Nelumbo nucifera flower drying method and hydrolat extraction method

Abstract

This invention provides a method for drying water lilies and extracting their hydrosol. Addressing the problems of low drying efficiency, high energy consumption, and easy loss of active ingredients in existing water lily flower drying processes, this invention employs microwave drying to pre-dry fresh water lilies, obtaining dried water lily flowers with high drying efficiency and low energy consumption. Hydrosol extraction uses the dried water lily flowers as raw material, which is obtained through crushing, liquid-material mixing, distillation, and purification. Compared with traditional drying methods, this invention significantly improves drying efficiency and significantly reduces energy consumption, effectively reducing production costs. Furthermore, the hydrosol extraction method is simple and maximizes the quality of the water lily hydrosol, making it suitable for industrial-scale water lily production.

Description

Technical Field

[0001] This invention relates to the field of flower processing technology, specifically to a method for drying water lilies and a method for extracting hydrosols. Background Technology

[0002] Water lilies (Nymphaea) are perennial aquatic herbaceous flowers belonging to the Nymphaeaceae family. They boast a rich variety of colors and a pleasant fragrance. Their flowers are rich in flavonoids, polyphenols, and volatile components, making them promising for applications in fragrances, cosmetics, and pharmaceuticals. Fresh water lilies have a high water content and are prone to browning, rotting, and loss of active ingredients after harvesting, making long-term preservation difficult. Therefore, drying is necessary for stable storage. Water lily hydrosol, on the other hand, retains water-soluble active ingredients and natural aroma, making it a high-quality raw material for natural skincare and daily chemical products.

[0003] Currently, the main drying methods for water lilies include hot air drying, vacuum drying, and microwave drying. Hot air drying equipment is simple and easy to operate, but the drying temperature is high and the drying time is long. The heat-sensitive aromatic components in water lilies are easily lost through volatilization, and the petals are prone to browning and curling. Vacuum drying can be carried out at low temperatures, which is beneficial for preserving volatile components, but the equipment investment is large, energy consumption is high, and the drying efficiency is low, making it difficult to meet the needs of large-scale production. Microwave drying utilizes the principle of dielectric heating, which has the advantages of fast drying speed and low energy consumption. However, if continuous microwave drying is used, due to the thin petals and high water content of water lilies, it is prone to localized overheating, petal cracking, even scorching, and significant damage to heat-sensitive active components. Traditional hydrosol extraction processes often use fresh water lilies directly as raw materials without combining efficient drying pretreatment. This not only results in low raw material utilization but also makes the hydrosol quality susceptible to spoilage during distillation.

[0004] Therefore, developing a water lily processing method that achieves excellent drying effect, preserves active ingredients completely, and is suitable for efficient extraction of hydrosols has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a high-efficiency and low-energy-consumption drying process for water lilies, solve the problems of low drying efficiency and high energy consumption in existing drying methods, and establish a water lily hydrosol extraction method adapted to the drying process.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for drying water lilies, the method comprising the following steps:

[0008] Fresh water lilies are subjected to microwave drying treatment, which includes a first stage of drying and a second stage of drying. The first stage of drying takes 3 to 5 minutes. After the first stage of drying is completed, there is an interval of 25 to 35 minutes, preferably 30 minutes, before the second stage of drying is carried out. The second stage of drying takes 1 to 3 minutes.

[0009] Preferably, before the microwave drying process, the process further includes a pretreatment step of washing the fresh water lilies, draining the surface moisture, and removing the receptacle and stem.

[0010] Preferably, the microwave power of the microwave drying process is 700-800 W, the material is laid in a single layer, and the water lily is turned over once every 0.5-1 min during the drying process.

[0011] Preferably, the initial moisture content of the fresh water lily is 85% to 95%, and the moisture content of the dried flower is controlled to be ≤15%.

[0012] Compared with hot air drying or vacuum drying, the microwave drying process of the present invention significantly improves drying efficiency and significantly reduces energy consumption under the same moisture content at the drying endpoint, and can effectively preserve the volatile aromatic components and heat-sensitive active substances of water lilies.

[0013] Secondly, this invention also protects a method for extracting water lily hydrosol based on the drying method described above, comprising the following steps:

[0014] The dried water lily flower raw material was crushed, mixed with sterile purified water at a material-to-liquid ratio of 1:12, distilled for 120-140 min, the distillate was collected and filtered, and sterilized with a 0.22μm microporous membrane.

[0015] Preferably, the dried water lily flower raw material can be crushed by hand or by mechanical crushing.

[0016] Preferably, the water lily varieties include, but are not limited to, 'Doris' and 'Zijiupin'.

[0017] This invention proposes a method for drying water lilies and extracting hydrosols. The method employs intermittent microwave drying. First, fresh water lilies are subjected to a first-stage microwave drying for 3-5 minutes to raise the overall temperature of the material and rapidly evaporate surface moisture. Then, the process is interrupted for 30 minutes to utilize residual heat and moisture concentration differences to promote the migration of moisture from the inside of the flower stamen to the surface of the petals. Finally, a second-stage microwave drying is performed for 1-3 minutes to completely remove residual moisture.

[0018] This invention ingeniously combines intermittent processing with multi-stage microwave drying, leveraging the advantages of high efficiency and low energy consumption of microwave drying while effectively avoiding problems such as localized overheating, petal cracking, or scorching caused by continuous microwave heating through the intermittent process. Compared with hot air drying, vacuum drying, and continuous microwave drying, this invention significantly reduces energy consumption while ensuring the highest drying efficiency, and retains a greater proportion of the volatile aromatic components and heat-sensitive active substances of water lilies, providing high-quality dried flower raw materials for subsequent water lily hydrosol extraction. Distillation extraction combined with the dried raw materials, by selecting the optimal material-to-liquid ratio and distillation time, yields a hydrosol with high clarity, pure aroma, and high levels of active ingredients. This method is simple, highly controllable, and suitable for the industrial-scale production of water lilies, demonstrating good economic benefits and application prospects. Attached Figure Description

[0019] Figure 1 The effect of different drying methods on the average drying rate during the drying process of 'Doris' water lily;

[0020] Figure 2 The effect of different drying methods on drying energy consumption during the drying process of 'Doris' water lily;

[0021] Figure 3 The effect of different drying methods on the average drying rate during the drying process of 'Purple Nine-Grade' water lily;

[0022] Figure 4 The effect of different drying methods on drying energy consumption during the drying process of 'Purple Nine-Grade' water lily;

[0023] Figure 5 Determination of the antioxidant capacity of 'Zi Jiu Pin' water lily hydrosol under different extraction conditions. Detailed Implementation

[0024] To better illustrate the present invention and facilitate understanding of its technical solutions, the present invention is exemplary but not limiting. Reagents or instruments used without a specified manufacturer are considered to be conventional products that can be purchased on the market.

[0025] Example 1

[0026] A method for drying water lilies, comprising the following steps:

[0027] The water lily variety 'Doris' was selected.

[0028] (1) Pretreatment: Rinse the fresh water lilies with clean water, drain the surface water, remove the receptacle and stem, and weigh and record the initial mass.

[0029] (2) Drying treatment: Hot air drying, microwave drying, and vacuum drying were used. Hot air drying involved placing fresh water lilies in a drying oven at temperatures of 40℃, 45℃, and 50℃ until the water lily flowers had a moisture content of <15%. Microwave drying involved placing fresh water lilies in a microwave oven using intermittent microwave heating. The microwave power was 800 W, and the microwave output was continuous. The heating time was the time the flowers were placed in the microwave field, and the interval time was the time the flowers were placed in a room temperature environment. The heating times were 3 min, 4 min, and 5 min, the interval time was 30 min, and the reheating times were 3 min, 2 min, and 1 min, respectively. Vacuum drying involved placing the wrapped water lilies in a vacuum drying oven with vacuum settings of -0.6 bar, -0.8 bar, and -1 bar, and the temperature was room temperature. The water lilies were dried until the moisture content of the flowers was <15%.

[0030] Table 1. Numbering of 10 different drying methods

[0031]

[0032] (3) After drying: the mass of the water lily was measured and the average drying rate and drying energy consumption of the water lily were calculated.

[0033] Formula (1) is used to calculate the average drying rate:

[0034]

[0035] In the formula: The average drying rate is expressed in g / min. Mass of water evaporated before and after drying, in grams; The time interval (in minutes) is the time between weighing the water lilies before and after drying.

[0036] The drying energy consumption can be obtained from formula (2):

[0037]

[0038] Where N is the average energy consumption (kJ / g), W is the power of the drying equipment (w), T1 is the drying time (h), and m1 is the weight of water removed (g).

[0039] according to Figure 1Different drying methods significantly affected the drying rate and energy consumption of 'Doris' water lily. In terms of average drying rate, the microwave intermittent drying methods W1-W3 achieved rates of 10.9667, 11.9778, and 12.2556, respectively, which were significantly higher than those of hot air drying (R1-R3, 0.1337 to 0.2711) and vacuum drying (Z1-Z3, 0.1642 to 0.2806). The highest drying efficiency, W3, was approximately 223 times that of CK.

[0040] like Figure 2 As shown, in terms of drying energy consumption, the microwave methods W1-W3 have energy consumptions of 21.9955, 20.1555, and 19.6829, respectively, which are significantly lower than those of hot air drying (1763.2636 to 894.257) and vacuum drying (5302.3557 to 3103.3659). In summary, intermittent microwave drying significantly reduces energy consumption while maintaining extremely high drying rates, making it the optimal method for preparing 'Doris' water lily dried flowers.

[0041] Example 2

[0042] A method for drying water lilies, comprising the following steps:

[0043] The water lily variety 'Zi Jiu Pin' was selected.

[0044] (1) Pretreatment: Rinse the fresh water lilies with clean water, drain the surface water, remove the receptacle and stem, and weigh and record the initial mass.

[0045] (2) Drying treatment: Hot air drying, microwave drying, and vacuum drying were used. Hot air drying involved placing fresh water lilies in a drying oven at temperatures of 40℃, 45℃, and 50℃ until the water lily flowers had a moisture content of <15%. Microwave drying involved placing fresh water lilies in a microwave oven using intermittent heating. The microwave power was 800 W, and the microwave output was continuous. The heating time was the time the flowers were placed in the microwave field, and the interval time was the time the flowers were placed in a room temperature environment. The heating times were 3 min, 4 min, and 5 min, the interval time was 30 min, and the reheating times were 3 min, 2 min, and 1 min, respectively. Vacuum drying involved placing the wrapped water lilies in a vacuum drying oven with vacuum settings of -0.6 bar, -0.8 bar, and -1 bar, and the temperature was room temperature. The water lilies were dried until the water content of the flowers was <15%.

[0046] (3) After drying: the mass of the water lily was measured and the average drying rate and drying energy consumption of the water lily were calculated.

[0047] according to Figure 3Different drying methods significantly affected the drying rate and energy consumption of 'Purple Nine-Grade' water lily. In terms of average drying rate, the microwave intermittent drying methods W1-W3 achieved rates as high as 20.0167, 18.7778, and 15.8667, respectively, which were significantly higher than the rates of 0.2694 to 0.5392 for hot air drying R1-R3 and 0.2556 to 0.4947 for vacuum drying Z1-Z3. The highest drying efficiency, W3, was approximately 208 times that of CK.

[0048] In terms of average energy consumption, such as Figure 4 As shown, the energy consumption of microwave methods W1-W3 is only 12.0151, 12.8191, and 15.1656, respectively, which is far lower than that of hot air drying (455.9839 to 910.5644) and vacuum drying (1759.2945 to 3406.8137). In summary, intermittent microwave drying achieves high drying rates while significantly reducing energy consumption, making it the optimal method for preparing dried 'Purple Nine-Grade' water lily flowers.

[0049] Example 3

[0050] A method for extracting water lily hydrosol, comprising the following steps:

[0051] The water lily variety 'Zi Jiu Pin' was selected.

[0052] (1) Pretreatment: The dried water lily flowers are crushed by hand.

[0053] (2) Distillation extraction: Distilled water was used as the extraction solvent, and different material-to-liquid ratios (raw material mass: solvent volume, g / mL) and distillation times were set for optimization. The material-to-liquid ratios were set at two levels: 1:12 and 1:13. For each material-to-liquid ratio, distillation times of 40 min, 60 min, 80 min, 100 min, 120 min, 140 min, 160 min, and 180 min were set. A 1000 mL round-bottom distillation flask was used as the distillation apparatus, equipped with an electric heating mantle for heating, condensation and collection, and filtration to obtain water lily hydrosol.

[0054] (3) Sensory evaluation: A panel of 12 evaluators was formed to conduct blind evaluations of hydrosol samples obtained under different conditions. Evaluation indicators included liking, aroma, and color. The average score and total score under each condition were calculated, and the total sensory evaluation score was used as the core evaluation indicator for hydrosol quality.

[0055] (4) Antioxidant capacity determination: The antioxidant capacity of hydrosol samples with high sensory evaluation scores were compared using the DPPH method, ABTS method and FRAP method.

[0056] Table 2 Scoring Rules for Each Evaluation Indicator

[0057]

[0058] Table 3 Sensory evaluation of 'Purple Nine Grades' hydrosol

[0059]

[0060] The hand-crushing pretreatment method avoids the problem of the powder being highly absorbent after grinding and causing scorching during heating. Preliminary experiments showed that scorching occurred when the material-to-liquid ratio was less than 1:12, and boiling occurred when the ratio was greater than 1:13. Therefore, it was determined that the hydrosol could be extracted normally at material-to-liquid ratios of 1:12 and 1:13. According to Table 3, different extraction conditions significantly affected the sensory quality of 'Zi Jiu Pin' water lily hydrosol. Under the material-to-liquid ratio of 1:12, the total sensory evaluation scores of the hydrosol at distillation times of 140 min, 160 min, and 180 min were 4.4, 4.1, and 4.1, respectively, which were higher than the scores of 2.4 to 3.9 at other time points under the same material-to-liquid ratio, and also better than the scores of 2.0 to 4.0 at all time points under the material-to-liquid ratio of 1:13. In addition, there was an evaluation criterion for color, but since the extracted hydrosols were all pale white liquids with no significant differences, they were not included in the data.

[0061] Based on the sensory evaluation of water lily hydrosol, three groups with higher total scores were selected for antioxidant capacity testing: 1:12, 140 min; 1:12, 160 min; and 1:12, 180 min. Figure 5 The scavenging rate of DPPH radicals was significantly higher in the 180 min treatment group (62.55%) than in the 140 min (46.41%) and 160 min (39.14%) groups. The scavenging rate of ABTS radicals did not differ significantly within the extraction time range of 140–180 min. The scavenging rate of the 140 min treatment group (18.85%) was slightly higher than that of the other two groups. The FRAP reducing capacity showed a significant decreasing trend with the extension of extraction time. The VC equivalent of the 140 min treatment group (0.095) was significantly higher than that of the 160 min (0.064) and 180 min (0.054) groups.

[0062] In summary, the process conditions of a material-to-liquid ratio of 1:12 and a distillation time of 140 min yield the 'Zi Jiu Pin' water lily hydrosol with the best sensory quality and strong antioxidant capacity, making it the optimal method for the extraction and preparation of 'Zi Jiu Pin' water lily hydrosol.

[0063] The scope of protection of this invention is not limited to the above embodiments. Variations and advantages that can be conceived by those skilled in the art without departing from the spirit and scope of the inventive concept are included in this invention and are protected by the appended claims.

Claims

1. A method for drying water lilies, characterized in that, The method includes the following steps: microwave drying of fresh water lilies, wherein the microwave drying process includes a first stage of drying and a second stage of drying, wherein the first stage of drying takes 3 to 5 minutes, and after the first stage of drying is completed, there is an interval of 25 to 35 minutes, preferably 30 minutes, before the second stage of drying is carried out, and the second stage of drying takes 1 to 3 minutes.

2. The method for drying water lilies according to claim 1, characterized in that, Prior to the microwave drying process, the process includes a pretreatment step of washing the fresh water lilies, draining the surface moisture, and removing the calyx and stem.

3. The method for drying water lilies according to claim 1, characterized in that, The microwave drying process uses a microwave power of 700-800 W, with the material laid in a single layer. The water lilies are turned over every 0.5-1 minute during the drying process.

4. The method for drying water lilies according to claim 1, characterized in that, The initial moisture content of the fresh water lilies is 85% to 95%, and the moisture content of the dried flowers is controlled to be ≤15%.

5. A method for extracting water lily hydrosol based on the drying method according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Crush the dried water lily flower material; (2) Mix with sterile pure water at a ratio of 1:12, distill for 120-140 min, collect the distillate, filter, and sterilize with a 0.22μm microporous membrane.

6. The method for extracting water lily hydrosol according to claim 5, characterized in that, In step (1), the dried water lily flower raw material is crushed by hand or by mechanical crushing.

7. The method for extracting water lily hydrosol according to claim 5, characterized in that, The water lily mentioned is either 'Doris' or 'Purple Ninth Grade'.

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