Alternative environmental friendly process for dehydration of edible Undaria pinnatifida brown seaweed by microwave hydrodiffusion and gravity
Introduction
Removing of moisture content by thermal systems for food preservation can be carried out using solar, conventional convective air drying, ultrasound, spray-drying or freeze-drying methods, among others, have been used. Today the industry food drying demands green and sustainable environmental technologies that require short operational time and reduce energy cost (Yao, 2016). Microwave hydrodiffusion and gravity (MHG) procedure could be an eco-friendly alternative for the dehydration of raw materials, as seaweeds, in contrast to the most common traditional dehydration techniques like solar methods or conventional convective air drying. Low environmental impact and high efficiency of the dehydration process can be achieved by MHG technology related to the shortest necessary time (Ferreira et al., 2018). Despite these advantages, scarce studies on the effect of MHG on the dehydration process has been reported. In contrast, this innovative technique has been used as an alternative extraction method for recovery the liquid bioactive fraction without a low energy and resources consumption of different vegetal matrix such as algae (Pérez et al., 2014) or plants (López-Hortas et al., 2016). This solvent-free technology also allows obtaining essential oil from different citrus fruits (Boukroufa et al., 2015) or aromatic plants (Asofiei et al., 2017). MHG technology can be the response of the industrial requirements of novel process for the enhancement of extraction procedures of high-added value compounds in comparison with otherconventional processes or alternative methods such as other types of microwave, enzyme, fermentation, electric pulses, surfactant or ultrasound assisted extraction, osmotic shock or supercritical fluid extraction (Wong-Paz et al., 2017, Okolie et al., 2019). This environmentally friendly process was also studied as a possibility technology to obtain fruit juices. For example, the extraction of strawberry juice by MHG was an efficient treatment with low energy consumption (Turk et al., 2017).
The growing planet population involves increasing food requirements. This circumstance encourages the exploitation of the marine environment for supplying innovative functional foodstuff. Therefore, the marine culture of different macroalgae reveals its importance as an alternative source of seaweed. Undaria pinnatifida (Harvey) Suringar (Laminariales, Phaeophyceae) brown seaweed stands out by its importance in this sector (Rebours et al., 2014). Although the consumption of this alga, so called wakame or sea mustard, is very popular in China, Japan and Korea (Balbas et al., 2015), at present its use is widespread in others cuisines of the world. This fact is reflected in the distribution of this seaweed aquaculture farms in American, African and European regions in addition to traditional Asiatic areas (Bharathiraja et al., 2015).
U. pinnatifida has diverse biological properties derived from its different chemical compounds. The high protein level among brown algae (Tascon et al., 2015) supplies an antihypertensive effect (Hayes and Tiwari, 2015). Carbohydrate fraction is the most abundant component (43.2%) and exhibits bioactive activities with multipurpose uses with pharmaceutical, cosmetic and food application (Hong et al., 2014). Diverse biological properties were described, i.e. fucoidan presents anticoagulant, anti-inflammatory, antitumoral and antiviral activities (Choo et al., 2016). The antifungal activity of this seaweed is promoted for the fatty acids content and phenolic compounds (De Corato et al., 2017). In addition, trace elements and some essential minerals are also supplied by this raw material (Rupérez, 2002). All above-mentioned provide a brown seaweed with attractive properties to be used in a broad range of food and non-food industries. Within the food applications, this seaweed can be found in pasta or cheeses matrices, among others (del Olmo et al., 2018). Concerning the non-food field, these macroalgae can be employed as bio-adsorbent for removal of heavy metals from aqueous ecosystem (Cho et al., 2013a). The extraction of biofuels (Cho et al., 2013b) and the improvement of the solar cell technologies (Calogero et al., 2014) are bioenergy production areas where U. pinnatifida can be also successfully used.
This work describes the dehydration of the edible brown U. pinnatifida seaweed by microwave hydrodiffusion and gravity. Several conditions of microwave irradiation power-time are proposed, based on the results previously optimized for other edible brown seaweeds (López-Hortas et al., 2018). Drying kinetics, shrinkage and the corresponding modelling are provided in addition to the estimation of the energy requirements. Color characteristics, structural changes and the antioxidant activity are also determined. For further insight, a systematic study on the seaweed rehydration kinetics and the corresponding modelling was also evaluated.
Section snippets
Raw materials, sample preparation and chemicals
Fresh U. pinnatifida brown seaweed (moisture content, 91.0 ± 0.1% w.b., wet basis) was harvested by a local producer (ALGAMAR, Pontevedra, Spain) which certified the authenticity of the seaweed species. Samples collected were packed in closed plastic bags protected from light and kept at −18 °C until further use. Seaweed samples were gathered and stored the same day. All the experiments were carried out during a period of two months from the date of gathering. Sea algae were defrosted (moisture
MHG dehydration curves
The collected liquid volumes during the Undaria pinnatifida brown seaweed dehydration by MHG using a broad range of microwave powers and time are shown in Fig. 2. The drained volume and the total processing time required for the seaweed dehydration dropped with rising microwave power. Operating at the lowest tested microwave power (50 W), about 180 min were necessary to dehydrate the seaweed up to a moisture content of 13.2 ± 0.3% w.b. (wet basis), after which the liquid drainage stopped (Figs.
Conclusions
It could be concluded that microwave hydrodiffusion and gravity is a promising method not only for U. pinnatifida dehydration, but also for the recovery bioactive compounds in an eco-friendly way, saving time and energy when compared with traditional dehydration process. The shortest dehydration and rehydration time are achieved using a sequential combination of microwave power and time method for an adequate final seaweed moisture content. RDM allows U. pinnatifida dehydration preserving the
Funding
Authors are grateful to the Ministry of Economy and Competitiveness of Spain (Ref. CTM 2015-68503-R) and FEDER for financial support. L. López-Hortas thanks the Xunta de Galicia for her pre-doctoral grant (2014/2020 European Social Fund). M. Gely acknowledges Erasmus + Learning Agreement for Traineeships. M.D. Torres acknowledges to the Ministerio de Economía, Industria y Competitividad for her post-doctoral grant (IJCI-2016-27535).
Declarations of interest
None.
Acknowledgements
Fresh seaweeds were kindly supplied by Algas Atlánticas ALGAMAR, S.L. (Pontevedra, Spain).
References (46)
- et al.
Effect of sonication on colour, ascorbic acid and yeast inactivation in tomato juice
Food Chem.
(2010) - et al.
Comparison of physicochemical characteristics, sensory properties and volatile composition between commercial and New Zealand made wakame from Undaria pinnatifida
Food Chem.
(2015) - et al.
The ferric reducing ability of plasma (FRAP) as a measure of antioxidant power: the FRAP assay
Anal. Biochem.
(1996) - et al.
Aquatic biomass (algae) as a future feed stock for bio-refineries: a review on cultivation, processing and products
Renew. Sustain. Energy Rev.
(2015) - et al.
Bio-refinery of orange peels waste: a new concept based on integrated green and solvent free extraction processes using ultrasound and microwave techniques to obtain essential oil, polyphenols and pectin
Ultrason. Sonochem.
(2015) - et al.
Comparison of two isolation methods for essential oil from rosemary leaves: hydrodistillation and microwave hydrodiffusion and gravity
Food Chem.
(2009) - et al.
Brown seaweed pigment as a dye source for photoelectrochemical solar cells
Spectrochim. Acta Mol. Biomol. Spectrosc.
(2014) - et al.
In vitro bioavailability of chlorophyll pigments from edible seaweeds
J. Funct. Foods
(2018) - et al.
Removal characteristics of copper by marine macro-algae-derived chars
Chem. Eng. J.
(2013) - et al.
Effect of different rehydration temperatures on the moisture, content of phenolic compounds, antioxidant capacity and textural properties of edible Irish brown seaweed
LWT - Food Sci. Technol. (Lebensmittel-Wissenschaft -Technol.)
(2012)
Antifungal activity of crude extracts from brown and red seaweeds by a supercritical carbon dioxide technique against fruit postharvest fungal diseases
Postharvest Biol. Technol.
Cheese supplementation with five species of edible seaweeds: effect on microbiota, antioxidant activity, colour, texture and sensory characteristics
Int. Dairy J.
Characterization of Spanish powdered seaweeds: composition, antioxidant capacity and technological properties
Food Res. Int.
Microwave assisted dehydration of broccoli by-products and simultaneous extraction of bioactive compounds
Food Chem.
Effect of air-drying temperature on physic chemical properties of dietary fibre and antioxidant capacity of orange (Citrus aurantium v. Canoneta) by-products
Food Chem.
Comparison of red, brown and green seaweeds on enzymatic saccharification process
J. Ind. Eng. Chem.
Sustainable dehydration of onion slices through novel microwave hydro-diffusion gravity technique
Innov. Food Sci. Emerg. Technol.
Flowers of Ulex europaeus L. - comparing two extraction techniques (MHG and distillation)
C R Chim.
Microwave hydrodiffusion and gravity (MHG) processing of Laminaria ochroleuca brown seaweed
J. Clean. Prod.
Preparation and functional properties of beverages made from sea algae
Food Chem.
Influence of conventional and recent extraction technologies on physicochemical properties of bioactive macromolecules from natural sources: a review
Food Res. Int.
Antioxidant/antiradical properties of microwave-assisted extracts of three wild edible mushrooms
Food Chem.
Microwave hydrodiffusion and gravity processing of Sargassum muticum
Process Biochem.
Cited by (22)
Drying of seaweed: Approaches, challenges and research needs
2023, Trends in Food Science and TechnologyOptimization of base catalytic transesterification toward maximum biodiesel yield from Azolla filiculoides macroalgae feedstock
2023, Industrial Crops and ProductsSeaweed as an alternative protein source: Prospective protein extraction technologies
2023, Innovative Food Science and Emerging TechnologiesPostharvest strategies—efficiency and novel processes for extending shelf life and reducing spoilage potential for minimizing food waste
2023, Future Proteins: Sources, Processing, Applications and the Bioeconomy