Extraction and protein removal of polysaccharides from hops

The hops were pre-processed which use supercritical carbon dioxide extraction as samples. The optimal extraction processing parameters were investigated by orthogonal experiments combined with single factor experiments. The best technological conditions for hot distilled water extraction by microwave-assisted was extraction time of 2h, ratio of solid-liquid 1∶10, extraction temperature of 90℃ and 750W of microwave power for 12min, and the yield of polysaccharides from hops was up to 2.76% under this condition. Protein removal rate and polysaccharide retention rate were used to evaluate and compare the effectiveness for several methods, namely Savage method, hydrochloric acid-n-butanol, trichloroacetic acid (TCA) -n-butanol, papain/bromelain method. Based on the investigation, the combinatorial method between enzymatic hydrolysis and chemical method was used to evaluate the technical of deproteinization. Bromelain-TCA-n-butanol was found to be the best method for the deproteinization of hop crude polysaccharides. The optimal operating conditions of Bromelain-trichloroacetic acid (TCA) -n-butanol method were temperature 45℃, hydrolysis time 0.5h, substrate concentration 22.5U/mL of bromelain and pH5.5 followed by once treatment with trichloroacetic acid (TCA) -n-butanol method, the amount of protein removed was 86.77% while polysaccharide remained 77.37% during the deproteinization process. But compared with the loss rate of polysaccharide, the papain-hydrochloric acid-n-butanol method was better. The optimal operating conditions of papain-hydrochloric acid-n-butanol method were temperature 55℃, hydrolysis time 0.5h, substrate concentration 36U/mL of bromelain and pH5.5 followed by once treatment with hydrochloric acid-n-butanol method, the amount of protein removed was 77.37% while polysaccharide remained 84.43% during the deproteinization process.