Fig crisp fruit rich in probiotics and preparation method thereof

Abstract

The invention provides fig crisps rich in probiotics and a preparation method of the fig crisps. The preparation method comprises the following steps: cleaning and cutting figs, rapidly infiltrating lactobacillus plantarum into fig pulp by adopting an ultrasonic-assisted impregnation method, carrying out a micro-fermentation process, reducing the sugar-acid ratio of the figs by utilizing the characteristic that sugar generates lactic acid through lactobacillus plantarum metabolism, and finally carrying out vacuum microwave freeze-drying until the moisture content is 5-7%. The ratio of sugar to acid is 30.62-41.5, the number of probiotics is greater than 1 * 10 < 8 > CFU / g, and the fig crisp fruit product has a remarkable probiotic effect.

Description

Technical Field

[0001] The invention belongs to the field of agricultural product processing, and particularly relates to a fig crisp rich in probiotics and a preparation method thereof. Background Art

[0002] Figs are rich in active polysaccharides, vitamin A, vitamin C and other physiological functional substances, as well as minerals such as potassium, calcium and magnesium. They can resist oxidation, promote collagen synthesis, clear away heat and promote body fluid, strengthen the spleen and stimulate appetite, detoxify and reduce swelling, and maintain bone strength and heart health. Figs also contain dietary fiber, which can promote intestinal peristalsis, help defecation, and prevent constipation. They have high nutritional and health effects.

[0003] Figs have a relatively high sugar content. For diabetic patients, excessive consumption may cause large fluctuations in blood sugar, which is not conducive to blood sugar control. At the same time, fresh figs are not resistant to storage. When they are put on the market in summer, they are easy to rot and deteriorate, causing great economic losses to fig farmers and seriously restricting the development of the fig industry.

[0004] At present, the fig preservation and processing technology is backward, and the traditional process generally uses salting, sugaring, natural drying or hot air drying to process figs. For example, the patent "Preparation Method of Dried Figs" with the publication number CN10348627A published on January 1, 2014 uses a drying method to prepare dried figs, and its product loses the flavor of figs to a great extent and has huge nutritional losses. Modern technology uses vacuum freezing to process dried figs, and its product quality is significantly higher than that of hot air drying products, but because the processing technology has high requirements for equipment, long time and high energy consumption, and the product has a higher sugar content after dehydration, it affects the promotion and application of the product. Summary of the invention

[0005] The present invention aims at the deficiencies in the prior art and provides a fig crisp rich in probiotics and a preparation method thereof, which can not only enrich the product with probiotics, but also retain the nutrients and functional substances in the raw materials to the maximum extent and significantly reduce the sugar content of the fig crisp product. The product has a crisp taste, is sweet and sour, and has great market promotion prospects.

[0006] In order to achieve the purpose of the present invention, the specific technical solutions adopted are as follows:

[0007] 1. A method for preparing a fig crisp rich in probiotics, characterized in that the method comprises the following steps:

[0008] 1) Cut the figs into 2 to 4 equal parts, add them into the prepared Lactobacillus plantarum liquid, and perform ultrasonic pretreatment;

[0009] 2) placing the figs pretreated by ultrasound in step 1) in an incubator at 20° C. for micro-fermentation;

[0010] 3) placing the processed figs in step 2) into a quick-freezer for quick freezing;

[0011] 4) The quick-frozen figs in step 3) are placed in a vacuum microwave freeze dryer and freeze-dried until the moisture content is 5%-7%, thereby obtaining fig crisps rich in probiotics.

[0012] Preferably, in step 1), the concentration of the Lactobacillus plantarum solution is 1×10 10 CFU / g.

[0013] Preferably, the ultrasonic pretreatment conditions in step 1) are: ultrasonic power is 100W-150W, ultrasonic time is 10-15min, and the material-liquid ratio is 1:1.

[0014] Preferably, the micro-fermentation time of the figs in step 2) is 8 to 20 hours.

[0015] Preferably, the fig quick-freezing time in step 3) is 6 hours.

[0016] Preferably, the vacuum microwave freeze-drying conditions in step 4) are: cold trap temperature is -35°C, microwave power is 2KW, vacuum degree is lower than 200Pa, and loading capacity is 1-2kg.

[0017] The fig crisps rich in probiotics prepared by the present invention have a live bacteria count greater than 1×10 8 The CFU / g and sugar-acid ratio ranged from 30.62 to 41.5.

[0018] In the step 1) of the present invention, when determining the impregnation method, three methods of normal pressure impregnation, vacuum impregnation and ultrasonic impregnation are used for comparison. By comparing and analyzing the effects of the impregnation methods on the fig crisp and the number of viable probiotics contained in the gastrointestinal tract after digestion, it is finally determined that the ultrasonic impregnation method is the best lactic acid bacteria liquid impregnation method. The test results are shown in the attached Figure 1 , attached Figure 2 .

[0019] By the attached Figure 1 It can be seen that after ultrasound-assisted impregnation with probiotics, the bacterial content of the impregnated fig crisps before and after drying was significantly higher than that of the normal pressure impregnation and vacuum impregnation treatment groups (P < 0.05). This is because ultrasound can accelerate molecular movement, greatly increasing the diffusion rate of Lactobacillus plantarum in the bacterial solution, and the bacteria quickly diffuse into the fig tissue, thereby increasing its probiotic content. Figure 2 It can be seen that the probiotic content of the fig crisps of the present invention after being digested by simulated gastrointestinal fluid is significantly higher than that of the fig crisps prepared by the other two impregnation methods (P<0.05). Therefore, the ultrasonic impregnation method is the best lactic acid bacteria liquid impregnation method.

[0020] In the step 1) and the step 2) of the present invention, when determining the ultrasonic impregnation process and the micro-fermentation time, the ultrasonic power (A), the ultrasonic time (B), and the micro-fermentation time (C) are used as experimental factors, and the number of viable Lactobacillus plantarum is used as an indicator. On the basis of a single factor experiment, an orthogonal experiment is used to optimize and determine the optimal process conditions. The test results are shown in Table 1.

[0021] As shown in Table 1, under the conditions of the set factor levels, the number of viable probiotics in the prepared fig crisps was 8.37-8.85 lg (CFU / g); the main factors affecting the number of probiotics were ultrasound time and fermentation time, and the influence of the three factors on the probiotic content of fig crisps was C>B>A. The optimal preparation process parameters of fig crisps were: ultrasound time of 12 min, ultrasound power of 100 W, and fermentation time of 20 h. Under these conditions, the number of probiotics in the prepared fig crisps was as high as 8.92 lg (CFU / g).

[0022] Table 1 Orthogonal experimental design and results

[0023]

[0024]

[0025] Beneficial effects:

[0026] 1. The present invention adopts an ultrasonic impregnation method to impregnate figs, and utilizes the cavitation effect of ultrasonic waves to accelerate molecular motion, thereby increasing the diffusion speed of plant lactobacillus, and allowing it to attach to and enter the fig pulp more quickly. The number of viable probiotic bacteria in the terminal product is significantly higher than that in the normal pressure impregnation and vacuum impregnation methods, and the health effect of the crisp fig fruit is significantly improved.

[0027] 2. The present invention adopts micro-fermentation technology to prepare fig crisps, and reduces the sugar-acid ratio of figs through the property of plant lactobacillus to metabolize sugars and produce lactic acid, thereby significantly improving the taste and flavor of fig crisps. The product has a crisp taste, is sweet and sour, is easy to store, and has huge market development potential.

[0028] 3. The present invention adopts vacuum microwave freeze-drying to prepare crispy figs, and the drying time is shorter than the traditional freeze-drying time, which significantly reduces energy consumption and production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Effects of three soaking methods on the number of Lactobacillus plantarum in figs before and after drying

[0030] Figure 2 Effects of three soaking methods on the number of viable bacteria in fig crisps after digestion in simulated gastrointestinal fluid DETAILED DESCRIPTION

[0031] The following is a detailed description of the embodiments of the present invention. It should be noted that the embodiments are descriptive and not restrictive, and the protection scope of the present invention cannot be limited by them. Unless otherwise specified, all detection techniques and methods in the following embodiments are conventional methods; the test materials used in the following embodiments are conventional chemical reagents and biochemical reagents.

[0032] Example 1

[0033] A method for preparing probiotic-rich fig crisps comprises the following steps:

[0034] Cut the figs into two equal parts and add the pre-prepared Lactobacillus plantarum at a concentration of 1×10 10 CFU / g of bacterial solution, the mass volume ratio of figs to bacterial solution is 1:1, then placed in an ultrasonic device, treated at an ultrasonic power of 100W for 10 minutes, and then placed in a 20℃ incubator for micro-fermentation for 12 hours. After the fermentation is completed, the figs are taken out and placed in a quick freezer for quick freezing for 6 hours; after quick freezing, they are placed in a vacuum microwave freeze dryer for drying. The drying conditions are: cold trap temperature is -35℃, microwave power is 2KW, vacuum degree is less than 200Pa, and loading capacity is 1-2kg.

[0035] The fig prepared in this embodiment has a crisp sugar-acid ratio of 41.2 and a probiotic count of 8.02 lg (CFU / g).

[0036] Example 2

[0037] A method for preparing probiotic-rich fig crisps comprises the following steps:

[0038] Cut the figs into 4 equal parts and add the pre-prepared Lactobacillus plantarum at a concentration of 1×10 10 CFU / g of bacterial solution, the mass volume ratio of figs to bacterial solution is 1:1, then placed in an ultrasonic device, treated at an ultrasonic power of 120W for 10min, and then placed in a 20℃ incubator for micro-fermentation for 16h. After the fermentation is completed, the figs are taken out and placed in a quick freezer for quick freezing for 6h; after quick freezing, they are placed in a vacuum microwave freeze dryer for drying. The drying conditions are: cold trap temperature is -35℃, microwave power is 2KW, vacuum degree is less than 200Pa, and loading capacity is 1-2kg.

[0039] The fig prepared in this example has a crisp sugar-acid ratio of 35.13 and a probiotic count of 8.211 g (CFU / g).

[0040] Example 3

[0041] A method for preparing probiotic-rich fig crisps comprises the following steps:

[0042] Cut the figs into 4 equal parts and add the pre-prepared Lactobacillus plantarum at a concentration of 1×1010 CFU / g of bacterial solution, the mass volume ratio of figs to bacterial solution is 1:1, then placed in an ultrasonic device, treated at an ultrasonic power of 150W for 15min, and then placed in a 20℃ incubator for micro-fermentation for 20h. After the fermentation is completed, the figs are taken out and placed in a quick freezer for quick freezing for 6h; after quick freezing, they are placed in a vacuum microwave freeze dryer for drying. The drying conditions are: cold trap temperature is -35℃, microwave power is 2KW, vacuum degree is less than 200Pa, and loading capacity is 1-2kg.

[0043] The fig prepared in this example has a crisp sugar-acid ratio of 30.62 and a probiotic count of 8.85 lg (CFU / g).

[0044] The effects of the present invention are further illustrated by some experiments below.

[0045] Comparative Example 1

[0046] A method for preparing probiotic-rich fig crisps comprises the following steps:

[0047] Cut the figs into 4 equal parts, add them into the pre-prepared Lactobacillus plantarum liquid with a concentration of 1×1010CFU / g, and the mass volume ratio of figs to the liquid is 1:1. Then put them into an ultrasonic device and treat them at an ultrasonic power of 150W for 15 minutes. Then put the figs into a quick freezer for quick freezing for 6 hours. After quick freezing, put them into a vacuum microwave freeze dryer for drying. The drying conditions are: cold trap temperature is -35℃, microwave power is 2KW, vacuum degree is less than 200Pa, and loading capacity is 1-2kg.

[0048] The fig fruit prepared in this comparative example has a crisp sugar-acid ratio of 60.12 and a probiotic count of 5.62 lg (CFU / g).

[0049] In summary, compared with the comparative example, the sugar-acid ratio of the fig crisp product prepared by the ultrasonic impregnation, micro-fermentation, vacuum microwave freeze-drying and other technologies of the present invention is significantly reduced, the number of probiotics is significantly increased, and it has obvious superiority.

Claims

1. A fig crisp rich in probiotics and a preparation method thereof, characterized in that: The method comprises the following steps: 1) Cut the figs into 2 to 4 equal parts, add them into the prepared Lactobacillus plantarum liquid, and perform ultrasonic pretreatment; 2) placing the figs pretreated by ultrasound in step 1) in an incubator at 20° C. for micro-fermentation; 3) placing the processed figs in step 2) into a quick-freezer for quick freezing; 4) The quick-frozen figs in step 3) are placed in a vacuum microwave freeze dryer and freeze-dried to a moisture content of 5-7%, thereby obtaining probiotic-rich fig crisps.

2. The method according to claim 1, characterized in that: The concentration of the Lactobacillus plantarum solution in step 1) is 1×10 10 CFU / g.

3. The method according to claim 1, characterized in that The ultrasonic pretreatment conditions in step 1) are: ultrasonic power of 100W to 150W, ultrasonic time of 10 to 15min, and material-liquid ratio of 1:

1.

4. The method according to claim 1, characterized in that: Step 2) The micro-fermentation time of the figs is 8-20 hours.

5. The method according to claim 1, characterized in that The fig quick-freezing time in step 3) is 6 hours.

6. The method according to claim 1, characterized in that The vacuum microwave freeze-drying conditions in step 4) are: cold trap temperature is -35°C, microwave power is 2KW, vacuum degree is lower than 200Pa, and loading capacity is 1-2kg.

7. A fig crisp rich in probiotics, characterized in that: The method according to any one of claims 1 to 6 is used to produce the fig crisp, wherein the number of viable bacteria is greater than 1×10 8 The CFU / g and sugar-acid ratio ranged from 30.62 to 41.5.

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