Study On The Aroma-enhancing Regulating Techniques Of Citrus Juice By Enzymolysis

The losing of aromatic substances is a significant technology difficulty whichcounteracting the development of fruit juice industry.This technology difficulty hasn't beensolved completely.How to enhance and improve the food flavor is an important content ofthe flavor chemistry research.In the fruit and vegetable flavor substances,some componentsare free forms, some components exist by forming indican with the carbohydrate.Theseindicans can produce natural flagrance substances and enhance the flavor of fruit andvegetable products naturally through enzyme hydrolyzing the glucosidic bound.Focusingon aroma-enhancing regulation of citrus juice by enzyme hydrolysis usingbeta-glucosidase,the existing Aspergillus niger were used to produce theβ-glucosidaseand its enzymology characters were studied;the optimum enzymolysis regulatingtechnology of citrus juice were carried out through Kramer organolepticinvestigation;Compared the effect of citrus juice aroma-enhancing through enzymolysis bymicrobial and almondβ-glucosidase;Discussed the influence of the physics and chemistrycharacteristic and the fragrant ingredient of the citrus juice by concentration and theenzymolysis.Based on the above studies,the following conclusions have been drawn:1st.The existing Aspergillus niger were used to produce theβ-glucosidase and itsenzymology characters were studied.The optimum incubate time of produceβ-glucosidase was 5d,and the enzyme activity was 4.8u/mL.The optimum temperature was45℃and the pH was 4.5 of theβ-glucosidase in this experiment.2nd.Based on the enzymology characters ofβ-glucosidase,the single factor and L₉(3⁴)orthogonal of citrus juice aroma-enhancing experiment had been carried out.The results ofKramer organoleptic investigation analysis indicated that the primary and secondary effectfactor on enzymolysis regulating technology of citrus juice which are asfollowed:temperature＞time＞usage.The temperature was the most important factor.Theoptimum enzymolysis regulating technology of orange juice was that:temperature was45℃,incubating time was 80min,usage of enzyme was 20u/L orange juice.The optimumenzymolysis regulating technology of lemon juice was that:temperature was45℃, incubating time was 100min,usage of enzyme was 30u/L lemon juice.Organolepticinvestigation and GC/MS analysis indicated that enzymolysis treatment has notable aroma-enhancing effect in citrus juice.3rd.The enzymolysis effect ofβ-glucosidase from different source on bound formaromatic components was dissimilar.In this experiment,the effect of citrus juicearoma-enhancing through enzymolysis by microbial and almondβ-glucosidase had beencompared.Organoleptic investigation indicated that the enzymolysis effect of almondβ-glucosidase was better than Aspergillus nigerβ-glucosidase in citrus juice.4th.The influence on nutritional ingredient,color and other index of citrus juice wasnotable in the concentrate processing.After the enrichment process,Vitamin C lossed36.89% and 37.18%,however, the influence wasn't notable in the enzymolysisprocessing,due to the moderate enzymolysis condition.5th. In this experiment,limonene,pinene,myrcene,terpineol,citronellol,nerol,linalool,geranyl acetate,linalyl acetate, aromadendrene and other aromatic components had beendiscovered in citrus juices,and the content of limonene was from 72% to 79%.Ethylacetate, 1-amylene-3-ketone,sabinene,β-caryophyllene,citral,nonanal,terpinene,phellandrene and linalool had been lost and furfural had produced in vacuum evaporation treatment.Isoamyl alcohol, 1-hexanol,lauryl alcohol,ethyl acetate,hexyl butyrate,phellandrene,terpinene,nonanal and bisabolene had produced in enzymolysis treatment.The totalaromatic components of citrus juices by vacuum evaporation had been decreasedobviously, because the aromatic components in fumet had been losed 40.43% and44.69%,but the aromatic components content promoted by 1.41% to 1.55% afterenzymolysis treatment.These results indicated that enzyme hydrolysis could break out theglycosidic bound of bound form aromatic components of citrus juice effectively andreleased the potential aromatic components to enhance the aroma of citrus juice naturally.