Study On The Chemical And Physical Properties Of Blueberry Extract On Oil And Oleogels

Blueberries contain anthocyanins,phenols,flavonoids and other active substances,but the different extraction conditions of blueberries lead to different nutritional components of the extract,and then the content of resveratrol is also different.Resveratrol,a phenolic substance,has a variety of functional and pharmacological properties,but there are few reports that it is regarded as a necessary trace element for human body and used as a natural antioxidant in grease and grease gel.Therefore,the following aspects are investigated in this experiment:(1)Response surface methodology was employed to optimize the extraction process to increase the content of resveratrol in blueberry extract.Thin layer chromatography and liquid chromatography were used for qualitative and quantitative analysis of resveratrol,and resveratrol was separated and purified from blueberry extract.Meanwhile,the correlation among total phenol,anthocyanin and resveratrol in the extract was assayed.(2)In order to determine the nutritional and oxidation characteristics of blueberry crude extract,the chemical components of blueberry crude extract were detected by gas chromatography-mass spectrometry(GC-MS).The free radicals scavenging capacity of 1,1-diphenyl-2-trinitrophenylhydrazine(DPPH·)and 2,2-diazo-bis(3-ethyl-benzothiazole-6-sulfonic acid)diammonium salt(ABTS·+),total antioxidant capacity,total reducing capacity and hydroxyl radical scavenging capacity of crude extract were determined by spectrophotometry.(3)Adding blueberry acid crude extract(AC),alkaline extract(AL),Resveratrol(R),synthetic antioxidant-BHA,natural antioxidant-VE,tea polyphenol(TP)to Peanut oil(PO)and Soybean oil(SO),peroxide value(POV)and thiobarbituric acid(TBA)were gauged by oven accelerated oxidation,and the oxidative storage stability of peanut oil and soybean oil was compared.(4)Soybean oil and peanut oil were used as base oil,sitosterol and lecithin were served as gel to prepare ternary oleogels loaded with blueberry extract and resveratrol.The changes of physical properties of gel system were detected by texture analyzer,polarizing microscope,X-ray diffractometer,pulsed nuclear magnetic resonance(SFC),differential scanning calorimeter(DSC)and Rheometer.The POV and TBA values of the oleogels were determined by oven accelerated oxidation,and the oxidation process of the oil gel during storage was studied by nuclear magnetic resonance(1H NMR).The results are as follows:1.The optimum extraction process for improving resveratrol content inblueberry powder extract is:solid-liquid ratio 1:20(g/ml),pectinase:cellulase(5:1,g/g),the enzymolysis temperature is 54.62?for 1 h.Under these conditions,the highest extraction rate of resveratrol is 235 mg/kg with pH=5.Ethyl acetate solution is most suitable for LC-18SPE column separation and purification,and the resveratrol content reaches 76.61%.Under the conditions of cellulose:pectinase(1:5),extraction temperature 50? pH=5,the highest total phenol content was 3358.12 mg/kg.Anthocyanin reached 1040.34 mg/kg when cellulose:pectinase(1:1),extraction temperature 50?,pH=6.There is a significant positive correlation between total phenol and resveratrol.There is a very weak negative correlation between total phenol and anthocyanin content.There is a very weak positive correlation between resveratrol and anthocyanin.2.By gas chromatography-mass spectrometry(GC-MS),26 kinds of active substances in acid blueberry powder extracted by complex enzyme and 11 kinds of active substances in alkaline blueberry powder were detected,of which acids were the main substances,followed by sugars.The antioxidant capacity of each sample had a dose-effect relationship with the sample mass concentration.The free radical scavenging ability of AC was significantly higher than that of AL,3.Results of oxidative storage stability of blueberry powder extract added with acid and alkali on oils:with the increase of oxidative storage time,the content of POV and TBA in each oil system slowly increased,and the bright colors in the oil gradually disappeared.AC had certain primary and secondary antioxidant capacity to PO and SO,AL promoted PO oxidation.4.Effect of adding blueberry crude extract on physical and chemical properties of oleogels:(1)The results of physical properties suggested that the texture index could distinguish peanut oil oleogels(POO)from soybean oil oleogels(SOO)by PAC analysis.With the extension of storage time,the number of crystalline particles in oleogels increased.The POO and SOO systems added with R showed a denser network structure,while the POO and SOO systems added with AL and AC showed a crystalline form of needle-shaped and round granular combination.In addition,each gel sample group added with AL,AC and R contained three crystal characteristic peaks of ?-,?'-and ?-,and diffraction intensity increased with storage time.The content of solid fat in the sample was inversely proportional to the temperature.The gel system added with AL,AC and R had a large number of internal crystalline units,and the formed cross-linked network structure was stable and has good spreadability.Compared with the blank sample,the gel system did not greatly change the internal stable crystalline structure,and the formed three-dimensional network structure was less brittle.The SFC content of the samples decreased rapidly after 50?,and the crystal number and internal structure of the gel system were greatly destroyed.On the 1st day of frequency scanning,POO and SOO storage modulus G'are both greater than energy dissipation modulus G";The POO and SOO strength added with AC and R are both higher than other samples.At the 10th day of storage,the internal network structure of each gel system was destroyed and all were on the edge of "true gel" state,and the consistency coefficient was the largest R and POO<SOO.(2)The oxidative storage stability of oleogels added with AL,AC and R showed that peroxide value(POV)and antioxidant capacity of POO,SOO were all R the best,followed by AC.AL promoted POO oxidation and could inhibit SOO oxidation to some extent.Compared with grease,the TBA value of oleogels was delayed in reaching the maximum value and the value was smaller.The secondary oxidation resistance of AC and R to POO showed "M" type,while that of AL,AC and R to SOO showed "N" type.Through 1H NMR fingerprint analysis of soybean oil and peanut oil,we found two E,E conjugated signal peaks,two suspected Z,E conjugated signal peaks and seven new substances with lower content.R and AC could effectively control the double bond hydrogen content,and AL promoted double bond hydrogen oxidation.The chemical shifts 8=5.0-9.0ppm of POOAL and POOB showed obvious oxidation peak shape,and the value of POOAL was larger.POOAC and POOR did not show oxidation peak signal.The peak value of SOO oxidation was SOOB>SOO AL>SOOAC>SOOR.