Estudo de cultivo e de biomoléculas da macroalga Gracilaria birdiae (Rhodophyta, Gracilariales)

Abstract

Gracilaria is the best represented genus of red algae, with more than 100 recognized species and is distributed in most tropical and temperate seas of the world. Thus, this genus is distinguished for being the world's leading source of agar. Agar is a substance which can be extracted from the cell wall of some red algae species. Its main feature is the ability to form a gel known generically as phycocolloids. This compound can be purified to be used in a wide variety of industrial products, such as food, medicines, cosmetics, chemicals, textile, among others. The present study aimed to determine the growth of the macroalgae Gracilaria birdiae cultivated in Pau Amarelo, Pernambuco, Brazil and the quality of its phycocolloids (agar). The experiment was divided into two parts: one conducted in field (cultivation of seaweed) and the other in laboratory (quality analysis of the macroalgae; carotenoids extraction and quality assessment of the agar). By comparing the total biomass produced during the dry and rainy seasons, higher values (p <0.01) were observed for the dry season (41.32 kg) in relation to the rainy season (13.36 kg). The maximum relative growth rates obtained at the end of cultivation in the dry period was 7.52% day-1 and the minimum was 0.32% day-1. In the rainy season the same measurements were 5.33 and -2.64% day-1. The bromatological parameters (g/100g) evaluated for the dry and rainy seasons were respectively moisture content and volatile substances (88.37 and 89.06%), proteins (14.78 and 21.48%), ash (41.78 and 40.85%), lipids (5.33% and 4.20%), carbohydrates (38.09% to 33.45%) and carotenoids (5.86 and 6.93 mg / mL). The results show the high performance of 30-day cultivation in this region in addition to the high bromatological properties and good quality of hardness of the agar from these macroalgae, which can be marketed and used for human consumption.