阅读说明：本技术 一种鲜银耳的干燥方法 (Drying method of fresh tremella ) 是由 杨晓春 谢桂林 卢卫红 马莺 张英春 王荣春 程翠林 丁忠庆 黎重阳 吴新春 孙 于 2021-09-24 设计创作，主要内容包括：本发明公开了鲜银耳的干燥方法,解决了现有鲜银耳干燥效果较差,影响其外观及品质的问题。本发明包括以下步骤：步骤1：原料预处理；选择整朵的鲜银耳原料,将鲜银耳原料用水洗掉表面杂质,沥干后得到鲜银耳a,备用；步骤2：分段冷冻；将步骤1中的鲜银耳a进行第一段预冷冻后,进行第二段冷冻后得到鲜银耳b,其中第二段冷冻时间设置为0.5h-1.5h；步骤3：分步干燥；将步骤2中鲜银耳b抽真空后进行升华干燥至银耳含水量为≤12％时,升温进行解析干燥,其中解析干燥的时间设置为13h-15h；步骤4：封装；步骤5：后处理；即完成鲜银耳的干燥。本发明具有保持了鲜银耳的外形色泽、口感及营养物质,品质稳定、方便携带等优点。(The invention discloses a method for drying fresh tremella, which solves the problems that the existing fresh tremella is poor in drying effect and affects the appearance and quality of the tremella. The invention comprises the following steps: step 1: pretreating raw materials; selecting a whole fresh tremella raw material, washing surface impurities of the fresh tremella raw material with water, and draining to obtain fresh tremella a for later use; step 2: freezing in sections; after pre-freezing the fresh tremella a in the step 1 for the first period, freezing the fresh tremella a for the second period to obtain fresh tremella b, wherein the freezing time of the second period is set to be 0.5h-1.5 h; and step 3: drying step by step; vacuumizing the fresh tremella fuciformis b in the step 2, carrying out sublimation drying until the water content of the tremella fuciformis b is less than or equal to 12%, heating for analysis drying, wherein the analysis drying time is set to be 13-15 h; and 4, step 4: packaging; and 5: post-treatment; thus completing the drying of the fresh tremella. The tremella fuciformis beverage has the advantages of keeping the appearance, color, taste and nutrient substances of fresh tremella fuciformis, being stable in quality, convenient to carry and the like.)

1. A drying method of fresh tremella is characterized by comprising the following steps:

step 1: pretreating raw materials; selecting a whole fresh tremella raw material, washing surface impurities of the fresh tremella raw material with water, and draining to obtain fresh tremella a for later use;

step 2: freezing in sections; after pre-freezing the fresh tremella a in the step 1 for the first period, freezing the fresh tremella a for the second period to obtain fresh tremella b, wherein the freezing time of the second period is set to be 0.5h-1.5 h;

and step 3: drying step by step; vacuumizing the fresh tremella fuciformis b in the step 2, carrying out sublimation drying until the water content of the tremella fuciformis b is less than or equal to 12%, heating for analysis drying, wherein the analysis drying time is set to be 13-15 h;

and 4, step 4: packaging;

and 5: post-treatment; and finishing the drying of the fresh tremella after post-treatment operation.

2. The method for drying fresh tremella according to claim 1, wherein the water content of the fresh tremella material selected in step 1 is 75-85%.

3. The method for drying fresh tremella according to claim 1, wherein the temperature of the first pre-freezing stage in step 2 is set to be-80 ℃ to-75 ℃, the temperature of the second pre-freezing stage is set to be-60 ℃ to-65 ℃, and the cooling rate from the first pre-freezing stage to the second pre-freezing stage is set to be 10 ℃/min to 15 ℃/min.

4. The method for drying fresh tremella according to claim 1, wherein the vacuum degree of the vacuum pumping in step 3 is set to 150-200 Pa, and the temperature of the cold trap is set to-60 ℃ to-55 ℃; the time for sublimation drying is set to be 6-7 h;

the temperature is increased to 45 ℃ before the desorption drying, and the operation pressure of the desorption drying is set to be 20Pa-30 Pa.

5. The method for drying fresh tremella as claimed in claim 1, wherein in step 4, the packaging is filled with dry air or nitrogen, and the packaging is sealed by an aluminum foil bag.

6. The method for drying fresh tremella as claimed in claim 1, wherein the post-treatment in step 5 includes coding, labeling, metal detection, boxing, outer box coding, stacking and warehousing.

7. The method for drying fresh tremella as claimed in claim 6, wherein the warehouse temperature in the warehouse is set to 28 ℃ and the warehouse humidity is set to 60%.

Technical Field

The invention relates to the technical field of food processing, in particular to a drying method of fresh tremella.

Background

Tremella, also known as Tremella and Tremella, is a traditional fungus used as both medicine and food in China. Tremella fuciformis is rich in nutrition, contains rich colloid, various vitamins, inorganic salts and amino acids, is one of famous "mountain delicacies" and is known as "crown of bacteria". Research data show that each hundred grams of dry tremella contains 5.0g of protein, 0.6g of fat, 79g of carbohydrate, 2.6g of crude fiber, 3.1g of ash, 380mg of calcium, 250mg of phosphorus, 30.4mg of iron, 0.002mg of thiamine, 0.14mg of riboflavin and 1.5mg of nicotinic acid.

Fresh tremella which is just harvested is easy to deteriorate due to high moisture content, and needs to be dried immediately so as to be convenient for long-time storage and transportation. The tremella is preserved by a natural airing drying method, a hot air drying method and the like which are commonly used at present, and the quality of the tremella can be seriously influenced due to the problems of damage, uneven drying, long drying period, dark color, yellowing, poor rehydration property, poor peptization, loss of nutritional ingredients and the like of the tremella caused by the method.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: in the prior art, the drying effect of fresh tremella is poor, the appearance and the quality of the fresh tremella are affected, and the invention provides the drying method of the fresh tremella, which solves the problems.

The invention is realized by the following technical scheme:

a drying method of fresh tremella comprises the following steps:

step 1: pretreating raw materials; selecting a whole fresh tremella raw material, washing surface impurities of the fresh tremella raw material with water, and draining to obtain fresh tremella a for later use;

step 2: freezing in sections; after pre-freezing the fresh tremella a in the step 1 for the first period, freezing the fresh tremella a for the second period to obtain fresh tremella b, wherein the freezing time of the second period is set to be 0.5h-1.5 h;

and step 3: drying step by step; vacuumizing the fresh tremella fuciformis b in the step 2, carrying out sublimation drying until the water content of the tremella fuciformis b is less than or equal to 12%, heating for analysis drying, wherein the analysis drying time is set to be 13-15 h;

and 4, step 4: packaging;

and 5: post-treatment; and (5) carrying out post-treatment operation to finish the drying of the fresh tremella.

Further preferably, the water content of the fresh tremella raw material selected in the step 1 is 75% -85%.

The water content of the selected fresh tremella raw material is controlled to be 75% -85%, and the selected fresh tremella needs to be natural in color, glossy, uniform in size, light in weight and thick in colloid, so that the stable state of the tremella is guaranteed when subsequent freeze drying treatment is carried out.

Further preferably, the temperature of the first-stage pre-freezing in the step 2 is set to be-80 ℃ to-75 ℃, the temperature of the second-stage freezing is set to be-60 ℃ to-65 ℃, and the cooling speed from the first-stage pre-freezing to the second-stage freezing is set to be 10 ℃/min to 15 ℃/min.

Fresh tremella a is uniformly spread and put into an ultra-low temperature refrigerator for first-stage pre-freezing treatment, the temperature is controlled to be-80 ℃ to-75 ℃, to achieve the purpose of quickly freeze-drying the fresh tremella, then controlling the freeze-drying box to reduce the temperature at the speed of 10-15 ℃/min, reducing the temperature of the freeze-drying box to-60-65 ℃, carrying out second-stage freezing treatment, continuously freezing for 0.5-1.5 h, preferably freezing for 1h, therefore, the moisture in the fresh tremella is quickly frozen and solidified, the higher the freezing speed is, the smaller the internal crystal of the fresh tremella is, the keeping effect of the taste of the fresh tremella is improved, the subsequent rehydration is improved, the peptization is improved, after the segmented freezing, the original physicochemical property and the biological activity can be maintained, and the loss of effective components and nutrient substances is avoided and reduced.

Further preferably, the vacuum degree of the vacuum pumping in the step 3 is set to be 150Pa-200Pa, and the temperature of a cold trap is set to be-60 ℃ to-55 ℃; the time for sublimation drying is set to be 6-7 h;

the temperature is increased to 45 ℃ before the desorption drying, and the operation pressure of the desorption drying is set to be 20Pa-30 Pa.

The fresh tremella fuciformis b is vacuumized by a vacuum pump, the temperature of a cold trap is controlled to be minus 60 ℃ to minus 55 ℃ and the vacuum degree is controlled to be 150Pa to 200Pa, sublimation drying treatment is carried out for 6h to 7h, so that the fresh tremella fuciformis is freeze-dried until the water content of the tremella fuciformis is less than or equal to 12%, the temperature is further increased from minus 55 ℃ to 45 ℃, the operating pressure is controlled to be 20Pa to 30Pa, analytical drying is carried out for 13h to 14h, the temperature of the fresh tremella fuciformis is controlled to be consistent with the temperature of a dryer, the drying operation of the fresh tremella fuciformis is finished, the combined water content in the fresh tremella fuciformis is reduced, the freeze-drying forming structure is maintained, the freeze-drying period is shortened, the rehydration performance is improved, the stability is improved, the storage time is prolonged, and the tremella fuciformis is not easy to deteriorate.

Preferably, in the step 4, dry air or nitrogen is filled in the package, and an aluminum foil bag is used for packaging and sealing.

The fresh tremella after drying is filled with dry air or nitrogen, and the packaging of the aluminum foil bag is sealed, so that the fresh tremella after being processed is convenient to store, carry and maintain the stability of the quality of the tremella, and the fresh tremella is prevented from absorbing moisture again.

Preferably, the post-processing in the step 5 comprises code printing, labeling, metal detection, boxing, outer box code spraying, stacking and warehousing.

Further preferably, the temperature of the warehouse in the warehouse is set to be 28 ℃, and the humidity of the warehouse is set to be 60%.

The warehouse temperature used in the warehousing process of the post-treatment step is set to be 28 ℃, meanwhile, the humidity in the warehouse is controlled to be 60%, and the storage environment is cool, dry and well ventilated, so that the freeze-dried fresh tremella can be conveniently stored for a long time.

The invention has the following advantages and beneficial effects:

the fresh tremella drying method effectively maintains appearance, color, taste and nutrient substances of the fresh tremella, is rich in nutrition, stable in quality, convenient to carry and long in storage time, overcomes the defects of poor color, unstable quality and serious nutrient loss of the dried tremella in the traditional drying method, and creatively develops a new fresh tremella storage method. In addition, the vacuum freezing technology is applied when the tremella is dried, so that the original color and flavor of the tremella are maintained, and the conditions of uneven drying, long drying period, dark color, yellowing, rehydration and poor peptization are effectively avoided. The freeze-dried fresh tremella retains the taste and nutrition of tremella to the maximum extent, meanwhile, the variety of tremella is enriched, and the added value of tremella is improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.

Example 1

The invention preferably discloses a drying method of fresh tremella, which comprises the following steps:

step 1: pretreating raw materials; selecting 1kg of whole fresh tremella raw material, wherein the water content of the fresh tremella is 80%, washing the surface impurities of the fresh tremella raw material with water, and draining to obtain fresh tremella a for later use;

step 2: freezing in sections; spreading and dishing the fresh tremella a obtained in the step 1, putting the tremella a into an ultra-low temperature refrigerator for first-stage pre-freezing, controlling the temperature in the ultra-low temperature refrigerator to be-75 ℃, then cooling the temperature of a freeze-drying box to-60 ℃ at a speed of 10 ℃/min, quickly spreading the frozen fresh tremella a subjected to the first-stage pre-freezing treatment on a material rack in a cavity of a pre-cooled vacuum freeze-drying machine, and performing second-stage freezing for 1h to obtain fresh tremella b;

and step 3: drying step by step; after the fresh tremella fuciformis b in the step 2 is vacuumized by using a vacuum pump, sublimation drying is carried out for 6.5 hours under the conditions that the temperature of a cold trap is controlled to be-60 ℃ and the vacuum degree is 150Pa, and at the moment, the water content of the fresh tremella fuciformis b is 12%; raising the temperature from-55 ℃ to 45 ℃, controlling the operating pressure to be 25Pa, carrying out analysis drying for 14h, and finishing distribution drying treatment when the temperature of the fresh tremella is consistent with the temperature of the dryer;

and 4, step 4: packaging; packaging the freeze-dried fresh tremella by using an aluminum foil bag, and then filling nitrogen for sealing to finish packaging;

and 5: post-treatment; and (3) sequentially carrying out code printing, labeling, metal detection, boxing, outer box code spraying, stacking and storage on the packaged fresh tremella products, wherein the temperature of a warehouse in the storage is 28 ℃, the humidity is 60%, the freshness is cool, dry and well ventilated, and the shelf life of the prepared freeze-dried fresh tremella products is 24 months.

Example 2

A drying method of fresh tremella comprises the following steps:

step 1: pretreating raw materials; selecting 1kg of whole fresh tremella raw material, wherein the water content of the fresh tremella is 75%, washing the surface impurities of the fresh tremella raw material with water, and draining to obtain fresh tremella a for later use;

step 2: freezing in sections; spreading and dishing the fresh tremella a obtained in the step 1, putting the tremella a into an ultra-low temperature refrigerator for first-stage pre-freezing, controlling the temperature in the ultra-low temperature refrigerator to be-78 ℃, then cooling the temperature of a freeze-drying box to-62 ℃ at the speed of 12 ℃/min, quickly spreading the frozen fresh tremella a subjected to the first-stage pre-freezing treatment on a material rack in a cavity of a pre-cooled vacuum freeze-drying machine, and performing second-stage freezing for 1.5 hours to obtain fresh tremella b;

and step 3: drying step by step; after the fresh tremella fuciformis b in the step 2 is vacuumized by using a vacuum pump, sublimation drying is carried out for 7 hours under the conditions that the temperature of a cold trap is controlled to be-55 ℃ and the vacuum degree is 160Pa, and at the moment, the water content of the fresh tremella fuciformis b is 10%; raising the temperature from-55 ℃ to 45 ℃, controlling the operating pressure to be 20Pa, carrying out analysis drying for 15h, and finishing distribution drying treatment when the temperature of the fresh tremella is consistent with the temperature of a dryer;

and 4, step 4: packaging; packaging the freeze-dried fresh tremella by using an aluminum foil bag, and then filling nitrogen for sealing to finish packaging;

and 5: post-treatment; and (3) sequentially carrying out code printing, labeling, metal detection, boxing, outer box code spraying, stacking and storage on the packaged fresh tremella products, wherein the temperature of a warehouse in the storage is 28 ℃, the humidity is 60%, the freshness is cool, dry and well ventilated, and the shelf life of the prepared freeze-dried fresh tremella products is 24 months.

Example 3

A drying method of fresh tremella comprises the following steps:

step 1: pretreating raw materials; selecting 1kg of whole fresh tremella raw material, wherein the water content of the fresh tremella is 85%, washing the surface impurities of the fresh tremella raw material with water, and draining to obtain fresh tremella a for later use;

step 2: freezing in sections; spreading and dishing the fresh tremella a obtained in the step 1, putting the tremella a into an ultra-low temperature refrigerator for first-stage pre-freezing, controlling the temperature in the ultra-low temperature refrigerator to be-80 ℃, then cooling the temperature of a freeze-drying box to-65 ℃ at a speed of 15 ℃/min, quickly spreading the frozen fresh tremella a subjected to the first-stage pre-freezing treatment on a material rack in a cavity of a pre-cooled vacuum freeze dryer, and performing second-stage freezing for 0.8h to obtain fresh tremella b;

and step 3: drying step by step; after the fresh tremella fuciformis b in the step 2 is vacuumized by using a vacuum pump, sublimation drying is carried out for 6 hours under the conditions that the temperature of a cold trap is controlled to be-58 ℃ and the vacuum degree is 200Pa, and at the moment, the water content of the fresh tremella fuciformis b is 11%; raising the temperature from-55 ℃ to 45 ℃, controlling the operating pressure to be 30Pa, carrying out analysis drying for 13h, and finishing distribution drying treatment when the temperature of the fresh tremella is consistent with the temperature of a dryer;

and 4, step 4: packaging; packaging the freeze-dried fresh tremella by using an aluminum foil bag, and then filling nitrogen for sealing to finish packaging;

and 5: post-treatment; and (3) sequentially carrying out code printing, labeling, metal detection, boxing, outer box code spraying, stacking and storage on the packaged fresh tremella products, wherein the temperature of a warehouse in the storage is 28 ℃, the humidity is 60%, the freshness is cool, dry and well ventilated, and the shelf life of the prepared freeze-dried fresh tremella products is 24 months.

Example 4

A drying method of fresh tremella comprises the following steps:

step 1: 1kg of whole fresh tremella raw material is selected, surface impurities of the fresh tremella raw material are washed away by water, and the tremella raw material is drained for later use;

step 2: and (3) naturally airing the fresh tremella processed in the step (1) to obtain a dried fresh tremella product.

Example 5

A drying method of fresh tremella comprises the following steps:

step 1: 1kg of whole fresh tremella raw material is selected, surface impurities of the fresh tremella raw material are washed away by water, and the tremella raw material is drained for later use;

step 2: and (3) carrying out hot air drying treatment on the fresh tremella processed in the step (1) to obtain a dried fresh tremella product.

The fresh tremella product prepared by the above embodiment is subjected to performance test and sensory evaluation:

1. detection of product quality (i.e. after drying): the test was performed using an electronic balance.

2. And (3) detecting the rehydration of the product: and (3) respectively adding distilled water of 30 ℃ into the fresh tremella products prepared in the above embodiments for soaking, wherein the adding amount of the distilled water is 15 times of that of the tremella, soaking the tremella products by the distilled water to permeate into the fresh tremella, and after the fresh tremella is restored to be semitransparent, finishing soaking, and recording the soaking time and the soaking volume (compared with the fresh tremella raw materials) to judge the rehydration property.

3. And (3) detecting the product glue solubility: soaking the fresh tremella products prepared in the above embodiments in 30 ℃ distilled water, wherein the amount of the distilled water is 15 times of that of tremella, cutting off wood stipes of the tremella products by using scissors after soaking and rehydration, rinsing the tremella products by using tap water to remove the stained and discolored fresh tremella, completely removing the wood stipes, tearing the tremella into sheets, and draining the tremella products for later use after water washing; adding the processed fresh tremella into a high-pressure tank according to the material-liquid ratio of 1:10, cooking at 115 ℃, and recording the gum-forming state and cooking time of the tremella to judge the gum solubility.

4. Sensory evaluation of the product: selecting experimenters with age classes of 18-25 years, 26-30 years, 31-45 years, 46-60 years and 61-75 years at random, wherein the number of the experimenters is equal in each age class, the male-female ratio is 1:1, the experiment time is 4 weeks, the experiment is performed once per week, the fresh tremella products prepared by the different embodiments are selected each time, the experimenters are asked to observe, and the three aspects of appearance color, smell and purchasing desire are scored according to 100 scores. And removing a highest score and a lowest score from the evaluation data of each aspect of each age class, and averaging the rest scores and then recording to finish sensory judgment.

TABLE 1 Performance index

TABLE 2 sensory indices

As can be seen from table 1, the rehydration and rehydration effects of the fresh tremella products in examples 1, 2 and 3 within the scope of the present application are all stronger than those of examples 4 and 5 as comparative examples, and the gum-yielding conditions of examples 1, 2 and 3 are also better than those of examples 4 and 5, so that gum is easily yielded, and therefore, the products prepared by the drying method for fresh tremella provided by the present application have good retention effects on the shape, quality and volume of the fresh tremella raw material, and the rehydration and peptization properties are effectively improved; as can be seen from table 2, the appearance color, smell and purchase desire of the fresh tremella fuciformis prepared by the method are all greater than 90 points and are better than the sensory evaluation of the fresh tremella fuciformis prepared by the method in the examples 3 and 3, so that the product prepared by the method has the advantages of good appearance color, more easiness for people to pay money voluntarily, higher market acceptance and better development prospect.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.