دانلود رایگان مقاله استخراج پلی ساکاریدها توسط هیدرولیز خودکار زمین قهوه

Abstract

The extraction of polysaccharides by autohydrolysis of spent coffee grounds (SCG) was studied. Experimental assays were performed using different temperatures (160–200 °C), liquid/solid ratios (5–15 ml water/g SCG) and extraction times (10–50 min) in order to determine the conditions that maximize the extraction of polysaccharides with high antioxidant activity. Autohydrolysis was demonstrated to be an efficient technique to recover antioxidant polysaccharides from SCG. The best process conditions consisted in using 15 ml water/g SCG, during 10 min at 160 °C. The polysaccharides obtained under these conditions were mainly in the form of galactomannans and arabinogalactans. They presented high antioxidant activity (assessed by four different methods), were thermostable in a large range of temperature, and had a typical carbohydrate pattern, being of interest for industrial applications, mainly in the food area.

4. Conclusion

Autohydrolysis was demonstrated to be an efficient technique to recover polysaccharides with high antioxidant activity from SCG, particularly when applied at 160 ◦C for 10 min, and using a liquid/solid ratio of 15 ml water/g SCG. Under these conditions, it was possible to obtain a lyophilized material containing 29.29%(w/w) of polysaccharides,from which galactose was the most representative sugar, followed by mannose, glucose, and arabinose. Additionally, the lyophilized material contained a high content of phenolic compounds (234.14 07 mg GAE/g LM) and reducing sugars (93.93 mg GLU/g LM), and presented high antioxidant activity, which as con- firmedby fourdifferentmethods. Furthermore,thepolysaccharides presented thermostability in a large range of temperature, being therefore of great interest for industrial applications, mainly in the food industry, for encapsulation of additives or as prebiotics, for example, due to their high antioxidant potential and other functional properties.