Identification And Extraction Technology Of Main Bitter Substances In Zhi Que

ZhiQue trees have vigorous growth ability and strong tolerance to cold and drought,which are often used as rootstocks.Because of the bitter taste and poor edibility,fruits of the trees are usually discarded,resulting in great waste of resources.At present,the study of ZhiQue is limited to small fruits pulverized for medicinal purposes.There are very few reports on the study of its bitter substances.In order to realize the comprehensive utilization of ZhiQue,this study has carried out the research related to its bitter characteristics.The results are as follows:(1)The sensory evaluation of ZhiQue juicy and other 5 kinds of citrus and grapefruit juice samples were carried out.The results of Friedman test showed that the bitter taste of the juice samples of ZhiQue was significantly higher than that of other samples.The value of the bitterness were 59.5,and the F1 value was 33.87>13.28.The bitter taste was significantly different from other samples at the 1% level.(2)The main bitter components in the endocarp and pulp of ZhiQue were determined by quantitative analysis.A certain concentration of bitter contributing standard was prepared and the taste test with the electronic tongue was carried out.It was indicated that the main bitterness contribution components were mainly dissolved in the organic solvent,and the main bitterness contributing components were identified as limonin and flavonoids.(3)Ultrasonic assisted ethanol extraction was used to obtain bitter substances from endocarp and flesh and the parameters were optimized.The parameters were optimized based on the bitter substance yield.The optimum technological process is to use 55.67% concentration of ethanol solvent,material ratio 47.28 mL/2 g,extract 31.53 min,63.25% concentration of ethanol solvent,material ratio 48.91 mL/2 g,extract 29.23 min,the predicted yield of main bitter substances was 18.23 mg/g and 15.37 mg/g respectively.Considering the actual production,the modified conditions are as follows: 56% ethanol solution,47 mL/2 g,leaching 32 min,63% ethanol solution,49 mL/2 g and 30 min.Under this condition,the average yield of the main bitterness material is 18.17 mg/g and 15.12 mg/g respectively.The yield RSD of endocarp and flesh,compared with the predict values,is 0.16% and 0.82% respectively.(4)Sodium cumene sulfonate,as water-soluble additives,is selected to increase the solubility of organic bitter substances in water.The optimum extraction condition is as follows: the concentration of sodium isopropyl sulfonate is 2.05 mol/L,the ratio of material is 30.72 mL/g,the extraction time is 7.32 h,the concentration of sodium isopropyl sulfonate is 2.16 mol/L,the ratio of material is 26.58 mL/g,and the extraction time is 6.6 h.The predicted yield of main bitter substances was 15.74 mg/g and 14.23 mg/g respectively.Considering the actual production,the process conditions were modified: the concentration of sodium isopropyl sulfonate is 2.1 mol/L,the ratio of material is 30.7 mL/g,the extraction time is 7.3 h,the concentration of sodium isopropyl sulfonate is 2.2 mol/L,the ratio of material is 27 mL/g,and the extraction time is 6.5 h.The average yield of main bitter substances was 15.16 mg/g and 13.96 mg/g respectively.And the RSD between the actual value and the predict one was also caculated,1.88% and 0.96% individually.(5)Acid-base water extraction method was applied to extract the main bitter substances of the endocarp and pulp of ZhiQue.And single factor and star point design experiments were performed to optimize parameters.The obtained extraction conditions are as follows: pH is 9.2,the ratio of material is 16 mL/g,the extraction time is 2 h and pH is 9.7.The ratio of material is 16.72 mL/g and the extraction time is 1.9 h.Under this condition,the prediction of the main bitterness material is 11.35 mg/g and 10.97 mg/g respectively.Under this condition,the average yield of main bitter substances was 11.17 mg/g(RSD 0.80%)and 10.69 mg/g(RSD 1.29%)respectively.(6)The main bitterness substances were purified by the combination of dichloromethane extraction and AB-8 macroporous resin purification,followed by the qualitative analysis of main bitter components by HPLC-MS.It can be concluded from the mass spectrogram and fragment ion map that bitter components are mainly naringin,neohesperidin,limonin,and nomilin.Meanwhile,narirutin was also detected in the pulp and hesperidin was detected in the flesh of ZhiQue,but hesperidin was not considered as a bitter ingredient given it is sweet.