| Crabapples (Rosaceae malus fruits), also called wild apples, have properties in diseaseresistance, high yield and similar flavor of cultivated apples. However, there are few reportson the processing of crabapple fruits although the trees are widely used as rootstocks in applebreeding and resources for ornamental and economic Malus. germplasms. In order to revealthe value of crabapple fruit in processing, ten different kinds of crabapples were employed tostudy polyphenol and flavonoid contents, antioxidant activities and bacteriostatic activities.The obtained major results were listed as follows:(1) Effect of extraction solvents on polyphenol content and profiles in the obtainedextracts.80%ethanol and ethyl acetate were separately used to extract polyphenol and flavonesfrom10crabapple samples. It was found that the extraction solution used had significantinfluence on the results of phenol extraction ratio and profiles. In detail, the detected totelpolyphenol content (PC) of the10crabapple samples ranged from302.83to1265.94mg GAE/100g, the average was566.58mg GAE/100g in the ethanol extracts. And from62.96to215.21mg GAE/100g, in ethyl acetate, the average was135.97mg GAE/100g. Thedetected total flavonoids (FC) ranged from352.45to2351.74mg RE/100g fresh weight withan average of965.05mg RE/100g for ethanol extracts and from83.77to369.21mg RE/100gfresh weight with an average of214.90mg RE/100g inethyl acetate extracts. The averagevalue of PC and FC in ethanol extracts was4.17and4.49fold, respectively, of that of ethylacetate extracts.Chlorogenic acid,(-)-epicatechin, rutin, hyperin, and phlorizin were detected in bothethanol and ethyl acetate extracts of all tested crabapples. P-coumaric acid, ferulic acid andcaffeic acid were only detected in some species and had low content. Even for a same wildMalus species, the obtained phenolic profiles were different depending upon the extractionsolvents used. For all tested species, the contents of chlorogenic acid and rutin were muchhigher in ethanol extracts than in ethyl acetate extracts.(2) Antioxidant activity of the obtained phenolic extracts. Results of antioxidant activities indicated that ethanol extracts had nearly6fold ofDPPH values and5fold of ABTS values higher than ethyl acetate extracts in average values.In ten crabapples, Lijiang-shanjingzi possessed the highest values of DPPH (3789.25μmolTE/100g) and ABTS (13056.68μmol TE/100g) in ethanol extracts. And the FRAP valuewas9356.14μmol TE/100g.PC and FC were also significantly correlated with DPPH, ABTS and FRAP for eachused extraction solvent. Comparatively, the correlation between PC and antioxidant activitywas more significant in ethanol extracts, indicating more active polyphenols and flavonoidswere extracted using ethanol.The ethanol extracts of Lijiang-shanjingzi significantly protected AAPH-induced bovineserum albumin (BSA) oxidative damage at concentration of30-240μg GAE/mL. Theprotective activity increased with the increase of polyphenol concentration in the ethanolextracts.(3) Antibactrial activity of the obtained polyphenol extracts.Among the10crabapple samples, when the concentration was6g/mL,Lijiang-shanjingzi exhibited the highest antibacterial activities on Escherichia coli andStreptococcus faecalis with an inhibition zone diameter of7.6mm and7.9mm, respectively;while red crabapple exhibited the highest antibacterial activities on Staphylococcus aureuswith an inhibition zone diameter of6.0mm. Overall, ethanol extracts of Lijiang-shanjingziand red crabapple whoed the lowest value of minimum inhibitory concentration (MIC),2g/mL, for the three tested bacteria.(4) Development of crabapple processing technology.Three kinds of different technologies were developed to process crabapples, such asdried fruits, fruit tablet and wine. All products showed desired quality. |
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