The effect of different drying methods on certain nutritionally important chemical constituents in edible brown seaweeds

Abstract

Seaweeds are potentially a valuable resource for the food, drink and pharmaceutical sectors. The effective utilization of seaweed usually requires post-harvest dehydration in order to prevent decomposition, increase shelf life and aid the extraction of certain chemical constituents. Drying is an expensive, time-consuming and energy-intensive process. Here, the presence of a range of nutritionally important compounds was studied in five brown seaweeds (Fucus spiralis, Laminaria digitata, Fucus serratus, Halidrys siliquosa, Pelvetia canaliculata) after oven-drying at 40 and 60°C, freeze-drying and microwave-drying at 385, 540 and 700 W. Antioxidant potential (total flavonoid content, total phenolic content, total antioxidant capacity and radical scavenging activity), soluble protein, lipid, amino acid and fatty acid profiles were determined in each case. Overall, results showed that low-temperature drying, such as freeze-drying and oven-drying at 40°C, produced products with higher concentrations of nutritionally important chemicals, as well as stronger antioxidant activities. Results suggest that concentrations of nutritionally important chemicals and antioxidant activity are influenced by both the drying treatment and seaweed species used. Where rapid drying techniques are found to be beneficial to levels of specific chemicals, microwave-drying could be a useful alternative to oven-drying, as it helps overcome issues associated with prolonged duration drying (contamination and oxidation). No single drying procedure could be identified as consistently superior for all species or all compounds of interest-indicating that the appropriate drying technique should be selected and optimized for each seaweed species whilst also taking into account potential end-use of the final product.

Current knowledge on the extraction, purification, identification, and validation of bioactive peptides from seaweed

“…For instance, higher yields of protein extracted (using the pH-shift method) were reported from brown seaweed (Saccharina latissima) biomass when using freeze-drying, oven-drying, and freezing (at −20°C) when compared to extraction from frozen (at −80°C), sun-dried, and ensiled biomass [25]. Similar results were observed by Badmus, U. O., Taggart, M. A. and Boyd, K. G. [26] who showed that freeze-drying prior to protein extraction resulted in higher protein content as well as antioxidant activity in five species of brown seaweeds (Fucus Table 1. The advantages and disadvantages of different protein extraction techniques (modified from [8,18,[20][21][22] spiralis, Laminaria digitata, Fucus serratus, Halidrys siliquosa, Pelvetia canaliculata).…”

“…For instance, higher yields of protein extracted (using the pH‐shift method) were reported from brown seaweed ( Saccharina latissima ) biomass when using freeze‐drying, oven‐drying, and freezing (at −20°C) when compared to extraction from frozen (at −80°C), sun‐dried, and ensiled biomass [25]. Similar results were observed by Badmus, U. O., Taggart, M. A. and Boyd, K. G. [26] who showed that freeze‐drying prior to protein extraction resulted in higher protein content as well as antioxidant activity in five species of brown seaweeds ( Fucus spiralis , Laminaria digitata , Fucus serratus , Halidrys siliquosa , Pelvetia canaliculata ). In the case of the green seaweed, Ulva sp., a convective drying (hot air at 70°C, airflow rate of 2.0 m/s for 120 min) method gave higher crude protein yield (20%) compared to freeze‐, vacuum‐, or solar‐drying [27].…”

Comparison between Natural and Cabinet Drying on Weight Loss of Seaweed Euchuema cottonii Weber-van Bosse

“…Drying with a cabinet dryer applied to sliced bananas has better color, texture, and natural aroma when compared to drying in the open sun (Aruna et al, 2019). Badmus et al (2019) also shown in their research that low-temperature drying, such as freezedrying and oven-drying at 40 °C, produced products with higher concentrations of nutritionally important chemicals.…”

Study on the drying characteristics of rice by microwave and hot air drying

“…Liu et al [5] used hot air-microwave combined drying technology to dry red dates; explored the contents of phenolic substances, soluble sugars, organic acids, triterpene acids, vitamin C, total phenols, and total flavonoids in red dates under different processing methods; and compared their antioxidant capacities. Badmus et al [6] studied the effects of different drying methods on the concentration and antioxidant activity of some important chemical substances in edible brown algae. Kay et al [7] measured the organoleptic characteristics of samples prepared at different drying temperatures and evaluated the energy consumption of the drying process.…”

“…Badmus et al. [6] studied the effects of different drying methods on the concentration and antioxidant activity of some important chemical substances in edible brown algae. Kay et al.…”