A drying method of meadowsweet can improve the tyrosinase activity of pericarp polyphenol

Abstract

The application discloses a quince peel drying method capable of improving tyrosinase activity of fruit skin polyphenols, and comprises the following steps: (1) pre-freezing fresh quince peel; (2) freeze-drying the product of step (1); (3) hot air drying the product of step (2) to obtain quince peel dry products. The quince peel drying method of the application combines the advantages of freeze-drying and hot air drying, compared with freeze-drying, the drying time is shortened by 25%, and the energy consumption is reduced; the polyphenol yield of the peel is improved, the polyphenol yield is higher than that of freeze-drying, and is increased by 43% than that of hot air drying; the polyphenol thermal degradation and oxidation are prevented, the polyphenol release is promoted, the polyphenol species and quantity with high tyrosinase activity inhibition are increased, and thus the tyrosinase activity of quince peel polyphenols is significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for drying fruit peels, and in particular to a method for drying cydonia oblonga mill. that can improve the tyrosinase inhibitory activity of polyphenols in the peels. BACKGROUND

[0002] Cydonia oblonga Mill., also known as wood pear, is a member of the Rosaceae family and has been cultivated for more than 4000 years. The fruit of cydonia oblonga mill. is similar to a pear in shape, yellow in color, and covered with down. It has a strong aroma and is rich in nutrients such as polyphenols, organic acids, dietary fiber, and minerals. The Compendium of Materia Medica records that cydonia oblonga mill. is used to treat diarrhea, intestinal weakness, and heat. Cydonia oblonga mill. is a traditional Uyghur medicine with strong national characteristics. It has the effects of promoting cardiovascular health, promoting digestion, anti-inflammatory, and anti-cancer. In the processing of cydonia oblonga mill., the peels are often discarded, resulting in waste of resources. Studies have shown that the polyphenol content of cydonia oblonga mill. peels is 5 times that of the flesh, making it a valuable resource for development and application.

[0003] Cydonia oblonga Mill. generally ripens between September and October, and the harvest period is short. Due to high water content and susceptibility to pests and diseases, it is prone to rot and spoilage, making it difficult to store. Drying is an effective technique for extending the shelf life. Freeze-drying preserves the shape and nutrients of food to the maximum extent by freezing water and directly sublimating it, but it is time-consuming and energy-intensive. Hot air drying quickly removes water through circulating hot air, has high thermal efficiency, and is simple to operate, but it can lead to the loss of nutrients. Both freeze-drying and hot air drying techniques are currently used in the drying of cydonia oblonga mill. Their advantages complement each other. Studies have shown that short-term high-temperature treatment can inactivate polyphenol oxidase activity, thereby reducing the loss of polyphenol substances during processing. High temperatures can also cause some polyphenol substances to transform into each other, changing the quantity and type of polyphenol substances.

[0004] Excessive accumulation of melanin can cause fruit and vegetable browning, skin diseases such as melanoma, and tyrosinase is a key enzyme in the process of melanin production. Currently used tyrosinase inhibitors such as kojic acid and arbutin have certain side effects on the human body. Therefore, it is of great value to screen new tyrosinase inhibitors with high efficiency and low toxicity. Cydonia oblonga mill. peels have a strong aroma and are a low-calorie and high-nutrient fruit peel rich in polyphenols, which have the potential to inhibit tyrosinase. By drying cydonia oblonga mill. peels through a reasonable method, the tyrosinase inhibitory activity components in the peels can be maximally preserved, which lays the foundation for developing substances with low side effects and high tyrosinase inhibitory activity, and improving the added value and market competitiveness of cydonia oblonga mill. products. SUMMARY

[0005]

Technical problem

[0006] The commonly used tyrosinase inhibitors such as kojic acid and arbutin have certain side effects on human body, and the quince peel has the potential to inhibit tyrosinase and can be used to develop new tyrosinase inhibitors with high efficiency and low toxicity. However, the existing drying methods of quince only use freeze-drying or hot air drying technology, and the freeze-drying takes a long time and consumes a lot of energy, and the hot air drying is easy to cause the loss of nutritional ingredients. Therefore, a suitable drying method is needed to reduce energy consumption and maximize the retention of tyrosinase inhibitory active ingredients in quince peel.

[0007]

Technical scheme

[0008] To solve the above technical problems, the freeze-drying and hot air drying are combined to improve the anti-tyrosinase activity of polyphenols in dried quince peel, prevent the damage of the peel structure during the drying process, and save energy and increase efficiency. First, the freeze-drying is used to maintain the color, structure and nutritional ingredients of the food, and then the hot air drying is used to quickly remove the residual moisture, thereby improving the drying efficiency. In the combined drying process, the ice will melt and cause damage to the sample if the freeze-drying is ended too early, and the efficiency will be reduced and the cost will be increased if the freeze-drying is delayed, therefore, the selection of the appropriate freeze-drying ending time is the key to the combined drying and is crucial to the quality and efficacy of the dried product.

[0009] The first object of the present application is to provide a quince drying method which can improve the anti-tyrosinase activity of polyphenols in the peel, comprising the following steps:

[0010] (1) pre-freezing fresh quince peel, the pre-freezing temperature is-82 to-78℃, and the pre-freezing time is 10 to 14h;

[0011] (2) freeze-drying the product of step (1);

[0012] (3) hot air drying the product of step (2) to obtain a dried quince peel product.

[0013] In an embodiment of the present application, in step (1), the fresh quince peel is obtained by washing the fluff and dirt on the surface of the quince with clean water, draining and peeling.

[0014] In an embodiment of the present application, in step (2), the drying temperature is-45 to-35℃, the pressure is 0.08 to 0.12mbar, and the drying time is 16 to 18h.

[0015] In an embodiment of the present application, in step (3), the drying temperature is 55 to 65℃, and the drying time is 0.3 to 0.5h.

[0016] In an embodiment of the present application, the moisture content of the dried quince peel product is below 25%.

[0017] The second object of the present application is to provide the application of the above-mentioned quince drying method in the field of food.

[0018] A third object of the present application is to provide the use of the above-mentioned drying method of quince fruit peel in the manufacture of anti-tyrosinase drugs.

[0019] A fourth object of the present application is to provide a dried quince fruit peel product prepared by the above-mentioned drying method of quince fruit peel.

[0020] A fifth object of the present application is to provide the use of the above-mentioned dried quince fruit peel product in the food industry, including functional foods, dietary supplements, colorants, flavorings, edible coatings, and food packaging films.

[0021] A sixth object of the present application is to provide the use of the above-mentioned dried quince fruit peel product in the manufacture of anti-tyrosinase drugs.

[0022]

Advantages

[0023] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0024] 1. By combining freeze-drying and hot-air drying, the fruit peel morphology is maximally preserved, and severe browning of the fruit peel caused by long-term hot-air drying is prevented.

[0025] 2. By combining freeze-drying and hot-air drying, the freeze-drying time is shortened by 25%, saving costs and reducing energy consumption.

[0026] 3. By combining freeze-drying and hot-air drying, severe polyphenol loss caused by long-term hot-air drying is prevented, and the polyphenol yield of the fruit peel is higher than that of freeze-drying and increased by 43% compared to hot-air drying.

[0027] 4. The drying method of the present application can significantly improve the anti-tyrosinase activity of quince fruit peel polyphenols. Freeze-drying operates in a low-temperature and vacuum environment, effectively preventing the thermal degradation and oxidation of polyphenols; short-term hot-air drying quickly removes residual moisture and destroys cell structure, promoting the release of polyphenols, increasing the number and types of polyphenols with high tyrosinase inhibitory activity, thereby comprehensively improving the polyphenol yield and anti-tyrosinase activity of quince fruit peel polyphenols. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a column chart of the polyphenol yield of dried quince fruit peel obtained by different drying methods. DETAILED DESCRIPTION

[0029] Test Method:

[0030] 1. Quince peel powder crushing and polyphenol extraction: Quince peel dry products were completely immersed in liquid nitrogen for 1 min and then frozen quickly. The frozen quince peel was crushed in a food processor at 15 000 rpm for 2 min and then sieved through a 20-mesh sieve. The sieved quince peel powder was stored in a refrigerator at 4 °C. 1 g of the sieved quince peel powder was accurately weighed into a 50-mL centrifuge tube, and 30 mL of 70% (V / V) ethanol was added. The mixture was ultrasonically extracted for 40 min, and then allowed to cool at room temperature. The mixture was centrifuged at 5000 rpm at 25 °C for 10 min. The supernatant was collected, and the extraction was repeated three times. The supernatants were combined and diluted to 100 mL. Thus, a 70% ethanol extract of quince peel was obtained, and the concentration of the extract was 10 mg / mL. The polyphenol content of the extract was determined by the Folin-phenol method, and the polyphenol yield was calculated as the percentage of the weight of the polyphenol extracted from the quince peel per unit dry weight of the quince peel.

[0031] 2. Anti-tyrosinase activity determination: The ethanol in the 100-mL extract was removed by rotary evaporation at 50 °C and 100 rpm for 20 min. The extract was pre-frozen in an ultra-low temperature freezer at -80 °C for 12 h, and then freeze-dried at a cold trap temperature of -40 °C and a pressure of 0.10 mbar for 24 h to remove the water. The freeze-dried extract was reconstituted to 10 mL with 0.1 M phosphate buffer solution (PBS) at pH 6.8. Thus, a PBS extract of quince peel was obtained, and the concentration of the extract was 100 mg / mL. The PBS extract was diluted by 5-fold, 7.5-fold, 10-fold, 12.5-fold, and 15-fold, respectively. L-tyrosine solution, sample solution / solvent, and PBS were sequentially added to a 96-well enzyme plate according to Table 1, and the mixture was thoroughly mixed. The mixture was incubated at 37 °C for 10 min, and then 20 μL of tyrosinase solution was added to each well. The mixture was thoroughly mixed and reacted at 30 °C for 5 min, and then the absorbance was immediately measured at 475 nm.

[0032] Table 1: Sample addition table for tyrosinase activity inhibition test

[0033]

[0034]

[0035] The tyrosinase activity inhibition rate Y (%) was calculated according to the following formula: Y (%) = [1 - (A d -A c ) / (A b -A a )] x 100. Wherein: A a and A b are the absorbance values of the solvent blank wells and the reaction wells, respectively, and A c and A d are the absorbance values of the sample blank wells and the reaction wells, respectively. The concentration of the PBS extract of quince peel at which the tyrosinase activity inhibition rate was 50% (IC 50The tyrosinase activity of the dried fruit peel is obtained.

[0036] Example 1

[0037] A drying method for improving the tyrosinase activity of the polyphenols in the fruit peel of a quince, comprising the following steps:

[0038] (1) Selecting quinces free of pests and damages, washing the surface of the quinces with clean water to remove the fluff and dirt, and then peeling the quinces to obtain fresh fruit peels.

[0039] (2) Placing the fresh fruit peels into an ultra-low temperature refrigerator and pre-freezing them at -80°C for 12 hours.

[0040] (3) Starting a freeze-drying device and keeping the temperature of the cold trap at -40°C, transferring the product of step (2) into the freeze-drying system, and starting the freeze-drying process, with a pressure of 0.10 mbar and a drying time of 18 hours.

[0041] (4) Starting a hot-air drying device and keeping the temperature in the cavity of the machine at 60°C, transferring the product of step (3) into the hot-air drying system, and starting the hot-air drying process, with a drying time of 0.4 hours, to obtain the dried fruit peels.

[0042] Example 2

[0043] A drying method for improving the tyrosinase activity of the polyphenols in the fruit peel of a quince, comprising the following steps:

[0044] (1) Selecting quinces free of pests and damages, washing the surface of the quinces with clean water to remove the fluff and dirt, and then peeling the quinces to obtain fresh fruit peels.

[0045] (2) Placing the fresh fruit peels into an ultra-low temperature refrigerator and pre-freezing them at -78°C for 14 hours.

[0046] (3) Starting a freeze-drying device and keeping the temperature of the cold trap at -35°C, transferring the product of step (2) into the freeze-drying system, and starting the freeze-drying process, with a pressure of 0.10 mbar and a drying time of 18 hours.

[0047] (4) Starting a hot-air drying device and keeping the temperature in the cavity of the machine at 65°C, transferring the product of step (3) into the hot-air drying system, and starting the hot-air drying process, with a drying time of 0.3 hours, to obtain the dried fruit peels.

[0048] Example 3

[0049] A drying method for improving the tyrosinase activity of the polyphenols in the fruit peel of a quince, comprising the following steps:

[0050] (1) Selecting quinces free of pests and damages, washing the surface of the quinces with clean water to remove the fluff and dirt, and then peeling the quinces to obtain fresh fruit peels.

[0051] (2) The fresh fruit peel is sent into an ultra-low temperature refrigerator and pre-frozen at -82°C for 10 hours.

[0052] (3) The freeze-drying device is started, the cold trap temperature is kept at -45°C, the product of step (2) is transferred into the freeze-drying system, the freeze-drying process is started, the pressure is 0.10 mbar, and the drying time is 16 hours.

[0053] (4) The hot air drying device is started, the temperature in the machine cavity is kept at 55°C, the product of step (3) is transferred into the hot air drying system, the hot air drying process is started, the drying time is 0.5 hour, and the fruit peel dried product is obtained.

[0054] Comparative Example 1

[0055] A quince drying method using only hot air drying, comprising the following steps:

[0056] (1) Select quince without pests and damage, wash the surface fluff and dirt with clean water, drain and peel to obtain fresh fruit peel.

[0057] (2) The hot air drying device is started, the temperature in the machine cavity is kept at 60°C, the fresh fruit peel is transferred into the hot air drying system, the hot air drying process is started, the drying time is 3.8 hours, and the fruit peel dried product is obtained.

[0058] Comparative Example 2

[0059] A quince drying method, comprising the following steps:

[0060] (1) Select quince without pests and damage, wash the surface fluff and dirt with clean water, drain and peel to obtain fresh fruit peel.

[0061] (2) The fresh fruit peel is sent into an ultra-low temperature refrigerator and pre-frozen at -80°C for 12 hours.

[0062] (3) The freeze-drying device is started, the cold trap temperature is kept at -40°C, the product of step (2) is transferred into the freeze-drying system, the freeze-drying process is started, the pressure is 0.10 mbar, and the drying time is 6 hours.

[0063] (4) The hot air drying device is started, the temperature in the machine cavity is kept at 60°C, the product of step (3) is transferred into the hot air drying system, the hot air drying process is started, the drying time is 2.0 hours, and the fruit peel dried product is obtained.

[0064] Comparative Example 3

[0065] A quince drying method, comprising the following steps:

[0066] (1) Selecting the healthy and intact quinces without pests, washing the surface of the quinces with clean water to remove the fluff and dirt, draining and peeling to obtain fresh quince peel.

[0067] (2) The fresh quince peel was sent into an ultra-low temperature refrigerator and pre-frozen at -80℃ for 12h.

[0068] (3) The freeze-drying device was started, the temperature of the cold trap was kept at -40℃, the product of step (2) was transferred into the freeze-drying system, the freeze-drying process was started, the pressure was 0.10mbar, and the drying time was 12h.

[0069] (4) The hot air drying device was started, the temperature in the cavity of the machine was kept at 60℃, the product of step (3) was transferred into the hot air drying system, the hot air drying process was started, the drying time was 1.4h, and the dried quince peel product was obtained.

[0070] Comparative Example 4

[0071] The quince drying method using only freeze-drying comprises the following steps:

[0072] (1) Selecting the healthy and intact quinces without pests, washing the surface of the quinces with clean water to remove the fluff and dirt, draining and peeling to obtain fresh quince peel.

[0073] (2) The fresh quince peel was sent into an ultra-low temperature refrigerator and pre-frozen at -80℃ for 12h.

[0074] (3) The freeze-drying device was started, the temperature of the cold trap was kept at -40℃, the product of step (2) was transferred into the freeze-drying system, the freeze-drying process was started, the pressure was 0.10mbar, and the drying time was 24h, and the dried quince peel product was obtained.

[0075] Figure 1 The different letters marked on the different columns in the figure represent that the polyphenol yield of the dried quince peel obtained by different drying methods is statistically different, p<0.05. Compared with the drying methods of Comparative Examples 1-4, the polyphenol yield of the dried quince peel obtained by the drying method of the application is significantly improved. This is because the freeze-drying operates in a low-temperature and vacuum environment, effectively preventing the thermal degradation and oxidation of polyphenols; the short-time hot air drying quickly removes residual moisture and destroys the cell structure, promoting the release of polyphenols. The polyphenol yield of the dried quince peel prepared in Comparative Examples 1 and 2 is the lowest, because the long-time hot air drying leads to the loss of polyphenols.

[0076] The anti-tyrosinase activity of the polyphenols from the fruit peels dried by different methods is shown in Table 2. In Comparative Examples 1-4, the polyphenols extracted from the fruit peel dried by freeze-drying (Comparative Example 4) showed higher anti-tyrosinase activity, but still lower than that of the polyphenols from the fresh fruit peel. The polyphenols from the fruit peels of the present application showed the highest anti-tyrosinase activity, which was significantly higher than that of the fresh fruit peel. The reason is that the freeze-drying under low temperature and vacuum environment effectively prevents the thermal degradation and oxidation of the polyphenols in the fruit peel. The short-time hot-air drying can quickly remove the residual moisture and destroy the cell structure, promote the release of the polyphenols, increase the number and types of the polyphenols with high anti-tyrosinase activity, thereby comprehensively improve the yield and anti-tyrosinase activity of the polyphenols from the fruit peels of the quince. Therefore, the drying method of freeze-drying for 16-18 h combined with hot-air drying for 0.3-0.5 h adopted in the present application is a new drying method that can significantly improve the anti-tyrosinase activity of the polyphenols from the fruit peels of the quince.

[0077] Table 2 Anti-tyrosinase activity of the polyphenols from the fruit peels of the quince dried by different methods

[0078]

[0079] Note: In the table, the same column of numbers with different letters indicates that the difference in the anti-tyrosinase activity of the polyphenols from the fruit peels of the quince dried by different methods is statistically significant, p<0.05.

[0080] The above provided examples are not intended to limit the scope covered by the present application, and the described steps are not intended to limit the execution order thereof. The improvements of the present application made by those skilled in the art in combination with the existing common knowledge are also within the protection scope defined by the claims of the present application.

Claims

1. A method for drying quince that can improve the anti-tyrosinase activity of polyphenols in the peel, characterized in that, Includes the following steps: (1) Pre-freeze fresh quince peel at a temperature of -82 to -78°C for 10 to 14 hours; (2) Freeze-dry the product from step (1); the drying temperature is -45 to -35℃, the pressure is 0.08 to 0.12 mbar, and the drying time is 16 to 18 h; (3) The product from step (2) is dried with hot air to obtain dried quince peel; the drying temperature is 55-65℃ and the drying time is 0.3-0.5 h.

2. The quince drying method according to claim 1, characterized in that, In step (1), fresh quince peel is obtained by washing the fuzz and dirt off the surface of the quince with clean water, draining it, and then peeling it.

3. The quince drying method according to claim 1, characterized in that, The moisture content of dried quince peel products is below 25%.

4. The application of the quince drying method according to any one of claims 1 to 3 in the food industry.

5. The use of the quince drying method according to any one of claims 1 to 3 in the manufacture of antityrosinase drugs.

6. The dried quince peel product prepared by any one of the quince drying methods according to claims 1 to 3.

7. The application of the dried quince peel product according to claim 6 in the food industry, characterized in that, This includes functional foods, colorants, flavorings, edible coatings, and food packaging films.

8. The use of the dried quince peel product according to claim 6 in the manufacture of anti-tyrosinase drugs.

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