阅读说明：本技术 一种异频微波协同加热姜黄片的干燥工艺 (Drying process for different-frequency microwave synergistic heating of curcuma longa slices ) 是由 黄志民 黄纪民 吴钊龙 陈先锐 曾繁政 胡文进 李秉正 于 2021-07-02 设计创作，主要内容包括：本发明公开了一种异频微波协同加热姜黄片的干燥工艺,其先将新鲜姜黄除去泥土和须根,洗净后将鲜姜黄切成厚度为2～5mm的姜黄片；接着将姜黄片放入温度为90～95℃的水中漂烫3～5 min；再将姜黄片放入复合护色液中浸泡10～20 min；然后将姜黄片放入箱式微波设备中,采用交替加热的方式加热干燥50～90min,即可得到姜黄干片,所述姜黄干片的含水量在5%以下。通过本发明可以生产得到色泽深黄鲜亮,酥脆,品质佳的姜黄干片,解决现有姜黄干燥技术中存在的干燥时间长、干燥加热不均匀、加热效率低和姜黄干片品质差的问题。(The invention discloses a drying process for a curcuma longa slice heated by using different-frequency microwaves in a synergistic mode, which comprises the steps of removing mud and fibrous roots from fresh curcuma longa, cleaning, and cutting the fresh curcuma longa into curcuma longa slices with the thickness of 2-5 mm; then, putting the turmeric slices into water with the temperature of 90-95 ℃ for blanching for 3-5 min; then placing the turmeric slices into the composite color protection liquid to soak for 10-20 min; and then putting the turmeric slices into box type microwave equipment, and heating and drying for 50-90 min in an alternate heating mode to obtain dried turmeric slices, wherein the water content of the dried turmeric slices is below 5%. According to the invention, the turmeric dry slices with dark yellow and bright color, crisp and good quality can be produced, and the problems of long drying time, uneven drying and heating, low heating efficiency and poor quality of the turmeric dry slices in the existing turmeric drying technology are solved.)

1. A drying process for turmeric slices by using different-frequency microwave synergistic heating is characterized in that: the method comprises the following steps:

(1) cleaning: removing mud and fibrous roots from fresh turmeric, and washing with water for 2-3 times; then cutting the fresh curcuma into curcuma pieces with the thickness of 2-5 mm;

(2) blanching: placing the turmeric slices into water with the temperature of 90-95 ℃ for blanching for 3-5 min;

(3) color protection: soaking the turmeric slices blanched in the step (2) in the composite color protection liquid for 10-20 min, wherein the mass ratio of the turmeric slices to the composite color protection liquid is (1) - (3); the composite color protection liquid comprises the following components in percentage by mass: 0.2 to 0.4 percent of ascorbic acid and 0.3 to 0.5 percent of citric acid;

(4) and (3) drying: putting the turmeric slices treated in the step (3) into box-type microwave equipment, heating and drying for 50-90 min to obtain dried turmeric slices, wherein the water content of the dried turmeric slices is below 5%; the box-type microwave equipment is provided with an A port and a B port, microwaves with the frequency of 2450MHz and the power of 1.0-2.0 kW are fed into the A port to heat the turmeric pieces, microwaves with the frequency of 915MHz and the power of 1.0-2.0 kW are fed into the B port to heat the turmeric pieces, the A port and the B port work alternately, the working time of the A port is 60-120 s each time, and the working time of the B port is 60s each time;

(5) packaging: and (4) filling nitrogen into the dried turmeric slices obtained in the step (4) and packaging.

2. The drying process of the curcuma longa slices by using the pilot frequency microwave synergistic heating according to claim 1, wherein the drying process comprises the following steps: the temperature of heating and drying in the step (4) is controlled to be 70-80 ℃.

3. The drying process of the curcuma longa slices by using the pilot frequency microwave synergistic heating according to claim 1, wherein the drying process comprises the following steps: when the turmeric slices are heated and dried in the step (4), the spreading density of the turmeric slices is 0.4-0.6 g/cm²。

4. The drying process of the curcuma longa slices by using the pilot frequency microwave synergistic heating according to claim 1, wherein the drying process comprises the following steps: in the step (4), the turmeric slices processed in the step (3) are placed into a box type microwave device for heating and drying for 50-90 min, wherein the total time for heating the turmeric slices by using the port A for working is 25-60 min, and the total time for heating the turmeric slices by using the port B for working is 25-45 min.

5. The drying process of the curcuma longa slices by using the pilot frequency microwave synergistic heating according to claim 1, wherein the drying process comprises the following steps: in the step (5), the dried turmeric slices are firstly placed under ultraviolet light to be irradiated for 20-30 min, and the intensity of the ultraviolet light is 0.5-1.5 mW/cm²Then the dried turmeric slices are filled with nitrogen and packaged.

Technical Field

The invention belongs to the technical field of agricultural product processing, and particularly relates to a drying process for a curcuma longa slice heated by different-frequency microwaves.

Background

Turmeric, originally recorded in "Xin Xiu Ben Cao", is an important medicinal plant of the genus Curcuma. The turmeric is also named as turmeric, turmeric and Baodingxiang, and is one of the common clinical Chinese, Mongolian and Tibetan medicines. Mainly produced in Guangxi, Sichuan, Guangdong, Fujian provinces, and also distributed in Andranbang, Tamilana DuPont, etc. in India. Turmeric has been a good medicine for promoting blood circulation and removing blood stasis since ancient times, and has the main effects of breaking blood and promoting qi circulation, and stimulating the menstrual flow and relieving pain. The traditional Chinese medicine composition is mainly used for chest and hypochondrium stabbing pain, amenorrhea, micro cripple, rheumatism, shoulder and arm pain and traumatic injury and swelling pain in clinic. The turmeric mainly contains volatile oil, wherein the chemical components comprise curcumenol, curdione, zedoarone, beta-elemene, germacrone and the like, and the turmeric has the pharmacological effects of resisting tumor, inflammation, thrombus, virus, bacteria, liver protection, immunity enhancement and the like. The fresh-cut decoction pieces are prepared from one of the fresh-cut decoction pieces in a production place, are prepared by the stipulation of 'Chinese pharmacopoeia' in 2020 edition, are picked up and dug after stem leaves wither in winter, are cleaned, remove fibrous roots, are longitudinally cut into thick pieces while being fresh, and are dried in the sun. Actually, the method has long drying time, generally needs about one month for natural drying, and if the turmeric cannot be dried in time in rainy days for a long time in winter, a large amount of rottenness is caused, economic loss is caused, and the development of the turmeric industry is severely restricted.

The microwave drying has unique heating characteristic and drying mechanism, and is an energy-saving, high-efficiency and green drying technology. The microwave heating has the characteristics of high heating speed, small heat loss, convenient operation and the like, can shorten the process time, improve the productivity, reduce the cost and improve the product quality. Therefore, microwave equipment is widely used, but with the continuous development of technology, the requirements of people on microwave equipment are gradually increased, especially on the aspects of heating uniformity, heating efficiency and the like of food. Only single frequency is adopted for heating, although the cavity of the microwave equipment is a multi-mode resonant cavity, a plurality of electromagnetic modes can be excited in the cavity, the number of the excited modes is limited, and the phenomenon of uneven heating is still more prominent.

Disclosure of Invention

Aiming at the defects, the invention discloses a drying process for a curcuma longa slice heated by using different-frequency microwaves in a synergistic manner, which solves the problems of long drying time, uneven drying and heating, low heating efficiency and poor quality of dried curcuma longa slices in the existing turmeric drying technology.

The invention is realized by adopting the following technical scheme:

a drying process for turmeric slices by using different-frequency microwave synergistic heating comprises the following steps:

(1) cleaning: removing mud and fibrous roots from fresh turmeric, and washing with water for 2-3 times; then cutting the fresh curcuma into curcuma pieces with the thickness of 2-5 mm;

(2) blanching: placing the turmeric slices into water with the temperature of 90-95 ℃ for blanching for 3-5 min;

(3) color protection: soaking the turmeric slices blanched in the step (2) in the composite color protection liquid for 10-20 min, wherein the mass ratio of the turmeric slices to the composite color protection liquid is (1) - (3); the composite color protection liquid comprises the following components in percentage by mass: 0.2 to 0.4 percent of ascorbic acid and 0.3 to 0.5 percent of citric acid;

(4) and (3) drying: putting the turmeric slices treated in the step (3) into box-type microwave equipment, heating and drying for 50-90 min to obtain dried turmeric slices, wherein the water content of the dried turmeric slices is below 5%; the box-type microwave equipment is provided with an A port and a B port, microwaves with the frequency of 2450MHz and the power of 1.0-2.0 kW are fed into the A port to heat the turmeric pieces, microwaves with the frequency of 915MHz and the power of 1.0-2.0 kW are fed into the B port to heat the turmeric pieces, the A port and the B port work alternately, the working time of the A port is 60-120 s each time, and the working time of the B port is 60s each time;

(5) packaging: and (4) filling nitrogen into the dried turmeric slices obtained in the step (4) and packaging.

Further, the temperature for heating and drying in the step (4) is controlled to be 70-80 ℃.

Further, when the turmeric slices are heated and dried in the step (4), the spreading density of the turmeric slices is 0.4-0.6 g/cm². The invention adopts single-layer laying, can ensure the uniform evaporation of water and improve the drying efficiency only by controlling the laying density of the curcuma longa pieces within the range.

Further, in the step (4), the turmeric slices processed in the step (3) are placed into a box type microwave device for heating and drying for 50-90 min, wherein the total time for heating the turmeric slices by using the port A for working is 25-60 min, and the total time for heating the turmeric slices by using the port B for working is 25-45 min. The microwave field cold and hot areas generated by the 2450MHz and 915MHz microwave sources are distributed differently, so that complementation can be formed by adopting an alternate heating mode, and the uniformity of the temperature field is improved. In addition, the 915MHz microwave heating capacity is weaker than 2450MHz microwave, and the purpose of preventing materials from being overheated can be achieved.

Further, in the step (5), the turmeric dried slices are firstly placed under ultraviolet light to be irradiated for 20-30 min, and the intensity of the ultraviolet light is 0.5-1.5 mW/cm²Then the dried turmeric slices are filled with nitrogen and packaged.

Compared with the prior art, the technical scheme has the following beneficial effects:

1. aiming at the problems of non-uniformity of microwave heating and low microwave energy absorption efficiency, the invention provides a different-frequency microwave drying method for improving heating uniformity by alternately heating turmeric pieces by using 915MHz electromagnetic waves and 2450MHz electromagnetic waves, wherein the heating ranges can complement each other when the method works at the working frequencies of 2450MHz and 915MHz respectively, the material can be dried by adjusting the working frequency and the heating time, the field distribution uniformity is improved, the heating uniformity is improved, the drying time is shortened, meanwhile, each turmeric piece is analyzed by using an infrared thermal imager at the later drying stage, and the difference between the hot point temperature and the cold point temperature is 7.0-11.0 ℃; the turmeric dry tablets are randomly selected, the volatile oil and the color of the turmeric dry tablets are respectively measured by a GC-MS and a colorimeter, the difference between the volatile oil of the turmeric dry tablets is 5.00-8.00%, and the color difference value Δ E of the turmeric dry tablets is 1.0-3.0. The calculation formula of the color difference value Δ E is as follows:

wherein L is the brightness of the dried turmeric slices; l is the brightness of the fresh curcuma longa tablets; a is the red degree of the dried turmeric slices; a is the red degree of the fresh curcuma longa tablets; b is the blue degree of the dried turmeric slices; b is the blueness of fresh turmeric pieces. For the dried curcuma longa slice product, the smaller the total color difference delta E is, the closer the color of the dried product is to the color of the fresh curcuma longa slice product, and the better the appearance index is.

2. Aiming at the characteristics of turmeric and the characteristics of microwave drying at different frequencies, the composite color protection liquid prepared by using ascorbic acid and citric acid in proportion is used for protecting the color of turmeric slices, inhibiting the activity of phenol oxidase and preventing the turmeric slices from browning; and simultaneously, before soaking the composite color fixative, blanching the turmeric slices in high-temperature water for 3-5 min to ensure that an oxidase system in the turmeric slices is destroyed, prevent browning and oxidation of nutrient substances, and control the blanching time and temperature to ensure that the optimal sterilization enzyme inactivation effect is obtained.

Detailed Description

The invention is further illustrated by the following examples, which are not to be construed as limiting the invention thereto. The specific experimental conditions and methods not indicated in the following examples are generally conventional means well known to those skilled in the art.

Example 1:

a drying process for turmeric slices by using different-frequency microwave synergistic heating comprises the following steps:

(1) cleaning: removing mud and fibrous root from fresh Curcuma rhizome, and washing with water for 2 times; then cutting fresh curcuma into curcuma pieces with the thickness of 2 mm;

(2) blanching: blanching Curcuma rhizome tablet in 90 deg.C water for 4 min;

(3) color protection: soaking the blanched turmeric slices in the step (2) in the composite color protection liquid for 10 min, wherein the mass ratio of the turmeric slices to the composite color protection liquid is 1: 1; the composite color protection liquid comprises the following components in percentage by mass: 0.2% ascorbic acid, 0.3% citric acid;

(4) and (3) drying: placing the turmeric slices treated in the step (3) into a box type microwave device, heating and drying for 80min, controlling the temperature at 75 ℃, and controlling the spreading density of the turmeric slices to be 0.5g/cm²Obtaining the dried turmeric slices, wherein the water content of the dried turmeric slices is below 5%; the box-type microwave equipment is provided with an A port and a B port, microwaves with the frequency of 2450MHz are fed into the A port to heat the curcuma longa pieces, microwaves with the frequency of 915MHz are fed into the B port to heat the curcuma longa pieces, the A port and the B port work alternately, the working time of the A port is 60s each time, the power of the A port is 1.5kW, the working time of the B port is 60s each time, and the power of the B port is 1.5 kW;

(5) packaging: placing the dried Curcuma longa slice obtained in step (4) under ultraviolet light for irradiating for 25min, wherein the ultraviolet light intensity is 1.0mW/cm²Then the dried turmeric slices are filled with nitrogen and packaged.

According to the method for producing the dried turmeric slices, in the later drying period, the temperature difference between a hot spot and a cold spot is 7.0 ℃, the difference between volatile oil of the dried turmeric slices is 5.20-5.30%, the water content of the obtained dried turmeric slices is below 4.33%, and the color difference value delta E of the dried turmeric slices is 1.6-1.8.

Example 2:

a drying process for turmeric slices by using different-frequency microwave synergistic heating comprises the following steps:

(1) cleaning: removing mud and fibrous root from fresh Curcuma rhizome, and washing with water for 3 times; then cutting the fresh curcuma into curcuma pieces with the thickness of 3 mm;

(2) blanching: blanching Curcuma rhizome tablet in 92 deg.C water for 3 min;

(3) color protection: soaking the blanched turmeric slices in the step (2) in the composite color protection liquid for 15 min, wherein the mass ratio of the turmeric slices to the composite color protection liquid is 1: 2; the composite color protection liquid comprises the following components in percentage by mass: 0.3% ascorbic acid, 0.4% citric acid;

(4) and (3) drying: placing the turmeric slices treated in the step (3) into a box type microwave device, heating and drying for 90min, controlling the temperature at 70 ℃, and controlling the spreading density of the turmeric slices to be 0.6g/cm²Obtaining the dried turmeric slices, wherein the water content of the dried turmeric slices is below 5%; the box-type microwave equipment is provided with an A port and a B port, microwaves with the frequency of 2450MHz are fed into the A port to heat the curcuma longa pieces, microwaves with the frequency of 915MHz are fed into the B port to heat the curcuma longa pieces, the A port and the B port work alternately, the working time of the A port every time is 120s, the power of the A port is 1.0kW, the working time of the B port every time is 60s, and the power of the B port is 1.0 kW;

(5) packaging: placing the dried Curcuma longa slice obtained in step (4) under ultraviolet light for 20min, wherein the ultraviolet light intensity is 1.5mW/cm²Then the dried turmeric slices are filled with nitrogen and packaged.

According to the method for producing the dried turmeric slices, in the later drying period, the temperature difference between a hot spot and a cold spot is 8.5 ℃, the difference between the volatile oil of the dried turmeric slices is 6.13-6.45%, the water content of the obtained dried turmeric slices is below 4.27%, and the color difference value delta E of the dried turmeric slices is 2.4-2.7.

Example 3:

a drying process for turmeric slices by using different-frequency microwave synergistic heating comprises the following steps:

(1) cleaning: removing mud and fibrous root from fresh Curcuma rhizome, and washing with water for 3 times; then cutting the fresh curcuma into curcuma pieces with the thickness of 5 mm;

(2) blanching: blanching Curcuma rhizome tablet in 95 deg.C water for 5 min;

(3) color protection: soaking the blanched turmeric slices in the step (2) in the composite color protection liquid for 20min, wherein the mass ratio of the turmeric slices to the composite color protection liquid is 1: 3; the composite color protection liquid comprises the following components in percentage by mass: 0.4% ascorbic acid, 0.5% citric acid;

(4) and (3) drying: placing the turmeric slices treated in step (3) into a box type microwave equipment, heating and drying for 50min, controlling the temperature at 80 ℃, and controlling the spreading density of the turmeric slices to be 0.4g/cm²Obtaining the dried turmeric slices, wherein the water content of the dried turmeric slices is below 5%; the box-type microwave equipment is provided with an A port and a B port, microwaves with the frequency of 2450MHz are fed into the A port to heat the curcuma longa pieces, microwaves with the frequency of 915MHz are fed into the B port to heat the curcuma longa pieces, the A port and the B port work alternately, the working time of the A port is 60s each time, the power of the A port is 2.0kW, the working time of the B port is 60s each time, and the power of the B port is 2.0 kW;

(5) packaging: placing the dried Curcuma longa slice obtained in step (4) under ultraviolet light for 30min, wherein the intensity of the ultraviolet light is 0.5mW/cm²Then the dried turmeric slices are filled with nitrogen and packaged.

According to the method for producing the dried turmeric slices, in the later drying period, the temperature difference between a hot spot and a cold spot is 10.0 ℃, the difference between volatile oil of the dried turmeric slices is 7.31-7.64%, the water content of the obtained dried turmeric slices is below 4.89%, and the color difference value delta E of the dried turmeric slices is 2.4-2.9.

Example 4:

a drying process for turmeric slices by using different-frequency microwave synergistic heating comprises the following steps:

(1) cleaning: removing mud and fibrous root from fresh Curcuma rhizome, and washing with water for 2 times; then cutting the fresh curcuma into curcuma pieces with the thickness of 3 mm;

(2) blanching: blanching Curcuma rhizome tablet in 95 deg.C water for 3 min;

(3) color protection: soaking the blanched turmeric slices in the step (2) in the composite color protection liquid for 20min, wherein the mass ratio of the turmeric slices to the composite color protection liquid is 1: 2; the composite color protection liquid comprises the following components in percentage by mass: 0.2% ascorbic acid, 0.4% citric acid;

(4) and (3) drying: putting the turmeric slices treated in the step (3) into a boxHeating and drying in microwave equipment for 90min at 70 deg.C, wherein the spreading density of Curcuma rhizome pieces is 0.5g/cm²Obtaining the dried turmeric slices, wherein the water content of the dried turmeric slices is below 5%; the box-type microwave equipment is provided with an A port and a B port, microwaves with the frequency of 2450MHz are fed into the A port to heat the curcuma longa pieces, microwaves with the frequency of 915MHz are fed into the B port to heat the curcuma longa pieces, the A port and the B port work alternately, the working time of the A port is 60s each time, the power of the A port is 1.0kW, the working time of the B port is 60s each time, and the power of the B port is 1.0 kW;

(5) packaging: placing the dried Curcuma longa slice obtained in step (4) under ultraviolet light for 20min, wherein the ultraviolet light intensity is 1.0mW/cm²Then the dried turmeric slices are filled with nitrogen and packaged.

According to the method for producing the dried turmeric slices, in the later drying period, the temperature difference between a hot spot and a cold spot is 7.5 ℃, the difference between volatile oil of the dried turmeric slices is 7.78-8.04%, the water content of the obtained dried turmeric slices is below 4.29%, and the color difference value delta E of the dried turmeric slices is 1.3-1.5.

Example 5:

a drying process for turmeric slices by using different-frequency microwave synergistic heating comprises the following steps:

(1) cleaning: removing mud and fibrous root from fresh Curcuma rhizome, and washing with water for 2 times; then cutting fresh curcuma into curcuma pieces with the thickness of 2 mm;

(2) blanching: blanching Curcuma rhizome tablet in 90 deg.C water for 4 min;

(3) color protection: soaking the blanched turmeric slices in the step (2) in the composite color protection liquid for 10 min, wherein the mass ratio of the turmeric slices to the composite color protection liquid is 1: 1; the composite color protection liquid comprises the following components in percentage by mass: 0.2% ascorbic acid, 0.3% citric acid;

(4) and (3) drying: placing the turmeric slices treated in the step (3) into a box type microwave device, heating and drying for 60min, controlling the temperature at 75 ℃, and controlling the spreading density of the turmeric slices to be 0.5g/cm²Obtaining the dried turmeric slices, wherein the water content of the dried turmeric slices is below 5%; an A end is arranged in the box type microwave equipmentThe port A and the port B are used for feeding microwaves with the frequency of 2450MHz to heat the curcuma longa slices, the microwaves with the frequency of 915MHz are fed into the port B to heat the curcuma longa slices, the port A and the port B work alternately, the working time of the port A is 80s each time, the power is 1.0kW, the working time of the port B is 60s each time, and the power is 1.5 kW;

(5) packaging: placing the dried Curcuma longa slice obtained in step (4) under ultraviolet light for irradiating for 25min, wherein the ultraviolet light intensity is 1.0mW/cm²Then the dried turmeric slices are filled with nitrogen and packaged.

According to the method for producing the dried turmeric slices, in the later drying period, the temperature difference between a hot spot and a cold spot is 8.9 ℃, the difference between the volatile oil of the dried turmeric slices is 6.14-6.37%, the water content of the obtained dried turmeric slices is below 4.30%, and the color difference value delta E of the dried turmeric slices is 1.9-2.2.

Example 6:

a drying process for turmeric slices by using different-frequency microwave synergistic heating comprises the following steps:

(1) cleaning: removing mud and fibrous root from fresh Curcuma rhizome, and washing with water for 3 times; then cutting the fresh curcuma into curcuma pieces with the thickness of 3 mm;

(2) blanching: blanching Curcuma rhizome tablet in 92 deg.C water for 3 min;

(3) color protection: soaking the blanched turmeric slices in the step (2) in the composite color protection liquid for 15 min, wherein the mass ratio of the turmeric slices to the composite color protection liquid is 1: 2; the composite color protection liquid comprises the following components in percentage by mass: 0.3% ascorbic acid, 0.4% citric acid;

(4) and (3) drying: placing the turmeric slices treated in step (3) into a box type microwave equipment, heating and drying for 70min, controlling the temperature at 80 ℃, and controlling the spreading density of the turmeric slices to be 0.6g/cm²Obtaining the dried turmeric slices, wherein the water content of the dried turmeric slices is below 5%; an A port and a B port are arranged in the box type microwave equipment, microwaves with the frequency of 2450MHz are fed into the A port to heat the curcuma longa pieces, microwaves with the frequency of 915MHz are fed into the B port to heat the curcuma longa pieces, the A port and the B port work alternately, and the A portThe working time of each time is 90s, the power is 1.5kW, the working time of the port B is 60s, and the power is 1.5 kW;

(5) packaging: placing the dried Curcuma longa slice obtained in step (4) under ultraviolet light for 20min, wherein the ultraviolet light intensity is 1.5mW/cm²Then the dried turmeric slices are filled with nitrogen and packaged.

According to the method for producing the dried turmeric slices, in the later drying period, the temperature difference between a hot spot and a cold spot is 9.7 ℃, the difference between the volatile oil of the dried turmeric slices is 7.01-7.44%, the water content of the obtained dried turmeric slices is below 4.25%, and the color difference value delta E of the dried turmeric slices is 2.5-2.7.

Example 7:

a drying process for turmeric slices by using different-frequency microwave synergistic heating comprises the following steps:

(1) cleaning: removing mud and fibrous root from fresh Curcuma rhizome, and washing with water for 3 times; then cutting the fresh curcuma into curcuma pieces with the thickness of 5 mm;

(2) blanching: blanching Curcuma rhizome tablet in 95 deg.C water for 5 min;

(3) color protection: soaking the blanched turmeric slices in the step (2) in the composite color protection liquid for 20min, wherein the mass ratio of the turmeric slices to the composite color protection liquid is 1: 3; the composite color protection liquid comprises the following components in percentage by mass: 0.4% ascorbic acid, 0.5% citric acid;

(4) and (3) drying: placing the turmeric slices treated in the step (3) into a box type microwave device, heating and drying for 80min, controlling the temperature at 78 ℃, and controlling the spreading density of the turmeric slices to be 0.4g/cm²Obtaining the dried turmeric slices, wherein the water content of the dried turmeric slices is below 5%; set up A port and B port among the box microwave equipment, follow the microwave that A port feed-in frequency is 2450MHz heats the turmeric piece, follow the microwave that B port feed-in frequency is 915MHz heats the turmeric piece, A port and B port alternate working, wherein in the preceding 30min A port operating time every time is 120s, and the power is 2.0kW, and B port operating time every time is 60s, and the power is 2.0kW, then in next 30min A port operating time every time is 90s, and the power is 1.0kW, B port every during operationThe time is 60s, the power is 1.0kW, the working time of the port A is 60s, the power is 1.0kW, the working time of the port B is 60s, and the power is 1.0kW in the last 20 min; the drying process is carried out in 3 sections, the working time of the port A with high early-stage drying frequency is long, the drying and heating efficiency can be improved, the moisture content of the turmeric pieces is low in the later stage of drying, the working time of the port B is prolonged, the heating uniformity can be ensured, and the materials can be prevented from being overheated;

(5) packaging: placing the dried Curcuma longa slice obtained in step (4) under ultraviolet light for 30min, wherein the intensity of the ultraviolet light is 0.5mW/cm²Then the dried turmeric slices are filled with nitrogen and packaged.

According to the method for producing the dried turmeric slices, in the later drying period, the temperature difference between a hot spot and a cold spot is 7.1 ℃, the difference between volatile oil of the dried turmeric slices is 5.02-5.34%, the water content of the obtained dried turmeric slices is below 4.37%, and the color difference value delta E of the dried turmeric slices is 1.0-1.3.

Example 8:

a drying process for turmeric slices by using different-frequency microwave synergistic heating comprises the following steps:

(1) cleaning: removing mud and fibrous root from fresh Curcuma rhizome, and washing with water for 2 times; then cutting the fresh curcuma into curcuma pieces with the thickness of 3 mm;

(2) blanching: blanching Curcuma rhizome tablet in 95 deg.C water for 3 min;

(3) color protection: soaking the blanched turmeric slices in the step (2) in the composite color protection liquid for 20min, wherein the mass ratio of the turmeric slices to the composite color protection liquid is 1: 2; the composite color protection liquid comprises the following components in percentage by mass: 0.2% ascorbic acid, 0.4% citric acid;

(4) and (3) drying: placing the Curcuma rhizome slices treated in step (3) into box type microwave equipment, heating and drying for 85min, controlling temperature at 70 deg.C, and spreading with density of 0.5g/cm²Obtaining the dried turmeric slices, wherein the water content of the dried turmeric slices is below 5%; an A port and a B port are arranged in the box type microwave equipment, microwaves with the frequency of 2450MHz are fed into the A port to heat the turmeric slice, and microwaves with the frequency of 915MHz are fed into the B portHeating the turmeric slices by microwaves, wherein the port A and the port B work alternately, the working time of the port A is 90s and the power is 1.5kW in the first 40min, the working time of the port B is 60s and the power is 1.0kW in the second 45min, and the working time of the port A is 60s and the power is 1.0kW in the last 45min, the working time of the port B is 60s and the power is 1.0 kW;

(5) packaging: placing the dried Curcuma longa slice obtained in step (4) under ultraviolet light for 20min, wherein the ultraviolet light intensity is 1.0mW/cm²Then the dried turmeric slices are filled with nitrogen and packaged.

According to the method for producing the dried turmeric slices, in the later drying period, the temperature difference between a hot spot and a cold spot is 7.5 ℃, the difference between the volatile oil of the dried turmeric slices is 6.88-7.05%, the water content of the obtained dried turmeric slices is below 4.30%, and the color difference value delta E of the dried turmeric slices is 1.7-1.9.

Comparative example 1:

this comparative example differs from the process described in example 1 in that in the drying in step (4), a single port drying mode was used, the frequency of the port was 915MHz, the power was 2.0kW, and the heating time was 160 min.

According to the method for producing the dried turmeric slices, in the later drying period, the temperature difference between a hot spot and a cold spot is 26.0 ℃, the difference between the volatile oil of the dried turmeric slices is 18.85-19.01%, the water content of the obtained dried turmeric slices is below 4.41%, and the color difference value delta E of the dried turmeric slices is 4.3-4.8.

Comparative example 2:

the comparative example differs from the method described in example 1 in that in the drying in step (4), a single port drying mode is adopted, the frequency of port is 2450MHz, the power is 2.0kW, and the heating time is 55 min.

According to the method for producing the dried turmeric slices in the comparative example, in the later drying period, the temperature difference between the hot spot and the cold spot is 18.0 ℃, the difference between the volatile oil of the dried turmeric slices is 15.42-15.96%, the water content of the obtained dried turmeric slices is below 4.22%, and the color difference value delta E of the dried turmeric slices is 5.1-5.4.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.