Research On The Processing Technology Of Clarified Jujube Juice Concentrate And Beverage

Jujube is a kind of food with high nutritional and medicinal value. It contains a variety ofcompounds with nutritional function or biological activity. It is of great significance toconduct deep research in order to exploit and utilize the jujube resource in China. In thisresearch, the optimized extraction, clarification and concentration process conditions of jujubejuice were studied. The physicochemical index and stability of jujube juice were investigatedduring the processing and storage. The jujube juice was developed from jujube concentrate. Itwas aimed mainly at providing the scientific basis for developing and utilizing jujuberesource.The extraction process of jujube was optimized. Orthogonal design based on singlefactor experiments was performed. Results revealed that the optimal conditions of extractionby enzymatic hydrolysis were, as follows: enzyme (pectinase) concentration0.4%(w/w) ofdried jujube sample,50oC of hydrolysis temperature,3h of treatment time. Amount of water(solvent) used was7times (w/w) of the original dry matter. Extraction rate was found to be75.76%.The clarification process of jujube extract was studied. Extract was clarified by bentonite,diatomite and chitosan, and analyzed for light transmittance using UV-spectrophotometer. Theclarification effect of bentonite, diatomite and chitosan was compared by analyzing color,storage stability, soluble solids, total sugar contents, protein and pectin. Results showed thatthe20mL samples treated with0.8mL of bentonite solution (20min at55oC),0.8mL ofdiatomite solution (30min at40oC) and1.0mL of chitosan solution (25oC for60) had hightransmittance values. Comparatively, chitosan had better ability to remove protein and pectin.After chitosan clarification, the jujube juice had high light transmittance, bright color, goodstorage stability and less reduction of soluble solids and total sugar.Effect of chitosan clarification on the content of main functional components andantioxidant activity was investigated. The slight reduction of cyclic adenosine monophosphate(cAMP), flavone and Vc content, and the decline of DPPH·, O2-·,·OH radical scavengingability was observed.Clarified jujube concentrate was studied. The effect of concentrating temperature andtotal soluble solids on single strength jujube juice was studied. The results showed that60oCtemperature and70°Brix had less effect on jujube concentrate quality. Additionally, jujubeconcentrate was precipitate free and exhibited good storage stability.With jujube concentrate as raw material, the formulation to prepare jujube juice was asfollow:7%jujube concentrate,4%sucrose，0.09%citric acid. The jujube juice beverage hadhigh light transmittance, bright color and better mouthfeel. Compared to commercial jujubebeverages, jujube juice beverage prepared in our laboratory had better mouthfeel and quality.