Inclusion of açaí (Euterpe oleracea Mart. 1824) in the diet of the Pacific white shrimp Litopenaeus vannamei (Boone, 1931) in a biofloc system: effect on zootechnical performance, biochemical responses and color
Pacific white shrimp (Litopenaeus vannamei) has been the most widely cultivated crustacean species in the world, but may be subject to abiotic factors that promote oxidative stress which leads to consider the importance of supplementing this species' diet with antioxidants. The Euterpe oleracea fruit, known in the Amazon region as açaí, contains significant amounts of antioxidants of the flavonoid class, such as anthocyanin and quercetin. Thus, the objective of the work was to evaluate the zootechnical performance, color and biochemical responses of L. vannamei, fed with different levels of inclusion of açaí Euterpe oleracea in the diet in a biofloc cultivation system. 16 units of 40 liters were used, with 4 repetitions, containing 20 shrimp (0.9 g) per unit.Four diets supplemented with freeze-dried açaí pulp (0; 2.5; 5; and 10% inclusion) were evaluated. At the end of the experiment, the zootechnical parameters and coloring (in the abdomen and cephalothorax region) in uncooked and cooked shrimp for 2 min at 70 oC, in the latter case the parameters L * (brightness), a * (red component / green) and b * (yellow / blue component) with digital colorimeter. Data on zootechnical performance, color, flavonoid and total polyphenol content and antioxidant capacity (DPPH) were submitted to mixed model variance analysis (ANOVA) and, when there were statistical differences, the means were contrasted using the Newman-Keuls test (α = 0.05).The averages of the results obtained from each treatment in the physical and chemical parameters of the water and total solids did not present significant differences between the treatments, as well as the zootechnical parameters (p> 0.05). The lipid values of the shrimp carcass fed diets with inclusion of açaí (2.5%, 5% and 10%), showed statistically significant differences (p <0.05) when compared to the control. There were differences (p <0.05) in the parameter L * in the cephalothorax region between the control and the inclusion of 10% açaí in the diet. In the abdomen of uncooked shrimp, there were also changes (p <0.05) between 2.5% and 10% of the concentration of açaí in the diet. Regarding chromaticity, a * difference (p <0.05) occurred only in the abdomen of both cooked and uncooked shrimp between the control and the inclusion of 10% açaí in the diet.In biochemical analyzes, the muscle did not show significant differences in the concentration of total polyphenols, total polyphenols, total flavonoids and in the total antioxidant capacity (DPPH) (p> 0.05). In the hepatopancreas there were statistical differences, between the inclusion of 2.5% of açaí, with higher values than the inclusion of 10% of açaí. In the gills, the control together with 2.5% of açaí inclusion had higher values (p <0.05) when compared to the treatment with 10% of açaí inclusion. The concentration of polyphenols in the biofloc was higher in treatments with 5 and 10% inclusion of açaí (p <0.05). In the biofilm, however, there were no significant differences between treatments (p> 0.05). The values of polyphenols in the diet did not show statistical differences between treatments (p> 0.05),however, the concentration of flavonoids in the diet showed significant differences (p <0.05) between treatments, showing a higher value in the greater inclusion of açaí. Regarding the flavonoids, only the gills had statistical differences (p <0.05) between the control and 2.5% of açaí inclusion showed lower values when compared with the treatments. The concentration of flavonoids in the bioflocus was not significantly different (p> 0.05). Changes in the biofilm occurred (p <0.05), when comparing 2.5% of açaí inclusion with 10% of açaí inclusion. The total antioxidant capacity in the biofilm also did not change (p> 0.05). The inclusion of 10% of açaí as a total replacement for fish oil does not alter the zootechnical performance,which can be used as a source of vegetable oil for shrimp in biofloc farming systems. The a * chromaticity in the shrimp abdomen in the inclusion of 10% açaí was satisfactory, since the evaluation of this color is attractive to the consumer. New analyzes should be carried out to evaluate the lipid profile and lipid peroxidation of the shrimp muscle since they have demonstrated a high content of ether extract. And make proximate composition of the biofilm and lipid profile, in addition to see if there are differences in the community of microorganisms that make up the biofilm and biofloc in the studied treatments.