| Purple sweet potato anthocyanins,which is a water-soluble natural pigment,is widely used in food,medicine,cosmetics and other fields,because of its safety,nutrient-rich,bright color,strong stability and other characteristics.This paper mainly studied on the following points: First,in order to improve the yield and purity of anthocyanins from purple sweet potato,the conditions of extraction and purification were optimized.Then,the structure of anthocyanin monomermoleculars from purple sweet potato,which were prepared by preparative liquid chromatograph,were identified by LC-MS/MS.Further more,the antioxidantive activity,proliferative effect on probiotics and inhibiting effect on harmful bacteria in vitro of the purple sweet potato were also studied.The main contents and results were as follows:1.Extract anthocyanins from purple sweet potato by enzymes.The yield of purple sweet potato anthocyanins as an evaluation index,through single factor tests and response surface analysis,The optimal extraction conditions were concentration of citric acid 3.5%,dosage of cellulase 79 U/m L,solid-liquid 1:15,extraction temperature 55 ? and extraction time 2 h.Under the condition,the highest extraction yield of the anthocyanins was 137.28±1.30 ?g/g.2.The crude extract was subjected to five kinds of macroporous adsorption resins,namely,DM301,D101,HP-20,X-5 and AB-8,to further purify the anthocyanins in terms of adsorptivity and desorptivity.The results showed that X-5 was the best,and its adsorption capacity was 14.00 m L/m L(wet resin)as the concentration of anthocyanins was 1.08mg/m L.The optimal operation conditions as follows: Sample filling and elution rate were 2 m L/min,solution p H value was 3 and eluent concentration(ethanol)was 80%.The purity of the anthocyanins was 36.82±1.03% after purification.3.The result showed that there were 12 components of anthocyanins from purple sweet potato analyzed by high performance liquid chromatography(HPLC).Afterwards,the 12 components were prepared by preparative liquid chromatography,and their purity was detected by HPLC.The results showed they were all single peaks,and the all peak areas were more than 95% except peak 4.Then,the structure of the 12 components were identified by LC-MS/MS.The results were as follows according to the mass spectras and literature: Cyanidin-3-sophoroside-5-glucoside,paeonidin-3-sophoroside-5-glucoside,cyanidin-3-p-hydroxy benzoyl sophoroside-5glucoside,paeonidin-3-p-hydroxy benzoyl sophoroside-5-glucoside,cyanidin-3-feruloyl sophoroside-5-glucoside,paeonidin-3-feruloyl sophoroside-5-glucoside,cyanidin-3-caffeoyl sophoroside-5-glucoside,cyanidin-3-caffeoyl-p-hydroxy benzoyl sophoroside-5-glucoside,cyanidin-3-caffeoyl-feruloyl sophoroside-5-glucoside,paeonidin-3-caffeoyl sophoroside-5-glucoside,paeonidin-3-coffeoyl-p-hydroxy benzoyl sophoroside-5-glucoside,paeonidin-3-caffeoyl-feruloyl sophoroside-5-glucoside.4.The antioxidant activity in vitro of the crude anthocyanins from purple sweet potato(PSPAs)and the five main anthocyanin monomers,P1(paeonidin-3-sophoroside-5-glucoside),P2(paeonidin-3-feruloyl sophoroside-5-glucoside),P3(paeonidin-3-caffeoyl sophoroside-5-glucoside),P4(paeonidin-3-caffeoyl-p-hydroxy benzoyl sophoroside-5-glucoside)and P5(peonidin-3-caffeoyl-feruloyl sophoroside-5-glucoside)was studied.The results showed that they all had not only the ability to scavenge DPPH radicals,hydroxyl radicals and superoxide anion,but also some reducing power and chelating ability to Fe2+.However,their antioxidation abilities,which were all weaker than those of positive control(Vc or EDTA),were different.This may be due to the H atoms,which could combine with free radicals,provided by phenolic hydroxyl groups existed in the anthocyanins.5.The effect of PSPAs,P1,P2,P3,P4 and P5 on Bifidobacterium bifidum,Bifidobacterium adolescentis,Bifidobacterium infantis and Lactobacillus acidophilus,which were cultured anaerobically in vitro,was studied.The results showed that all samples could stimulate the proliferation of the four probiotics significantly.In the experiment range,the probiotics proliferation increased fastly and then decreased slowly with the concentration increase of the samples,but they were all weaker than that of FOS.Due to the chemical structure,the molecular weight,the degree of branching,the number and type of the glycosides,the effects of P1,P2,P3,P4 and P5 on the four probiotics were different.For the four probiotics,the growth-promoting effect of P1 was best,and those of P2 and P3 were lower than that of P1,while those of P4 and P5 were lowest.The p H of the culture mediums were significantly decreased during the probiotics cultivation after adding PSPAs,P1,P2,P3,P4 and P5,indicating that probiotics could effectively utilize the anthocyanins and produced organic acids.Therefore,purple sweet potato anthocyanins is a potential prebiotics because of proliferative effect on intestinal probiotics.6.The effects of the purple sweet potato anthocyanins on harmful bacteria were studied by filter paper method.The results showed that PSPAs,P1,P2,P3,P4 and P5 had a certain role in inhibiting the growth of Staphylococcus aureus and Salmonella.All the samples had the strongest inhibitory effect on Salmonella,followed by Staphylococcus aureus.The inhibitory effect of the different samples on the same pathogen was: P4>P5> P3>P2>PSPAs>P1.Further more,the minimum inhibitory concentration of P4 and P5 on the two kinds of pathogens were the smallest(0.25 mg/m L). |
PDF Full Text Request