Analysis on Nutritional and Functional Components of Different Pueraria lobata Roots

Jinping WU，F(xiàn)engling GUO，Xianqiang SHAO ，Yan HU，Jianjun ZHAO，Zhengming QIU*

1．Institute Industrial Crops，Hubei Academy of Agricultural Sciences，Wuhan 430064，China；2．Hubei Gewa Food Co．Ltd．Zhongxiang 445000，China；3．Wuhan Gujun Plant Professional Cooperatives，Wuhan 430223，China4．Ezhou Linjiang Township Xinchang Agricultural Products Professional Cooperatives，Ezhou 436035，China

1 Introduction

Pueraria lobata belongs to Pueraria DC．of Leguminosae．The plant is a member of the pea family，with reddish-purple flower clusters．It is perennial deciduous liana．Its big roots are rich in starch and essential nutritional components for human body and also active components for physiological functions．In China，there are 9 varieties and 2 variants of Pueraria lobata［1］．Except Xinjiang and Tibet，most provinces and regions of China have distribution of Pueraria lobata．Pueraria lobata food functions as improving memory，suppressing postnatal diseases，and beauty care［3］．Starch and flavone separated from Pueraria lobata roots can be processed into foods clearing heat，removing toxin，preventing and curing high blood pressure，high fat of blood，coronary heart disease，and diabetes，etc［4］．In March of 1998，the Ministry of Public Health of China listed Pueraria lobata into Catalogue of Food and Medicine Homology．With development of China's foreign trade，especially increase in demands of international market for Pueraria lobata root powder and Pueraria lobata root flavone，the area of cultivating wild Pueraria lobata is gradually expanding．However，because Pueraria lobata roots have high ability of survival and rich wild resources，all areas input little to variety selection of Pueraria lobata roots，local Pueraria lobata roots are mainly domesticated germplasm resources，the nutritional and functional components are not well known．In order to better use and develop Pueraria lobata roots and provide reference for variety selection of Pueraria lobata roots，we made an analysis on major nutritional and functional components of Pueraria lobata roots．

2 Materials and methods

2．1 MaterialsSamples we used are Pueraria lobata roots obtained from two years of growing Pueraria lobata roots in experimental base of HubeiGewa Food Co．Ltd．We cleaned them with tap water，chopped and put them into 105℃ baking oven for 20 minutes，dried at80105℃ to constant weight，and ground samples to powder with pulverizer and screened with 50 mesh sieve，put into reagent bottles and affixed with labels for experiment．

2．2 MethodsWater content was measured by direct drying method with reference to methods stated in GB／T5009．3－2003．Ash content was measured by methods specified in GB／T 5009．4－2003．Starch was measured by enzymic hydrolysis method with reference to methods stated in GB／T5009．9－2003．Fat was measured with acid hydrolysis method with reference to methods stated in GB／T 5009．6－2003．Total dietary fiber was measured by methods stated in GB／T 5009．10－2003．Reducing sugar was measured by direct titration with reference to methods stated in GB／T5009．7－2003．Flavone was measured by sodium nitrite-aluminum nitrate-sodium hydroxide colorimetric method．Polyphenol was measured using Folin-Ciocalten method．

3 Results

3．1 Nutritional components of Pueraria lobata roots Ash content is mainly mineral salts or inorganic salts，including essential inorganic salts or minerals for human body，such as calcium（Ca），magnesium（Mg），potassium（K），sodium（Na），and sulfur（S），accounting for 80%of ash content weight，as well as trace elements such as iron（Fe），copper（Cu），zinc（Zn），manganese（Mn），selenium（Se）．From Table1，we can see that Pueraria lobata root No．1 has the highest ash content，next is Pueraria lobata root No．2．With constant deepening of nutrition research and constant upgrade of diet concept，it is generally acknowledged that cardiovascular disease，high fat of blood，hypertension，obesity and cancer are connected with high intake of fat．Table1 indicates that Pueraria lobata root No．1 has the lowest fat content，next is Pueraria lobata root No．2．Starch of Pueraria lobata roots has a series of unique features，such as transparency of starch paste，high viscosity，starch gel not easy to syneresis，and as well as unique fragrance of Pueraria lobata roots［4］．Therefore，foodsmade of starch of Pueraria lobata roots are characterized by special nutrition and can beused as foods and medicine．From Table 1，we know that Pueraria lobata root No．5 has starch content as high as 64．43%，followed by Pueraria lobata root No．8 and Pueraria lobata root No．7，respectively 54．37%and 53．93%．Cellulose features high water holding capacity and chelation and can be exchanged with anion，improve bacteria micro environment of digestive system，so it plays extremely important role in human health．Its functions include easing constipation and preventing intestinal cancer，preventing diabetes and controlling obesity，reducing blood pressure and preventing and curing coronary heart disease，preventing cancer，preventing dental caries，and protecting oral health［5］．Besides，cellulose can be used as excellent food additives［6－7］．From Table1，it can be seen that Pueraria lobata root No．4 has cellulose ashigh as17．97%，next is Pueraria lobata root No．2 and Pueraria lobata root No．1．

Table 1 Nutritional components of Pueraria lobata roots（Unit：%）

3．2 Functional components of Pueraria lobata rootsWith constant development of modern medical and food science and technologies，use value of Pueraria lobata roots receives higher and higher concern［8］．Major functional components of Pueraria lobata roots are flavonoids，aromatics，triterpenoids，polyphenol，etc．Flavone functions as expanding coronary artery and cerebral blood vessels，improving cardiovascular and cerebrovascular circulation，reducing myocardial consumption of oxygen，strengthening body immunity，reducing blood sugar and anti-oxidation［9－10］．Polyphenol has high anti-oxidation and ability of removing free radical．In addition，polyphenol has high ability of absorbing ultraviolet and far-ultraviolet，thus，it can reduce the incidence of such diseases as cancer，cardiovascular diseases，arthritis，and chronic diseases［11］．Table 2 lists polyphenol and flavone content of 8 samples of Pueraria lobata roots．From Fig．1，we can see that polyphenol content is directly proportional with flavone content．Pueraria lobata root No．1 has the highest polyphenol and flavone，next is Pueraria lobata root No．4，followed by Pueraria lobata root No．3．

Table 2 Functional components of Pueraria lobata roots（Unit：%）

4 Conclusions

In the selective breeding of Pueraria lobata varieties，it is recommended to select varieties with high yield，high resistance of disease and suitability according to different purposes of use．For ex-ample，it is recommended to select varieties with high starch content to process powder of Pueraria lobata roots．For medical purpose，it is recommended to select varieties with high content of polyphenol and flavone．For processing into tablets of Pueraria lobata roots，it is recommended to select varieties with high content of cellulose．For fresh eating or making dishes，it is recommended to select varieties with low content of cellulose and few sclerotic cells．Pueraria lobata root is a wild natural plant resource still not developed fully．With constant deepening of extraction，separation，and detection technologies of effective components of Pueraria lobata roots，as well as in-depth understanding of pharmacological functions，application value of Pueraria lobata roots receives higher and higher concern．As a type of easily cultivated cash crop，Pueraria lobata has wide suitability for soil，including sandy and clay soil．In intense sunshine and high temperature，Pueraria lobata still can grow．Besides，resistance to aridity and barren land is also a special characteristic．Therefore，Pueraria lobata is suitable for planting in mountain areas，especially for economic development of poormountain areas，it is of realistic significance for farmers shaking off poverty and setting out on the road to prosperity．For example，if planting 66700 hectare Pueraria lobata using standardized cultivation technologies，it is able to harvest 2 million tons of fresh Pueraria lobata roots，which can replace 0．652 million tons of grain．Calculating at9000 kg／ha grain，it is equivalent to increasing 72000 hectare farmland and providing grain for2million people for one year［12］．Therefore，planting and developing Pueraria lobata roots have prominent economic benefits and important social significance．

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