CN1161031C - Concentrated tea juice with original flavor maintained and its production process - Google Patents

Abstract

The present invention relates to a method for preparing concentrated tea juice by means of the methods of ultrafiltration (UF), reverse osmosis (RO), ultrahigh-temperature instant sterilization (UHT) and aseptic packaging. The present invention is characterized in that a hollow polypropylene fiber ultrafiltration membrane is adopted to carry out ultrafiltration after tea extraction liquid is cooled and placed stationarily, and ultrafiltration membranes with different catch molecular weights are adopted according to different varieties of tea; a low-pressure composite reverse osmosis membrane is adopted to ultrafiltration liquid so as to carry out the concentration of tea juice, and penetrated liquid obtained by reverse osmosis is recovered into the ultrafiltration liquid and is concentrated by means of reverse osmosis for utilization.

Description

The tea juice concentrating and the manufacture method thereof that keep former tea local flavor

The present invention relates to a kind of tea juice concentrating and manufacture method thereof, especially relevant ultrafiltration (UF) membrane filtration, reverse osmosis membrane (RO) method for concentration of adopting produced tea juice concentrating and manufacture method thereof.

Evaporation concentration technique is all adopted in the production of traditional tea juice concentrating, as falls (liter) film evaporator, centrifugal evaporator etc.Adopt evaporating and concentrating process to have the high advantage of evaporation efficiency, but the loss of aroma of product is serious, fragrance poorness, blunt, the soup look oxidizing brown stain of flavour, active ingredient and nutritional labeling also have bigger loss in the tea juice.Product viscosity is big, and after the dilution, millet paste is owed clear, easily forms muddy and precipitation.In order to address this problem, people consider to adopt the membrane separation technique of no phase transformation stalling characteristic to carry out the production of tea juice.

In the prior art, Chinese patent notification number 1039525 discloses a kind of technology for processing instant tea.This method is that fresh tea passes is obtained fresh tea juice with pressing method, and filter at the beginning of carrying out then, flat ultrafiltration, counter-infiltration (RO) concentrate, and adopts freeze drying or spray-drying to make product.This kind method can keep original tea aroma, flavour preferably.But because tea juice without anticipating, makes colloid and impurity in the fresh tea juice very easily stop up milipore filter.The patent disclosure of notification number 1154798 a kind of manufacturing process of instant tea be that tealeaves soaks in cold distilled water, tea extract is got its supernatant and is directly concentrated through reverse osmosis membrane (RO) after coarse filtration and smart filter, carries out the manufacture method of vacuum freeze drying again.The instant tea that this method makes can keep the original color of tealeaves preferably.But directly adopt the RO film to concentrate, colloid in the tea juice and impurity very easily stop up the RO film, cause cycles of concentration very low, and tea juice is muddy and a spot of precipitation or insoluble shape thing arranged.Notification number 1101506 discloses a kind of novel inspissated juice health drink new method.This method be with tea extract after filter just, vacuum concentrate, obtain a kind of tea juice concentrating through ultrafiltration again, though this method has solved clearing up problems of millet paste, owing to adopt vacuum concentrate method fully, thereby the fragrance of tea juice is also relatively poor.

Japan Patent JP91-80457 discloses the method that a kind of tea extract directly adopts the RO film to concentrate, and this method is to adopt PCIZF99 type RO film direct method of concentrated tea juice under 35 ℃, 40 Pasteur's pressure.Though can obtain to keep the tea juice concentrating of preferable color in this way, the coarse filtration muddiness of tea juice also has a spot of precipitation or insoluble shape thing.Japan Patent JP92-61613 discloses and has added caseinate (addition is the 10-40% of tea juice solid content) handle tea juice in tea extract, centrifugally then goes to mix, again the technology that concentrates through the RO film.Though this method can obtain the tea juice of certain clarity, owing to need to add relatively large caseinate, therefore network and removed active ingredient in a large amount of tea juice correspondingly causes tea juice flavour to reduce.JP145347 discloses a kind of employing molecular cut off 2500 dalton UF film pre-concentrations, and the liquid that sees through of UF concentrates through polyamide RO film again, then two kinds of manufacturing process that inspissated juice merges.This method effect of UF film in fact is concentrated, so tea juice still is to present muddy state.JP93-51260 discloses a kind of tea juice concentrating that adopts tannase to separate with film to combine or the manufacturing process of instant tea powder.This technology is because the employing molecular cut off is 5000 milipore filter, thereby the macromolecular compound in the tea juice very easily stops up the UF film, thereby propose at tea juice through handling tea juice (enzyme dosage 0.5-500 enzyme unit/restrain dried tea) with tannase in advance before the UF and then concentrating, though can make tea juice concentrating or the instant tea powder that does not have muddiness with this technology through the RO film.But owing to adopt molecular cut off 5000 daltonian UF films, still can hold back the active ingredient in a large amount of tea juice, cause tea juice flavour flat.

The purpose of the inventive method is the color and the effective composition of the overwhelming majority that should keep former tea extract, the back of concentrated tea juice dilution simultaneously millet paste clear, the tea juice concentrating manufacture method of no turbidity sediment.

Another object of the present invention provides the tea juice concentrating with the fragrance roughly the same with the tea that directly brews with tea juice such as green tea, jasmine tea, oolong tea, black tea, soup look, mouthfeel, and can directly make the beverage of promptly drinking tea in order to dilution.

Technical scheme of the present invention is as follows:

The extract of tealeaves cooled off in advance leave standstill processing, being cooled to temperature is 0-25 ℃, leave standstill the accurate filter pre-flock that passed through 1-10 μ m in 1-2 hour again, remove visible more tiny tea juice particle or the impurity of naked eyes, use the polypropylene hollow fiber ultrafiltration membrance filter then, it is 5-10 ten thousand dalton that green tea, jasmine tea adopt molecular cut off; Oolong tea and black tea molecular cut off are 10-20 ten thousand dalton.To concentrate (LFC) with the low low pressure complex reverse osmosis membrane that pollutes through the filtrate of ultrafiltration then, make that solid content reaches 20-30% in the tea juice.Counter-infiltration (RO) see through liquid when solid content reaches 0.2-0.8%, this can be recycled in the ultrafiltrate again through the reverse osmosis concentration second time through liquid, and then carry out high-temperature short-time sterilization and sterile filling.Wherein said tea can be selected from green tea, oolong tea, black tea and jasmine tea etc.

Below be to be that example describes content of the present invention in detail with green tea:

Green tea is extracted with hot-water soak, obtain green tea extractive liquor, with cooling water tea extract is cooled to room temperature (below 30-35 ℃) then.And carry out centrifugal filtration and separate, with thick tealeaves particle removal.With the tea extract that obtains, further tea liquid is cooled to 20 ± 2 ℃ with chilled water, and left standstill 1 hour, accurate filter with 5 μ m apertures filters again, further remove macroscopic subparticle and impurity in the tea liquid, the transparency of tea liquid is further improved, also can reduce clogging simultaneously the UF film.

If further reduce the chilling temperature of tea juice or prolong time of repose, though help the polymerization sedimentation of macromolecular compound in the tea juice, thus it is bright that tea juice is clarified more.But low temperature leaves standstill for a long time, and the sedimentation material is too much, also can cause the active ingredient in the tea juice to remove too much, makes tea juice flavour flat, and production efficiency is also lower.

Tea liquid after ultrafiltration carries out RO and concentrates, and the RO film is the low pollution low pressure complex reverse osmosis membrane (LFC film) of Hydranautics company, and operating pressure is controlled at 1.8-2.5Mpa, does not surpass 3.0Mpa.Concentrate the later stage at RO, the temperature of tea juice can rise gradually, therefore can adopt the cooling waterside to concentrate the limit cooling, the temperature of tea juice is controlled at＜40 ℃.Solid content reaches 20%-30% to the tea juice.In the later stage that RO concentrates, raising along with the tea juice concentration, the osmotic pressure of tea juice also rises thereupon, cause inlet hydraulic to strengthen, thereby understand some low-molecular-weight chemical composition such as caffeine in the tea juice, amino acid, Tea Polyphenols etc. see through the RO film with water, thereby cause loss of active ingredients, reduce the system rate.Therefore manufacturing process of the present invention is seeing through in the liquid that RO concentrates, when the diopter of tea juice reaches 0.2Brix-0.8Brix, is about to this and sees through liquid and be recycled in the ultrafiltrate that next group treats that RO concentrates, to recycle.

It is more suitable that the tea juice concentration that the RO film concentrates is controlled at 20-30%.If require to concentrate excessive concentration, then need concentrate at RO long-time, along with the raising of tea juice concentration, the increase of tea juice osmotic pressure, the concentration of tea juice also can rise thereupon, causes the oxidizing brown stain of tea juice quality, RO concentrates the rising that also causes production cost for a long time.As if the concentration too low (being lower than 15%) that RO concentrates, then can increase the packaging material volume of inspissated juice, also can increase freight., RO inspissated juice carried out high-temperature short-time sterilization, can adopt the method for board-like high-temperature short-time sterilization machine or the instantaneous machine that goes out of bushing-type high temperature, by aseptic filler tea juice concentrating is poured in the sterile bag then thereafter.

Below with example the present invention is specifically described.Be to be understood that following examples just to explanation technical scheme of the present invention, rather than the present invention is construed as limiting.

Embodiment 1

Drop into 100kg green tea in extractor, add hot water 2000kg, lixiviate 20 minutes obtains solid content and is 2.0% the about 1700kg of tea extract, cool off coarse filtration after, tea extract further is cooled to 20 ± 2 ℃, and left standstill 60 minutes.Remove cooled precipitum by the accurate filter of 5 μ m then.Carry out ultra-filtration filters again, the molecular cut off of milipore filter is 7-10 ten thousand dalton.By the tea juice solid content behind the UF is 1.8-1.9%., again carry out reverse osmosis concentration, adopt the low low pressure complex reverse osmosis membrane (LFC) that pollutes to be concentrated into solid content 25% in the tea juice thereafter.When tea juice diopter reached 18Brix in the RO concentration process, the liquid that sees through of RO film presented oyster, and when diopter reached 20Brix, the diopter that sees through liquid reached 0.2Brix, can will be recycled in the next group ultrafiltrate through liquid.Solid content reaches at 25% ± 1% o'clock to the tea juice, and tea juice can carry out high-temperature short-time sterilization and sterile filling, obtains condensed juice of green tea.By the condensed juice of green tea that the present invention obtains, each extracts the 2ml condensed juice of green tea and adds 150ml room temperature water and 15 ℃ of cold water dilutions, and the tea clarification is bright, the soup look yellowish green is bright, and fragrance is pure and mild, fresh taste, can under normal temperature condition, keep 2 years the basic no change of its quality and flavor.

Embodiment 2

In extractor, drop into the 100kg oolong tea, add hot water 2000kg, lixiviate obtained the oolong tea crude extract through the cooling coarse filtration after 20 minutes.Crude extract is cooled to 15 ± 2 ℃ with cooling water temperature, and left standstill 60 minutes, filter with the accurate filter of 5 μ m the back, removes the insoluble thing of sedimentation.Be that 100,000 daltonian milipore filters are crossed liquid by molecular cut off again, obtain the oolong tea ultrafiltrate of clarification, carrying out reverse osmosis concentrated compression method according to embodiment 1 same technology again, to be concentrated into tea juice solid content be 20%.After high-temperature short-time sterilization and sterile filling.The oolong inspissated juice that makes is in this way respectively got 2ml respectively in two cups, adds the cold water of room temperature water or 15 ℃, the equal clear of tea, no muddiness or deposited phenomenon, and the fragrance and the feature that have kept former oolong tea juice to be had.

Oolong tea is owing to be semi-fermented tea, and it is more to contain macromolecular compounds such as theaflavin, congo red element in the tealeaves, gets final product so it is concentrated into 20% through RO.If require further to improve its concentration, then need continue the long duration.

Embodiment 3

In extractor, drop into leaflet kind congou tea 100kg, add hot water 2000kg, soak 20 minutes, obtain black tea coarse filtration liquid through the cooling coarse filtration.Black tea coarse filtration liquid further is cooled to 10 ± 2 ℃ with chilled water, and after leaving standstill 60 minutes, with the smart membrane filtration of 5 μ m, carries out ultra-filtration filters again, the molecular cut off of milipore filter is 10-20 ten thousand dalton.Obtain the bright black tea ultrafiltrate of clarification.Carry out RO by embodiment 1 same reverse osmosis concentrated compression method again and concentrate,, contain more theaflavin, congo red element and other macromolecular compound in the tealeaves because black tea is fermented tea.Therefore, the black tea inspissated juice of reverse osmosis concentration solid content to 15% to the tea liquid is through high-temperature short-time sterilization and sterile filling.Obtain the black tea inspissated juice.Get each 2ml of black tea inspissated juice respectively at two cups, each adds the cold water of normal-temperature water and 15 ℃, tea clear at normal temperatures; But tea slightly seems and owes bright in 15 ℃ of water.But the fragrance of tea, flavour, color and luster and former tealeaves local flavor remain unchanged substantially.

So tea juice concentrating manufacture method provided by the invention, with traditional tea juice concentrating manufacture method or comparison of existing technology, The tea juice concentrating product that produces, the tea clarification does not thoroughly better have muddy or precipitation after diluting. And the former tealeaves institute tool of having guaranteed the quality Standby color qualitative characteristics. Special fragrance and the tradition such as transparent or prior art have significantly to be improved. Be fit to very much rare Release the rear beverage of namely drinking tea of directly drinking or prepare.

Claims (4)

1. a manufacture method that keeps the tea juice concentrating of former tea local flavor is characterized in that tea extract is adopted pre-flock, ultrafiltration membrance filter and reverse osmosis concentration after cooling is left standstill, and carries out high-temperature short-time sterilization and sterile filling again; Wherein:

Described pre-flock to tea extract is to use the accurate filter pre-flock of 1-10 μ m, to remove visible comparatively tiny tea juice particle or the impurity of naked eyes;

What described ultrafiltration membrance filter used is the polypropylene hollow fiber milipore filter, and it is 5-10 ten thousand dalton that green tea, jasmine tea adopt molecular cut off; It is 10-20 ten thousand dalton that oolong tea and black tea adopt molecular cut off;

See through liquid when solid content reaches 0.2-0.8% after the described counter-infiltration, this can be recycled to through liquid and carry out the reverse osmosis concentration second time in the ultrafiltrate again;

Described reverse osmosis concentration is to concentrate with the low low pressure complex reverse osmosis membrane that pollutes through the filtrate of ultrafiltration, makes that solid content reaches 20-30% in the tea juice.

2. method as claimed in claim 1, wherein said tea extract through the cooling condition of leaving standstill is: be cooled to temperature 0-25 ℃, time of repose 1-2 hour.

3. method as claimed in claim 1, wherein said tea are selected from a kind of in green tea, oolong tea, black tea or the jasmine tea.

4. the tea juice concentrating that any one described method is produced among the claim 1-3.