Bio-processing of macroalgae Palmaria palmata: metabolite fractionation from pressed fresh material and ensiling considerations for long-term storage

Abstract

Red algae, belonging to the phylum Rhodophyta, contain an abundance of useful chemicals including bioactive molecules and present opportunities for the production of different products through biorefinery cascades. The rhodophyte Palmaria palmata, commonly termed dulse or dillisk, grows predominantly on the northern coasts of the Atlantic and Pacific Oceans and is a well-known snack food. Due to its abundance, availability and cultivation capacity, P. palmata was selected for study as a potential candidate for a biorefinery process. In addition to studying juice and solid fractions of freshly harvested P. palmata, we have investigated the novel possibility of preserving algal biomass by ensilaging protocols similar to those employed for terrestrial forage crops. In the metabolite partitioning within the solid and liquid fractions following screw-pressing, the majority of the metabolites screened for—water soluble carbohydrates, proteins and amino acids, lipids, pigments, phenolics and antioxidant activity—remained in the solid fraction, though at differing proportions depending on the metabolite, from 70.8% soluble amino acids to 98.2% chlorophyll a and 98.1% total carotenoids. For the ensiling study, screw-pressed P. palmata, with comparative wilted and chopped, and chopped only samples, were ensiled at scale with and without Safesil silage additive. All samples were successfully ensiled after 90 days, with screw-pressing giving lower or equal pH before and after ensiling compared with the other preparations. Of particular note was the effluent volumes generated during ensiling: 26–49% of the fresh weight, containing 16–34% of the silage dry matter. This may be of advantage depending on the final use of the biomass.

Improving fermentation of Saccharina latissima and Alaria esculenta silages with additives for preserving biomass and antioxidants

“…The DM content in FA was significantly higher than in CON in noPW silages, but not in the PW silages in both Alaria and Saccharina. The same interaction was reported in Palmaria palmata silages using acids-based additive (Gallagher et al 2021). Also using acids-based additive was reported to increase DM density in wet grass silages (Randby & Bakken 2021).…”

“…Besides, the silage production of Alaria has not been studied yet despite this alga's commercial significance. Moreover, the effects of additives were found to differ in silages made of fresh and prewilted seaweed biomass (Gallagher et al 2021).…”

Sheep Performance on Valuable Silage and Wafer from Agricultural Waste

“…Good silage has a pH between 3.80-4.20 (Ratnakomala et al, 2006). A high pH value (6.4-7.0) is also produced in the manufacture of silage from red algae (Gallagher et al 2021). Silage pH silage can be grouped as very good, good, medium, and bad with a pH range of 3.…”

Macroalgae biorefineries as a sustainable resource in the extraction of value-added compounds

“…While Ascophyllum nodosum leads to a yield value of 31-38 %, a yield of 50 % is achieved with Fucus vesiculosus [43]. It is the case of red macroalgae P. palmata, using a solvent mixture of NaOH with sodium dodecyl sulphate, higher protein extraction yield is obtained, reaching a value of 95 % [45].…”