Spirulina Harvesting Techniques & Equipment

The blue-green algae, Spirulina is now gaining more attention due to its high nutritional value and global food insecurity. This cultivation has recently grown into a novel industry, shifting our perspective concerning the sustainable food industry. There is an increase in demand for advanced spirulina harvesting techniques and efficient processing technology.

Harvesting spirulina is a delicate and time-sensitive process to ensure that it remains nutrient-rich and intact. The major objective is to effectively remove the spirulina from the water while preserving its quality.

Designing an Ideal Cultivation System

An effective grasp of the cultivation system is required to enhance the total yield. It also entails improving other parameters such as light, nutrient levels, and other environmental factors. Three primary approaches have emerged: raceway pond optimization, photobioreactor innovations, and hybrid system approaches.

Raceway Pond Optimization

Raceway ponds are a widely adopted method for spirulina cultivation. These shallow, oval-shaped ponds allow efficient light penetration and circulation of the spirulina culture. To increase the productivity of a raceway pond, the parameters that can be varied include the depth, the speed of the paddle wheel, and the nutrients that are added. It has been demonstrated that one factor in which metabolism of the Arthrospira used for the production of spirulina is directly dependent on light energy availability, the productivity of a raceway pond system is likely to be volumetric at a high rate by optimizing the two parameters. In this case, the nutrients, as well as light, are sure to be utilized fully.

Photobioreactor Innovations

Photobioreactors are ideal for the cultivation of fresh spirulina because they allow the regulation of numerous factors including light, intensity,  temperature, and pH. Optimizing light use and reducing water consumption are some of the new goals achieved. For instance, with the use of optic fibers or thin-plate technology, it is possible to optimize volumetric productivity by providing uniform light penetration within the culture.

Hybrid System Approaches

Combining the advantages of raceway ponds and photobioreactors, hybrid systems offer a balanced approach in producing fresh spirulina. These systems often incorporate elements like closed photobioreactors for initial inoculation and growth, followed by transfer to open raceway ponds for large-scale production. This approach allows precise control during the initial stages while leveraging the cost-effectiveness of raceway ponds for mass cultivation.

Hybrid systems can also integrate innovative technologies, such as the curtain wall photobioreactor concept, which aims to create sustainable cities by integrating microalgae cultivation into building facades.

Creating a perfect system that meets specific needs and environmental factors can help producers maximize their output, decrease water usage, and improve overall efficiency.

Advanced Harvesting Technologies

Advanced harvesting technologies are cutting-edge methods and equipment that effectively harvest the thick green algae grow from fields with minimal loss, more production, and less of an adverse effect on the environment. These technologies are developing quickly in order to meet the issues of labour shortages, the requirement for sustainability in agriculture, and the rising demand for food. Some of the methods includes : membrane filtration techniques, flocculation methods, dissolved air flotation, centrifugation, and drum filtration. They have been further refined by Greenbubble and put on specially designed drum filtration-based systems.

Preserving Quality During Processing

To maintain the potential of this thick green algae grow as a superfood, nutritional value, and quality must be preserved during processing. Three key strategies have emerged:  spray drying, vacuum drying, and RWD drying.

Gentle Drying Technologies

Commonly, high-temperature levels involving spray drying methods (95 to 180°C) are disadvantageous because they induce major nutrient losses. Results of these studies show decreases of over 10% for β-carotene contents and more than 25% for total carotenoids of spirulina or other microalgae powder. To mitigate these losses, gentle drying technologies like RWD and vacuum drying have been developed.

Spirulina, a powerhouse of nutraceutical components, requires careful handling during the drying process, particularly when it comes to temperature-sensitive elements such as phycocyanin – a crucial ingredient. Conventional drying methods, like spray dryers, drum dryers, oven dryers, and even sun drying, pose challenges related to high temperatures, extended drying times, and the degradation of valuable spirulina components.

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