CN112268412A

CN112268412A - Longan pretreatment liquid and method for quickly drying longan

Info

Publication number: CN112268412A
Application number: CN202011154039.0A
Authority: CN
Inventors: 林丽静; 刘佳梦; 黄晖; 刘义军
Original assignee: Agricultural Products Processing Research Institute of CATAS
Current assignee: Agricultural Products Processing Research Institute of CATAS
Priority date: 2020-10-26
Filing date: 2020-10-26
Publication date: 2021-01-26
Anticipated expiration: 2040-10-26
Also published as: CN112268412B

Abstract

The invention discloses a longan pretreatment liquid, which comprises, by weight, 0.01-0.2% of organic acid, 0.001-0.1% of inorganic salt, 0.01-0.5% of organic solvent, 0.01-0.1% of thickening agent and the balance of water. The method uses the pretreatment liquid with a specific formula to treat the longan, so that the structure of the longan shell is changed, the permeability of the longan shell is increased, the diffusion speed of the water of the longan is improved, the drying time of the longan is shortened, the method is quickly carried out at a lower temperature, and a large amount of energy is saved.

Description

Longan pretreatment liquid and method for quickly drying longan

Technical Field

The invention relates to the technical field of agricultural product processing, in particular to longan pretreatment liquid and a method for quickly drying longan.

Background

Longan (Dimocarpusungganlaur) is a typical subtropical fruit, is rich in nutrition, and has antibacterial, anticancer, antioxidant, antiaging, insomnia relieving, immunity enhancing, and memory improving effects. Since ancient times, longan has been regarded as a good tonic, and li shizhen is recorded in the compendium of materia Medica: the food is expensive litchi and good longan. Longan is popular among people due to its rich nutritional effects and good flavor characteristics, and the market demand of longan is increasing year by year in recent years.

The dried longan product is the first processed product of longan, comprises longan pulp, dried longan and the like, has the annual output of about 2.4-2.5 ten thousand tons, and accounts for the vast majority of processed longan products. The dried longan is dried by electric heating basically in the prior art, and generally needs more than 24 hours; or drying at a higher temperature, for example, chinese patent CN106387742A discloses a method for quickly dehydrating and drying longan, wherein the longan needs to be treated with boiling water at 90-100 ℃ and drying temperature as high as 100 ℃. Therefore, the cost of drying the dried longan is mainly in terms of energy consumption.

Disclosure of Invention

In order to solve the above problems, the first aspect of the present invention provides a longan pretreatment liquid, which comprises, by weight, 0.01 to 0.2% of an organic acid, 0.001 to 0.1% of an inorganic salt, 0.01 to 0.5% of an organic solvent, 0.01 to 0.1% of a thickener, and the balance water.

As a preferable technical scheme, the pretreatment solution comprises, by weight, 0.05-0.1% of an organic acid, 0.01-0.03% of an inorganic salt, 0.1-0.2% of an organic solvent, 0.02-0.05% of a thickening agent, and the balance of water.

As a preferable technical scheme, the organic acid is one or a mixture of more of glacial acetic acid, formic acid, citric acid, tartaric acid, ascorbic acid, oxalic acid, malic acid and citric acid.

In a preferred embodiment, the inorganic salt is selected from one or more of chloride, sulfate, carbonate and sulfite.

As a preferable technical scheme, the chloride salt is selected from one or more of sodium chloride, potassium chloride, calcium chloride and magnesium chloride.

As a preferable technical scheme, the carbonate is one or more selected from sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, sodium bicarbonate and potassium bicarbonate.

As a preferred technical scheme, the sulfite is selected from one or more of sodium sulfite, potassium sulfite and calcium sulfite.

As a preferred technical scheme, the organic solvent is selected from one or more of methanol, ethanol, acetone and diethyl ether.

As a preferred technical scheme, the thickening agent is selected from one or more of xanthan gum, arabic gum, octenyl succinic acid starch ester, starch and gelatin.

In a second aspect of the present invention, there is provided a method for rapidly drying longan, comprising the steps of:

a. cutting fresh longan into complete single fruits, cleaning, and airing the surface moisture;

b. b, putting the longan obtained in the step a into the pretreatment liquid at the temperature of 60-80 ℃, soaking for 5-10 min, and fishing out and airing the surface water;

c. and c, drying the longan obtained in the step b at the temperature of 60-80 ℃ for 4-6 h, and then drying at the temperature of 40-60 ℃ for 10-15 h until the water content is reduced to be less than or equal to 25%.

Has the advantages that: the invention provides a longan pretreatment liquid and a method for quickly drying longan, after the longan is treated by the pretreatment liquid with a specific formula, the structure of longan shell is changed, the permeability of longan shell is increased, the diffusion speed of longan moisture is improved, the longan drying time is shortened, and the method is quickly carried out at a lower temperature, thereby saving a large amount of energy.

Drawings

To further illustrate the beneficial effects of the longan pretreatment liquid and the method for rapidly drying longan provided by the present invention, the accompanying drawings are provided, and it should be noted that the accompanying drawings provided in the present invention are only selected from individual examples in all drawings and are not intended to limit the claims, and all other corresponding diagrams obtained by the accompanying drawings provided in the present application should be considered as within the protection scope of the present application.

FIG. 1 is an electron microscope scan of dried longan pericarp obtained in example 1 of the present invention.

FIG. 2 is an electron microscope scan of dried longan pericarp obtained in comparative example 1 of the present invention.

FIG. 3 is the scanning electron microscope image of longan shell of fresh longan.

FIG. 4 is an electron microscope scan of dried longan pericarp obtained in comparative example 2 of the present invention.

FIG. 5 is an electron microscope scan of dried longan pericarp obtained in comparative example 3 of the present invention.

FIG. 6 is an electron microscope scan of dried longan pericarp obtained in comparative example 4 of the present invention.

Detailed Description

The disclosure may be understood more readily by reference to the following detailed description of preferred embodiments of the invention and the examples included therein. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

The term "prepared from …" as used herein is synonymous with "comprising". The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

The conjunction "consisting of …" excludes any unspecified elements, steps or components. If used in a claim, the phrase is intended to claim as closed, meaning that it does not contain materials other than those described, except for the conventional impurities associated therewith. When the phrase "consisting of …" appears in a clause of the subject matter of the claims rather than immediately after the subject matter, it defines only the elements described in the clause; other elements are not excluded from the claims as a whole.

When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", and the like. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.

The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. "optional" or "any" means that the subsequently described event or events may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

Approximating language, as used herein throughout the specification and claims, is intended to modify a quantity, such that the invention is not limited to the specific quantity, but includes portions that are literally received for modification without substantial change in the basic function to which the invention is related. Accordingly, the use of "about" to modify a numerical value means that the invention is not limited to the precise value. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. In the present description and claims, range limitations may be combined and/or interchanged, including all sub-ranges contained therein if not otherwise stated.

In addition, the indefinite articles "a" and "an" preceding an element or component of the invention are not intended to limit the number requirement (i.e., the number of occurrences) of the element or component. Thus, "a" or "an" should be read to include one or at least one, and the singular form of an element or component also includes the plural unless the stated number clearly indicates that the singular form is intended.

The present invention is described below by way of specific embodiments, but is not limited to the specific embodiments given below.

In order to solve the problems in the prior art, the first aspect of the invention provides a longan pretreatment liquid, which comprises, by weight, 0.01-0.2% of an organic acid, 0.001-0.1% of an inorganic salt, 0.01-0.5% of an organic solvent, 0.01-0.1% of a thickener, and the balance of water.

In some preferred embodiments, the longan pretreatment liquid comprises, by weight, 0.05 to 0.1% of an organic acid, 0.01 to 0.03% of an inorganic salt, 0.1 to 0.2% of an organic solvent, 0.02 to 0.05% of a thickener, and the balance of water.

From the viewpoint of improving the treatment efficiency of longan, in some preferred embodiments, the organic acid is selected from one or more of glacial acetic acid, formic acid, citric acid, tartaric acid, ascorbic acid, oxalic acid, malic acid, citric acid; further preferably, the organic acid is selected from one or more of glacial acetic acid, malic acid and citric acid; further, the organic acid is glacial acetic acid and/or citric acid.

From the viewpoint of balancing the treatment rate and the treatment quality, in some preferred embodiments, the inorganic salt is selected from a mixture of one or more of chloride, sulfate, carbonate, sulfite.

Examples of the chloride salt include sodium chloride, potassium chloride, calcium chloride, and magnesium chloride; examples of the sulfate include sodium sulfate, potassium sulfate, zinc sulfate, and the like; examples of the carbonate include sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, and the like; examples of the sulfite include sodium sulfite, potassium sulfite, and calcium sulfite.

In some preferred embodiments, the inorganic salt is selected from a mixture of one or more of sodium chloride, sodium carbonate, potassium carbonate; further preferably, the inorganic salt is sodium carbonate and/or potassium carbonate.

From the viewpoint of improving the uniformity of the pretreatment solution, in some preferred embodiments, the organic solvent is selected from a mixture of one or more of methanol, ethanol, acetone, and diethyl ether; further preferably, the organic solvent is methanol and/or ethanol; further, the organic solvent is ethanol.

From the viewpoint of stability and effectiveness of the pretreatment liquid, in some preferred embodiments, the thickener is selected from a mixture of one or more of xanthan gum, gum arabic, starch octenyl succinate, starch, gelatin.

As used herein, the term "whole single fruit" refers to a single longan fruit with longan pericarp. The method of measuring moisture content in the present invention may be any one known to those skilled in the art, for example, using a moisture content rapid tester.

The inventor finds that the structure of the longan shell can be changed by treating the longan with the pretreatment liquid, so that the surface of the longan shell is wrinkled, the permeability of the longan shell is increased, the diffusion speed of longan moisture is increased, the drying time of longan is shortened, and the color of the longan is kept at the same time.

Examples

The present invention will be specifically described below by way of examples. It should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and that the insubstantial modifications and adaptations of the present invention by those skilled in the art based on the above disclosure are still within the scope of the present invention.

Example 1

Example 1 provides a method for rapidly drying longan, comprising the steps of:

b. b, putting the longan obtained in the step a into a pretreatment solution at 60 ℃, soaking for 10min, taking out, airing and drying the surface water; the pretreatment solution comprises 0.02% of starch octenyl succinate, 0.2% of ethanol, 0.1% of glacial acetic acid, 0.02% of potassium carbonate and the balance of water in percentage by weight;

c. and c, drying the longan obtained in the step b at 70 ℃ for 5h, and then at 50 ℃ for 12 h.

Fig. 1 is an electron microscope scanning image of the dried longan shell obtained in example 1, which shows that the longan shell surface has wrinkles, the permeability of the longan shell is increased, the diffusion speed of the water of the longan is increased, the drying time of the longan is shortened, and the water content of the longan is measured to be less than or equal to 25%.

Example 2

Example 2 provides a method for rapidly drying longan, comprising the steps of:

b. b, putting the longan obtained in the step a into a pretreatment solution at 80 ℃, soaking for 5min, taking out, airing and drying the surface water; the pretreatment solution comprises 0.03 percent of octenyl succinic acid starch ester, 0.1 percent of ethanol, 0.2 percent of glacial acetic acid, 0.01 percent of potassium carbonate and the balance of water according to weight percentage;

c. and c, drying the longan obtained in the step b at 70 ℃ for 5h, and then drying at 50 ℃ for 15h to obtain the longan tea.

Example 2 has similar effects to example 1.

Example 3

Example 3 provides a method for rapidly drying longan, comprising the steps of:

b. b, putting the longan obtained in the step a into a pretreatment solution at 60 ℃, soaking for 10min, taking out, airing and drying the surface water; the pretreatment solution comprises 0.02 percent of starch octenyl succinate, 0.2 percent of ethanol, 0.1 percent of citric acid, 0.02 percent of potassium carbonate and the balance of water according to weight percentage;

Example 3 has similar effects to example 1.

Comparative example 1

Comparative example 1 provides a method for drying longan comprising the steps of:

b. and c, drying the longan obtained in the step a at 70 ℃ for 12h, and then at 50 ℃ for 18 h.

Fig. 2 is an electron microscope scanning image of dried longan shell obtained in comparative example 1, which shows that the surface of longan shell is flat, and it takes a long time to measure that the water content of longan is less than or equal to 25%.

Comparative example 2

Comparative example 2 provides a method for drying longan comprising the steps of:

b. b, putting the longan obtained in the step a into a pretreatment solution at 60 ℃, soaking for 10min, taking out, airing and drying the surface water; the pretreatment solution comprises 0.02% of starch octenyl succinate, 0.2% of ethanol, 0.02% of potassium carbonate and the balance of water by weight percentage;

c. and c, drying the longan obtained in the step b at 70 ℃ for 12h, and then at 50 ℃ for 18 h.

Fig. 4 is an electron microscope scanning image of dried longan shell obtained in comparative example 2, which shows that the surface of longan shell is flat, and it takes a long time to measure that the water content of longan is less than or equal to 25%.

Comparative example 3

Comparative example 3 provides a method for drying longan comprising the steps of:

b. b, putting the longan obtained in the step a into a pretreatment solution at 60 ℃, soaking for 10min, taking out, airing and drying the surface water; the pretreatment solution comprises 0.02 percent of starch octenyl succinate, 0.2 percent of ethanol, 0.1 percent of glacial acetic acid and the balance of water by weight percentage;

c. and c, drying the longan obtained in the step b at 70 ℃ for 10h, and then at 50 ℃ for 16h to obtain the longan tea.

Fig. 5 is an electron microscope scan of dried longan shell obtained in comparative example 3, which shows that a small amount of wrinkles appear on the surface of longan shell, and it takes a long time to measure that the water content of longan is less than or equal to 25%.

Comparative example 4

Comparative example 4 provides a method for drying longan comprising the steps of:

b. b, putting the longan obtained in the step a into a pretreatment solution at 60 ℃, soaking for 10min, taking out, airing and drying the surface water; the pretreatment solution comprises 0.02 percent of starch octenyl succinate, 0.2 percent of ethanol, 0.1 percent of citric acid and the balance of water according to weight percentage;

c. and c, drying the longan obtained in the step b at 70 ℃ for 10h, and then at 50 ℃ for 14 h.

Fig. 6 is an electron microscope scanning image of the dried longan shell obtained in comparative example 4, it can be observed that micropores appear on the surface of the longan shell, which is beneficial to increase permeability, but the inner arillus longan loses effective barrier and is easy to be polluted or oxidized, and the water content of the longan is measured to be less than or equal to 25% only after a long time.

According to the embodiments and the comparative examples, the longan shell structure is changed, the permeability of the longan shell is increased, the diffusion speed of longan moisture is increased, the longan drying time is shortened, and the method is performed at a lower temperature, so that a large amount of energy is saved.

The foregoing examples are merely illustrative and serve to explain some of the features of the method of the present invention. The appended claims are intended to claim as broad a scope as is contemplated, and the examples presented herein are merely illustrative of selected implementations in accordance with all possible combinations of examples. Accordingly, it is the intention of the inventors that the appended claims not be limited by the choice of examples illustrating the features of the invention. Also, where numerical ranges are used in the claims, subranges therein are included, and variations in these ranges are also to be construed as possible being covered by the appended claims.

Claims

1. The longan pretreatment liquid is characterized by comprising, by weight, 0.01-0.2% of organic acid, 0.001-0.1% of inorganic salt, 0.01-0.5% of organic solvent, 0.01-0.1% of thickening agent and the balance of water.

2. The longan pretreatment solution of claim 1, wherein the pretreatment solution comprises 0.05 to 0.1% by weight of an organic acid, 0.01 to 0.03% by weight of an inorganic salt, 0.1 to 0.2% by weight of an organic solvent, 0.02 to 0.05% by weight of a thickener, and the balance of water.

3. The longan pretreatment solution of claim 1 or 2, wherein the organic acid is one or more selected from the group consisting of glacial acetic acid, formic acid, citric acid, tartaric acid, ascorbic acid, oxalic acid, malic acid, and citric acid.

4. The longan pretreatment solution of claim 1 or 2, wherein the inorganic salt is selected from the group consisting of chloride, sulfate, carbonate, sulfite, and mixtures thereof.

5. The longan pretreatment solution of claim 4, wherein the chloride salt is selected from the group consisting of sodium chloride, potassium chloride, calcium chloride, and magnesium chloride.

6. The longan pretreatment solution of claim 4, wherein the carbonate is selected from the group consisting of sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, sodium bicarbonate and potassium bicarbonate.

7. The longan pretreatment solution of claim 4, wherein the sulfite is selected from the group consisting of sodium sulfite, potassium sulfite, and calcium sulfite.

8. The longan pretreatment solution of claim 1 or 2, wherein the organic solvent is one or more selected from the group consisting of methanol, ethanol, acetone, and ethyl ether.

9. The longan pretreatment solution of claim 1 or 2, wherein the thickener is one or more selected from the group consisting of xanthan gum, gum arabic, starch octenyl succinate, starch, and gelatin.

10. A method for rapidly drying longan is characterized by comprising the following steps:

b. b, putting the longan obtained in the step a into the pretreatment liquid of any one of claims 1 to 9 at the temperature of 60-80 ℃, soaking for 5-10 min, taking out and airing the longan to remove water on the surface;