| Lycium Barbarum,or Goji berry or wolfberry,is the only halophytic perennial plant of the genus Lycium in the family Solanaceae and has been commonly used in China as a herbal medicine for thousands of years.The Goji berry fruit is now increasingly being presented as a functional food throughout Europe and in Asian countries.The consumption of Goji berry has been suggested as promoting many pharmacological functions particularly relating to the kidney,liver,and eyes and has been marketed in the West as a health food and is now readily available commercially.In appearance,dried Goji berries appear with a pericarp which is red to dark red which in terms of consumer perception is of primary interest in terms of product presentation.The objectives of this research were to study the optimum conditions of ultrasound assisted extraction(UAE)of Lycium Barbarum crude polysaccharides,and to investigate three multi-frequency ultrasound assisted extraction modes on the yield of Lycium Barbarum crude polysaccharides.Lycium Barbarum polysaccharides have important value in enhancing immunity,antiaging,anticancer and inhibiting tumor growth.But traditional methods of extracting polysaccharides have a very low extraction rate,and a longer extraction time.The ultrasonic assisted extraction is time and energy effective.It is widely used in the extraction of sensitive ingredients in agricultural products.Since the extraction process is continues process,the on-line in situ real-time detection is important to control the end of the extraction process and decision-making for an effective processing.The effect of ultrasound-assisted extraction(UAE)on the extraction rate of Lycium Barbarum polysaccharide was studied firstly.Secondly,the effect of three kinds of ultrasonic modes on extracting rate of Lycium Barbarum polysaccharide was studied,and the content of polysaccharide extracted was detected and modeled by NIR Technique,and then the realtime analysis and planning of extracting process were realized.The main research work and its results are as follows:The optimal extraction conditions of energy aggregation counter-flow sing-frequency UAE were extraction time of 30 mins,extraction temperature of 60 o C,solid/liquid ratio of 20 g/600 ml and ultrasound frequency of 28 k Hz,under these conditions the Lycium Barbarum crude polysaccharides yield was 26.38 %.Comparing to traditional hot water extraction,the crude polysaccharides yield increased 17.51 % under a reduction in temperature and extraction time to 33.3 % and 50 % respectively.The opposite-sit dual-frequency ultrasound extractor from USA had yield of 33.6 % at(20 k Hz,16 k Hz),increased 49.67 % than traditional hot water extraction.The energy aggregation counter flow dual-frequency UAE mode gave the yield of 38.93 % at(20 k Hz,40 k Hz),increased 73.41 % than traditional hot water extraction.So,Comparing to energy aggregation counter-flow sing-frequency and opposite-sit dual-frequency ultrasound,the energy aggregation counter-flow dual-frequency(20 k Hz,40 k Hz)UAE is best mode for Lycium Barbarum crude polysaccharides.After the UAE,NIR spectrometer was used to predict the polysaccharide content in the extraction.In-situ and real-time monitoring of Lycium Barbarum polysaccharides UAE was carried out by miniature fiber near-infrared(NIR)spectrometer and in conjunction with multivariate analysis.The Si-PLS algorithm was performed to variables selection and the regression model was calibrated.The performance of a model was evaluated by the correlation coefficient(Rp)and the root mean square error(RMSEP)in the prediction set.The results showed that Rp = 0.994,RMSEP = 0.49 for polysaccharides content.According to the results,the miniature fiber optical spectrometer combined with Si-PLS model can be used as an alternative method for in-situ and real-time monitoring the UAE of Lycium Barbarum polysaccharides. |
PDF Full Text Request