A preservation method for peeled garlic

Abstract

The present application provides a preservation method for peeled garlic, in which a solution containing garlic polysaccharide is used to coat or spray the peeled garlic; the method of the present application can effectively improve the preservation performance of peeled garlic without affecting the product flavor.

Description

Technical Field

[0001] This application belongs to the field of agricultural product preservation. Specifically, this application provides a preservation method for peeled garlic. Background Art

[0002] Garlic has a long history of cultivation, consumption, and medicinal use. Under the protection of the garlic skin and the antibacterial components in garlic, garlic has good storage performance by itself.

[0003] Currently, for the convenience of consumption or processing, the market demand for peeled garlic is increasing. However, after garlic loses the protection of the garlic skin, it is more vulnerable to external factors such as temperature, humidity, and oxygen, resulting in a decline in its performance such as water retention and color retention.

[0004] Garlic polysaccharide has multiple edible, health-care, and medicinal uses. However, due to the presence of flavor components such as allicin in crude garlic polysaccharide, it is not suitable for the preservation of general foods. Summary of the Invention

[0005] The applicant attempts to use garlic polysaccharide for the film preservation of peeled garlic, avoiding the problem that crude garlic polysaccharide affects the flavor of preserved products, and at the same time providing good preservation effects in terms of moisture, color, and growth.

[0006] On the one hand, this application provides a preservation method for peeled garlic, in which a solution containing garlic polysaccharide is used to coat or spray the peeled garlic.

[0007] Further, in the method, a solution containing garlic polysaccharide is used to coat the peeled garlic.

[0008] Further, the solution containing garlic polysaccharide contains 3 - 8 g / L of garlic polysaccharide and optionally 5 - 10 g / L of chitosan.

[0009] Further, the extraction method of the garlic polysaccharide is as follows:

[0010] Peel the garlic and chop it into garlic pieces; freeze-dry and powder the garlic pieces to make garlic freeze-dried powder; add 100 g of the garlic freeze-dried powder to 1 - 2 L of water, and under an ultrasonic power of 100 - 200 W, perform ultrasonic-assisted extraction for 30 - 60 minutes; filter to obtain the filtrate; concentrate the filtrate to one-half to one-fifth of the volume; add 90 - 95% edible ethanol, which is 2 - 4 times the volume of the concentrated filtrate, and let it stand and precipitate at 4 - 8°C for 12 - 24 hours; filter to obtain the precipitate, and after freeze-drying, obtain garlic polysaccharide.

[0011] Further, the garlic polysaccharide is garlic polysaccharide modified by inulinase or xylanase.

[0012] Further, the preparation method of the inulinase- or xylanase-modified garlic polysaccharide is as follows:

[0013] Prepare an aqueous solution of garlic polysaccharide at 30 - 60 g / L; add 500 - 100 U / mL of inulinase or xylanase to the garlic polysaccharide solution, adjust the pH to 6 - 7; carry out enzymatic hydrolysis at 45 - 60 °C for 1 - 4 hours; inactivate the enzyme; concentrate and then freeze-dry to obtain the inulinase- or xylanase-modified garlic polysaccharide.

[0014] Further, the preparation method of the inulinase- or xylanase-modified garlic polysaccharide is as follows:

[0015] Prepare an aqueous solution of garlic polysaccharide at 50 g / L; add 800 U / mL of inulinase or xylanase to the garlic polysaccharide solution, adjust the pH to 6.5; carry out enzymatic hydrolysis at 50 °C for 2 hours; inactivate the enzyme; concentrate and then freeze-dry to obtain the inulinase- or xylanase-modified garlic polysaccharide.

[0016] Further, the method includes the steps of low-temperature and / or modified atmosphere storage after coating.

[0017] Further, the storage temperature is 4 - 25 °C.

[0018] Further, the storage humidity is 30 - 60%.

[0019] The preservation method of the present application can be used for various garlic varieties, including but not limited to Cangshan garlic, Soviet garlic, soft-leaf garlic, Puning garlic, etc.

[0020] The present application uses garlic polysaccharide or modified garlic polysaccharide as a coating component for garlic preservation, which can effectively improve the preservation performance of peeled garlic without affecting the product flavor. The concept is novel and the practical effect is good. Description of the Drawings

[0021] Figure 1 : Effects of different coating agents on the change in moisture content of peeled garlic;

[0022] Figure 2 : Effects of different coating agents on the change in color of peeled garlic;

[0023] Figure 3 : Effects of different coating agents on the change in the proportion of bud petals of peeled garlic;

[0024] Figure 4 : Effects of the enzyme-modified garlic polysaccharide coating agent on the change in color of peeled garlic;

[0025] Figure 5 : Effects of the enzyme-modified garlic polysaccharide coating agent on the change in the proportion of bud petals of peeled garlic. Detailed Embodiments

[0026] Example 1 Experimental Materials

[0027] Garlic:

[0028] Use Cangshan garlic harvested during the same period from the same planting enterprise in Shandong. Manually select garlic without mechanical damage, pest damage, and with similar size and maturity as experimental materials, and peel them manually.

[0029] Garlic polysaccharide:

[0030] During the experimental stage, use self-made products. The extraction method is as follows: Microwave-inactivate the enzymes of garlic, peel it, and chop it into garlic pieces; Freeze-dry the garlic pieces and powder them into freeze-dried garlic powder; Add 100 g of freeze-dried garlic powder to 1.5 L of water, and under an ultrasonic power of 150 W, perform ultrasonic-assisted extraction for 30 minutes; Filter to obtain the filtrate; Concentrate the filtrate to one-third of its volume; Add 95% edible ethanol three times the volume of the concentrated filtrate, and let it stand and precipitate at 4°C for 12 hours; Filter to obtain the precipitate, and after freeze-drying, it is garlic polysaccharide. The yield is 26 - 28%, the polysaccharide content measured by the sulfuric acid-phenol method is 62 - 65%, and the protein content is 2 - 3%. Later, use the garlic polysaccharide from Shandong Xinhuasheng Biotechnology Co., Ltd. for verification (the manufacturer claims that it is water-extracted and ethanol-precipitated polysaccharide with a content of 70%).

[0031] Index and detection method of Example 2

[0032] Storage conditions and sampling:

[0033] Store at 8°C, in a natural atmosphere, with a humidity of 40% (without packaging); At each time point, sample 15 garlic cloves, measure the water content and color, and then take the average value. Another 10 garlic cloves are sampled to measure the proportion of sprouted cloves and take the average value (in all experiments, the selected undamaged garlic cloves have never shown signs of rotting).

[0034] Water content:

[0035] Weigh the fresh weight of peeled garlic and place it in an oven; Dry it at 80°C until it reaches a constant weight; After cooling, accurately weigh the dry weight:

[0036] Water content % = (fresh weight - dry weight) / fresh weight × 100%.

[0037] Color:

[0038] Use a 3nh handheld colorimeter (NR60CP+) to detect the lightness value L in the Lab color system.

[0039] Proportion of sprouted cloves:

[0040] Measure the length of the garlic clove and then cut it open to measure the length of the inner sprout:

[0041] Proportion of sprouted cloves % = inner sprout length / garlic clove length × 100%.

[0042] Antioxidant property

[0043] Measure the ABTS free radical scavenging rate of a 10 g / L polysaccharide solution by the ATBS method: Take ammonium ABTS and prepare a 10 mmol / L distilled water solution; take potassium persulfate and prepare a 2 mol / L distilled water solution; mix the two solutions in equal volumes and place them in the dark at room temperature for 12 hours to obtain the ABTS working solution; dilute the working solution with distilled water after use (absorbance at 734 nm is 0.7 - 0.8); fully mix the sample solution to be measured (or distilled water control) with the diluted working solution (or distilled water blank) and let it stand for 5 minutes, and record the absorbance at 734 nm:

[0044] ABTS free radical scavenging rate % = [1 - (A_sample - A_blank) / A_control] × 100%.

[0045] Example 3: Use of garlic polysaccharide for fresh-keeping of peeled garlic

[0046] In addition to polysaccharides, the crude extract of garlic polysaccharide also contains a large amount of garlic flavor substances. Its obvious smell and taste make it not suitable for the fresh-keeping of most agricultural products. However, when used for peeled garlic, these smells and tastes are no longer a problem. The applicant tried to use garlic polysaccharide as a coating agent for the fresh-keeping of peeled garlic. The coating agents used include:

[0047] Dissolve chitosan (100 kDa, deacetylation degree 90%) in a 1% w / w acetic acid solution to prepare a 5 g / L coating solution 1

[0048] Dissolve sodium carboxymethyl cellulose (FH6) in water to prepare a 5 g / L coating solution 2

[0049] Dissolve the garlic polysaccharide of Example 1 in water to prepare a 5 g / L coating solution 3

[0050] Immerse the peeled garlic in the coating solution for 3 minutes and then take it out. Let it dry; use uncoated peeled garlic as a control.

[0051] The changes in water content, color, and bud petal ratio are as Figures 1 - 3 shown. The results show that compared with the control and other coating solutions, the garlic polysaccharide coating can slow down the changes in color and bud petal ratio to a certain extent. However, due to its film-forming performance not being comparable to that of chitosan, etc., its performance in inhibiting the decrease in water content is significantly insufficient.

[0052] Example 4: Modification of garlic polysaccharide

[0053] The applicant tried to modify garlic polysaccharide with a variety of food enzymes, with antioxidant properties as the main consideration index (in principle, further enzymatic hydrolysis of polysaccharides will not help with film-forming properties):

[0054] The enzymes used include: cellulase, pectinase, inulinase, α-amylase, cellobiase, dextranase, xylanase (all domestic, food grade).

[0055] The enzyme treatment method is as follows: Prepare an aqueous solution of garlic polysaccharide at 50 g / L; add 800 U / mL of enzyme to the garlic polysaccharide solution, adjust the pH to 6.5; enzymatically hydrolyze at 50 °C for 2 hours; inactivate the enzyme at 90 °C for 5 minutes; concentrate and then lyophilize to obtain enzyme-modified garlic polysaccharide.

[0056] The results are shown in Table 2. Enzyme modification with pectinase, inulinase, and xylanase can effectively improve the antioxidant performance of garlic polysaccharide.

[0057] Table 2 Antioxidant properties of enzyme-modified garlic polysaccharide

[0058]

[0059]

[0060] Example 5 Preparation of a coating agent using the modified polysaccharide

[0061] Prepare the following coating agents:

[0062] Coating agent 4: 5 g / L of the pectinase-modified garlic polysaccharide of Example 4;

[0063] Coating agent 5: 5 g / L of the inulinase-modified garlic polysaccharide of Example 4;

[0064] Coating agent 6: 5 g / L of the xylanase-modified garlic polysaccharide of Example 4.

[0065] The effects of the three coating agents on color change and bud scale ratio are as Figure 4 and Figure 5 shown. The results indicate that compared with coating solution 3 (unmodified garlic polysaccharide), coating solutions 4 - 6 can further stabilize the change in L value; while coating solutions 5 and 6 can further delay bud development, and buds only start to develop after 90 days, while coating solution 4 has no such effect. Therefore, the applicant predicts that enzymatic hydrolysis with xylanase and inulinase further releases certain compounds that inhibit bud formation or certain small molecular weight sugars / glycans produced have an inhibitory effect in this regard.

[0066] The applicant further incorporated 5 g / L of inulinase-modified garlic polysaccharide / xylanase-modified garlic polysaccharide into coating solution 1, obtaining a coating solution with similar color retention and bud scale ratio retention effects as coating solutions 5 and 6. At the same time, its water retention function was also ensured, and the water content remained above 60% after 90 days.

[0067] The applicant conducted preservation and enzymatic modification experiments using the commercially available garlic polysaccharide described in Example 1, and the effects were similar to those of self-made garlic polysaccharide.

Claims

1. A preservation method for peeled garlic, characterized in that, In the method, a solution containing inulinase- or xylanase-modified garlic polysaccharide is used to coat peeled garlic; the solution containing inulinase- or xylanase-modified garlic polysaccharide contains 3 - 8 g / L of inulinase- or xylanase-modified garlic polysaccharide; The preparation method of the inulinase- or xylanase-modified garlic polysaccharide is as follows: Prepare an aqueous solution of garlic polysaccharide at 30 - 60 g / L; add 500 - 100 U / mL of inulinase or xylanase to the garlic polysaccharide solution, adjust the pH to 6 - 7; at 45 - 60 °C, enzymatically hydrolyze for 1 - 4 hours; inactivate the enzyme; concentrate and then freeze-dry to obtain inulinase- or xylanase-modified garlic polysaccharide.

2. The method according to claim 1, wherein the extraction method of the garlic polysaccharide is: Peel and chop garlic into garlic pieces; freeze-dry and powder the garlic pieces to obtain garlic freeze-dried powder; add 100 g of the garlic freeze-dried powder to 1 - 2 L of water, and under an ultrasonic power of 100 - 200 W, perform ultrasonic-assisted extraction for 30 - 60 minutes; filter to obtain the filtrate; concentrate the filtrate to one-half to one-fifth of the volume; add 90 - 95% edible ethanol, which is 2 - 4 times the volume of the concentrated filtrate, and let it stand for precipitation at 4 - 8 °C for 12 - 24 hours; filter to obtain the precipitate, and after freeze-drying, obtain garlic polysaccharide.

3. The method according to claim 1, wherein the preparation method of the inulinase- or xylanase-modified garlic polysaccharide is: Prepare an aqueous solution of garlic polysaccharide at 50 g / L; add 800 U / mL of inulinase or xylanase to the garlic polysaccharide solution, adjust the pH to 6.5; at 50 °C, enzymatically hydrolyze for 2 hours; inactivate the enzyme; concentrate and then freeze-dry to obtain inulinase- or xylanase-modified garlic polysaccharide.

4. The method according to claim 1, wherein the method includes the steps of low-temperature and / or modified atmosphere storage after coating.

5. The method according to claim 4, wherein the storage temperature is 4 - 25 °C.

6. The method according to claim 4, wherein the storage humidity is 30 - 60%.

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