Evolution of the composition of the halophyte Salicornia ramosissima with ageing : protein yield

Details

Supervisors

Cybulska, Iwona ; Braem, Lukas

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries, à finalité spécialisée

Abstract

Following the increase in global population, the decrease in fresh water resources and the salinity threat inching further into arable lands, one of the most important challenge of this century is going to be to find ways to meet the world’s need for sustainably produced biomass. Halophytes, like Salicornia ramosissima, could fill this role, for both the food and the growing non-food bio-products sector. However, up until now, no attempt at cultivating this plant on a larger scale has economically succeeded. Since only 20% of the harvested biomass could be valorized as a food product, while the remaining biomass has been considered as worthless residues by the farmers, due to high salt content. The European Aquacombine project was created in order to better understand the composition and yield of several promising halophytes, and develop different valorization pathways for the residual biomass fractions from this information. The aim of this master thesis was to analyze the chemical composition of Salicornia ramosissima and its changes depending on the age of the plant at harvest in order to identify the most appropriate harvest time(s) in order to maximize the potential earnings from the sale of the crop. For this, the soluble fractions was analyzed with Soxhlet extraction and the polysaccharides and Klason lignin content were characterized from the insoluble fraction by acidic hydrolysis and HPLC. The evolution was monitored over 15 weeks, between the 7th and 21st week of growth. A decrease in the extractives fraction and protein content was observed with plant age. On the contrary, the structural polysaccharides (glucans and xylans) and lignin increased with plant age. The structural ash content stayed the same with plant age. There is no consensus on which specific week is best to harvest, based on just the chemical composition. The results should be presented in terms of units of weight per surface area (t/ha) to grasp the potential earnings. There, it was clearly observed that the yield in ton/ha in the last weeks of growth overshadows the yield from any other weeks, for all components. A repetitive harvesting system of the upper extremities of the branches was suggested to increase biomass yield. Combining aquaculture with halophyte farming could allow for a reduction in the associated costs of Salicornia cultivation, in a hydroponics system, by removing the need for additional nutrient solution to feed the plants.