Chemical composition and antioxidant capacity of coffee pulp

ABSTRACT Coffee pulp is produced in large quantities, and its disposal can pollute the environment. However, the nutritional value and antioxidant content of coffee pulp make it a good option for animal feed. Therefore, the objective of this study was to determine the chemical composition, the phenolic compounds and the antioxidant capacity of coffee pulp using fresh (FCP), ensiled (ECP), and ensiled and sun-dried (EDCP) coffee pulp. The study design was completely randomized with three treatments (n=4). Dry matter (DM), crude protein (CP), ash, acid detergent fiber (ADF), neutral detergent fiber (NDF), lignin, phenolic compounds and antioxidant capacity were determined. Data were analyzed by analysis of variance, and means were compared with the Tukey test. The percentage of CP, NDF and ADF was higher in ECP and EDCP than in FCP. There were no changes in lignin content. Ensiling and sun drying did not decrease (P>0.05) caffeine or tannins. No differences were found in caffeic acid (2.031±2.873, 5.103±0.391, 4.913±0.018 mg g-1 DM in FCP, ECP, EDCP, respectively). The concentration of chlorogenic acid (FCP 2.593±1.756; ECP 5.368±0.422; EDCP 4.875±0.678 mg g-1) increased with the ensiling process, but it was not affected by sun drying. Ethanol decreased in ECP and EDCP relative to FPC (FPC 15.88±0.97%; ECP 7.04±1.16%; EDCP 0.00%); however, antioxidant capacity was not affected. It was concluded that the ensiling process and sun drying affected the nutritional value of coffee pulp but not its antioxidant capacity.

摘要 咖啡果浆（Coffee Pulp）的产量巨大，若处置不当会对环境造成污染。但其具备的营养价值与抗氧化物质含量，使其成为动物饲料的优质备选原料。因此，本研究旨在通过分析新鲜咖啡果浆（Fresh Coffee Pulp, FCP）、青贮咖啡果浆（Ensiled Coffee Pulp, ECP）以及青贮后日晒干燥咖啡果浆（Ensiled and Sun-dried Coffee Pulp, EDCP）的化学成分、酚类物质组成与抗氧化能力，探究其应用潜力。本研究采用完全随机设计，设置3组处理（n=4）。测定指标包括干物质（Dry Matter, DM）、粗蛋白（Crude Protein, CP）、灰分、酸性洗涤纤维（Acid Detergent Fiber, ADF）、中性洗涤纤维（Neutral Detergent Fiber, NDF）、木质素、酚类物质含量及抗氧化能力。数据采用方差分析进行统计检验，组间均值差异采用Tukey检验进行多重比较。结果显示，青贮与青贮后日晒干燥处理的咖啡果浆的粗蛋白、中性洗涤纤维与酸性洗涤纤维占比均高于新鲜咖啡果浆；木质素含量未发生显著变化。青贮及日晒干燥并未使咖啡因与单宁含量出现显著降低（P>0.05）。咖啡酸含量在三组样品中未出现显著差异：新鲜咖啡果浆、青贮咖啡果浆、青贮后日晒干燥咖啡果浆的咖啡酸含量分别为2.031±2.873、5.103±0.391、4.913±0.018 mg每克干物质。绿原酸含量在青贮处理后显著升高（新鲜咖啡果浆组为2.593±1.756 mg每克干物质，青贮组为5.368±0.422 mg每克干物质，青贮后日晒干燥组为4.875±0.678 mg每克干物质），但日晒干燥对其含量无显著影响。与新鲜咖啡果浆相比，青贮咖啡果浆与青贮后日晒干燥咖啡果浆的乙醇含量均有所下降（新鲜咖啡果浆组为15.88±0.97%，青贮组为7.04±1.16%，青贮后日晒干燥组为0.00%）；但抗氧化能力未受处理方式的影响。综上，青贮与日晒干燥工艺可改变咖啡果浆的营养价值，但不会对其抗氧化能力产生显著影响。