Study On Anthocyanins Extraction By High Hydrostatic Pressure From Blueberry Pomace And Its Degradation Kinetics Under High Hydrostatic Pressure Processing

As a natural colorant and antioxidant,anthocyanins has a variety of physiological functions.But anthocyanins is unstable,which would be degraded because of many factors during processing and storage.There are a lot of anthocyanins in blueberry pomace which was obtained after blueberry processing.A suitable extraction technology not only solve the problem of blueberry processing waste,but also improve the added value of blueberry.The pomace obtained after Rabbiteye blueberry wine fermentation was used as the raw material.Extracts from different extraction methods were compared for colour,antioxidants,extraction yield of anthocyanins and total polyphenols.High Hydrostatic Pressure Assisted Extraction(HHPE)was found to be the most suitable.The HHPE method was optimized and its effects on monomeric anthocyanins studied.The mechanism for HHPE on the improvement of extraction yield was investigated based on its effects on extraction solvent.Degradation of anthocyanins was studied under different pressure and holding time.Lastly the storage stability of the anthocyanins from HHPE and solvent extraction were assessed and compared in a model juice system.The findings are as follows:(1)Five extraction methods: Heating Extraction(HE),Ultrasonic Assisted Extraction(UE),Microwave Assisted Extraction(ME),High Hydrostatic Pressure Assisted Extraction(HHPE)and High Hydrostatic Pressure Enzyme Assisted Extraction(HHPEE).The extraction methods were compared with HE,UE,ME,HHPE and HHPEE could increase the extraction yield of anthocyanins and total polyphenols.HHPE obtained the highest anthocyanins extraction yield(61.59%)and UE obtained the highest total polyphenols extraction yield(71.22%).The highest lightness value,hue value,chroma value and browning index of extracts was obtained from HHPE,meanwhile,a better of OH radical scavenging rate and lipid peroxidation inhibition rate of extracts was obtained from HHPE.There were a significant positive correlation between anthocyanins content and OH radical scavenging rate,reducing power,lipid peroxidation inhibition rate.Based on these primary data,HHPE was selected as the best anthocyanins extraction method for blueberry pomace and its extraction parameters optimized.(2)After screening from single factor experimental design and Plackett-Burman(PB)exerimental design,three influenced significantly factors contained liquid solid radio(25~45,mL/g),ethanol concentration(45%~75%)and extraction pressure(300 MPa~600 MPa)were optimized by Box-Bohnken response surface design.The highest anthocyanins content(106.57±1.25)mg/100 g was obtained at liquid solid radio 41 mL/g,ethanol concentration 66% and extraction pressure 443 MPa.The highest total polyphenols content(16.42±0.53)mgGAE/g was obtained at liquid solid radio 43 mL/g,ethanol concentration 61% and extraction pressure 489 MPa.(3)Twelve known monomeric anthocyanins were isolated from the extract of blueberry pomace using HPLC-MS.The content of malvidin-3-galactoside and malvidin-3-glucoside were higher,both of the two anthocyanins had reached 64.27% of total anthocyanins.The monomeric anthocyanins extracted under different HHPE conditions were semi-quantitatively by HPLC,the total anthocyanins content would increase as extraction pressure increased,but the monomeric anthocyanins had a different trend.There were more content of delphinidin-3-glucoside,delphinidin-3-galactoside and malvidin-3-galactoside obtained from solvent extraction,but there are moremalvidin-3-glucoside and Petunidin-3-glucoside under HHPE.Compared to solvent extraction,anthocyanins obtained from HHPE had higher storage stability in model juice,but there was no significant difference in antioxidant activity between that from solvent extraction and HHPE after 90 days storage at 4?.This may be because of the constitute of monomeric anthocyanins.(4)High hydrostatic pressure processing could affect intermolecular hydrogen bonding between ethanol and water,with the increasing of pressure,the hydrogen bonding between ethanol and water would be more stable.A significant positive correlation was found between anthocyanins extraction yield and chemical shift of intermolecular hydrogen bonding.The pressure changed intermolecular hydrogen bonding of extraction solvent,the change of hydrogen bonding caused further change of physical properties of extraction solvent,this may be the reason why HHPE could increase anthocyanins extraction yield from blueberry pomace.(5)The degradation of anthocyanins under 200 MPa and 600 MPa high hydrostatic pressure processing were in accord with first order kinetics equation in blueberry juice.The degradation rate constant of 200 MPa was higher than 600 MPa.The degradation rate was high at 600 MPa with a corresponding increase in temperature from 22 to 40?.This implies that degradation is not only dependent on temperature but also pressure.However,there was no degradation at 200 MPa and 400 MPa in model juice.The effects of high hydrostatic pressure on polyphenol oxidase(PPO)and peroxidase(POD)activity was different in blueberry juice.The PPO activity increased to 103.3% after 200 MPa processing 20 min,the lowest PPO activity(86.33%)was obtained at 600 MPa processing 20 min.The highest POD activity residual rate(96.34%)after 200 MPa processing 10 min,the lowest POD activity(86.8%)was obtained at 600 MPa processing 20 min.After Peason's correlation analysis,we supposed anthocyanins degradations was caused holding time and oxidase in blueberry juice.