Floral bio-residues of saffron: a potential source of valuable components; extraction and application

Prevalently known as red gold, saffron is one of the popular and expensive spices throughout the world. Assortment of the spice is an energy-intensive process where the stigma part of the flower is separated as a primary resource. Structurally, the stigma accounts for the small part of the flower and the remaining major proportions including petals, stamen, style etc. are discarded as waste fractions. With saffron being known for the culinary, medicinal and functional properties, there is higher value attributed to the waste fractions of the flower. Bio-fractions are known sources of protein (8.17-24.45 g/100 g of dry weight), lipids (2.22-10.73 g/100 g of dry weight), carbohydrates (33.8-64.9 g/100 g of dry weight), minerals and dietary fractions (14.4-32.3 g) and are highly comparable with the nutritional percentages of stigma. Phytochemical profiles of these parts are prominent with higher percentages of carotenoids, flavanols and anthocyanins making them a valuable extraction source. Maceration and solvent extraction are traditional methods employed in the extraction of these plant components. The involvement of modern extraction methods like ultrasound, microwave, supercritical extraction techniques have increased the efficiency and functional quality of the extract obtained. This review aims at assessing the phytochemical and nutritional profile of these bio fractions, emphasizing the positives of different extraction techniques and also covering the unlimited potential applications of so-called waste fractions.