# _Psyllium_ and _Laminaria_ Partnership--An Overview of Possible Food Gel Applications
## 1 Introduction  
_Laminaria sp._ are industrially used for alginate extraction (17.1-32% _w/w_, dry basis) [1], a hydrocolloid with unique gelling abilities at low temperature and good heat stability, widely used as a thickener, stabilizer, and restructuring agent in the food, cosmetic, pharmaceutical, biomedical, and textile industries [2; 3].  
Mainly valued for alginate extraction, this natural resource presents other interesting compounds for human nutrition such as fatty acids, proteins, minerals [4], vitamins (A, C, D, B group, E, K, PP) [1], pigments such as carotenoids and polyphenols with proved antioxidant, hypoglycemic, antitumoral, and antimicrobial activities [5; 6]. Due to their high content in biologically active compounds, seaweeds, and especially _Phaeophytecae_ (brown algae), have great potential to act as a functional food and as a food ingredient [7; 8].  
_Psyllium_ (_Plantago ovata_) is an annual plant found mainly in India and Pakistan, but also on Madeira Island (Portugal) due to its subtropical climate. Used in traditional medicine for centuries, _Psyllium_ husk has gained more attention by the scientific community since its health allegation was approved by the Food and Drug Administration in 2012 [9] regarding its benefits in reducing the riskof coronary heart disease. These features come from its high soluble fiber composition, which has the capacity of absorbing up to 15 g of water per g of _Psyllium_[10].  
_Psyllium_ husk is composed of 85% arabinoxylan, a neutral highly branched polysaccharide with about 35% of non-reducing terminal residues and a 15% non-polysaccharide fraction [11]. It has applications as an edible coating [12] and drug delivery [13].  
Innovation in food and feed production is a reality and a tendency for the upcoming years, whether this is the use of poorly exploited raw materials, the reformulation of foods based on green and sustainable technologies, or \"back to tradition\". Many of the food and feed industries' products are gels (e.g., yoghurt, puddings, confectionery products, pasta, pet food, among others) or present gelling agents in their formulation (cream cheese, sauces,... ), making gel-systems a growing market.  
Among the edible biopolymers, the use of plant seed mucilages namely chia and flax seed [14; 15] are one of today's trends. Aside from the sustainability issue, these ingredients also have health benefits such as the regulation of colonic microbiota, reduction of hyperlipidemia, anti-inflammatory effect, control of glycemic response, and control of satiation [16]. Due to their technological properties, these biopolymers are often used in the food industry as texturizing agents.  
To our knowledge, the gel forming ability of the combination of _L. achroleuca-Psyllium_ has not been previously investigated. Therefore, the interaction between _Psyllium_ husk gel and the edible brown seaweed _Laminaria achroleuca_, either in its liquid fraction or its puree-like mixtures, with _Psyllium_ will be studied, taking advantage of both these poorly exploited natural resources. The aim of the present work is to lay the foundation for a systematic textural and rheological description of _Laminaria-Psyllium_ gels, focusing on their mechanical features intended for future food applications.