Spent coffee grounds (SCG) are a promising source of natural by-products which can be used for different purposes. In this work, a possible use of oligosaccharides isolated from SCG as functional ingredients was investigated. SCGs were treated with an acid hydrolysis at high temperature (200 °C) in a closed reactor setting reaction time of 30, 60 and 90 s depending on the sample (original or defatted). A comprehensive study of the resulted water-soluble hydrolysate using a high-resolution mass spectrometry analysis was performed. Additionally, the growth of four Lactobacillus strains was tested to assess the prebiotic potential of the hydrolysate. Oligosaccharide chains formed by hexoses with a degree of polymerization ranging from 3 to 6 were identified and characterized. Regardless of the composition and the reaction time of hydrolysis, the bacterial activity of SCG extracts exhibited significantly higher values than the well-known versatile carbohydrate used by food industry, i.e., inulin. The results pave the way toward the use of hydrolysate SCG as an innovative ingredient intended to fortify food formulations. The diversity in coffee oligosaccharides composition suggests their selective prebiotic activity for specific bacterial strains.

中文翻译：

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废咖啡渣的酸水解：对低聚糖可能的益生元活性的影响

废咖啡渣 (SCG) 是一种很有前途的天然副产品来源，可用于不同目的。在这项工作中，研究了从 SCG 中分离出的低聚糖作为功能成分的可能用途。根据样品（原始或脱脂），在封闭反应器中将 SCG 在高温（200°C）下进行酸水解处理，将反应时间设置为 30、60 和 90 秒。使用高分辨率质谱分析对所得水溶性水解物进行了全面研究。此外，测试了四种乳杆菌菌株的生长，以评估水解产物的益生元潜力。由聚合度为 3 到 6 的己糖形成的寡糖链被鉴定和表征。无论水解的成分和反应时间如何，SCG 提取物的细菌活性值显着高于食品工业使用的众所周知的多功能碳水化合物，即菊粉。结果为使用水解产物 SCG 作为旨在强化食品配方的创新成分铺平了道路。咖啡低聚糖组成的多样性表明它们对特定细菌菌株具有选择性的益生元活性。