Biological drying method for longan

Abstract

The invention discloses a biological drying method for longan, which comprises the following steps: soaking fresh longan in an ethanol water solution with the volume fraction of 30-90% for 2-8 hours, and then drying at 37 DEG C; the method provided by the invention can effectively reduce the moisture and sugar content of the dried longan, so that the dried longan can be enjoyed by people who are not suitable for high sugar, and customer groups of the dried longan are expanded to a certain extent.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a longan biological drying method. Background Art

[0002] Longan (Dimocarpus longan), a subtropical plant belonging to the genus Dimocarpus of the Sapindaceae family, is also known as Longyan, Yizhi and Longan. It has a sweet taste, a refreshing texture, a high sugar content, and has multiple effects such as anti-stress, anti-anxiety, anti-tumor and immune regulation. It is a fruit that is both medicinal and edible and is loved by everyone. Dried longan refers to dehydrated longan with a moisture content of less than 25%. Domestic and foreign research on longan drying mainly includes hot air, heat pump, microwave, vacuum freezing and their combined drying methods. However, some high-temperature treatments will damage the antioxidant activity in dried longan, and freeze-drying treatment has a high cost. Therefore, it is particularly important to develop a longan drying method that can improve the antioxidant capacity of dried longan and has a relatively low cost. Dried longan has a high sugar content, but high-sugar foods can cause obesity, and excessive intake of sugar by the human body will affect the secretion of insulin. Therefore, some people are not suitable for eating high-sugar dried longan, so it is necessary to develop a low-sugar dried longan. Summary of the invention

[0003] The present invention is aimed at the high sugar content of dried longan and the reduction of antioxidant activity after the drying process. It discloses a method for treating fresh longan with 70% ethanol solution and then drying it at room temperature to obtain dried longan, aiming to reduce the total sugar content of the dried longan to meet the needs of some customers due to preferences or physical reasons.

[0004] To achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0005] A biological drying method for longan comprises the following steps: soaking fresh longan in an ethanol aqueous solution and drying at room temperature to obtain the longan.

[0006] Preferably, the concentration of the ethanol aqueous solution is 30 to 90% by volume.

[0007] More preferably, the concentration of the ethanol aqueous solution is 70% by volume.

[0008] Preferably, the soaking time is 2 to 8 hours.

[0009] More preferably, the soaking time is 8 hours.

[0010] Preferably, the room temperature drying is drying in an oven at 37°C.

[0011] The present invention has the following beneficial effects: the method of the present invention can effectively reduce the glucose content of dried longan, which is conducive to the enjoyment of some people who are not suitable for high sugar, and to a certain extent expands the customer group of dried longan. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The total sugar content of dried longan obtained by treating fresh longan with ethanol solutions of different concentrations and then drying at room temperature.

[0013] Figure 2 The total sugar content of dried longan obtained by treating fresh longan with 70% ethanol solution for different lengths of time and then drying at room temperature. DETAILED DESCRIPTION

[0014] The following examples are provided to further illustrate the present invention, rather than to limit the present invention.

[0015] Example 1

[0016] First, the experiment set up CK (clean water), 30%, 50%, 70% and 90% ethanol aqueous solutions with five concentration gradients to soak fresh longan for 2 hours, and then placed it in a 37°C oven to dry. Take some of the fresh longan treated with clean water, place it in a 65°C oven to dry, and weigh it.

[0017] The ethanol concentration (70%, volume fraction) with the highest dehydration rate for fresh longan was screened out, and then the fresh longan was soaked in 70% ethanol for different soaking times and dried in an oven at 37°C to determine the total sugar content and dehydration efficiency of the longan pulp.

[0018] The total sugar content of longan pulp was determined using the Solebow total sugar content detection kit (Cat. No.: BC2710).

[0019] Figure 1 It shows the total sugar content of dried longan at room temperature after being treated with different ethanol concentrations. The total sugar content is the lowest when treated with 70% ethanol concentration.

[0020] Figure 2 It indicates the total sugar content in the dried longan pulp after being treated with 70% ethanol and dried at room temperature. After being treated with 70% ethanol for 8 hours, the total sugar content of dried longan is the lowest.

[0021] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for bio-drying longan, characterized in that: The following steps are involved: Soak fresh longan in ethanol-water solution and then dry at room temperature to obtain the product.

2. The method for bio-drying longan according to claim 1, characterized in that: The concentration of the ethanol aqueous solution is 30 to 90% by volume.

3. The method for bio-drying longan according to claim 2, characterized in that: The concentration of the ethanol aqueous solution is 70% by volume.

4. The method for bio-drying longan according to claim 1, characterized in that: The soaking time is 2 to 8 hours.

5. The method for bio-drying longan according to claim 4, characterized in that: The soaking time is 8 hours.

6. The method for bio-drying longan according to claim 1, characterized in that: The room temperature drying is drying in a 37°C oven.

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