Preparation method and application of difunctional gardenia gel

Abstract

The invention discloses a preparation method of difunctional cape jasmine gel, and the gel system comprises the following components in parts by mass: 0.5-2.5% of cape jasmine extract and 50-70% of cane sugar, and the pH value is adjusted to 1.5-2.5 by using citric acid. Through directional extraction and gelation design of the gardenia waste residues, efficient utilization of waste resources is achieved, the functional gel which has controllable rheological characteristics and is adaptive to 3D printing is developed, and the functional gel has remarkable technical advantages and application potential in the fields of food industry (personalized nutritious food and swallowing supplementary food) and sustainable manufacturing.

Description

Technical Field

[0001] The present invention belongs to the technical field of gels, and particularly relates to a preparation method and application of a bifunctional gardenia gel. Background Art

[0002] Gardenia jasminoides J.Ellis belongs to the genus Gardenia of the Rubiaceae family and is a plant with both edible and medicinal uses. The fruits of Gardenia jasminoides are rich in effective ingredients such as oil, pectin, iridoids, diterpenes, flavonoids, and organic acids, and have dual uses of food and medicine. The oil content of Gardenia jasminoides fruits is about 20%, comparable to that of olives and soybeans, and has the potential to be a high-end oil source. The main fatty acid components of Gardenia jasminoides oil include linoleic acid, oleic acid, and palmitic acid, which are beneficial to health, such as regulating blood pressure, reducing serum cholesterol levels, and regulating lipid metabolism. Therefore, Gardenia jasminoides oil has gained considerable favor among consumers.

[0003] At present, the by-product of Gardenia jasminoides oil extraction - Gardenia jasminoides waste residue - is treated as waste, causing serious waste of resources and environmental pollution. The Gardenia jasminoides waste residue still contains high-value substances such as pectin and crocin. Among them, pectin is a widely used emulsifier, stabilizer, and thickener. As an important soluble dietary fiber, it has various beneficial biological activity characteristics for human health, such as reducing cholesterol levels, promoting intestinal peristalsis, and promoting fat metabolism; crocin is a natural coloring agent and food additive, which has the effects of protecting nerves and enhancing memory. In order to improve the added value of Gardenia jasminoides waste residue, it is necessary to implement a recycling strategy for Gardenia jasminoides waste residue to convert waste into valuable resources.

[0004] Using the extract of Gardenia jasminoides waste residue to prepare gels expands the application of Gardenia jasminoides in the food industry, increases the added value of Gardenia jasminoides, and improves the social benefits of Gardenia jasminoides in terms of economic and ecological benefits. The prepared Gardenia jasminoides gel can be pattern-customized according to aesthetic preferences through 3D printing, and can easily achieve the production of foods with delicate shapes and unique structures, meeting the pursuit of consumers.

[0005] How to recycle Gardenia jasminoides waste residue, use the extract to prepare gels and apply them to 3D printing is the key issue to improve the value of Gardenia jasminoides waste residue and broaden the application of Gardenia jasminoides. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art to some extent. For this purpose, the present invention provides a preparation method and application of a bifunctional gardenia gel.

[0007] According to one aspect of the present invention, a preparation method of a bifunctional gardenia gel is provided. The gel system, by mass fraction, includes: 0.5 - 2.5% of gardenia extract, 50 - 70% of sucrose, and the pH is adjusted to 1.5 - 2.5 using citric acid. The remaining component is water.

[0008] Preferably, the preparation method of the gardenia extract includes: mixing gardenia waste residue with water, heating for extraction, rotary evaporation and then freeze-drying to obtain the gardenia extract (GJW).

[0009] Preferably, the material-liquid ratio is 1:15 - 1:25, the heating temperature is 70 - 90 °C, and the heating time is 60 - 120 minutes. If the material-liquid ratio is too high, the extraction is incomplete and the extraction efficiency is low. If the material-liquid ratio is too low, the workload of subsequent treatment will increase, and the rotary evaporation will consume too much time.

[0010] Preferably, the preparation method of the gardenia extract includes: successively extracting gardenia waste residue with ethyl acetate, absolute ethanol and water, mixing the extracts, rotary evaporation and then freeze-drying to obtain the gardenia extract (GJM).

[0011] Preferably, the material-liquid ratio is 1:15 - 1:25, ethyl acetate and absolute ethanol are extracted at room temperature for 60 - 120 minutes; water extraction is carried out at 70 - 90 °C for 60 - 120 minutes.

[0012] Preferably, (1) heating the gardenia extract in water to fully dissolve it; (2) adding sucrose to the solution in step (1) and heating to fully dissolve it; (3) adding citric acid to the solution in step (2) to adjust the pH.

[0013] Preferably, the heating temperature in steps (1), (2) and (3) is 70 - 90 °C, the heating time in step (1) is 5 - 10 min, the heating time in step (2) is 5 - 10 min, and the heating time in step (3) is 2 - 5 min. In the experiment, it was observed that if the heating time is too short, the solute cannot be completely dissolved, and if the heating time is too long, excessive evaporation of water in the system may occur. This time range is the preferred solution.

[0014] Preferably, the gardenia extract contains the gelling agent pectin and the natural pigment crocin.

[0015] According to another aspect of the present invention, a 3D printing method is provided. Using the above-mentioned gardenia extract as a raw material, the printing temperature is set at 25 °C, the printing pressure is adjusted to 0.4 - 0.6 MPa, and the printing speed is 6 - 10 mm / s.

[0016] In view of the above problems, the present invention provides a method for preparing a bifunctional gardenia gel and its application. Through the directional extraction and gelation design of gardenia waste residues, the present invention realizes the efficient utilization of waste resources, develops a functional gel with controllable rheological properties suitable for 3D printing, and has significant technical advantages and application potential in the food industry (personalized nutritional foods, swallowing assistance foods) and the field of sustainable manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0018] Figure 1 shows the appearance of GJWG under different conditions (A); steady shear scanning diagrams of GJWG with different GJW contents (B), sucrose contents (C), and pH values (D); the appearance of GJMG under different conditions (E); steady shear scanning diagrams of GJWG with different GJW contents (F), sucrose contents (G), and pH values (H).

[0019] Figure 2 shows the dynamic frequency scanning diagrams of GJMG with different GJM contents (A), sucrose contents (B), and pH values (C); dynamic frequency scanning diagrams of GJMG with different GJM contents (D), sucrose contents (E), and pH values (F).

[0020] Figure 3 shows the schematic diagrams of the 3D printing behaviors of GJWG and GJMG provided according to the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The following listed embodiments are for those skilled in the art to better understand the present invention. It should be noted that the following embodiments do not limit the protection scope required by the present invention and are only illustrative embodiments. The raw materials, reagents, or devices mentioned in the following embodiments can be obtained from commercial channels or through known existing methods without special instructions.

[0022] Example 1

[0023] Extraction of Gardenia Extract (GJW) from Gardenia Waste Residues

[0024] Gardenia jasminoides Ellis was purchased from Shanghai Tonghanchuntang Chinese Herbal Pieces Co., Ltd. (batch number: 180528). After removing the shells, the Gardenia jasminoides Ellis was pressed for 10 minutes at 10 Mpa and 60 °C using a press. The residue of Gardenia jasminoides Ellis after oil extraction was mixed with waste Gardenia jasminoides Ellis shells, which was the Gardenia jasminoides Ellis waste residue. The key indicators of the content of residual active ingredients were shown in Example 4. The Gardenia jasminoides Ellis waste residue was pulverized and passed through a 24-mesh sieve. Gardenia jasminoides Ellis powder (10 g) was extracted with 200 mL of water at 90 °C for 2 h. After cooling, it was centrifuged at 5000 rpm for 10 min at room temperature. The supernatant was rotary evaporated at 40 °C and 80 mbar, frozen at -80 °C for 12 h, then placed in a freeze dryer and dried at -70 °C for 48 h to obtain the water extract GJW.

[0025] Example 2

[0026] The present invention aims to efficiently recover valuable pectin and crocin in the Gardenia jasminoides Ellis waste residue, as well as extract and utilize other small molecules with antioxidant properties such as chlorogenic acid, rutin, and geniposide in the Gardenia jasminoides Ellis waste residue. Among them, pectin is extracted with water, while small molecules are extracted with organic solvents. To achieve the purpose of the present invention, two extraction methods of water extraction and sequential extraction with ethyl acetate - ethanol - water are used for extraction and comparison, and a highly efficient and economical extraction method is preferably selected.

[0027] Extraction of Gardenia jasminoides Ellis extract (GJM) from the Gardenia jasminoides Ellis waste residue

[0028] 10 g of the Gardenia jasminoides Ellis waste residue powder was poured into 200 mL of ethyl acetate, stirred at 25 °C for 2 h, and centrifuged (5000 rpm, 10 min). Subsequently, 200 mL of absolute ethanol was used to extract the precipitate in the same manner. After drying the centrifuged precipitate after ethanol extraction, it was extracted with 200 mL of water at 90 °C for 2 h, centrifuged at 5000 rpm for 10 min at room temperature, and the supernatant was collected. The supernatants extracted with ethyl acetate, absolute ethanol, and water were mixed, rotary evaporated at 40 °C and 80 mbar, frozen at -80 °C for 12 h, then placed in a freeze dryer and dried at -70 °C for 48 h and collected, named GJM.

[0029] Example 3

[0030] Preparation of Gardenia gel

[0031] GJW was dispersed in water, stirred at 70 °C for 5 min, then sucrose was added and heated until completely dissolved. Then, the pH of the solution was adjusted with citric acid and stirred for 5 minutes, and it was placed at 4 °C for 4 h. The final compositions of GJWG were 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% (w / w) GJW and sucrose (50%, 55%, 60%, 65%, 70% w / w), and the pH values were 1.5, 2.0, and 2.5 respectively. Except for using GJM which was different from the above, GJMG was prepared using the same preparation method as GJWG.

[0032] Example 4

[0033] Comparison between GJW and GJM

[0034] (1) Comparison of small molecules in GJW and GJM

[0035] Crocin is the main component of gardenia yellow pigment. The contents of crocin in GJW and GJM were determined by LC-MS analysis. Quantitative analysis was carried out using an Agilent QQQ mass spectrometer (6490), and quantitative analysis was achieved by electrospray ionization in the negative ion mode and dynamic multiple reaction monitoring (MRM) mode. The MS parameter settings were as follows: capillary voltage was 3000 V, sheath gas temperature was 225 °C, and flow rate was 12 L / min. An ACQUITY UPLC@BEH C18 column (2.1×100 mm, 1.7 μm) was used. The mobile phase consisted of (A) an aqueous solution of 0.1% formic acid and (B) an acetonitrile solution of 0.1% formic acid. The mobile phase gradient was: 0 - 1 min: 15% B, 1 - 3 min: 15% - 22% B, 3 - 6 min: 22% - 30% B, 6 - 8 min: 30% - 95% B, 8 - 10 min: 95% - 95% B. It was found that the contents of crocin in GJW and GJM were 5.33 ± 0.30 and 3.01 ± 0.05 mg / g, respectively. The extraction rates of crocin by water extraction and sequential extraction with three solvents were 0.173 ± 0.003% and 0.117 ± 0.002%, respectively.

[0036] (2) Comparison of pectin in GJW and GJM

[0037] The 50 mg / mL GJW solution and GJM solution were precipitated overnight with 3 volumes of absolute ethanol, respectively. The alcohol-insoluble solid part was washed several times with absolute ethanol, frozen at -80 °C for 12 h, then placed in a freeze dryer, dried at -70 °C for 48 h, and then collected and freeze-dried to obtain pectin. The pectin content in the extract was weighed and calculated. The completely dried sample was mixed with KBr and pressed into a tablet for FT-IR spectrum collection. The scanning range was 500 to 4000 cm-1, and the resolution was 4 cm -1 . For the FT-IR spectrum of pectin, the baseline was automatically corrected using OMNIC 9.2 and then smoothed. The Peakfit 4.2 software was used to perform second derivative on the 1900 - 1500 cm -1 spectral region, and calculate 1749 cm -1 and 1630 cm -1The peak area at [location], calculate DE. Through water extraction and sequential extraction with three solvents, it was found that the pectin contents of GJW and GJM were 27.20 ± 0.10% and 20.80 + 0.53% respectively, and the pectin extraction rates from gardenia waste residue were 8.90 ± 0.13% and 8.08 ± 0.13% respectively. Through FTIR analysis, with the Area1749 / (Area1749 + Area1630) of the standard sample as the x-axis and DE as the y-axis, the equation y = 93.387x - 0.897 was derived, and the R 2 value was 0.9984. The pectins obtained from GJW and GJM were named GJWP and GJMP respectively, with DE values of 63.51% and 60.91% respectively, and both were high-methoxyl pectins (HMP)( Figure 2 ). Pectin has excellent gelling properties and can form gels. However, the DE of pectin affects the conditions required for gel formation. Specifically, HMP requires a low pH value and a high sugar concentration to form gels.

[0038] Example 5

[0039] Rheological properties of GJWG and GJMG

[0040] Under the condition of pH 2.0, gels were prepared with 60% (w / w) sucrose and 0.5% - 2.5% (w / w) GJW to evaluate the effect of GJW content on the properties of GJWG. At pH 2.0, GJWG containing 1.5% (w / w) GJW and sucrose content of 50% - 70% (w / w) was prepared to evaluate the effect of sucrose content on the rheological properties of GJWG. GJWG composed of 1.5% (w / w) GJW and 60% sucrose was prepared, and the pH was adjusted from 1.5 to 2.5 to study the effect of pH on the rheological behavior of GJWG. GJMG was studied by the same method as GJWG for the effects of GJM content, sucrose content and pH on its rheological properties.

[0041] (1) Apparent viscosity

[0042] The rheological properties of GJWG and CJMG were measured using a rheometer (Haake Mars40, Germany), equipped with a 40 mm parallel plate geometry (gap of 1 mm). Steady shear scans were performed at 25 °C with a shear rate range of 1 - 1000 s -1 , to measure the apparent viscosity. By comparing the steady shear flow behaviors of GJWG and GJMG, the effects of GJW or GJM, sucrose and pH on the rheological properties of the samples were analyzed( Figure 1)。The apparent viscosities of GJWG and GJMG decrease with the increase of shear rate, indicating that they are both typical pseudoplastic fluids. The stable shear process destroys the entanglement of pectin chains, resulting in shear thinning. Research shows that foods that rapidly lose viscosity at a shear rate are easier to swallow. The apparent viscosity increases with the increase of GJW and GJM( Figure 1 B、 Figure 1 F). With the increase of sucrose concentration, the apparent viscosities of GJWG and GJMG increase, which may be due to the hydrophilic groups of sucrose competing with water molecules and reducing the water activity( Figure 1 C、 Figure 1 G). With the increase of pH value, the apparent viscosities of GJWG and GJMG increase( Figure 1 D, Figure 1 H).

[0043] (2) Viscoelasticity

[0044] At 25 °C, dynamic viscoelastic scanning was carried out using a strain of 1%, and the storage modulus (G') and loss modulus (G") were recorded when the oscillation frequency varied from 1 to 100 rad s -1 −1. Figure 2 Shows G' and G″ of GJW and GJM samples at different concentrations. With the increase of scanning frequency, both G' and G″ of the two gels increased to varying degrees. In the concentration range of 0.5% to 2.5% GJW, GJWG always showed G' greater than G″, indicating that gelation occurred at all concentration levels( Figure 2 a). For GJMG with a concentration of 0.5% GJM, G' was less than G″. In the concentration range of 1% - 2.5% GJM, G' of GJW exceeded G″, indicating that the gelling property of GJW was better than that of GJM( Figure 2 d). The concentrations of both GJW and GJM were 1.5% to further study the effects of pH value and sucrose content on the gel properties. At different sucrose contents, G' was greater than G″, indicating that GJWG and GJMG had typical gel behaviors. With the increase of sucrose concentration, the viscoelasticity of GJWG and GJMG first increased and then decreased. With the decrease of pH value, G' and G″ of the samples increased. The acidic environment made the molecules in the samples entangle more tightly together, resulting in an increase in pectin viscosity( Figure 2 c and Figure 2 f).

[0045] Example 6

[0046] 3D printing technology

[0047] 3D printing was carried out using the Regenovo 3D Bio-Architect@PRO instrument, which directly supports the STL format. The printing conditions were as follows: the printing temperature was set at 25 °C, the printing pressure was adjusted to 0.4 MPa, and the printing speed was 8 mm / s. The gel composition was 1.5% GJW, 60% sucrose, and pH = 2. 3D food printing technology, as an emerging food processing method, allows customization according to personal aesthetic preferences. This technology can also be used to produce specially designed foods that are easy to chew. Rheological tests provide predictive insights into the effectiveness of 3D printing to a certain extent. The shear-thinning property of the material is crucial for ensuring smooth extrusion from the nozzle. Flow stress is an indicator of the extrusion difficulty. G' and G” obtained from the frequency sweep test indicate the self-supporting ability of the material after printing. GJWG has better rheological properties, so GJWG was selected for 3D printing. Nine patterns, such as hexagon, heart, circle, taiji diagram, butterfly, little dolphin, lattice, duck, and must, were selected for printing( Figure 3 ). The surface structures of all printed patterns were smooth. The gel not only retained the original nutrients and flavors but also exhibited typical shear-thinning behavior, making it suitable for food-related 3D printing applications. Additionally, gardenia waste residue was selected as the raw material, and the gardenia extract extracted with water as the solvent has dual functions of gel formation and coloring, which is economical, green, and environmentally friendly. The printed 3D gel has a sour and sweet taste due to the presence of sucrose and citric acid, meeting the taste requirements of the general public.

[0048] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a bifunctional gardenia gel, characterized in that, The gel system, by mass fraction, comprises: 0.5-2.5% of gardenia extract, 50-70% of sucrose, and the pH is adjusted to 1.5-2.5 with citric acid.

2. The preparation method according to claim 1, characterized in that, The preparation method of the gardenia extract comprises: mixing gardenia waste residue with water, heating for extraction, rotary evaporation and then freeze-drying to obtain the gardenia extract.

3. The preparation method according to claim 2, characterized in that, The material-liquid ratio is 1:15-1:25, the heating temperature is 70-90 °C, and the heating time is 60-120 minutes.

4. The preparation method according to claim 1, characterized in that, The preparation method of the gardenia extract comprises: sequentially extracting gardenia waste residue with ethyl acetate, absolute ethanol and water, mixing the extracts, rotary evaporation and then freeze-drying to obtain the gardenia extract.

5. The preparation method according to claim 4, characterized in that The material-liquid ratio is 1:15-1:25, ethyl acetate and absolute ethanol are extracted at room temperature, and the extraction time is 60-120 minutes; water extraction is carried out at 70-90 °C, and the extraction time is 60-120 minutes.

6. The preparation method according to claim 1, characterized in that, Comprises: (1) Dissolving the gardenia extract according to any one of claims 2 to 5 in water by heating; (2) Adding sucrose to the solution in step (1) and heating to dissolve; (3) Adding citric acid to the solution in step (2) and heating to dissolve to adjust the pH.

7. The preparation method according to claim 6, characterized in that, The heating temperatures in steps (1), (2) and (3) are 70-90 °C, the heating time in step (1) is 5-10 min, the heating time in step (2) is 5-10 min, and the heating time in step (3) is 2-5 min.

8. The preparation method according to claim 1, wherein, The gardenia extract contains the gelling agent pectin and the natural pigment crocin.

9. A 3D printing method, characterized in that, Using the gardenia extract according to any one of claims 2 to 5 as a raw material, setting the printing temperature to 25 °C, adjusting the printing pressure to 0.4-0.6 MPa, and the printing speed to 6-10 mm / s.

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