Solarte Daniela Alejandra, Ruiz-Matute Ana Isabel, Chito-Trujillo Diana M, Rada-Mendoza Maite, Sanz María Luz
Grupo de Investigación Biotecnología, Calidad Medioambiental y Seguridad Agroalimentaria (BICAMSA), Universidad del Cauca, Popayán 190003, Colombia.
Instituto de Química Orgánica General (IQOG-CSIC), Juan de la Cierva 3, 28006 Madrid, Spain.
Foods. 2021 Feb 6;10(2):346. doi: 10.3390/foods10020346.
Despite the nutritional properties of alfalfa, its production is mainly for animal feed and it is undervalued as a food source. In this study, the valorization of alfalfa as a potential source of bioactive carbohydrates [inositols, α-galactooligosaccharides (α-GOS)] is presented. A Box-Behnken experimental design was used to optimize the extraction of these carbohydrates from leaves, stems, and seeds of alfalfa by solid-liquid extraction (SLE) and microwave-assisted extraction (MAE). Optimal extraction temperatures were similar for both treatments (40 °C leaves, 80 °C seeds); however, SLE required longer times (32.5 and 60 min vs. 5 min). In general, under similar extraction conditions, MAE provided higher yields of inositols (up to twice) and α-GOS (up to 7 times); hence, MAE was selected for their extraction from 13 alfalfa samples. Pinitol was the most abundant inositol of leaves and stems (24.2-31.0 mg·g and 15.5-22.5 mg·g, respectively) while seed extracts were rich in α-GOS, mainly in stachyose (48.8-84.7 mg·g). In addition, inositols and α-GOS concentrations of lyophilized MAE extracts were stable for up to 26 days at 50 °C. These findings demonstrate that alfalfa is a valuable source of bioactive carbohydrates and MAE a promising alternative technique to obtain functional extracts.
尽管苜蓿具有营养特性，但其生产主要用于动物饲料，作为食物来源的价值被低估。本研究展示了苜蓿作为生物活性碳水化合物（肌醇、α-低聚半乳糖）潜在来源的价值提升。采用Box-Behnken实验设计，通过固液萃取（SLE）和微波辅助萃取（MAE）优化从苜蓿叶、茎和种子中提取这些碳水化合物的工艺。两种处理的最佳萃取温度相似（叶40℃，种子80℃）；然而，SLE所需时间更长（32.5和60分钟，而MAE为5分钟）。总体而言，在相似的萃取条件下，MAE能提供更高产量的肌醇（高达两倍）和α-低聚半乳糖（高达7倍）；因此，选择MAE从13个苜蓿样品中提取这些成分。叶和茎中最丰富的肌醇是松醇（分别为24.2 - 31.0毫克·克和15.5 - 22.5毫克·克），而种子提取物富含α-低聚半乳糖，主要是水苏糖（48.8 - 84.7毫克·克）。此外，冻干的MAE提取物中的肌醇和α-低聚半乳糖浓度在50℃下长达26天保持稳定。这些发现表明苜蓿是生物活性碳水化合物的宝贵来源，MAE是获得功能性提取物的一种有前景的替代技术。
