract is as a natural ingredient for savory flavor creation and enhancement, salt replacement, and nutritional profile enhancement of processed foods.
Fermentation is key to producing yeast extract from virgin yeast cultures. After fermentation, yeast cells undergo self-digestive autolysis, where enzymes break down the cells and release their contents. Spent yeast from other processes, like brewer’s yeast, can also be used. The autolyzed yeast is then purified, separating the yeast extract from the remaining cell mass through centrifugation and clarification to eliminate spent cell fragments and suspended fines.
Today’s yeast extract manufacturers seek cost-effective, eco-friendly clarification solutions that provide high product quality and maximum yield while ensuring process reliability and minimal waste.
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Challenge
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Solution
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Benefits
After biomass separation, a yeast extract manufacturer sought to replace old rotary vacuum drum filters and pressure leaf filters for yeast extract clarification. Using diatomaceous earth (DE) filter aids resulted in several thousand tons of waste annually, leading to high disposal costs and significant product losses. The abrasive DE also escalated maintenance expenses and required intensive labor for daily management.
Additional trap filtration was employed for further purification, but it did not consistently meet premium quality standards, often necessitating varying fining agents. Additionally, pressure leaf filters were ineffective for pre-concentrated yeast broth.
The new separation technology needed to provide optimal clarification to produce premium products with maximum yield while focusing on cost and waste reduction. It needed to be automated, reliable, simple, and robust.
Membralox ceramic crossflow technology was chosen for its superior filtrate quality. Unlike diatomaceous earth filtration, membrane separation offers a consistent barrier for precise separation, independent of initial broth properties.
In crossflow filtration, feed fluid sweeps across the membrane, allowing permeate (filtrate) to pass through while recirculating and concentrating retentate.
Membrane cut-off selection depends on the yeast source and broth quality; fermented virgin yeast uses 100 nmZ membranes, while spent brewer’s yeast requires 50 nmZ membranes due to increased cell fragmentation.
Process Flow diagram for yeast extract production
Enclosed, Filter Aid-Free Systems
The enclosed ceramic system limits product exposure to the environment and potential contamination. Ceramic technology operates without the need for filter aids and their associated storage, handling, and waste disposal costs.
Workers’ exposure to DE filter aids is eliminated. The retentate stream can be reintroduced into lower-value process streams or dried and sold as animal feed, reducing the environmental burden.
Crossflow Filtration Principle
High Product Yield
High volumetric concentration factors (VCF) and diafiltration optimize mass transfer yield into the permeate. In low-concentration yeast extract, solids are concentrated from 1% to 50% (VCF=50) with a 98% recovery. For pre-concentrated yeast extract with higher solids, approximately 20% is concentrated to 50% (VCF=2.5) with additional diafiltration, achieving a 92% recovery.
The size of the membrane channels impacts the ability to achieve the required VCF. The larger the channels, the greater the ability to attain high VCF and high permeate yield. Both 4 mm (EP48- 40IC) and 5.5 mm (EP27-60IC) channels are available, and their selection is based on product concentration, viscosity and suspended solids load in the feed fluid (Figure 3).
The optimal balance of flux and trans-membrane pressure (TMP) enhances product recovery. Membralox IC membranes are designed for compactness and maximize the filtration area for yeast extract clarification, offering 39-47% more filtration area than traditional concentric ring ceramic membranes. This compact module design improves system configuration and cost efficiency, allowing 400 m² of membrane area to fit within a 20 m² footprint.
Choosing Membralox IC instead of traditional ceramic membranes offers the following:
- CAPEX savings from a higher membrane area in fewer modules, reducing hardware needs.
- OPEX savings from reduced hold-up volume, leading to lower cleaning water and chemical usage, less wastewater, and energy savings.
Membralox ceramic crossflow technology enabled the production of premium quality yeast extract at an attractive cost of ownership due to the following factors:
- Precise membrane separation of desirable product components
- Elimination of any further filtration steps after crossflow microfiltration
- High product recoveries on both low-concentration and pre-concentrated feed fluid
- Waste and disposal cost reduction, reuse of retentate stream possible
- Labor cost reduction
- Minimal maintenance costs, elimination of DE-caused abrasion to plant equipment
- Energy savings in comparison to rotary vacuum drum filtration
- Maximum product protection due to the enclosed system
- Elimination of operator exposure to DE
- Process simplicity, reliability and safety due to system automation
- Space and cost savings due to a compact footprint
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