CN102422877A - Lichee-drying method - Google Patents
Lichee-drying method Download PDFInfo
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- CN102422877A CN102422877A CN2011103854700A CN201110385470A CN102422877A CN 102422877 A CN102422877 A CN 102422877A CN 2011103854700 A CN2011103854700 A CN 2011103854700A CN 201110385470 A CN201110385470 A CN 201110385470A CN 102422877 A CN102422877 A CN 102422877A
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Abstract
A lichee-drying method includes the following steps: (1) lichees are preprocessed, i.e., the lichees are graded and chosen according to size, washed and dried; (2) the lichees processed in step 1 are dried by coupled microwaves and hot wind, i.e., the lichees are put into a microwave-hot wind coupling drier, the temperature of the hot wind is kept at 70 DEG C to 80 DEG C, the power density of the microwaves is 0.8 W/g to 2.2W/g, the speed of the hot wind is 1.5m/s to 2.8m/s, the drying time is 90 to 160 minutes, and the lichees are dried until the water content of the lichees is 7 to 12 percent. The lichee-drying method can dry lichees in a large batch in a short time, the drying time is shortened, the drying quality is increased, and the produced dried lichees are rich in the flavor of undried lichees.
Description
Technical field
The present invention relates to a kind of fresh fruit processing method, especially relate to the processing method that a kind of lichee dehydrates.
Background technology
Litchi pulp is white and moist, and the juice multi-flavor is beautiful, and is very popular.Along with cultivated area is significantly expanded, China's lichee output constantly increases.The litchi fruits maturity period is short, and ripe in high-temperature high humidity season, reaches as high as 84% according to the kind different moisture content.The characteristics that " sunlight becomes, and perfume became on 2nd, and flavor became on 3rd, and color, smell and taste were gone to the greatest extent on 4th " arranged without preserving the lichee of handling.Lichee very easily rots, rotten, very not storage tolerance and transportation, fruit colour becomes kermesinus by cerise soon under the normal temperature, last overstrike has a strong impact on the commodity value of lichee.The fresh-keeping comparatively difficulty of lichee was preserved 7 days under 20 ~ 25 ℃ of temperature at the most, under 4 ℃ of temperature, preserved at the most 35 days.Lichee results periods, the selling pressure that the increasing substantially of output caused fresh fruit is very big, and at cold storing and fresh-keeping, under the situation that the first-class means of manufacturing tank are difficult to satisfy the demand, the lichee dry fruit of production high-quality is that the orchard worker protects an important channel of producing extra earning.
The lichee fresh fruit is because moisture content is high, and sugar content is big, and whole fruit be that nuclear, meat, film, shell multiple institutional framework, particularly shell have hindered heat transmission and internal moisture in the dry run and is diffused into the shell outer surface and evaporates, thereby is difficult to drying especially.The main drying means of domestic lichee dry fruit has solarization method, fiery roasting method and hot-air seasoning.Traditional natural drying generally needs 20 ~ 25 days, drying time long, poor quality; Fire roasting method is also long drying time, and its quality and output all are difficult to satisfy the demand; Though heated-air drying than solarization method and the shortening consuming time of fiery roasting method, generally still need more than 20 hours, and the lichee brown stain is serious, the energy that is consumed is bigger; The time of microwave drying is shorter, but lichee is easy to explosion in the dry run, so sugar overflows, black scab occurs; Hot wind and microwave series connection intermittently drying is difficult to grasp the two blanking time, and when carrying out heating using microwave separately and microwave drying the situation of lichee explosion all can appear; Be difficult to control the balance of energy and moisture transmission in the dry run, superheated occur through regular meeting, local temperature is above 100 ℃; Cause the bad change of thermal sensitivity composition in the article, the loss of nutrition and local flavor etc. are so will prick the hole with fine steel needle in advance on lichee; If produce in batches; Expend very big labour, production capacity is also limited, has restricted its practical application.The home and abroad does not also have very desirable method and apparatus to the scale drying of lichee fresh fruit at present.
Application number is that 01107669.0 proprietary material provides that a kind of low-temperature vacuum drying roasting lichee is done, the method for dried longan.With ripe fresh lichee behind steam beating, low temperature (50 ~ 70 ℃), vacuum (0.08 ~ 0.099Mpa) drying.Do back pulp outward appearance and be golden yellow, translucent, can keep the lichee of strong former fruit local flavor to do.This method adopts low-temperature vacuum drying, can keep the fragrance and the mouthfeel of lichee to greatest extent, but drying time is long, and equipment requirements is high, and energy consumption is big, and particularly treating capacity is little, is difficult to industrialization promotion.
Summary of the invention
To the problems referred to above that prior art exists, the applicant provides a kind of drying means of lichee.The present invention can short time dried lichee in enormous quantities, shortens drying time, improves drying quality, and the lichee dry fruit of production has strong former fruit local flavor.
Technical scheme of the present invention is following:
A kind of drying means of lichee may further comprise the steps:
(1) to the preliminary treatment of lichee, promptly lichee is carried out choosing, clean, draining according to size fractionation;
(2) it is dry the lichee after step (1) processing to be carried out the microwave hot air coupling; Be about to lichee and put into microwave hot air coupling drying machine; Keep 70 ~ 80 ℃ of hot blast temperatures, Microwave Power Density 0.8 ~ 2.2W/g, hot blast wind speed 1.5 ~ 2.8m/s; Drying time 90 ~ 160min, the water content that is dried to lichee is 7 ~ 12%.
The dry condition of preferred microwave hot air coupling is in the step (2): hot blast temperature remains on 75 ℃, Microwave Power Density 2.0 W/g, hot blast wind speed 2.5 m/s, drying time 100min.After step (2) finishes, can pack the lichee after handling, dried lichee cools off naturally even microwave hot air is coupled, and adopts high-barrier composite material to pack.Said high-barrier composite material can be high-barrier high density food-grade polyethylene foil laminated film.
Beneficial technical effects of the present invention is:
To the whole fruit of lichee is nuclear, meat, film, the multiple institutional framework of shell; Moisture such as inside are difficult to be diffused into the characteristics of surface evaporation; Adopt the microwave hot air dry lichee that is coupled; Hot blast field and microwave field act on dried material simultaneously, and the benefit that can obtain has: heating simultaneously inside and outside (1) real realization, improve speed hot, that matter is transmitted.Heating using microwave is different from traditional convection current, conduction and radiation heating, and the water in the litchi meat (polar molecule) directly absorbs microwave energy, and heat simultaneously the innner and outer and speed is exceedingly fast; (2) environment temperature rising increasing system dehumidifier ability; (3) reasonably distribute energy proportion between the two, can play the effect of getting twice the result with half the effort, both accelerated the rate of drying of system, improve the quality of products, reduce drying cost again; (4) give full play to separately process advantage, big like the treating capacity of hot blast, drying cost is low, and heat in the microwave field, matter transmission are fast.
The dry simple series connection drying that is different from hot blast and microwave of hot blast and microwave coupling; A lot of bibliographical informations the technology or the patent of microwave drying behind the first hot blast; Though the later stage adopts microwave drying to accelerate rate of drying; But the control of microwave energy is required high, be easy to overheated and damage material, in actual large-scale production, be difficult to carry out.Hot blast that the coupling drying of hot blast and microwave is more simple and microwave drying have bigger quality and energy consumption advantage.
Can shorten to drying time of the present invention about 2 hours; Also realized the requirement of health such as sterilization, desinsection through the microwave radiation.Adopt this programme that fresh lichee is reduced to safe moisture, in enormous quantities in the time of can efficiently solving the lichee results, short time drying problems have reduced the loss of lichee, have practiced thrift cost, have improved quality.
Description of drawings
Fig. 1 handles the form of back lichee for the different dry drying method;
Among the figure: (a) heated-air drying; (b) the microwave hot air coupling is dry; (c) vacuum freeze drying.
The specific embodiment
Embodiment 1:
Select fresh lichee of uniform size, with the lychee leaf in the fresh lichee, foreign matters such as leaf are chosen and are removed; The lichee that to damage by worms and rot is then sorted out rejecting; Fresh lichee 200 g after will passing through removal of impurities again and choosing clean up, and remove surperficial earth and foreign material, then drain away the water naturally;
Pretreated lichee is positioned on the dry net of drying chamber of hot blast-microwave coupling drying box; Change microwave power to 0.8kW/g through regulating the microwave generator knob; Regulate the knob controlling variations in temperature of heater resistance, adjust to 70 ℃ of temperature values, control hot blast wind speed 1.8m/s; Microwave hot air dry 90 min that are coupled, the moisture content 12% of lichee.With dried lichee airing, naturally cool to room temperature, adopt high-barrier high density food-grade polyethylene foil laminated film to pack.
Embodiment 2:
Select fresh lichee of uniform size, with the lychee leaf in the fresh lichee, foreign matters such as leaf are chosen and are removed; The lichee that to damage by worms and rot is then sorted out rejecting; Fresh lichee 1000g after will passing through removal of impurities again and choosing cleans up, and removes surperficial earth and foreign material, then drains away the water naturally;
Pretreated lichee is positioned on the dry net of drying chamber of hot blast-microwave coupling drying box; Change microwave power to 2.2kW/g through regulating the microwave generator knob; Regulate the knob controlling variations in temperature of blower fan, adjust to 80 ℃ of temperature values with thermo detector then, control hot blast wind speed 2.0 m/s; Microwave hot air dry 140 min that are coupled, the moisture content 7% of lichee.With dried lichee airing, naturally cool to room temperature, adopt high-barrier high density food-grade polyethylene foil laminated film to pack.
Embodiment 3:
Select fresh lichee of uniform size, with the lychee leaf in the fresh lichee, foreign matters such as leaf are chosen and are removed; The lichee that to damage by worms and rot is then sorted out rejecting; Fresh lichee 405g after will passing through removal of impurities again and choosing cleans up, and removes surperficial earth and foreign material, then drains away the water naturally;
Pretreated lichee is positioned on the dry net of drying chamber of hot blast-microwave coupling drying box; Change microwave power to 2.0 W/g through regulating the microwave generator knob; Regulate the knob controlling variations in temperature of blower fan, adjust to 75 ℃ of temperature values with thermo detector then, control hot blast wind speed 2.5 m/s; Microwave hot air dry 100 min that are coupled, the moisture content 10% of lichee.With dried lichee airing, naturally cool to room temperature, adopt high-barrier high density food-grade polyethylene foil laminated film to pack.
The moisture content of lichee is the wet basis moisture content, refers to (gross mass-over dry quality)/gross mass, and the over dry quality is to be dried to lichee moisture under 105 ℃ no longer to change.
Comparative example:
Adopt vacuum freeze drying, heated-air drying to handle lichee.The processing method of vacuum freeze drying is: with lichee precooling 12h in the refrigerator of low temperature-30 ℃; Fast the lichee that precooling is good moves in the freeze dryer material disc that the freezing trap temperature is reduced to-49 ℃; Be tiled on the drying plate of freeze dryer; Unlatching vacuumizes button, continuous drying 72h under the vacuum of 0.008mbar.The processing method of heated-air drying is: lichee places in the hot air drier, and the hot blast wind speed is that a fixing value is 4.5m/s, and under this hot blast wind speed, it is 70 ℃ that hot blast temperature is set to.
The moisture content of microwave hot air coupling drying litchi pulp, heated-air drying litchi pulp and the vacuum freezing drying litchi pulp of comparison fresh litchi pulp, embodiment 3, content of reducing sugar, protein content be drying time when; The result sees shown in the table 1; Wherein content of reducing sugar is measured with reference to GB/T 5009.7-2008, and protein content is than measuring with reference to GB/T 5009.5-1985.
Table 1
Can find out that from the drying effect contrast of several method the vacuum freeze drying lichee is the best in quality, but drying time is the longest; The heated-air drying quality is the poorest, and reaches 34 hours drying time; The microwave hot air coupling is shortened drying time greatly, and less than 2 hours, and content of reducing sugar compared all obviously greater than heated-air drying with protein content, approached vacuum freeze drying.
Fig. 1 is the configuration of surface that above-mentioned three kinds of drying means are handled the back lichee; As can be seen from the figure, the warpage of lichee is maximum after the heated-air drying, sees Fig. 1 (a); And that the shape of lichee keeps after the microwave hot air of the present invention coupling dried is best; See Fig. 1 (b), the lichee form keeps better seeing Fig. 1 (c) after the vacuum freeze drying.
Microwave hot air coupling drying means keeps lichee content of reducing sugar and protein content aspect that good effect is all arranged saving energy consumption, reduce drying time, improving drying efficiency.
Above-described only is preferred implementation of the present invention, the invention is not restricted to above embodiment.Be appreciated that other improvement and variation that those skilled in the art directly derive or associate under the prerequisite that does not break away from spirit of the present invention and design, all should think to be included within protection scope of the present invention.
Claims (4)
1. the drying means of a lichee is characterized in that may further comprise the steps:
(1) to the preliminary treatment of lichee, promptly lichee is carried out choosing, clean, draining according to size fractionation;
(2) it is dry the lichee after step (1) processing to be carried out the microwave hot air coupling; Be about to lichee and put into microwave hot air coupling drying machine; Keep 70 ~ 80 ℃ of hot blast temperatures, Microwave Power Density 0.8 ~ 2.2W/g, hot blast wind speed 1.5 ~ 2.8m/s; Drying time 90 ~ 160min, the water content that is dried to lichee is 7 ~ 12%.
2. the drying means of a kind of lichee according to claim 1; It is characterized in that the dry condition of preferred microwave hot air coupling is in the step (2): hot blast temperature remains on 75 ℃; Microwave Power Density 2.0 W/g, hot blast wind speed 2.5 m/s, drying time 100min.
3. according to the drying means of claim 1,2 described a kind of lichee; After it is characterized in that step (2) finishes; Can pack the lichee after handling, dried lichee cools off naturally even microwave hot air is coupled, and adopts high-barrier composite material to pack.
4. the drying means of a kind of lichee according to claim 3 is characterized in that said high-barrier composite material can be high-barrier high density food-grade polyethylene foil laminated film.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011103854700A CN102422877A (en) | 2011-11-29 | 2011-11-29 | Lichee-drying method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011103854700A CN102422877A (en) | 2011-11-29 | 2011-11-29 | Lichee-drying method |
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| CN102422877A true CN102422877A (en) | 2012-04-25 |
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| CN2011103854700A Pending CN102422877A (en) | 2011-11-29 | 2011-11-29 | Lichee-drying method |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102754893A (en) * | 2012-07-23 | 2012-10-31 | 钟春燕 | Foodstuff drying method |
| CN106720214A (en) * | 2016-12-09 | 2017-05-31 | 广州聚禅现代农业研究院有限公司 | A kind of method that hot wind and microwave dries lichee bacterium |
| CN111670981A (en) * | 2020-05-29 | 2020-09-18 | 徐州旺达农副产品有限公司 | Preparation method of multistage continuous intermittent microwave hot air drying burdock tea |
| CN113558166A (en) * | 2020-04-28 | 2021-10-29 | 中国农业机械化科学研究院 | Microwave-assisted drying method for agricultural products |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1317252A (en) * | 2000-04-11 | 2001-10-17 | 黄克明 | comprehensive physical method for antistaling litchi |
| CN101878882A (en) * | 2010-04-30 | 2010-11-10 | 陆爱章 | Processing method of dried lychee and dried longan |
| CN102067904A (en) * | 2010-12-24 | 2011-05-25 | 深圳职业技术学院 | Method for drying berry with shell by microwave in vacuum |
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2011
- 2011-11-29 CN CN2011103854700A patent/CN102422877A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1317252A (en) * | 2000-04-11 | 2001-10-17 | 黄克明 | comprehensive physical method for antistaling litchi |
| CN101878882A (en) * | 2010-04-30 | 2010-11-10 | 陆爱章 | Processing method of dried lychee and dried longan |
| CN102067904A (en) * | 2010-12-24 | 2011-05-25 | 深圳职业技术学院 | Method for drying berry with shell by microwave in vacuum |
Non-Patent Citations (2)
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| 周韵等: "热风微波耦合干燥胡萝卜片工艺", 《农业工程学报》 * |
| 罗树灿等: "热风和微波结合干燥荔枝加工工艺研究", 《现代食品科技》 * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102754893A (en) * | 2012-07-23 | 2012-10-31 | 钟春燕 | Foodstuff drying method |
| CN102754893B (en) * | 2012-07-23 | 2013-12-04 | 钟春燕 | Foodstuff drying method |
| CN106720214A (en) * | 2016-12-09 | 2017-05-31 | 广州聚禅现代农业研究院有限公司 | A kind of method that hot wind and microwave dries lichee bacterium |
| CN113558166A (en) * | 2020-04-28 | 2021-10-29 | 中国农业机械化科学研究院 | Microwave-assisted drying method for agricultural products |
| CN111670981A (en) * | 2020-05-29 | 2020-09-18 | 徐州旺达农副产品有限公司 | Preparation method of multistage continuous intermittent microwave hot air drying burdock tea |
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Application publication date: 20120425 |