Nutritional composition, antioxidant activity and gossypol level of Nazilli glandless cottonseed, cottonseed kernel and their cold-pressed meal

Abstract

Abstract Background The study was conducted to determine the nutrient composition and gossypol levels of glandless cottonseed (GCS), glandless cottonseed kernel (GCSK) glandless cottonseed meal (GCSM) and cottonseed kernel meal (GCSKM) obtained by cold pressing of cotton seeds and kernels (Glandless Nazilli variety) as a raw material of compound feed industry. Result Feed and dry matter (DM)-based nutrient analyses showed significant differences (p < 0.05) in DM, OM (organic matter), CP (crude protein), EE (ether extract), ash and NFE (nitrogen-free extract) contents between GCS and GCSK. The DM-based K, P, S, Mg, Ca, Na, Fe, Cu, Zn and Al contents were significantly different (p < 0.05) between GCS and GCSK. The concentrations of nonessential heavy metals (Cd, Pb, Ni and Al) in GCS, GCSK, GCSM and GCSKM samples were below the permissible limits. The linoleic acid (C18:2; ω6) was the main component (55.55%) among the 20 fatty acids identified in GCS oil. The level of unsaturated fatty acids (70.78%) was higher than that of saturated fatty acids (29.22%). Total phenolics concentrations of GCS, GCSK, GCSM and GCSKM samples were 7.87, 2.18, 5.86 and 1.91 mg gallic acid equivalents (GAE)/g, respectively. Free and total gossypol levels of GCS and GCSK were 294 and 440, and 521 and 706 mg/kg, respectively. Conclusion The results revealed that nutritional properties of Nazilli GCS with low gossypol and high linoleic acid content were relatively higher compared to the other meals investigated. The antioxidant activity of phenolic compounds, albeit at low levels in Nazilli GCS and GCSM, may contribute to animal health and production efficiency when used in animal rations.