Techniques of preparation of mushrooms extracts

Most of culinary-medicinal mushrooms contains high amount of bioactive compounds such as vitamins, minerals, proteins, polysaccharides, polyphenols, and other nutrients that are important for human health. Mushrooms of medicinal interest are known to have a high polysaccharide content. Before performing polysaccharide extraction, a collection of the mushroom in the wild, isolation in the laboratory on Petri plates, and subsequent cultivation on solid substrate or in liquid culture is required. The collected mushrooms can be dehydrated or lyophilized to completely remove humidity and powdered before starting the extraction process that can be performed by applying low- or high-temperature methods. Regarding hot extraction, Soxhlet extraction and microwave assisted extraction are the commonest. Soxhlet extraction needs solvents of increasing polarity, high temperature, and the process is long and hard to perform. Microwave assisted extraction is also a potential effective method of hot extraction because heating causes water to evaporate in the target cells and the generated pressure cause cells rupture. Compared with the Soxhlet the amount of solvent used greatly reduced, and the preparation time is shortened. Freezing extraction and ultrasound assisted extraction are two common cold extraction methodologies. In the former, polysaccharide extraction is carried out by freezing (72 hours) and subsequent thawing of the sample placed in distilled water, while in the latter, cell rupture is carried out by using an ultrasonic probe (30 minutes). An appropriate choice must be made because each extraction method has its own specific characteristics (yield, quality, chemical structure, and biological activities).