| Gardenia oil is a kind of vegetable oil extracted from gardenia dried fruit,in addition to containing tocopherols,phytosterols,squalene and saturated/unsaturated fatty acids and other commonly present bioactive substances in oils and fats,but also contains saffronin,gardeniside,geniposide and other unique active substances of gardenia oil,these active substances make gardenia oil have a variety of physiological and pharmacological functions such as calming,liver and choleretic protection,anti-inflammatory and anti-tumor.In this project,a method of ultrasound-assisted aqueous enzymatic extraction was established and the extraction process was optimized,and the quality difference of gardenia oil extracted by different extraction methods before and after refining was compared,and the O/W nanoemulsion system was made from gardenia oil and the natural emulsifier whey protein isolate(WPI),and its stability was studied.1.Using gardenia dried fruit as raw material,ultrasonic assisted method was used to extract at different powers(0 W,120 W,240 W,360 W,480 W,640 W)and time(0 min,15 min,30 min,45 min,60 min),and it was found that ultrasonic pretreatment could significantly improve the oil yield,and the optimal sonication condition was 480 W,30 min.The nutrients content,rheology and apparent characteristics of the gardenia powder before and after ultrasound were analyzed and compared.It was found that ultrasonic pretreatment reduced the protein content in the raw material,increased the folds and pores on the surface of the powder,increased the specific surface area,increased the fluidity of the powder,and compared with the gardenia powder without sonication,the surface pores of the gardenia powder after enzymatic hydrolysis after ultrasonic pretreatment were more.The roles of different enzymes in the extraction of gardenia oil were compared,Cellic Ctec3 and Alcalase2.4L were screened as suitable enzymes,and the response surface optimization experimental model was established on the basis of single-factor experiments to obtain the optimal oil extraction conditions of the two enzymes,and finally the optimal extraction conditions of the two enzymes were combined to extract gardenia oil by two-step aqueous enzymatic extraction method.The optimal extraction conditions of the two enzymes were Cellic Ctec3: the solid-liquid ratio was 1:6 g/m L,the enzymatic hydrolysis temperature was 45°C,the enzymatic hydrolysis time was120 min,and the enzyme concentration was 1.7%.Alcalase 2.4L: solid-liquid ratio was 1:6 g/m L,enzymatic hydrolysis temperature was 51°C,enzymatic hydrolysis time was 120 min,enzyme concentration was 1.3%.The optimized oil premium rate obtained by ultrasound-assisted water enzymatic extraction is as high as 18.25%.2.Ultrasonic-assisted aqueous enzymatic extraction(UAEE),cold pressing extraction(CPE),solvent extraction(SE),Supercritical fluid extraction(SFE).The four methods extracted gardenia crude oil and refined it,compared the oil yield of the four methods,and detected the physicochemical properties(acid value,peroxide value,saponification value and iodine value),tocopherol,phytosterol,squalene,total flavonoids and total carotenoids and fatty acid composition of the four gardenia oil before and after refining by High Performance Liquid Chromatography(HPLC),Gas Chromatography-Mass Spectrometry(GC-MS)and Ultraviolet spectrophotometer(UV),and compared their antioxidant capacity in vitro.UAEE and SE have the highest oil lifting rate;the acid value and peroxide value of the oil extracted from UAEE before and after refining were the lowest,and the iodine value was the highest,indicating that the content of unsaturated fatty acids in gardenia oil extracted from UAEE was high;The proportion of unsaturated fatty acids in UAEE before and after refining was 77.28% and 77.51%,respectively;SFE gardenia oil had the largest squalene content before and after refining,692.75 μg/g and 627.82 μg/g,respectively;the tocopherol content extracted from SFE and UAEE in crude oil was higher,but the total tocopherol content was higher in SE and CPE after refining;the largest plant sterol content before and after refining was CPE;the total flavonoid content of UAEE crude oil was the lowest but became the highest after refining,while the total carotenoid content of CPE and UAEE ranked in the top two before and after refining;CPE and UAEE were obtained by detecting the scavenging ability of DPPH and ABTS free radicals,the antioxidant capacity of the extracted gardenia oil in vitro is slightly stronger than that of SFE and SE.3.WPI was selected as an emulsifier,and O/W type gardenia oil nanoemulsion(GO-N)was prepared by ultrasound,using single-factor experiments to screen for optimal preparation conditions.It was prepared the most stable GO-N with a particle size of 208.15 nm under the conditions of WPI content of 0.5%,gardenia oil content of 10%,ultrasonic power of 240 W and ultrasonic time of 12 min;under confocal scanning microscope,it was observed that ultrasound has a good effect on the stabilization of nanoemulsions.The results of physical stability experiments showed that the nanoemulsions prepared by ultrasound had good thermal stability,p H stability and storage stability.In addition,β-carotene,hesperidin and naringin were dissolved in gardenia oil to prepare gardenia oil nutrient nanoemulsions,to explore the oxidation stability of these three kinds of gardenia oil nutrient nanoemulsions,GO-N and gardenia oil,and to establish in vitro digestion model to explore their free fatty acid release rate.The results showed that the preparation of the four kinds of gardenia oil nanoemulsions could improve the oxidation stability of gardenia oil,and the oxidation stability of three nutrients nanoemulsion also significantly(p < 0.05)increased compared with GO-N,and the release rate of free fatty acids of the three nutrients nanoemulsion were significantly decreased. |
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