Tannase Production Under Solid-state Fermentation Using Tea Stalks And The Study Of Enzyme Preparation

Tannase specifically breaks the galloyl ester bond of tannins and produce gallic acid andglucose. The enzyme can be used to deal with turbidity of tea, make propyl gallate and improvequality of leather. Because of this property, the enzyme has been used extensively in foods,beverages, pharmaceuticals and chemical industries. Tannase is an inducible enzyme, can beproduced by microorganism with the presence of tannin. Tea stalks contains18-36%tannin,which can induce microorganism producing tannase. So, the tea stalks can be used as substratefor tannse production.In this study, tea stalks were used as low-cost substrate for tannase production byAspergillus niger JMU-TS528. Effects of fermentation conditions on tannase production byAspergillus niger JMU-TS528were elucidated, the technical process of tannase preparation wasestablished as well as its parameters optimized, at the same time, the storage stability wasinvestigated. These studies will set an important foundation for the industrial enlarged-scaleproduction of tannase preparation and promote extensive application of tannase.Maximum tannase production was obtained when SSF was carried out at28oC, pH6.06,liquid-to-solid ratio (v/w)1.8, inoculum size2ml (1×108spores/ml), medium contents5g,5.69%(w/v) ammonium chloride as nitrogen source and5%(w/v) lactose as additional carbonsource. Under optimum conditions, tannase activity reached62U g dry substrate (U/gds) after96h of fermentation, the tannase activity under optimum conditions was5.17times as high asthat under initial conditions.The tannase solid enzyme preparation was obtained by the process of filtration,decolouration, aseptic filtration, ultrafiltration enrichment and spray drying. Maltodextrin wasused as drying aid in spray drying. Took the tannse activity recovery as index, the spray dryingparameters were optimized. The optimum conditions of spray drying were as follow: inlet airtemperature96oC, inlet flow rate182mL/h, solids content8%. Under this condition, the tannaseactivity recovery was79.8%. Using the established process and optimum parameters, the tannaseactivity and total recovery reached690U/g and77.2%, respectively.The research of storage stability demonstrated that temperature, air and humidity had greatinfluence for the storage stability of tannase solid enzyme preparation but the light was notobvious. The tannase solid enzyme preparation showed good stability during storage, retainingrate of tannase activity was98.9%when preserved in the condition that-20oC, vacuum and lucifuge for90d.In this study, tea stalks were used as low-cost substrate for tannase production, developing anew road for the use of tea stalks. The application of tea stalks is certainly economical and alsominimizes environmental pollution.