CN104431802A - Method for improving production efficiency of rice cracker employing microwave and hot air combined drying - Google Patents

Abstract

The invention discloses a method for improving production efficiency of a rice cracker employing microwave and hot air combined drying, and belongs to the technical field of processing of rice puffed leisure foods. The method has the characteristics that formed green bodies of the rice cracker adopt a novel microwave and hot air combined drying process; rapid rise of internal temperature of the rice cracker is achieved by using the characteristics of internal microwave heating and high heating rate; meanwhile, the balance of mass and heat transfer of the green bodes in the drying process is enhanced by adopting forced convective drying of hot air; the moisture in the green bodies is rapidly and uniformly reduced to 12%-15% required for late baking from about 40% under the combined drying action; the drying time is shortened to tens of minutes from several hours, and thus the target of improving the production efficiency of the rice cracker is achieved; in addition, the microwave drying has a certain puffing effect on materials; the puffing degree of the rice cracker can be further improved; the product quality of the rice cracker is finally improved, and therefore, through the method for drying the green bodies of the rice cracker employing the microwave combined with hot air, so that the drying time can be shortened; the energy consumption for production is reduced; and the product quality is improved.

Description

A kind of method utilizing microwave and hot air combined drying to improve rice cracker production efficiency

Technical field

A kind of method utilizing microwave and hot air combined drying to improve rice cracker production efficiency of the present invention, belongs to rice puffed leisure food processing technique field.

Background technology

Rice cracker to be a kind of with rice be raw material bake cake, low sugar, less salt, low fat " three is low " food, it is soft that mouthfeel is crisp, there is the intrinsic fragrant local flavor of rice, be easy to carry, instant, easy to digest, being suitable for the consumption of children and adolescents, person in middle and old age's each age group crowd, is very by the amusement and travel food that consumers in general welcome.

Rice cracker production technology normally rice through immersion, powder process, steaming, shaping, dry, bake, seasoning, the operation such as packaging process.In rice cracker process of manufacture, green compact drying process is one of rice cracker production quality control CCP.Green compact bake expanded before moisture must control within a suitable scope, if moisture is too high, can because a large amount of instantaneous rapid loss of water vapour, thus cause finished product to produce a large amount of bubble in baking, expanded uneven, and expanded overlong time; If green compact moisture contains too low after redrying, again can be inadequate because producing water vapour and pressure thereof, expansion effect is poor even can not be expanded and easily occur dry and cracked, and therefore green compact drying process is very crucial.Current green compact drying adopts second stage drying method usually, though because adopt the continuous drying of single to shorten drying time, there is green compact uneven drying, easily occurs the phenomenons such as the quality deteriorations such as cracking.Adopt 70-75 DEG C of hot blast in the production technology research about long-grained nonglutinous rice fruit such as Li Qinglong (2002), after starting to be about 4.5h drying time, leave standstill 8-13 hour, then drying about 3.5 hours, make green compact moisture content initial about 40% be down to 11%-13% by twice drying.Visible in rice cracker production process, green compact adopt the whole process of heated-air drying sometimes to need tens of hours, and drying time is long especially, directly has influence on whole rice cracker production efficiency, also can bring the problem that capacity usage ratio during drying is low simultaneously.

The present invention about the method utilizing microwave and hot air combined drying to improve rice cracker production efficiency, mainly for shortening the drying time of rice cracker green compact, a kind of method energy-conservation when saving that simultaneously must ensure again drying quality.One of comparatively universal efficient, power-saving technology is applied in microwave drying in the world, and be characterized in producing thermal source at internal batch, drying time shortens greatly.Microwave is the electromagnetic wave of frequency at 300MHZ to 300GHZ.From dielectric structure, molecule is non-polar molecule dielectric, and another kind of is polar molecule dielectric.In the ordinary course of things, they are all random arrangement, if among the electric field that they are placed in alternation, the polar molecule orientation of these media also changes along with the change in polarity of electric field, is called polarization.Extra electric field is stronger, and polarization is also stronger, and extra electric field change in polarity must be faster, and polarize also faster, the rubbing action between the warm-up movement of molecule and adjacent molecule is also strong with regard to Shaoxing opera.Namely the conversion of electromagnetic energy to heat energy is completed in the process, when heated material is placed in microwave field, its polarity orientation changes along with the change of external electric field, polar molecule swings back and forth with microwave frequency with the high frequency of tens times per second, rubs, microwave electric field can be converted into the heat energy in medium, temperature of charge is raised, and moisture spreads rapidly from inside to outside, makes product while drying, create expanded effect.

The drying machine serial or parallel connection of two or more form is adopted to combine, just can reach single dry inaccessiable object, this drying mode is called combined drying, also combination drying is claimed, its main feature is in conjunction with dried material character according to the feature of single drying, the advantage of multi-form drying is recombinated, the features such as drying energy saving, rate of drying raising, quality guarantee can be realized.Because microwave drying is the drying mode of high strength, so be used to combine with other dry technology the most extensive, but mainly concentrate in fruits and vegetables ' dehydration drying about microwave and combined drying research thereof at present, Han Qinghua etc. are studied the expanded apple crisp slices of micro-wave vacuum, under preferably technological parameter, draw the apple crisp slices of high-quality high bulking rate; Fito etc. (2001) adopt five kinds of different combining forms to take dry banana chip to drying modes such as hot blast, infiltration, vacuum, microwaves respectively, and its moisture and soluble solid content are contrasted, conclusion is: hot blast/microwave combination rate of drying is the fastest, vacuum combines with other with infiltration: fresh mango, pineapple are become crisp by vacuum microwave drying by Durance etc., shrink very little, and keep original local flavor, and there is unique thin crisp mouthfeel; Krokida etc. compare the quality characteristic after the fruit and vegetable drynesses such as the apple under vacuum microwave, microwave and heated-air drying condition, banana, carrot and potato respectively, much lower than the latter of the bulk density of the former two, and porous is all better than the latter, maximum stress strain value is also less, the look deterioration that microwave drying also limit enzyme reaction and causes.These researchs all show, adopt microwave and combined drying thereof, and moisture evaporation rate when can significantly improve drying, compare with single dried forms, microwave combining drying can improve the quality of dry products.

The present invention is about utilizing microwave and the application of hot air combined drying in the drying of rice cracker green compact, and in existing rice cracker drying, its application also still locates blank.Hua Nanli work large Bing Hamming, Zhang Liyan have applied for that (patent No.: 200510036230.4), adopts normal pressure microwave or vaccum microwave puffing pigskin, and expansion rate can be controlled in 3-5 doubly left and right, crisp taste for a kind of pigskin puffed foods and processing method thereof.A kind of instant sliced fish and processing method (publication number: CN1205188A) thereof, is characterized in that water content is fillet or the fish silk explosion puffing drying of 40%-65% by employing microwave bulking technology.A kind of utilize microwave to process potato crispy chip and processing method (publication number: CN 891072A), main method be by potato crispy chip by through rinsing potato block saline solution in boiling under carry out blanching after, cooling, draining; By freezing for the potato chips after draining, dry, by palm oil, yolk powder mixes afterwards and potato chips are mixed thoroughly, finally carries out microwave baking, then sprays flavoring.A kind of fermented microwave puffing minced fillet leisure food such as Yang Ruijin and the to the effect that different material combination of production method (Authorization Notice No.: CN 101904518 B) thereof by Feedstock treating, alkali salt rinsing, dewater, cut mix, shaping, fermentation, heating using microwave production method.These patented technologies applied in leisure dilated food about microwave technology, mainly utilize microwave drying there is the feature of bulking effect, carry out directly expanded to institute's processing object, the method adopted is single microwave heating method, with the present invention about compared with the application of microwave hot air combined drying in rice cracker green compact, in research object, method and to realize object all not identical.

The present invention heats abundant applied microwave inside and firing rate is fast, impel rice cracker green compact internal moisture rapid temperature increases and to external diffusion, adopt outside hot blast forced convection, the moisture that heating using microwave is produced is enough can discharge with hot-air rapidly, play green compact uniformity of temperature profile, reach the object of uniform moisture evaporation.By this microwave and hot air combined dry rice cracker green compact, moisture Quick uniform evaporation when achieving dry in rice cracker production process, greatly shorten drying time, microwave also has bulking effect simultaneously, can strengthen the follow-up expansion effect baked of rice cracker.The inventive method does not have any report in rice cracker production and processing.

Summary of the invention

The object of this invention is to provide rice cracker green compact uniform drying microwave and hot air combined drying means fast in a kind of rice cracker production process.Main contents of the present invention are: Raw Materials Rice is eluriated and after soaking certain hour, carry out powder process, boiling, cooling, shaping, shaping after green compact adopt microwave and the parallel drying of hot blast, bake, seasoning again, packaging.The present invention have employed the new technology of microwave and hot air combined drying in the drying of rice cracker green compact, its effect utilizes the heating of microwave inside and the fast feature of firing rate, realize the quick rising of rice cracker internal temperature, adopt heated-air drying to strengthen the balance of green compact at dry run mass-and heat-transfer simultaneously, under microwave and hot air combined desiccation, realize moisture in green compact and be also reduced to 12%-15% required in later stage baking technology equably rapidly by initial about 40%, shorten drying time, thus reach the object improving rice cracker production efficiency; In addition microwave and hot air combined drying also strengthen the expansion effect of microwave drying to green compact, can further improve the puffed degree of rice cracker, improve the product quality of final rice cracker.Therefore, by the method for microwave and hot air combined dry rice cracker green compact, can drying time be shortened, reduce energy consumption and improve product quality, thus also realize improving the efficiency that whole rice cracker produces, shorten the process-cycle of product.

What the green compact drying of traditional rice cracker production process adopted is heated-air drying stage by stage, and the subject matter that the method exists is that dry time is long, and energy consumption is high, and drying time reaches tens of hours, has influence on the production cycle of whole rice cracker.For these problems that traditional rice cracker green compact heated-air drying exists, the present invention innovates green compact drying mode, adopt microwave drying in conjunction with hot blast forced convection drying, green compact are shortened dramatically drying time, and moisture distribution is even after drying, by the inside heating feature of microwave, pine has changed rice starch compact tissue structure, make product tentatively have certain expansion effect, thus serve the object improving product quality and shorten the rice cracker production cycle.

Technical scheme of the present invention: a kind of method utilizing microwave and hot air combined drying to improve rice cracker production efficiency, the rice cracker green compact after shaping adopt microwave and hot blast combined drying stage by stage; Its processing step is:

1) eluriate, soak: take rice as raw material, rice in steep time 6-9h after elutriation;

2) powder process: adopt wet pulverizing, smashing fineness controls at 80-100 order;

3) steaming: adopt pressure cooking method, steaming rice group thickness is no more than 60mm, and cooking pressure is 0.10-0.15MPa, time 20min;

4) shaping: the rice group after steaming is cooled to 55-60 DEG C, adopt mould extruded, obtain rice cracker green compact;

5) microwave and hot air combined drying: microwave and hot air combined drying adopt seasoning stage by stage, the first stage is that single hot blast is xeothermic, and temperature is 85-90 DEG C, and wind speed is 2-3m/s, time 10 min; Second stage is that microwave and hot blast are jointly dry, and microwave output power controls as 2-3 W/kg, and hot blast temperature is 80-85 DEG C, and wind speed is 1-3m/s, drying time 30-40 min, by green compact moisture control after combined drying at 12%-15%;

6) bake: baking technology parameter is: preheating: temperature 185 DEG C, time 1-2min; Expanded: temperature 300 DEG C, time 2min; Cooling: temperature 200 DEG C, time 1-3min.

Raw Materials Rice is polished rice or long-grained nonglutinous rice.

Beneficial effect of the present invention:

By the method for this microwave and hot air combined dry rice cracker green compact, pass through microwave fast heating, in conjunction with hot blast forced convection effect, effectively can improve moisture evaporation rate during green compact drying, shorten drying time, microwave drying simultaneously has bulking effect to material, and green compact obtain preliminary pre-puffed effect, and improves inner institutional framework.Checking is obtained from following several respects:

The remarkable shortening of green compact drying times: rice cracker green compact are dry in actual production process, traditional single hot-wind-drying time is adopted usually to need 4-10h, sometimes also need in dry run to leave standstill process, time is then longer, therefore in rice cracker actual production processing, green compact drying process is the key link restricting whole rice cracker manufacturing schedule.And adopt the inventive method microwave and hot air combined drying, utilize heating using microwave speed fast, in material, moisture can evaporate rapidly, auxiliary heated-air drying simultaneously, the large quantity of moisture that material surface can be enable to produce due to evaporation is shifted timely, prevents excess steam from occurring condensation situation on material surface.Under the forced convertion effect of this external hot air, green compact are more even at dry run mass-and heat-transfer, make the Temperature Distribution of green compact and moisture evaporate evenly, ensure dry quality.Adopt drying means of the present invention, the whole drying of rice cracker green compact can be controlled in 50min total time, green compact moisture content can be completed and bake required 12%-15%(wet basis from initial about 40% to follow-up) moisture content, therefore compared with heated-air drying single with tradition, this method significantly reduces drying time, effectively improves rice cracker production efficiency.

The improvement of green compact drying quality: the present invention adopts the method for sectional type hot air drying-microwave and hot air combined drying, green compact after can making drying have certain expansion effect, early stage adopts single heated-air drying main purpose to be carry out preliminary pre-gelatinized process to the surface starch of green compact, starch gelatinization produces shrinks, the film of a relative close is formed at green surface, adopt heating using microwave afterwards, the evaporation of green compact internal moisture is by outer closely membrane interaction, therefore inner water vapor pressure becomes large, this internal water steam pressure can impel green compact volume to swell, i.e. bulking effect; Simultaneously under microwave action, green compact internal starch can produce loose or cellular structure, is easier to follow-uply bake expanded object.Adopt the puffed degree difference 1.12 and 0.85 after drying means of the present invention and single heated-air drying green compact by contrast, the green compact after two kinds of distinct methods dryings are by identical baking technology process, and its puffed degree is 2.96 and 2.63 respectively.Visible, adopt green compact drying means of the present invention, the puffed degree after green compact bake can be improved.

Detailed description of the invention

Embodiment 1

The production rice cracker of polished rice microwave and hot air combined drying: twice eluriated by the northeast polished rice taking some, carries out wet powder-making after soaking 6h under room temperature, carries out microwave and hot air combined drying by steaming, cooling, shaping obtained rice cracker green compact.Its stage by stage Drying Technology Parameter be: the first stage adopts single heated-air drying to carry out the pre-heat treatment to the top layer of rice cracker green compact, and hot blast temperature controls at 85-90 DEG C, and wind speed is 2m/s, drying time 10 min; Second stage is that microwave and hot blast are jointly dry, microwave output power controls at 2 W/kg, hot blast temperature is 80-85 DEG C, wind speed is 2m/s, drying time 40 min, by rice cracker green compact moisture content after combined drying 13.4 ± 0.84%, puffed degree 1.09, whole dry total time is 50 min (from preheating reaches design temperature meters); Green compact after drying bake process, and baking technology parameter is: preheat temperature 185 DEG C, time 1min; Expanded: temperature 300 DEG C, time 2min; Cooling: temperature 200 DEG C, time 2min, recording rice cracker puffed degree after baking is 3.02.

Comparative examples 1

The production rice cracker of the single heated-air drying of polished rice tradition: twice eluriated by the northeast polished rice taking quantity in the same manner as in Example 1, wet powder-making is carried out after soaking 6h under room temperature, pass through steaming, cooling, shaping obtained rice cracker green compact carry out heated-air drying, its drying process is, initial drying temperature controls as 85-90 DEG C, wind speed is 2m/s, time 2.5h, later stage baking temperature control 80-85 DEG C, wind speed 1m/s, time 2h, after drying, rice cracker green compact record its moisture content is 13.8 ± 1.04%, puffed degree 0.84, whole dry total time is 4.5h(meter from preheating reaches design temperature), green compact after drying bake process, and baking technology parameter is: preheat temperature 185 DEG C, time 1min, expanded: temperature 300 DEG C, time 2min, cooling: temperature 200 DEG C, time 2min, recording rice cracker puffed degree after baking is 2.76.

Embodiment 2

The production rice cracker of long-grained nonglutinous rice microwave and hot air combined drying

Take some long-grained nonglutinous rices (Xian excellent 369, early Xian) and eluriate twice, carry out wet powder-making after soaking 9h under room temperature, carry out microwave and hot air combined drying by steaming, cooling, shaping obtained rice cracker green compact.Its stage by stage Drying Technology Parameter be: the first stage adopts single heated-air drying to carry out the pre-heat treatment to the top layer of rice cracker green compact, and hot blast temperature controls at 85-90 DEG C, and wind speed is 3m/s, drying time 10 min; Second stage is that microwave and hot blast are jointly dry, microwave output power controls at 2.5 W/kg, hot blast temperature is 80-85 DEG C, wind speed is 3m/s, drying time 30 min, after recording microwave hot air combined drying, green compact moisture content is 12.5 ± 0.28%, puffed degree 1.13, and whole dry total time is 40 min (from preheating reaches design temperature meters); Green compact after drying bake process, and baking technology parameter is: preheat temperature 185 DEG C, time 1min; Expanded: temperature 300 DEG C, time 2min; Cooling: temperature 200 DEG C, time 2min, recording rice cracker puffed degree after baking is 2.84.

Comparative examples 2

The production rice cracker of the single heated-air drying of long-grained nonglutinous rice tradition: take quantity long-grained nonglutinous rice in the same manner as in Example 2 (Xian excellent 369, early Xian) eluriate twice, wet powder-making is carried out after soaking 9h under room temperature, pass through steaming, cooling, shaping obtained green compact carry out heated-air drying, its drying process is, initial drying temperature controls as 85-90 DEG C, wind speed is 3m/s, time 2h, later stage baking temperature control 80-85 DEG C, wind speed 2m/s, time 2h, after drying, green compact record its moisture content is 12.9 ± 0.96%, puffed degree 0.87, whole dry total time is 4h(meter from preheating reaches design temperature), green compact after drying bake process, and baking technology parameter is: preheat temperature 185 DEG C, time 1min, expanded: temperature 300 DEG C, time 2min, cooling: temperature 200 DEG C, time 2min, recording rice cracker puffed degree after baking is 2.56.

Claims (2)

1. utilize microwave and hot air combined drying to improve a method for rice cracker production efficiency, it is characterized in that shaping after rice cracker green compact adopt microwave and hot blast combined drying stage by stage; Its processing step is:

1) eluriate, soak: take rice as raw material, rice in steep time 6-9h after elutriation;

2) powder process: adopt wet pulverizing, smashing fineness controls at 80-100 order;

3) steaming: adopt pressure cooking method, steaming rice group thickness is no more than 60mm, and cooking pressure is 0.10-0.15MPa, time 20min;

4) shaping: the rice group after steaming is cooled to 55-60 DEG C, adopt mould extruded, obtain rice cracker green compact;

5) microwave and hot air combined drying: microwave and hot air combined drying adopt seasoning stage by stage, the first stage is single heated-air drying, and temperature is 85-90 DEG C, and wind speed is 2-3m/s, time 10 min; Second stage is that microwave and hot blast are jointly dry, and microwave output power controls as 2-3 W/kg, and hot blast temperature is 80-85 DEG C, and wind speed is 1-3m/s, drying time 30-40 min, by green compact moisture control after combined drying at 12%-15%;

6) bake: baking technology parameter is: preheating: temperature 185 DEG C, time 1-2min; Expanded: temperature 300 DEG C, time 2min; Cooling: temperature 200 DEG C, time 1-3min.

2. the method utilizing microwave and hot air combined drying to improve rice cracker production efficiency according to claim 1, is characterized in that Raw Materials Rice is polished rice or long-grained nonglutinous rice.