The BIOCARB-4-FOOD project seeks, in collaboration with industry, for environmentally friendly seaweed extraction techniques with the valorization of the remaining biomass still rich in bioactive compounds, to obtain novel carbohydrate-based extracts and fiber (cellulose-based fractions and nanocellulose). Seaweeds and seagrasses are a valuable, under-exploited source for carbohydrates being key ingredients for food formulations as thickeners, stabilizers, or gelling agents. Structure, technological properties, toxicity and bioactivity of the extracted fractions are characterized and a life cycle assessment is conducted for proving procedure sustainability. The project outcomes will positively affect the competitiveness of seaweed food and non-food companies at EU scale.
Figure 1 Extracted seagrass and algae in BIOCARB-4-FOOD
Current carbohydrate extraction procedures are inefficient in terms of processing time, water and energy use. Remaining biomass (generally more than 50% of the initial material) is usually used as compost or disposed as organic waste. BIOCARB-4-FOOD targets to improve the extraction process and its resource efficiency by combining conventional extraction methods, i.e. heat, with ultrasound and enzyme-based extraction (Figure 2), and the development of ingredients with high added value from already commercialized seaweed species and from underexploited sources like seagrasses (Figure 3). Valorization of extracted biomass will further enhance the process efficiency. Extraction products serve as food additives, e.g. agar, or biodegradable packaging material, i.e. aerogels and films.
Figure 2 Schematic sketch of the applied extraction procedures
Figure 3: Schematic sketch of the educts, intermediates and products
Several works have been published up to date, regarding some of the outcomes derived from the project which are summarized below.
Since the project start, initial project results showed the possibility of producing less purified agar-based extracts from the algae species Gelidium sesquipedale using less expensive and more environmentally friendly extraction protocols (Martinez-Sanz et al. 2019). Martinez-Sanz et al. (2019) developed an extraction protocol reducing the extraction time 4-fold compared to conventional methods by using ultrasound. Sonication and hot water proved to be a cost-effective alternative to generate agar-based extracts.
The properties of agar (gel strength, degree of purity, color etc.) can be influenced by using different algae species and by modifying the extraction process. The less purified extracts also have additional functionalities such as antioxidant properties that make them interesting for various food applications. For instance, Alehosseini et al. (2018) investigated, how matrices from seaweed-derived agar-based fractions protected probiotic bacteria compared to conventional purified agar microcapsules. It could be shown that the less purified fractions from Gelidium sesquipedale performed better than pure agar due to the presence of polyphenolic seaweed compounds, acting as antioxidants. Another example of application was shown by De Oliveira et al. (2018), who were able to produce an agar-based aerogel from Gelidium sesquipedale seaweed. They incorporated water-soluble plant extracts together with cellulose or nanocellulose, allowing a sustained release of the bioactive substances from the extract for food preservation applications. The tested combinations of PVA/cellulose/nanocellulose aerogels find possible fields of application in packaging for the food industry and can help to e.g. decelerate fruit senescence. The unpurified agar-based extracts can also be used as packaging films in the food industry, as shown by Martinez-Sanz et al. (2019). Normally, plasticizers are added to purified agars to increase their flexibility. However, the most frequently used plasticizer is glycerol, often derived from petrochemical propene. Using unpurified agar-based extracts from Gelidium sesquipedale can make the use of plasticizers obsolete, since a plasticizer effect is caused by the presence of other compounds such as proteins. More so, unpurified agar films are much more resistant to humidity, one of the major flaws of agars in the food packaging industry. Further investigations to optimize the process parameters are currently carried out, e.g. adaptation of agar properties to the respective applications. In addition, the same strategy is applied to other varieties.
Figure 4: Recently produced films from Gelidium sesquipedale
Apart from this, the residues and their extracted cellulose-rich fractions, also from Posidonia oceanica, have been used for the production of biodegradable packaging materials. Benito-Gonzalez et al. (2018) investigated the application of cellulosic fractions extracted from Posidonia oceanica seaweed. Cellulose-based materials can be potentially used to replace certain fossil fuel based materials. However, discussions have come up since plant-based cellulose is normally derived from sources currently used as food products, fact which is not desirable given the predictions of future food scarcity. Residues of Posidonia oceanica can be found in huge amounts on beaches, and in turn, lead to negative effects on tourism and high costs for municipalities. As a side effect, the project, hence, contributes to cleaning touristic areas.
One promising application of Posidonia oceanica is the use as filler material to improve the properties of biopolymers. Synthetic plastics are widely used in the food packaging industry, mainly due to their mechanical properties. Bio-based substitutes made from starch often lack these mechanical properties. The incorporation of cellulose from Posidonia oceanica into the starch composites enhanced mechanical properties and limited the degree of starch retrogradation upon storage (Benito-Gonzalez et al. 2019).
Extraction and purification of cellulose from algae and seaweed still consumes lots of chemicals and, therefore, diminishes the environmental advantage over petroleum based synthetic alternatives, and their physical properties often cannot reach those of synthetic plastics. Benito-Gonzalez et al. (2019) were able to work out more sustainable extraction methods, consuming less chemicals by reducing the purification steps. It could be shown that less purified cellulose fractions and nanocrystals have promising functional properties such as improved mechanical and barrier performance. These simplified extraction methods yielded films that outperformed most benchmark biopolymers (Figure 4).
Extracts from Posidonia oceanica waste biomass can also serve medical purposes. Bioactive extracts from this seaweed proved to have high antioxidant capacities due to phenolic compounds, proteins and polysaccharides. Some extracts also showed antimicrobial properties against several foodborne fungi and even the ability to reduce the infectivity of viruses such as feline calicivirus and murine norovirus (Benito-Gonzalez et al. 2019).
Literature BIOCARB-4-FOOD (status February 2020)
Alehosseini, A., Gomez del Pulgar, E.-M., Gómez-Mascaraque, L. G., Martínez-Sanz, M., José Fabra, M., Sanz, Y., Sarabi-Jamab, M., Ghorani, B., Lopez-Rubio, A. (2018). Unpurified Gelidium-extracted carbohydrate-rich fractions improve probiotic protection during storage. LWT 96, pp. 694-703.
Benito-González, I., López-Rubio, A., Martínez-Sanz, M. (2018). Potential of lignocellulosic fractions from Posidonia oceanica to improve barrier and mechanical properties of bio-based packaging materials. International Journal of Biological Macromolecules 118, pp. 542-551.
Benito-González, I., López-Rubio, A., Gavara, R., Martínez-Sanz, M. (2019). Cellulose nanocrystal-based films produced by more sustainable extraction protocols from Posidonia oceanica waste biomass. Cellulose 26, pp. 8007-8024.
Benito-González, I., López-Rubio, A., Martínez-Sanz, M. (2019). High-performance starch biocomposites with celullose from waste biomass: Film properties and retrogradation behavior. Carbohydrate Polymers 216, pp. 180-188.
Martínez-Sanz, M., Martínez-Abad, A., López-Rubio, A. (2019). Cost-efficient bio-based food packaging films from unpurified agar-based extracts. Food Packaging and Shelf Life 21, pp. 1-9.
Martínez-Sanz, M., Gómez-Mascaraque, L. G., Ballester, A. R., Martínez-Abad, A., Brodkorb, A., López-Rubio, A. (2019). Production of unpurified agar-based extracts from red seaweed Gelidium sesquipedale by means of simplified extraction protocols. Algal Research 38, 101420.
de Oliveira, J. P., Pinheiro Bruni, G., José Fabra, M., da Rosa Zavareze, E., López-Rubio, A., Martínez-Sanz, M. (2019). Development of food packaging bioactive aerogels through the valorization of Gelidium sesquipedale seaweed. Food Hydrocolloids 89, pp. 337-350.
Benito-González, I., López-Rubio, A., Martínez-Abad, A., Ballester, A.-R., Falcó, I., González-Candelas, L., Sánchez, G., Lozano-Sánchez, J., Borrás-Linares, I., Segura-Carretero, A., Martínez-Sanz, M. (2019a). In-Depth Characterization of Bioactive Extracts from Posidonia oceanica Waste Biomass. Mar. Drugs 17, 409.
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 727473.