Study On The Processing Techniques Of Guanxi Pomelo Juice And Preseved Peel

Guanxi pomelo (Citrus grandis (L.) Osbeck c.v.) which becomes famous for its big fruit,thin peel, tender, juicy, sweet and slightly acidic is native to Guanxi Fujian province in China.The processing technologies of entire fruit are getting more and more prominent for Guanxipomelo planting protection development.On the early study, we have screened one high naringinase-producing strain namedAspergillus niger DB056, developed its optimal fermentation process of naringinase-production,purified and obtained hygienic security naringinase preparation, which could debitter naringin inpomelo juice efficiently. On this paper we mainly research on the technologies of compressionand clarification of Guanxi pomelo juice, optimize the processing parameters of pomelo juicedibbittered by naringinase, develope both the formula of the juice beverage and make perservedpreparation using peel, which provided experimental basis for the realization of the furtherprocessing of the whole pomelo fruit. The main results were as follows:Before squeezing, pulp was treated with pectinase that could reduce the concentration ofnaringin in pomelo juice, simultaneously, increase the yield and stability of the juice. Comparedwith the process of directly squeezing, the naringin concentration reduced by58.54μg/mL andthe yield increased by8.8%when pulp was treated with5%pectinase. The conditions ofclarification process of Guanxi pomelo juice optimized were that the content of pectinase was0.1%, temperature was45°C and enzymolysis time was60min.The optimized conditions of debittering pomelo juice with naringinase from Aspergillusniger DB056were that the dosage of enzyme was90U/mL, the temperature was40-55°C andincubated for80min at nature pH. Under this condition, a good bitter removal rate in pomelojuice was achieved, reaching up to89%. The sugar content of concentrated juice effectedsignificantly on naringinase debittering. When the sugar content of concentrated juice was over45%, the debitter ratio of naringin rapidly decreased.Using the concentrated debitter juice, an formula of clarify pomelo beverage was devoloped,the list of which were20%recovery juice,10%sugar,0.1%citric acid,0.02%ascorbic acid. Andthe formula list of muddy pomelo beverage were20%recovery juice,10%sugar,0.1%citricacid,0.02%ascorbic acid,1%pectin,0.25%CMC. The debbittering technology process optimized of pomelo peel was: first, cutting pomelopeel into small pieces, then boiling them for4times with0.8%salt solution on the condition thatthe solid-liquid ratio was20:1. The optimized formula of syrup were60%maltose,5%modifiedstarch,1.0%gelatin,0.1%citric acid,33%water. And the optimized processing of sugarpenetration was that the sugar solution was concentrated firstly to make its content up to70%,and then the peel with14.43%water was added into it, permeated fully, finally translucentnaringin preserve was achieved. The springiness of the product was0.665Ratio and the contentsof water, fiber, reducing sugar and total sugar were17.63%,0.12‰,42.6%and72.8%,respectively. The health indicators, the total number of coliform bacteria and pathogenic bacteriaSalmonella indicators met "preserves hygiene standards" of GB14884-2003.On this study, the technologies of compression and clarification, the enzymatic dibitterprocess and concentrate technology of pomelo juice, the production processes of juice beverageand preserved peel were developed, which would provide the basis for entire fruit processingtechnology of Guanxi pomelo.