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Newsletter January 2021

The IDEA consortium started the year 2021 with their 7th general consortium meeting on January 12-13th. After presenting the progress made, the remaining activities were listed and plans were made to finalize the project tasks before the final event.

The IDEA final event will be organized as an online event on July 6th, with lectures, break-out discussion sessions and virtual tours. In addition, an e-poster session will be organized to share additional information on IDEA results.  Other projects are welcome to contribute as well to the e-poster session.  A call for abstracts will be launched soon via the IDEA website. More information about the final event will be made available soon.

 

 

Wet preservation of algae biomass

It is often impossible in practice to process micro-algae immediately after their cultivation and harvest. Therefore, an optimization of algae preservation is one of the project goals of IDEA, with a focus on optimizing the wet preservation of algae. Wet preservation of algae allows us to bridge the time between harvest and processing while avoiding the costs and nutritional losses associated with algae drying. When algae can be stored for a few days, algae processing does not have to take place at the same place as algae growth. Temporary algae preservation eliminates the need for immediate and local processing and enables centralized processing. In this way, the equipment for processing can be shared among algae growers and the associated costs are reduced. VITO examined wet preservation in detail for two algae species.

On the left image we can see local processing, on the right image we can see centralized processing.
  • Storage of Nannochloropsis gaditana
First, lab-scale tests were performed to identify suitable storage conditions for the wet preservation of Nannochloropsis gaditana concentrates. The impact of storage temperature, time and the way of closing the storage recipient was evaluated. The study demonstrated that temperature control is needed because off-odors were rapidly formed during uncooled storage. Acetic acid supplementation(50 mM) suppressed the formation of short-chain fatty acids during 8°C storage in unsealed recipients and reduced the aerobic microbial count and the number of yeasts and molds. Yet, acetic acid addition also induced lipid hydrolysis and decreased chlorophyll levels when algae were stored for more than one week. It can be concluded that temperature control is needed and that acetic acid addition is a promising approach when N. gaditana concentrates are stored for less than one week. The details of this study can be found here.

The next step was to test the storage of N. gaditana on a pilot scale. An N. gaditana culture was stored under continuous stirring in a 2 cubic meter vessel (picture below) and kept at 8°C.



In a first pilot-scale test, no large organic matter or chlorophyll loss was observed. Also the mass of organic matter obtained by centrifugation of the stored culture did not decrease. In a second pilot-scale test, the culture had experienced stress before the start of the experiment. This was inferred from the rather high free fatty acid level in the initial biomass (around 10% of oil). Moreover, there was a significant organic matter loss during storage. The relative levels (expressed as a % of the pellet obtained by centrifugation) of lipids and eicosapentaenoic acid (the most valuable fatty acid in Nannochloropsis) did not decrease during storage while the relative free fatty acid level (indicator for lipid hydrolysis) decreased slightly.
 
It can be concluded that these storage conditions avoid respiration losses and limit chlorophyll degradation during storage of a healthy N. gaditana culture. However, respiration losses become significant when a stressed culture is stored in this way.
  • Storage of Porphyridium purpureum
Lab-scale tests were performed to identify good storage conditions for the wet preservation of Porphyridium purpureum. Algae were stored either as a concentrate or as a dilute culture at 4°C, 8°C, or 20°C for 14 days and their quality was monitored.



Concentrate storage tended to result in higher microbial numbers than dilute culture storage and clearly led to higher concentrations of malodorous organic acids. Butyric and isovaleric acid concentrations were about two orders of magnitude larger than their odor threshold values after 14 days of concentrate storage at 20 °C. Average B-phycoerythrin (B-PE) levels were slightly higher after concentrate storage than after dilute culture storage, probably due to respiration losses of other organic compounds in the first case. Significant amounts of organic matter got lost during concentrate storage (4–35%) as a result of carbohydrate degradation. The main restriction of concentrate storage was the rapid viscosity increase and formation of a weak gel structure complicating the later processing of the concentrates. All details of this study can be found here.

Based on the results of the lab-scale test, it was decided to start a pilot-scale storage test with Porphyridum purpureum. A 400 L culture was stored for 3 weeks at 8°C under continuous stirring. No large organic matter losses were observed during this period. Accordingly, the losses of glucose and carbohydrates in general were minimal. Moreover, the B-phycoerythrin level did not decrease during storage either. Rheology analyses on the pellets obtained after centrifugation of the fresh and stored biomass indicated that the pellets displayed predominantly elastic behavior. The gel stiffness was higher for the pellets obtained after storage than for the pellets obtained from the fresh biomass. In addition, the viscosity of the fresh pellets was lower than that from the pellets obtained after storage. These rheological data point towards a stronger interaction between Porphyridium cells for stored biomass than for fresh biomass. All in all, these results suggest that the tested storage method is appropriate for Porphyridium storage at pilot-scale.

IDEA Farmer's webinar in September 2020

In the search for new protein crops, many crops are put forward. One of those interesting crops is algae. Most people are familiar with macro-algae, seaweeds, and may have eaten them sushi wrapping sheets. Less known to the general public are the micro-algae, single-celled organisms of which Spirulina and Chlorella are the best known. These are often offered in powder and tablet form as a dietary supplement.

With the aim to emphasize on microalgae as potential new crop for farmers, IDEA partners Centrale Supélec (France) and Innovation Support Center (Belgium) organized two farmer workshops, one in French (16/9/2020) and another in English (17/9/2020). The topics covered were:
  • Introduction and explanation of the IDEA project goals;
  • Market potential of the microalgae with also attention to the added value of microalgae in food or food supplements;
  • Possibilities of circular production of micro-algae;
  • The economic side of algae production;
  • Cultivation systems & semi-industrial production of micro-algae;
  • Practical applications of micro-algae such as human and animal nutrition and certification.
More than 80 participants from all over the world were brought together, from the USS over Europe and Africa to Australia and China. The diversity of feedback received is summarized in the word tree above. We made the presentations available on our website for those who were not able to attend.

Short updates

  • In the Sunbuilt algae growth pilot plant (Geel, Belgium) Chloromonas is growing in 1500 L photobioreactors under supervision of Thomas More, while VITO is preparing to start harvesting early February. The Submerged membrane technology (MAF) will be used for preconcentration of biomass and medium re-use.
        
  • IDEA collaborates with the Interreg 2seas project ValgOrise by integrating in the IDEA final event the ValgOrize stakeholders meeting. ValgOrize aims at using micro-algae and seaweeds as flavorsome ingredients for food and feed applications. More information can be found here.

Upcoming events

  • July 6th 2021: Final IDEA event

Any questions?

 
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