The synergy of Box-Behnken designs on the optimization of polysaccharide extraction from mulberry leaves

The synergistic effect of hot water extraction (HWE) and enzyme-assisted extraction (EAE) optimized by the Box-Behnken design (BBD) was investigated for a more efficient extraction method for mulberry leaf polysaccharide (MLP) with an improved dried crude MLP yield of 24.04   ±   0.98% under the optimal conditions for HWE (liquid-solid ratio 30, extraction temperature 85   °C and time 60   min) and EAE (pH 6.5, extraction temperature 45   °C and time 50   min), respectively. Furthermore, the static absorption of AB-8 macroporous resin performed the best among decoloring agents for the further crude MLP purification, from which three ethanolic fractions (MLP-40, MLP-60 and MLP-80) were derived with their characterization in carbohydrate, protein and total phenolic contents. The molar ratio of the monosaccharide composition in MLP-80 was 1:14.8:29.3:0.8:0.5:2.2 corresponding to mannose, rhamnose, ribose, glucose, galactose and galacturonic acid, respectively. In addition, the prebiotics effect of MLPs was investigated compared with conventional inulin and oligofructose, in which MLP-80 was finally demonstrated itself as the most promising natural additives in liquid dairy products like yoghourt.