Application of tamarind kernel extract in fruit and vegetable preservation

Abstract

The invention discloses an application of a tamarind fruit core extract in fruit and vegetable preservation, the tamarind fruit core extract has an effect of inhibiting pathogenic bacteria causing fruit and vegetable spoilage, and experimental results show that the tamarind fruit core extract has a good inhibition effect on the pathogenic bacteria causing citrus spoilage, namely Penicillium digitatum. And the tamarind kernel extract is used for preserving the citrus, has no obvious influence on the quality of the citrus, is green, safe and reliable, is simple to prepare and low in cost, and is suitable for industrial production and market popularization and application.

Description

Technical Field

[0001] This invention belongs to the field of fruit and vegetable preservation technology, specifically relating to the preparation of a tamarind kernel extract and its application in fruit and vegetable preservation. Background Technology

[0002] Tamarind ( Tamarindus indica Tamarind (Tamarindus linn.), also known as tamarind or sour bean, is a subtropical evergreen tree belonging to the genus Tamarind in the legume family (Fabaceae). Native to tropical Africa, it was introduced to India via Sudan, and then spread from southern Asia to Arab countries and Europe. It is now cultivated in tropical and subtropical regions worldwide, including Yunnan province in my country. Tamarind is highly adaptable, grows relatively quickly, tolerates drought and poor soil, is relatively resistant to pests and diseases, suits various soil types, and is easy to cultivate and manage. It is a slow-growing, long-lived evergreen tree. The tamarind kernel (i.e., tamarind seed), as a byproduct, contains various active ingredients such as polyphenols, tannins, flavonoids, chitin, and fatty acids, which can effectively inhibit Gram-positive and Gram-negative bacteria. Studies by Vijayan et al. have demonstrated that the ethanol extract of tamarind nucleus exhibits a significant inhibitory effect on Staphylococcus aureus. Its inhibitory mechanism may involve interaction with the lipid bilayer on the bacterial cell membrane, altering membrane permeability and ultimately leading to leakage of intracellular biomolecules and cell death. Saini et al. found that tannins and flavonoids in tamarind nucleus interfere with the cell wall synthesis of Candida albicans, inhibiting its cell wall integrity and thus preventing Candida albicans from dying. Candida albicans The inability of cells to grow normally results in a good antibacterial effect. Studies by Puri et al. have shown that polyphenols in tamarind kernels can penetrate bacterial membranes and interfere with intracellular metabolic pathways, including enzyme activity and DNA synthesis, ultimately inhibiting the growth and reproduction of *Pseudomonas aeruginosa*. Currently, there are no reports on the research and application of tamarind kernels in postharvest disease control of fruits and vegetables, especially in the control of *Penicillium fingernail*. Summary of the Invention

[0003] This invention provides a new use for tamarind kernel extract, namely its application in the preservation of fruits and vegetables. Tamarind kernel extract has the effect of inhibiting pathogens that cause spoilage and deterioration of fruits and vegetables.

[0004] The main pathogen causing spoilage and deterioration of fruits and vegetables is *Penicillium fingernail* (… Penicillium digitatum ).

[0005] The tamarind kernel extract is obtained by crushing cleaned and dried tamarind kernels, extracting the tamarind kernel powder with a 25-100% (v / v) methanol solution, a 25-100% (v / v) ethanol solution, or a pH 7.0, 0.1M phosphate buffer solution, separating the solid and liquid components, and collecting the extract.

[0006] The tamarind seed kernel extract can also be prepared into a fresh-keeping preparation, including a liquid preparation, a solid preparation or a gel preparation, and a preparation or product prepared by compounding the tamarind seed kernel extract with other active components or adjuvants.

[0007] Advantages and technical effects of the present application: The tamarind seed kernel extract provided by the present application has a good inhibitory effect on Penicillium digitatum, which is a main pathogenic bacterium causing spoilage of fruits and vegetables, and the use of the tamarind seed kernel extract for preserving citrus fruits shows that the extract has no significant effect on the quality of citrus fruits, and is green, safe and reliable. Penicillium digitatum The development of a postharvest preservative for fruits and vegetables using the tamarind seed kernel extract has multiple advantages, including low cost, simple operation and good safety, and the method of the present application is suitable for industrialized production and market promotion and application. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 The upper graph is the antibacterial result, and the lower graph is the statistical result of the size of the antibacterial circle. Figure 2 The effect of anhydrous ethanol directly acting on Penicillium digitatum; Figure 3 The effect of anhydrous ethanol directly acting on Penicillium digitatum; Figure 4 The effect of anhydrous ethanol directly acting on Penicillium digitatum; Figure 5 The effect of anhydrous ethanol directly acting on Penicillium digitatum; Figure 6 The effect of anhydrous ethanol directly acting on Penicillium digitatum; Figure 7 The weight loss rate detection result of the citrus fruit; Figure 8 The titratable acid detection result; Figure 9 The VC content detection result; Figure 10 The soluble solid detection result. DETAILED DESCRIPTION

[0009] The method of the present application will be further described below by means of the accompanying drawings and examples, but the protection scope of the present application is not limited to the described content, and the reagents in the examples are conventional reagents or reagents prepared according to conventional methods unless otherwise specified; Example 1: Inhibition experiment of the extract prepared by extracting the tamarind seed kernel with different solvents on Penicillium digitatum 1. Using PDA solid medium, activate the culture of Penicillium digitatum at 28℃, pick up the activated Penicillium digitatum in sterile water to prepare a spore suspension with a concentration of 1.0×10 6 2. Wash and dry the tamarind seeds, and use a powdering machine to make fine and uniform powder; 3. According to the ratio of g:mL=1:5, use volume concentration of anhydrous methanol, anhydrous ethanol, 0.1M PBS buffer (pH7.0), 90℃ hot water, and pure ethyl acetate to extract the tamarind seed powder, respectively. After stirring overnight at room temperature, centrifugal filtration is performed to take the supernatant to prepare the extract; 4. Prepare PDA solid medium, drop 50µL of the spore suspension of step 1 on the PDA solid medium for coating, make crosswise holes (hole diameter of 10mm) in the middle and around each medium, set the corresponding solvent as control, drop the above different extracts in the surrounding three holes for experiment, seal the culture dish and place it in 28℃ incubation, record the size of the inhibition zone diameter after 7 days of incubation.

[0010] The results are shown in Figure 1 As can be seen from the figure, the extracts prepared by methanol, ethanol, and PBS buffer have significant inhibitory effect on Penicillium digitatum, and the extract prepared by ethanol has the best effect, but the extracts prepared by hot water and ethyl acetate have no inhibitory effect on Penicillium digitatum.

[0011] Example 2: Inhibition experiment of extracts prepared by different concentrations of ethanol extracted from tamarind seeds on Penicillium digitatum 1. Anhydrous ethanol is directly inoculated on the PDA solid medium coated with Penicillium digitatum, and incubated at 28℃ for 7 days to detect whether ethanol itself has antibacterial effect. The results are shown in Figure 2 As can be seen from the figure, no obvious inhibition zone appears, indicating that ethanol itself has no antibacterial effect on Penicillium digitatum.

[0012] 2. The extraction method of tamarind seed powder in this example is the same as that in Example 1, except that anhydrous ethanol, 75%, 50%, and 25% volume concentration of ethanol solution are used to extract the tamarind seed powder, respectively; and the antibacterial effect detection method is the same as that in Example 1. The results are shown in Figure 3 The tamarind seed extracts prepared by different concentrations of ethanol solution all have obvious inhibitory effect on Penicillium digitatum, and there is no significant difference, indicating that the inhibitory effect of extracts prepared by different concentrations of ethanol on Penicillium digitatum is equivalent.

[0013] Example 3: Inhibition effect experiment of extracts prepared by ultrasonic extraction on Penicillium digitatum ​The extraction method of the tamarind seed kernel powder in this example is the same as that in Example 1, except that anhydrous ethanol is used as the extraction agent. The anhydrous ethanol is mixed with the tamarind seed kernel powder, and then extracted under ultrasonic conditions for 0 min, 15 min, 30 min, 60 min, and 90 min, respectively. Then, the mixture is stirred overnight at room temperature, centrifuged and filtered to obtain the supernatant to prepare the extract. The antibacterial effect monitoring method is the same as that in Example 1. The results are shown in Table 1. Figure 4 There is no significant difference between the non-ultrasonic and 15 min ultrasonic conditions, but the antibacterial effect of the tamarind seed kernel alcohol extract gradually decreases with the increase of the ultrasonic time. It is thus speculated that the ultrasonic time is too long, which may destroy the antibacterial substances in the tamarind seed kernel alcohol extract and thus reduce its antibacterial effect. Therefore, ultrasonic assisted extraction is not needed during the extraction of the tamarind seed kernel antibacterial solution.

[0014] Example 4: Effect of different solid-liquid ratios on the inhibition of Penicillium digitatum The extraction method of the tamarind seed kernel powder in this example is the same as that in Example 1, except that anhydrous ethanol is used as the extraction agent. The anhydrous ethanol is mixed with the tamarind seed kernel powder, and then extracted under ultrasonic conditions for 0 min, 15 min, 30 min, 60 min, and 90 min, respectively. Then, the mixture is stirred overnight at room temperature, centrifuged and filtered to obtain the supernatant to prepare the extract. The antibacterial effect monitoring method is the same as that in Example 1. The results are shown in Table 1. Figure 5 The extracts prepared by the solid-liquid ratios of 1:3-20 have inhibitory effect on Penicillium digitatum, and the tamarind seed kernel ethanol extract with a solid-liquid ratio of 1:3 has the best inhibitory effect on Penicillium digitatum.

[0015] Example 5: Inhibition of tamarind seed kernel alcohol extract on Penicillium digitatum on citrus 1. The PDA solid culture medium is used to activate and culture Penicillium digitatum at 28°C. 2. Fresh citrus with no mechanical damage on the surface is selected, wiped with sodium hypochlorite solution, washed with water, and dried. 3. An appropriate amount of activated Penicillium digitatum in step 1 is added to the tamarind seed kernel ethanol extract with a solid-liquid ratio of 1:3 in Example 4 and anhydrous ethanol to prepare spore suspension A1 and spore suspension A2 (both with a concentration of 1.0×10 6 4. The experimental group and the blank control group are set up, each with 6 citrus. The citrus is punched at the largest diameter with a hollow needle, 20 µL of A1 bacterial solution is inoculated in the experimental group, and 20 µL of A2 bacterial solution is inoculated in the blank control group. The two groups of citrus are placed at 28°C, and the pathogen diameter on the citrus is observed and recorded.

[0016] The results are shown in Table 1. Figure 6 The results show that the 6 citrus in the blank control group are infected with Penicillium digitatum after 96 hours, while the experimental group only shows infection symptoms after 168 hours. The results indicate that the tamarind seed kernel alcohol extract has a significant inhibitory effect on Penicillium digitatum on citrus.​

[0017] Example 6: Experiment on the effect of Physalis pruinosa L. nuclear alcohol extract on the quality of citrus preservation 1. Select citrus fruits (sugar oranges) with uniform size and color, and no obvious surface scratches; after cleaning and drying, soak in 2% sodium hypochlorite solution for disinfection, then rinse and dry, and place neatly; 2. Divide the citrus into three groups and soak in sterile water (negative control, CK), fruit wax (positive control, Fruit wax), and Physalis pruinosa L. nuclear alcohol extract (experimental group, Treat) for 2 minutes, respectively, and place under natural conditions (temperature 20±2℃, humidity 85%-90%). Then, measure the quality of the citrus (weight loss rate, titratable acid, VC content, and soluble solids) every 5 days, and observe for 30 days. Each group has 20 fruits, and the experiment is repeated 3 times. The Physalis pruinosa L. nuclear alcohol extract is the Physalis pruinosa L. ethanol extract with a material liquid ratio of 1:3 in Example 4; The weight loss rate results are shown in Figure 7 As can be seen from the figure, the weight loss rate of the fruits in the negative control group (CK), the positive control group (fruit wax Fruit wax), and the experimental group (Physalis pruinosa L. nuclear alcohol extract, Treat) generally showed an upward trend with the increase of time. Although the weight loss rate of the experimental group was higher than that of the other two groups within 0-15 days of storage, it was lower than that of the other two groups in the later storage period. It can be seen that the Physalis pruinosa L. nuclear alcohol extract has the effect of inhibiting water loss of fruits. Therefore, it can be concluded that the Physalis pruinosa L. nuclear alcohol extract has no effect on the quality of citrus.

[0018] The titratable acid (TA) detection results are shown in Figure 8 Although the titratable acid of the three groups fluctuated significantly during storage, the TA content generally showed an upward trend first and then a downward trend with the extension of storage time. In the early stage of storage, the increase of soluble sugar and other substances may be caused by the degradation of starch in citrus, and at this time the sweetness of citrus is best. In the later stage of storage, the decrease of TA may be caused by the consumption of nutrients such as sugar in citrus with the extension of storage time, and at this time the quality of citrus gradually decreases. The TA of the experimental group and the other two groups sometimes has significant difference and sometimes has no significant difference, but overall, the TA content of the experimental group is higher than that of the other two groups, which shows that the treatment of the experimental group has no effect on the quality of citrus.

[0019] The VC content detection results are shown in Figure 9 With the increase of storage time, the VC content of the three groups generally showed a downward trend, and the experimental group and the negative control group had significant difference with the positive control group. It can be seen that fruit wax has an effect on the VC content of citrus, causing the VC content of citrus to be lower than that of the other two groups, which damages the quality of citrus, but the Physalis pruinosa L. extract has no effect on the quality of citrus.

[0020] The soluble solid detection results are shown in Table 2 Figure 10 The soluble solid (TSS) content of the negative control group, the positive control group and the experimental group fluctuated during the storage time, but the overall change was not large. According to the comparison within the group, it can be seen that there was a significant difference between the experimental group and the negative control group, but it was always fluctuating. It can be seen that the TSS content of the experimental group has no great influence on the citrus, that is, the acid angle kernel alcohol extract has no effect on the quality of the citrus.

[0021] In summary, the acid angle kernel alcohol extract has no effect on the quality of the citrus and can be safely applied.

Claims

1. An application of tamarind kernel extract in fruit and vegetable preservation, characterized in that: Tamarind kernel extract has the effect of inhibiting pathogens that cause spoilage and deterioration of fruits and vegetables.

2. The application according to claim 1, characterized in that: The pathogen causing spoilage and deterioration of fruits and vegetables is Penicillium finger-shaped mold ( Penicillium digitatum ).

3. The application according to claim 1, characterized in that: Tamarind kernel extract is prepared by crushing cleaned and dried tamarind kernels, extracting the tamarind kernel powder with a 25-100% (v / v) methanol solution, a 25-100% (v / v) ethanol solution, or a pH 7.0 phosphate buffer solution, separating the solid and liquid components, and collecting the extract.

4. The application according to claim 1, characterized in that: Preservatives made from tamarind kernel extracts include liquid, solid, or gel formulations.

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