The potential of the pecan nut cake as an ingredient for the food industry

Pecan nut [Carya illinoinensis (Wangenh.) K. Koch] cake (PNC) is a co-product from the oil extraction industry and its potential as an ingredient for the food industry are not well known. In this work, the nutritional composition and the functional properties of PNC were studied. Additionally, the influence of different solvents (ethanol, water, and acetic acid) on the phytochemical composition and antioxidant capacity (reducing potential of the hydrophilic compounds - RPHC, 2,2-diphenyl-1-picrylhydrazyl - DPPH, and total reducing capacity - TRC) of PNC extracts were established using a simplex-centroid design. PNC is a source of carbohydrates, protein, and dietary fiber (40.5; 21.87 and 13.01 g 100 g^-1, respectively). The PNC exhibited a low energy value when compared to the raw nut (398.8 kcal 100 g^-1 and 645.54 kcal 100 g^-1, respectively). Mg, Mn and Co (416.74; 23.21 mg 100 g^-1 and 59.00 μg 100 g^-1, respectively) were the main minerals identified in PNC. The PNC also presented functional properties such as emulsifying and oil absorption capacities and a great ability to absorb water. Using the proposed solvent mixture system, the content of total phenolic compounds and condensed tannins recovered from PNC ranged between 172.43 and 2744.24 mg GAE 100 g^-1, and 253.42 to 1376.44 mg CE 100 g^-1, respectively. The antioxidant capacity of the PNC extract was showed through its ability to reduce hydrophilic (172.06-1714.96 mg GAE 100 g^-1) to transfer hydrogen atoms (12.55-74.11% scavenging activity) and lipophilic compounds (509.87-2070.80 mg QE 100 g^-1) using RPHC, DPPH, and TRC methods, respectively. Combining ethanol, water, and acetic acid at 30 °C for 15 min, positively affects the extraction of bioactive compounds from PNC, as well as the antioxidant activity of the extracts. The physicochemical, functional, phytochemical, and antioxidant properties demonstrate that pecan nut cake may represent a potential ingredient or additive for the food, pharmaceutical, and cosmetic industries.