Sustainable Valorization of Green Tea Waste as a Nutraceutical to Reduce Fat Deposition in Striped Catfish (Pangasianodon Hypophthalmus)
摘要
The study examines the potential of an organic food waste, green tea (Camellia sinensis) waste (GTW), to mitigate excessive fat accumulation in Pangasianodon hypophthalmus. In-vitro evaluations revealed a significant presence of bioactive compounds and antioxidant activities in GTW extracts, with the highest levels observed in the methanolic extract. Seven isonitrogenous (32% CP) and isocaloric (around 3700 kcal kg−1 DE) diets were formulated with varying levels of GTW methanolic extract (GE) or powder (GP)), comprising: control (without GE and GP), GE2 (2 g kg−1GE), GE4 (4 g kg−1GE), GE8 (8 g kg−1GE), GP5 (5 g kg−1GP), GP10 (10 g kg−1GP), and GP20 (20 g kg−1GP). A 60-day feeding trial was conducted with these diets by stocking P. hypophthalmus juveniles (35.61 ± 0.75 g) in seven groups in triplicates. Post-trial results showed enhanced growth and nutrient utilization in GE4 and GP10 groups but a significant decline in these parameters at higher doses (GE8, GP20). These changes were associated with a decrease in whole-body lipid content, with the GP20 group exhibiting a significant (p < 0.05) 28.66% reduction compared to the control. Other groups displayed moderate lipid reductions. Fatty acid profiles indicated decreasing SFAs and increasing MUFAs, PUFAs, Σn-3, and Σn-6 fatty acids in muscle and viscera as GE and GP levels increased. Serum lipid profiles showed reduced TG, TC, and LDL-c, along with increased HDL-c levels as GE and GP doses increased. These effects were attributed to the downregulation of lipogenic enzymes (G6PDH, ME) and upregulation of the lipolytic gene PPAR-α in the liver with increasing GE and GP doses. The study concludes by recommending 20 g kg−1 GTW powder supplementation for maximum fat reduction and 4 g kg−1 GTW extract or 10 g kg−1 GTW powder for moderate fat reduction while maintaining optimal growth in P. hypophthalmus diets.
Graphical Abstract