Study On Concentrating Cloudy Juice And Processing Cloudy Juice Of Sea Buckthron

Sea buckthorn(Hippophae rhamnoides L.)is a Hippophae shrubs or small trees of the family Elaeagnaceae,whose fruit have highly nutrition and health value.But sea buckthorn fruit too acidic to eat fresh and intolerant storage for nutrient-rich,must be processed before having economic value.Therefore,carried out the study on sea buckthorn juice processing technology was great significant for achieving nutritional value and economic benefits.On account of this,cold crushing sea buckthorn berries,vitamin C kinetics in sea buckthorn juice,concentrating cloudy juice and processing cloudy juice beverage were investigated systematically,and the main components of sea buckthorn juice were measured and compared in this paper.Based on the research of topoic and further analysis of data,the main conclusions can be summarized as followed:(1)The quality of sea buckthorn juice obtained by cold crushing process technology was excellent.The contents of soluble solids and total acidity reached to 18.0%and 4.24%in sea buckthorn juice respectively.It contained vitamin C 729.69 mg/100mL,flavonoids 445.17 mg/100mL,total polyphenols 924.67 mg/100mL and polysaccharides 25.22 mg/100mL.In order to study the volatile components changes during processing sea buckthorn cloudy juice,solid phase micro-extraction followed by GC/MS and computer-assisted library search was used to analysis volatile compounds in each sample obtained before and after decanter centrifuge,after disc centrifugation and UHT sterilized.They were identified 133,134,132 and 117 kinds of volatile compounds respectively,and their contents were 99.30%,99.06%,98.32%and 92.27%in that order.After initial inferred,2-methylbutyl isovalerate,pentanoic acid,1-methylpropyl ester,isobutyl caproate,2-methylbutyl 2-methylbutyrate,ethyl caproate,ethyl acetate,ethyl isovalerate,isobutyl isovalerate,ethyl alcohol,tert-butyl alcohol,3-methyl-l-butanol,heptaldehyde,1-heptanol were the most abundant compounds identified.Sea buckthorn juice obtained before and after decanter centrifuge separation,after disc centrifugation separation was not significantly differences in volatile components.And esters were the most numerous compounds found in each sample except sea buckthorn juice sterilized by UHT.(2)Vitamin C degradation kinetics results in sea buckthorn juice complyed with first-order kinetic models.And,the degradation pathway of vitamin C in sea buckthorn juice mainly was the aerobic oxidation pathway that AA through DHA continued degradation.Meanwhile,there may be an irreversible way that AA without passing through DHA generated other products,but it did not dominate.AA oxidation was the main cause of vitamin C loss in sea buckthorn juice,and DHA concentration reflected the rate of vitamin C continue degradation and deactivation under the aerobic conditions,and the reaction was greatly influenced by temperature.Anaerobic degradation rate was below aerobic degradation speed of vitamin C in sea buckthorn juice(k3<k1,k2),and with the temperature rised,the aerobic degradation rate of vitamin C in sea buckthorn juice accelerated,but anaerobic degradation speed changes of that relatively insignificant.(3)The optimum temperature of concentrating sea buckthorn cloudy juice under reduced pressure was 45?.Different concentration multiples of sea buckthorn juice were processed at 45? by evaporation in the vacuum of 0.095-0.1 MPa,with the increase of concentration multiples,the loss rate of nutrients and browning index became larger,the total acidity and 5-HMF content increased and pH value decreased.Compared with the three-fold and four-fold sea buckthorn concentrated cloudy juice,the rate of nutrient preservation was highest,browning index and 5-HMF content is low of two-fold sea buckthorn cloudy juice.Moreover,different concentration juice production were placed at room(10 to 25?)and refrigerated conditions(5 to 8?)for 60 days,their physicochemical properties changes were as follows:Vitamin C,flavonoids,total polyphenols and polysaccharides contents decreased gradually,pH and total acidity did not change significantly,browning index and 5-HMF content increased.Furthermore,compared with the room temperature condition,refrigerated conditions were conducive to the preservation of the sea buckthorn juice.What's more,2-fold sea buckthorn cloudy juice stored at room temperature conditions instability,but the stability of 2-fold concentrated cloudy juice at refrigerated conditions was better than that of 3 times and 4 times concentrated cloudy juice.In order to study the volatile components changes of sea buckthorn concentrated cloudy juice,solid phase micro-extraction followed by GC/MS combined with computer-assisted library search was used to analysis volatile compounds in 2-fold,3-fold concentrated sea buckthorn cloudy juice.They were identified 86 and 88 kinds of aroma chemical composition respectively,and their contents were 87.41%and 87.04%.And concentrated sea buckthorn juice by evaporation under reduced pressure had more significant effects on volatile components.Combined with sea buckthorn juice sterilized by UHT,the volatile components of 2-fold concentrated sea buckthorn cloudy juice declined by 31 species,and its content reduced by 4.86%.In our analogy,the volatile compounds specie and content of 3-fold concentrated sea buckthorn cloudy juice respectively reduced by 29 and by 5.25%.Compared to 3-fold sea buckthorn concentrated cloudy juice,the aroma of 2-fold concentrated sea buckthorn cloudy juice was better,but the soluble solids content of 3-fold concentrated sea buckthorn cloudy juice reached up to 54%,it was easier to storage and transport than 2-fold sea buckthorn concentrated cloudy juice.(4)In order to ensure the suspension stability and reduce the nutrient loss of sea buckthorn cloudy juice as much as possible,xanthan gum,guar gum and CMC(ratio of 2:1:0.6)could be used as compound stabilizer in sea buckthorn cloudy juice beverage,and it should be homogenized twice at 25 Mpa.Meanwhile,the optimum technological parameters of sea buckthorn cloud juice were determined through orthogonal experiments and sensory evaluation methods,and the result showed that the best formula of sea buckthorn cloud juice was:the dosageof original sea buckthorn jucie 10%,the dosage of sucrose 15%,the dosage of compound stabilizer 0.4%.