Storage and fresh-keeping method for potatoes

Abstract

The invention discloses a postharvest potato storage and fresh-keeping method, which belongs to the technical field of agricultural product storage and fresh-keeping, and comprises the following steps: delaying low-temperature saccharification treatment, healing, drying and storage. After potatoes are harvested, tubers are soaked in a salicylic acid solution, callus is performed after blow-drying, and finally the tubers are stored at low temperature. By adopting a chemical method, water loss of potatoes is effectively maintained, degradation of starch is relieved, and synthesis of cane sugar and soluble sugar is inhibited, so that the method can be used for post-harvest treatment, storage and preservation of potato tubers, the shelf life of the tubers is prolonged, low-temperature saccharification is relieved, and the economic value of the potatoes is improved; salicylic acid is a micromolecular phenolic compound, has no toxic or side effect, and is expected to become an excellent potato storage and preservation method to delay the low-temperature saccharification phenomenon.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural product storage and preservation. Background Art

[0002] In order to ensure the supply cycle of potato raw materials and reduce the germination rate, water loss rate and disease infection of tubers, potatoes are usually stored at a low temperature of 4°C after harvest. However, low-temperature storage will affect the production of a large amount of reducing sugars in tuber cells, which is the cold-induced sweetening (CIS) phenomenon, which is a self-protection phenomenon of plants under low temperature stress. CIS has a very serious impact on the potato processing industry. During storage, reducing sugars accumulate in large quantities. After high-temperature frying, Maillard reaction occurs, and a large amount of reducing sugars and free amino acids generate black bitter substances and acrylamide. Studies have shown that the more reducing sugars there are, the more likely acrylamide is produced during frying, and the content of acrylamide is positively correlated with the color of the fried food, which seriously affects the processing quality of the product. What is more serious is that acrylamide is a potential neurotoxin and carcinogen, which will affect the health of consumers. Therefore, the food safety problems caused by CIS and the yield loss caused by potato germination have posed huge challenges to the potato processing industry. Summary of the invention

[0003] The purpose of the present invention is to solve the existing potato saccharification problem during low-temperature storage and disclose a potato storage and preservation method. The specific steps are as follows:

[0004] After the potato tubers are harvested, the temperature is balanced at room temperature, the mud on the surface of the potatoes is cleaned, and the tubers are soaked in a salicylic acid solution with a concentration of 2-8 mmol / L for 10-20 minutes. After being dried with a large fan, they are packed in boxes and stored at room temperature for 7-14 days for healing. The healing is completed when wound tissue is formed, and they are stored at low temperature after the healing is completed.

[0005] Preferably, the room temperature is placed at 22°C, the room temperature healing is 22°C, and the low temperature storage is 4°C.

[0006] Preferably, the room temperature placement time is 2-3 hours and the healing time is 7 days.

[0007] Preferably, the concentration of the salicylic acid solution is 4 mmol / L, and the soaking time is 15 minutes.

[0008] The beneficial effects of the present invention are as follows: salicylic acid is found to be able to effectively maintain potato water loss, alleviate starch degradation and inhibit sucrose and soluble sugar synthesis, and therefore can be used for post-harvest processing, storage and preservation of potatoes, prolonging the shelf life of potatoes, thereby improving the economic value of fried potato chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a schematic diagram showing the effect of salicylic acid on the weight loss rate of potatoes after harvest.

[0010] Figure 2 This is a schematic diagram showing the effect of salicylic acid on the soluble sugar content of potatoes during postharvest storage.

[0011] Figure 3 This is a schematic diagram showing the effect of salicylic acid on the sucrose content of potatoes during postharvest storage.

[0012] Figure 4 This is a schematic diagram showing the effect of salicylic acid on the starch content of potatoes during postharvest storage.

[0013] Figure 5 Schematic diagram of the effect of salicylic acid treatment on the color of fried potato chips after low-temperature storage. DETAILED DESCRIPTION

[0014] The present invention is described in detail below in conjunction with the accompanying drawings. The present invention and its implementation methods are described below, and this description is not restrictive, and the actual implementation methods are not limited to this. In short, if a person of ordinary skill in the art is inspired by it, without departing from the purpose of the invention, a structural method and an embodiment similar to the technical solution without creativity should belong to the protection scope of the present invention.

[0015] Implementation Cases:

[0016] 1. Materials and Methods

[0017] 1.1 Experimental materials and treatment

[0018] After the "Atlantic" potato tubers were transported back to the laboratory, they were stored at low temperature for 10 days and then placed at room temperature for wound healing. Tubers of uniform size, without disease or insect eyes, without germination, and with smooth surfaces were selected and randomly divided into three groups. The surface of the potato tubers was rinsed with tap water, disinfected with 1% sodium hypochlorite for 3 minutes, and then soaked in 4 mmol / L SA for 15 minutes. After drying, they were stored in a warehouse at 4°C. On the 0th, 3rd, 10th, 30th, and 60th days, the skin was peeled and then samples were taken and related indicators were measured.

[0019] 1.2 Experimental Materials and Instruments

[0020] Experimental materials: salicylic acid, sodium hypochlorite, anthrone reagent, perchloric acid, KOH.

[0021] Experimental instruments: electronic balance, water bath, colorimeter, centrifuge, test tube, volumetric flask, constant temperature fryer.

[0022] 2. Measurement indicators and methods

[0023] 2.1 Determination of weight loss rate

[0024] At the sampling point, each group of treatment samples were taken out from the 4°C storage, weighed, and the values ​​were recorded.

[0025] Weight loss rate (%) = (m0-m) / m0×100

[0026] Where m0: initial weight on the first day; m: potato weight at each sampling point in the control and treatment groups.

[0027] 2.2 Determination of sugar and starch content

[0028] The starch, soluble sugar and sucrose contents were determined by anthrone colorimetry. Take 0.01 g of freeze-dried sample and place it in a test tube, add 5 mL of 80% ethanol, and heat it in a water bath at 80°C for 20 minutes. After cooling, centrifuge at 4000 r / min for 10 minutes, take the supernatant and place it in a 50 mL volumetric flask, and extract it twice in the same way. Combine the supernatants and use them in a 50 mL volumetric flask, dilute to the mark, shake well, and measure the sugar content.

[0029] Determination of soluble sugar: Accurately pipette 100 μL of supernatant into a test tube, add 3 ml of anthrone reagent, boil in a boiling water bath for 10 min, cool and measure the absorbance at 620 nm.

[0030] Determination of sucrose: Accurately pipette 100 μL of supernatant into a test tube, add 0.1 mL of 30% KOH, place in a boiling water bath for 10 min, cool to room temperature, add 3 mL of anthrone reagent, place in a boiling water bath for 10 min, and measure the absorbance at 620 nm after cooling.

[0031] The precipitate is used to measure the starch content. After adding 4 mL of water to the precipitate, add 2 ml of 9.2 N perchloric acid, boil in a boiling water bath for 20 minutes, take out and cool, centrifuge at 4000 r / min for 10 minutes, transfer the supernatant to a 50 mL volumetric flask, add 5 mL of water to the precipitate, add 1 mL of 9.2 N perchloric acid, extract in a boiling water bath for 20 minutes, take out and cool, centrifuge at 4000 r / min for 10 minutes, transfer the supernatant to a 50 mL volumetric flask, wash with water twice, make up to volume, and shake well. Determination of starch content: Accurately pipette 100 μL of supernatant into a test tube, add 3 mL of anthrone reagent, boil in a boiling water bath for 10 minutes, cool and measure the absorbance at 620 nm.

[0032] 2.3 Frying experiment

[0033] On the 10th day of storage, the potatoes were taken out, peeled and cut into uniform slices of 4-5 mm thickness. The water stains on the surface were gently wiped off with a clean paper towel, and the slices were quickly fried in a constant temperature fryer at 180°C. After 2 minutes, the slices were quickly taken out and the excess oil was drained. The color was measured with a DIGIEYE colorimeter, and the L* value, a* value and b* value were read and photographed for record.

[0034] 3. Results and Analysis

[0035] 3.1 Changes in potato weight loss rate

[0036] As storage time increases, Figure 1 As mentioned above, the weight loss rate of potato tubers showed a continuous upward trend. During storage at 4°C, there was no significant difference in the weight loss rate of potato tubers between the control group and the SA treatment. Studies have shown that salicylic acid is beneficial for peaches to maintain a lower weight loss rate and better quality during low-temperature storage. The results show that salicylic acid treatment can maintain the water loss of potatoes during low-temperature storage, and thus maintain the quality of potatoes during storage.

[0037] 3.2 Changes in sugar and starch content of potatoes

[0038] The sugar content of tubers stored at 4°C was measured, and the soluble sugar and sucrose content of the tubers continued to increase ( Figure 2 , Figure 3 ), the soluble sugar and sucrose content of potatoes in the control group was significantly higher than that in the SA treatment group. The starch content decreased significantly, and the starch degradation rate of potatoes treated with salicylic acid was significantly slower than that of the control group on the 10th day ( Figure 4 ).

[0039] The above results show that salicylic acid treatment can effectively inhibit the accumulation of sugar content, and salicylic acid storage at 4°C inhibits the synthesis and decomposition of sucrose and the degradation of starch. It is speculated that salicylic acid treatment can slow down the occurrence of low-temperature saccharification of potatoes.

[0040] 4. Conclusion

[0041] During low-temperature storage, the weight loss rate of potatoes increases, the starch content decreases rapidly, the sugar content gradually accumulates, and the browning is serious after frying. Salicylic acid treatment can effectively maintain the weight loss rate, alleviate starch degradation, inhibit the accumulation of sugar content, and alleviate the browning of potato chips after frying, thereby extending the low-temperature storage time of potatoes and improving the economic value of fried potato chips.

Claims

1. A method for storing and preserving potatoes, characterized in that: After the potato tubers are harvested, the temperature is balanced at room temperature, the mud on the surface of the potatoes is cleaned, and the tubers are soaked in a salicylic acid solution with a concentration of 2-8 mmol / L for 10-20 minutes. After being dried with a large fan, they are packed in boxes and stored at room temperature for 7-14 days for healing. The healing is completed when wound tissue is formed, and they are stored at low temperature after the healing is completed.

2. The method according to claim 1, characterized in that: The room temperature for placement is 22°C, the room temperature for healing is 22°C, and the low temperature storage is 4°C.

3. The method according to claim 2, characterized in that: The time of standing at room temperature is 2-3 hours, and the healing time is 7 days.

4. The method according to claim 1, characterized in that: The concentration of the salicylic acid solution is 4 mmol / L, and the soaking time is 15 minutes.

5. The method according to claim 1, characterized in that: The potato variety in question was Atlantic.

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