Study On The Extraction Of Maca Flavonoids And Polyphenols And Its Analysis Of Nutritional Compositions In Different Parts Of Plant

Maca(Lepidium meyenii Walp.),belonging to the family of Cruciferae,is an annual or biennial herbaceous plant as a food and medicine crop.The pharmacological studies showed that maca has many biological activities,such as fertility enhancer,improvement of sexual function,antifatigue,regulation of endocrine and the treatment of femal climacteric syndrome.At present,the reaserch works and application of maca were mainly focused on maca tubers.However,the use of maca root hair and leaves has not been caused enough attention,which results in a waste of resources.The reaserch on extraction process of active substances from maca and comparative analysis of the nutritional compositions of maca tubers,root hair and leaves are of great theoretical significance and practical value for making better use of maca resources.In this paper,the total flavoniods and total polyphenols were extracted by microwave-assisted method from maca grown in Yunnan.Their optimum extraction conditions were obtained by using response surface methodology(RSM).Based on this process,the.nutritional components of maca tubers,root hair and leaves were systematically analyzed by using modern analysis technology,and the structural features and physico-chemical properties of maca starch were also studied.The optimum extraction conditions by RSM of total flavonoids from maca tubers by microwave assisted extraction were ethanol concentration 70%,liquid-to-solid ratio 25:1(mL/g),extraction time 16.0 min and extraction temperature 70?.Under these conditions,the extraction yield of total flavonoids was(3.19±0.021)mg/g,which was close to the measured value.The optimum extraction conditions by RSM oftotal polyphenols from maca tubers by microwave assisted extraction were ethanol concentration 45%,liquid-to-solid ratio 25:1(mL/g),extraction time 18.00 min and extraction temperature 48?.Under these conditions,the extraction yield of total polyphenols was(4.29±0.059)mg/g,which was close to the measured value.The experimental results showed that the maca tubers,root hair and leaves cultivated in Yunnan province were rich in protein,amino acids,mineral elements and other nutrient compositiion.The content of their protein was between 16.5 g/100g and 21.1 g/100g.Their amino acids were rich and balanced.Their fat contents were low,but their fatty acid had abundant species and higher proportion of unsaturated fatty acid.Compared with maca tubers,the root hair and leaves also showed some values on exploiting and utilizing.The granules of maca starch presented oval and irregular morphology.A square crossing was observed for polarization cross of maca starch.The X-ray powder diffraction showed C-type crystalline patterns of maca starch Unlike potato and Chinese yam starch,the maca starch showed lower values in onset temperature(To,46.88 0C),peak temperature(Tp,50.42 ?)and conclusion temperature(Tc,54.82 ?),and its enthalpy of gelatinization(?H)was 7.37 J/g.The solubility and transparency of maca starch were superior to Chinese yam starch,worse than potato starch;its peak viscosity was similar to Chinese yam starch,but was lower than potato starch,its swelling power and freeze-thaw stability were higher than those of Chinese yam and potato starch.The maca starch,as a new starch resource,has some utilization values and expansive development prospects.