Linear programming formulation of a dairy drink made of cocoa, coffee and orange by-products

The agricultural industry generates large amounts of residues, commonly considered as waste. By-products from industrial processing of cacao, coffee and orange were used to formulate a dairy drink. The enriched dairy product was elaborated using a 10% aqueous extract of cocoa bean shells, coffee silverskin and orange peel. A design of mixtures of extreme vertices was applied to test the proportions of the ingredients of the aqueous extract. Sensorial characteristics like taste, odor, color and appearance were evaluated by a semi-trained testing panel applying the method of multiple comparisons, comparing the test formulations with a commercial drink of coffee and cocoa. The test formulations that were rated similar to the reference drink were selected to improve their total polyphenol content (TPC) applying a mathematical process of linear optimization. This approach indicated an optimal formulation containing 74 % cocoa bean shells, 24.50% coffee silverskin and 1.50% orange peel. This formulation gave TPC values of 5.74 +/- 0.41 Gallic Acid Equivalent (GAE) mg/g, 82.20 +/- 0.08% antioxidant activity by the diphenylpicrylhydrazyl (DPPH) assay and 114.78 mg/l caffeine content. The results demonstrate the feasibility to produce a drink enriched in antioxidant compounds retaining good sensorial attributes using industrial by products.