CN1176592C - Frozen dry jujube and preparation thereof - Google Patents
Frozen dry jujube and preparation thereof Download PDFInfo
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- CN1176592C CN1176592C CNB02151741XA CN02151741A CN1176592C CN 1176592 C CN1176592 C CN 1176592C CN B02151741X A CNB02151741X A CN B02151741XA CN 02151741 A CN02151741 A CN 02151741A CN 1176592 C CN1176592 C CN 1176592C
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- Freezing, Cooling And Drying Of Foods (AREA)
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Abstract
The present invention relates to a freeze-dried jujube which is prepared by the following method: after kernels are removed, fresh jujubes are pre-frozen and are continuously frozen in a cold trap of a vacuum freeze drier; then, the fresh jujubes are dried in vacuum so that ice crystal in the fresh jujubes is directly sublimated into water vapor for eliminating water. The process of sublimation drying is realized by a vacuum freeze drier. The freeze-dried jujube has the advantages of small nutrient component loss and small product shrinkage ratio, and the original color and taste of fresh jujubes are maintained. The freeze-dried jujube is an ideal high-quality dehydrated food.
Description
Affiliated technical field
The present invention relates to the drying of jujube and jujube, specifically relate to a kind of freeze-drying jujube that utilizes Vacuum Freezing ﹠ Drying Technology to make, the invention still further relates to the preparation method of this freeze-drying jujube.
Background technology
Red date is a kind of medicinal and high fruit of nutritive value.The sweet acid of bright jujube is good to eat, contains abundant sugar, vitamin, protein, amino acid and trace element etc., and especially VC content is very high, and the laudatory title of vitamin pill alive is arranged.But because water content is about 70% in the bright jujube, be difficult for storage and transport, according to statistics, annual bright jujube because of the loss quantity of rotting to cause up to 20%-30%, number is very surprising.
The conventional dry of jujube is shaped on air-dry drying and two kinds of methods of bake drying, and air-dry seasoning is that bright jujube is placed under the natural conditions, shines and the gravity-flow ventilation evaporation drying by solar irradiation, and in 3-4 week drying time, dried jujube contains 20% left and right sides moisture.Its shortcoming is that sanitation degree is poor, nutritional labeling loss late height, in case meet with overcast and rainyly, it is rotten easily to go rotten, and causes the underproduction reduction of income.The bake drying method is that bright jujube is placed baking burning in drying room or the baking box, about 70 ℃ of temperature, time 20-24 hour, dried jujube water content about 20%.Its drying red date hygiene that goes out is good slightly, but because of long-time high-temperature process, the nutritional labeling loss late is also very high.The drying red date that goes out of above-mentioned two kinds of methods has all lost original local flavor of bright jujube and characteristic, and not only the nutritional labeling loss is serious, and taste changes, and the dry-making red date profile shrinks, and very big variation has taken place form, and the dried product shrinkage factor is big.
Summary of the invention
The purpose of this invention is to provide a kind of drying freeze-drying jujube that obtains of Vacuum Freezing ﹠ Drying Technology that utilizes, this freeze-drying jujube has kept the original color and luster of bright jujube, taste, nutritional labeling and face shaping.
The preparation method of this freeze-drying jujube is provided, and is another goal of the invention of the present invention.
Adopt Vacuum Freezing ﹠ Drying Technology, behind fast food freezing, making moisture wherein under vacuum condition is water vapour by the solid ice distillation, thereby makes the food-dewatering drying, can obtain frozen dried food, and the present invention just is being based on this principle and bright jujube is being carried out dry.
Freeze-drying jujube provided by the invention can be prepared by following method:
The bright jujube of stoning-15 ℃～-40 ℃ pre-freezes 1～5 hour, is put into cold-trap ,-25 ℃～-55 ℃ continuous freezing 0.5～2 hour, put into dryness storehouse again, regulate 50 ℃～70 ℃ of heating-up temperatures, vacuum drying is 9～14 hours under vacuum 30～80pa, prepares the freeze-drying jujube.
The bright jujube of stoning wherein is the bright jujube that obtains after sorting, washing, stoning, can directly dehydrate with it, also can will dehydrate after its section again.
The present invention also provides the preparation method of this freeze-drying jujube, comprises the steps:
1, with the bright jujube of stoning-15 ℃～-40 ℃ pre-freezes 1～5 hour.
2, the bright jujube of pre-freeze is put into the cold-trap of vacuum freeze drier ,-25 ℃～-55 ℃ continuous freezing 0.5～2 hour.
3, freeze the dryness storehouse that bright jujube is put into vacuum freeze drier, regulate 50 ℃～70 ℃ of temperature of heating plate, vacuumize, keep dryness storehouse vacuum 30～80pa, and control condenser temperature-40 ℃～-55 ℃ of dryings obtain the freeze-drying jujube after 9～14 hours.
Among the present invention, earlier bright jujube is carried out pre-freeze and make it reach solidification point rapidly, continuous the freezing of cold-trap of putting into vacuum freeze drier again makes it deep colling.Bright jujube freezes soon more, and the ice crystal that its internal moisture forms is more little, and is also just more little to the destruction of bright jujube institutional framework.
Bright jujube after freezing must carry out the vacuum sublimation drying rapidly.When in dryness storehouse, carrying out lyophilization, require dryness storehouse can reach required vacuum rapidly.The ice crystal of bright jujube inside will absorb certain heat in sublimation process, therefore should regulate the temperature of heating plate, in time to replenish the required heat of ice crystal distillation.The water vapour that distillation produces is by being connected the cold-trap aggegation between dryness storehouse and the vavuum pump, and the height of condenser temperature is concerning water vapour, and whether aggegation is complete.
Freeze-drying jujube of the present invention is after the bright jujube that water content is higher freezes, and makes the ice crystal distillation in the bright jujube obtain dried product for water vapour under low-temp low-pressure, compares with traditional dry-making method of dried, and the present invention has many advantages.
Many compositions in the bright jujube have thermal sensitivity and easily oxidizable, the freeze-drying jujube is to dehydrate under the vacuum and low temperature condition, heat-sensitive ingredients and the easily destroyed decomposition of oxidizing component in the in season jujube have been avoided processing, compare with the traditional drying method, nutritional labeling loss in the bright jujube is less, the physiologically active ingredient retention rate is the highest, can preserve the nutritional labeling in the bright jujube to greatest extent, and storage rate reaches more than 85%.
Bright jujube carries out pre-freeze before lyophilization handles, and makes the bright jujube after freezing form a stable solid skeletal, during tiny ice crystal fills and is clipped in.After the ice crystal distillation, original solid skeletal structure remains unchanged substantially, and the ice crystal position forms the very easily micropore of suction, makes the shrinkage factor of freeze-drying jujube well below other dried product, has kept original form of bright jujube and institutional framework.
After bright jujube was frozen, its moisture existed with the form of ice crystal, and originally water-soluble dissolved matters such as inorganic salts are distributed evenly at bright jujube inside.After the ice crystal distillation, these dissolved matters are separated out on the spot, avoided in the traditional drying method because of bright jujube internal moisture to surface migration, entrained thereupon compositions such as inorganic salts are separated out the surperficial hardening phenomenon that causes on the surface, make freeze-drying jujube moisture when rehydration can penetrate into the inside of jujube rapidly, rehydration is fast, and retention ability is strong.
The freeze-drying jujube that adopts preparation method of the present invention to obtain, owing to be dry at low temperatures, avoided the decomposition of various pigments to fade and enzyme and amino acid whose brown stain, kept the original color and luster of bright jujube, the loss late of volatile aromatic composition is starkly lower than heated-air drying in the freeze drying, and fragrance ingredient concentration increases relatively in the product of dry back, therefore, freeze-drying jujube not only local flavor is constant, and fragrance is stronger.
Freeze-drying jujube water content of the present invention is below 5%, can long preservation, undergo no deterioration in three to five years.
The specific embodiment
Embodiment 1:
Get fresh fine horse jujube 3.025kg, clean, after the stoning, section, in the dish of packing into, pre-freeze is 3 hours under-30 ℃ of conditions, open the refrigerator of vacuum freeze drier, pre-freeze fine horse jujube is put into-40 ℃～-55 ℃ cold-traps are continuous to be frozen 1 hour, move to then in the middle of the heating plate in the dryness storehouse, regulate temperature of heating plate to 50 ℃～60 ℃, vacuumize drying, and keep vacuum 30-50pa in the dryness storehouse, condenser temperature-40 ℃～-55 ℃, behind the continuous drying 12 hours, obtain freeze-drying fine horse jujube sheet 0.533kg.
Embodiment 2
Get fresh pear and date-printing blocks 1.950kg, clean, after the stoning, section, pack in the dish, pre-freeze is 5 hours under-25 ℃ of conditions, open the refrigerator of vacuum freeze drier, the pre-freeze pear and date-printing blocks put into-40 ℃～-55 ℃ cold-traps are continuous to be frozen 1 hour, move to then in the middle of the heating plate in the dryness storehouse, regulate temperature of heating plate to 50 ℃～70 ℃, keep vacuum 40-60pa in the dryness storehouse, condenser temperature-40 ℃～-55 ℃ vacuumized dry 14 hours continuously, obtained freeze-drying pear and date-printing blocks 0.4175kg.
Embodiment 3
Get fresh wooden jujube 2.658kg, clean, in the dish of packing into after the stoning, pre-freeze is 1.5 hours under-35 ℃ of conditions, opens the refrigerator of vacuum freeze drier, pre-freeze wood jujube is put into-40 ℃～-55 ℃ cold-traps are continuous to be frozen 1.5 hours, move to then in the middle of the heating plate in the dryness storehouse, regulate 50 ℃～70 ℃ of temperature of heating plate, keep vacuum 50-70pa in the dryness storehouse, condenser temperature-40 ℃～-55 ℃, vacuumized continuously dry 13 hours, and obtained freeze-drying wood jujube 0.6249kg.
Comparative example
The freeze-drying fine horse jujube of embodiment 1 and the active ingredient of bright jujube and common dried jujube are compared (in the jujube sample of 100 grams), and the result is as follows:
Claims (1)
1, a kind of preparation method of freeze-drying jujube, this method may further comprise the steps:
1) with the bright jujube of stoning-15 ℃～-40 ℃ pre-freezes 1～5 hour;
2) the bright jujube of pre-freeze is put into the cold-trap of vacuum freeze drier ,-25 ℃～-55 ℃ continuous freezing 0.5～2 hour;
3) freezes the dryness storehouse that bright jujube is put into vacuum freeze drier, regulate 50 ℃～70 ℃ of temperature of heating plate, vacuumize, keep dryness storehouse vacuum 30～80pa, and the control condenser temperature be-40 ℃～-55 ℃ that drying obtained the freeze-drying jujube after 9～14 hours.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB02151741XA CN1176592C (en) | 2002-12-30 | 2002-12-30 | Frozen dry jujube and preparation thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB02151741XA CN1176592C (en) | 2002-12-30 | 2002-12-30 | Frozen dry jujube and preparation thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1423950A CN1423950A (en) | 2003-06-18 |
| CN1176592C true CN1176592C (en) | 2004-11-24 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNB02151741XA Expired - Fee Related CN1176592C (en) | 2002-12-30 | 2002-12-30 | Frozen dry jujube and preparation thereof |
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| Country | Link |
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| CN (1) | CN1176592C (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102550989A (en) * | 2012-02-09 | 2012-07-11 | 李英姬 | Method for preparing crispy sliced apple pears |
| CN102845690B (en) * | 2012-08-21 | 2014-09-03 | 承德神栗食品有限公司 | Hawthorn freeze-dried whole fruit and preparation method thereof |
| CN109717427A (en) * | 2019-01-25 | 2019-05-07 | 好想你健康食品股份有限公司 | A kind of freeze-dried fruit composite jujube piece and its manufacture craft |
| CN110122554A (en) * | 2019-05-21 | 2019-08-16 | 新疆黑果枸杞生物科技有限公司 | A kind of freeze-drying method of jujube |
| CN111493137A (en) * | 2020-04-30 | 2020-08-07 | 南京农业大学 | Vacuum freeze-drying method for non-heading Chinese cabbage and yellow rose |
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2002
- 2002-12-30 CN CNB02151741XA patent/CN1176592C/en not_active Expired - Fee Related
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| Publication number | Publication date |
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| CN1423950A (en) | 2003-06-18 |
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