Brazil is the largest producer of orange in the world, consequently, has a huge amount of juice processing industries in the country. In this processing, more than 50 % of the fruit becomes waste, which is mainly destined to feed industries. However, this residue contains a high nutritional value, and therefore its reuse would be a strategy. For this reason, the objective of this study was to produce flour using the Orange Residue Flour (ORF), characterize it and then evaluate its application on the production of cookies. The ORF was produced by drying the residue of oranges juice at 60 C for 24 hours. ORF was characterized in relation to chemical composition, phenolic compounds and hygroscopic properties (water absorption capacity (WC) and oil (OC)). ORF was applied in the formulation of cookies, evaluating its effect on the partial substitution of wheat flour, in the concentrations of 5, 10, 15 and 20 %. Cookies were analyzed in relation to their structure, color parameters, specific volume, moisture, water loss, and spread factor. As a result, the ORF yield was 4.26 %, a result superior to the literature. The chemical composition of the ORF showed the following values: moisture 10.38 0.36 %, ash 2.72 0.02 %, ethereal extract 0.33 0.1%, crude protein 5.94 0.1 % and glycidic fraction 80.63 %, and a phenolic compound concentration of 534.01 mg gallic acid equivalent / 100 g dry matter. In addition, 13.28 g of water per gram of dry matter and 2.78 g of oil per gram of dry matter were obtained for the analysis of CA and CO, respectively. For the cookies, it was obtained a variation on moisture content from 8.3 0.2 % to 6.6 0.7 %, in which the first represents the standard formulation and the second with a substitution of 20 %, the higher the ORF concentration the lower the moisture content. Between color parameters (L *, a *, b *) L* was which one that presented the greatest difference, the higher the ORF concentration the lower the L * values, i.e., the cookies became darker. The specific volume reduced from 1.56 0.03 to 1.385 0.04 mL / g, for 0 and 20 % of ORF, respectively. And finally, the average spreading factor of the cookies was 4.39 0.1, presenting more significant results in relation to the diameter and the thickness of the cookie, which were decreasing with the increase of ORF. Thus, it was concluded that ORF production is possible, with interesting characteristics for application in bakery product, besides to be possible to obtain cookies with ORF at 20 % without great changes in its properties. Furthermore, it could be proposed that the ORF production could be interesting in orange juice industries.
Acknowledgments: To FAPESP (Foundation for Research Support of the State of São Paulo) for financials grants (2018/03324-5; 2013/12693-0) and IC grant of student L.A.C (2017/10815-2), “Reitoria da USP” (RUSP) for the IC grant of the students GB.P and J.M.L..