Extraction,Identification Of The Anthocyanin From Corncob And Development Of Black Glutinous Corn Lactobacillus Fermented Beverage

As a natural pigment,anthocyanins have lots of physiological functions such as removing free radicals,antioxidation,anti-inflammatory,proliferating lutein,preventing cardiovascular disease,improving eyesight,increasing immunity and so on,which has become a hot academic research in the 21st century.Black glutinous corncob,as a byproduct in the production and processing from the black glutinous corn,is still rich in anthocyanins.However,there are not so many literature reports.So we took an uncommon maize variety—the black glutinous corn as a research subject.The black glutinous corn was first fermented with lactic acid bacteria to obtain a functional product combining the health benefits of probiotic microorganisms with the anthocyanins.Then process parameters of probiotic beverage was optimized with orthogonal experiment.Meanwhile,we studied the rheological properties,nutrition and shelf life analysis of the fermented beverage.In order to make good use of the surplus black glutinous corncob,we intended to extract the anthocyanins from it by response surface analysis method to know their structural features and physiological functions,which can reuse waste materials and create economic value.This paper analyzes the composition and antioxidant activities of anthocyanins and provides some theoretical guidance and basis for the development and application of the black glutinous corncob in real life.Main contents and results are as follows:1.Taking the acid ethanol as solvent to extract anthocyanins from the black glutinous corncob,the UV absorbance of the extraction solution as the measure of extraction effect,and response surface analysis method to optimize the extraction condition,we analyzed the influences of the extraction effect by the five single factors,including ethanol concentration,PH value,solid-liquid ratio,extraction time and temperature.At last,by quantitative analyses of the freeze-dried samples from the black glutinous corncob,it finds out the content of the total phenol,anthocyanins and flavonoids,which then compares with the extraction content from the black rice bran.Results showed that the optimum condition as follows:when the extraction temperature is 47?,liquid-solid ratio24:1,the ethanol concentration is 62%,extraction time 120 min and p H value is 2.0,the extraction ration is 1.25%.The influence of extraction effects was solid-liquid ratio>the ethanol concentration>extraction temperature>extraction time>p H.The concent of anthocyanin extracted from the black glutinous corncob was 66.29±1.24 mg/g,total phenol was 206.49±2.45 mg/g,flavonoid was 52.11±1.16 mg/g.2.High performance liquid chromatography with diode array detection combined with electrospray ionization tandem mass spectrometry(HPLC-MS)was used to analyze the anthocyanidin compositions of the black glutinous corncob and black rice bran.And the antioxidant activities of anthocyanins were also observed with ascorbic acid as a control,which including scavenging DPPH,ABTS free radicals,total reducing power and iron reducing power.Three mian anthocyanins from the black glutinous corncob were identified:cyanidin-3-glucoside,pelargondin-3-glucoside,petunidin-3-glucoside.Among them,the content of cyanidin-3-glucoside was the highest and there were no acidylated anthocyanins.Two kinds of anthocyanins from black rice bran were identified:cyanidin-3-glucoside and petunidin-3-glucoside.The highest content was still cyanidin-3-glucoside and there were no acidylated anthocyanins either.The IC₅₀values of scavenging effects on ABTS radical of anthocyanidins from black glutinous corncob and black rice bran were 103.86±1.25 mg/Land 132.79m±2.11 g/L.The IC₅₀values of scavenging effects on DPPH radical of anthocyanidins from black glutinous corncob and black rice bran were 17.15±0.79 mg/L and 18.26±1.01 mg/L.The results showed that the anthocyanins of black glutinous corncob and black rice bran had strong ability of scavenging free radicals,strong total reducing power and ferric reducing power.3.Taking the black glutinous corn as material and using the broke cell wall,gelatinization,saccharification and other methods,we inoculated the fermented lactobacillus to prepare black corn fermented beverage and optimized the fermentation process.It showed that the most suitable optimum condition were:the amount of lactic acid bacteria 0.07%,fermentation temperature 42?,fermentation time 12 h.The influence of fermentation effects was the amount of lactic acid bacteria>fermentation time>fermentation temperature.After using the optimized fermented process,the nutritional content of the beverage were:the ash content 0.36±0.06 g/m L,moisture content 63.54±1.57 g/m L,fat content 0.81±0.06 g/100m L,protein content 2.48±0.32g/100m L,reducing sugar content 8.31±0.29 g/100m L,anthocyanins content 305.32±1.16mg/100m L,free amino acid 32.56±1.32 mg/100m L.The beverage tastes better when p H value was 3.62,number of viable count was 8.83,titratable acidity value was 70.9°T.In the process of storage for 7 days at low temperature,the number of viable count value decreased by 0.35,the value of p H decreased,titratable acidity increased,but it still remains in an acceptable range.Meantime when the anthocyanins content decreased in small scale,the amplitude of reducing sugar content remains the same in basic,beverage stability and the overall quality is still good.Analyzing by reological measurement,the beverage is the typical pseudoplastic fluid on the condition of 5?and its viscosity changing condition with temperature can be described by Arrhenius Equation.