Method for incorporating phenolic compounds extracted from plant waste into aerogels using supercritical technology and aerogel with incorporated phenolic compounds

Abstract

The present invention provides methods and formulations constituting novel systems for the controlled release of bioactive compounds. Systems for releasing bioactive compounds are an area of interest and research aimed at developing new health-promoting products. Thus, the present invention discloses a method for incorporating a phenolic compound extract into amide aerogels, wherein the phenolic compounds are incorporated into the aerogels of the present invention using supercritical impregnation technology. Also disclosed is the aerogel with incorporated phenolic compounds obtained using this invention. Thus, the present invention relates to the field of phenolic compound-containing compositions with applications in sectors such as food, cosmetics and pharmaceuticals.

Description

"METHOD FOR INCORPORATING PHENOLIC COMPOUNDS EXTRACTED FROM VEGETABLE RESIDUE INTO AEROGELS USING SUPERCRITICAL TECHNOLOGY AND AEROGEL INCORPORATED WITH PHENOLIC COMPOUNDS" FIELD OF THE INVENTION

[0001] The present invention discloses methods for incorporating phenolic compounds into starch aerogels, wherein the incorporation of the phenolic compounds occurs through supercritical impregnation technology. Furthermore, the aerogel incorporated with phenolic compounds obtained by the method of the present invention is disclosed.

[0002] Thus, the present invention falls within the field of compositions containing phenolic compounds with applications in areas such as food, cosmetics and pharmaceuticals. FUNDAMENTALS OF THE INVENTION

[0003] Phenolic compounds, also known as phenolic compounds, are a class of chemical compounds widely found in plants, which are known for their antioxidant properties. They play a crucial role in protecting plants against environmental stresses, such as ultraviolet radiation and pathogen attacks. In addition, phenolic compounds have been associated with human health benefits, including reducing the risk of chronic diseases, such as cardiovascular disease, some cancers, and degenerative diseases.

[0004] Thus, phenolic compounds have become an area of ​​growing interest in the food industry, aiming at the development of new food ingredients that promote health.

[0005] However, considering the instability of phenolic compounds, the use of biomaterials as carriers of phenolic compounds has been presented as an alternative to provide chemical and biological stability. Therefore, one approach that has been investigated is the incorporation of these phenolic compounds in controlled release systems of bioactive compounds, for example, from the incorporation of phenolic compounds in biopolymers.

[0006] The state of the art reveals incorporation of phenolic compounds into biopolymers through encapsulation techniques, such as spray-drying, freeze-drying, extrusion, complex coacervation, molecular inclusion, supercritical antisolvent and rapid expansion of supercritical solution.

[0007] However, these techniques have deficiencies such as the use of organic solvents, use of high temperatures, restricted use of certain polymers, long dehydration periods, difficulties in scaling up, and an unstable final product with the potential for agglomeration.

[0008] Thus, an alternative for the incorporation of phenolic compounds into biopolymer matrices would be through supercritical impregnation.

[0009] However, supercritical impregnation is mainly used to incorporate nonpolar compounds into polymers, given the high affinity of these compounds with supercritical CO2. Consequently, the use of the supercritical impregnation technique for polar compounds is difficult, at least because of the affinity between the material to be impregnated and CO2, due to its polarity.

[0010] Furthermore, regarding the biopolymers used as polymeric matrices for the development of phenolic compound release systems, aerogels are candidates, which are structured materials with high porosity and low density, with advanced physical and chemical properties. Aerogels are produced by removing the agents that expand a hydrogel, so that its structure and volume remain preserved.

[0011] Aerogels can be formed from inorganic polymers, synthetic polymers, or biological materials such as starch. In particular, starch aerogels are attractive due to their availability, sustainability, and low cost.

[0012] Among these possible applications of aerogels, the incorporation of active compounds into starch-based aerogels represents an interesting approach, as it preserves the bioavailability of the compound, protecting it from extrinsic factors, which guarantees control of its release.

[0013] Although several works have investigated different starch sources (e.g., potato, corn, cassava, pea, and wheat) to produce aerogels for bioactive compound delivery system applications, most works on supercritical impregnation focus on drug loading and the formulation of active packaging materials.

[0014] For example, patent application WO2022223861 discloses supercritical impregnation of pharmacologically active products, being restricted to the pharmaceutical field. Furthermore, the article by Franco et al. (2018), entitled "SUPERCRITICAL ADSORPTION OF QUERCETIN ON AEROGELS FOR ACTIVE PACKAGING APPLICATIONS", published in Industrial & Engineering Chemistry Research, is restricted to applications in active packaging.

[0015] Furthermore, the use of supercritical impregnation to deliver bioactive components into starch aerogels has been reported only a few times, and yet most studies are restricted to compounds of apolar nature. For example, the paper by Dias et al. (2022) , entitled "ROLE OF SUPERCRITICAL CO 2 IMPREGNATION VARIABLES ON B-CAROTENE LOADING INTO CORN STARCH AEROGEL PARTICLES", despite presenting supercritical impregnation of bioactive compounds in a starch aerogel, is restricted to the incorporation of an apolar compound (beta carotene) and does not mention any application for compounds of a polar nature. Similarly, patent US11369895B discloses starch aerogel nanoporous impregnated with phytosterol nanoparticles, which is also a nonpolar compound.

[0016] The use of supercritical impregnation for polar compounds has even been investigated, as in the studies by Viganó et al. (2020) , and in patent application W02020018759; however, these studies use supercritical CO2 only in one stage of the preparation, for example the drying stage. For example, the article Viganó et al. (2020) , entitled "IMPREGNATION OF PASSION FRUIT BAGASSE EXTRACT IN ALGINATE AEROGEL MICROPARTICLES", even reveals the impregnation of phenolic compounds in aerogel matrices; however, this article mentions that the use of the supercritical CO2 impregnation technique is influenced by the solubility of the compounds of interest in supercritical CO2, so that low solubility may be a limiting factor for this process. Furthermore, this article uses the wet impregnation technique to perform the impregnation of phenolic compounds. In this technique, supercritical technology is used only as a drying step.Similarly, patent application W02020018759 also employs the wet impregnation technique, which uses supercritical technology only in the drying stage; so that contributions from the adsorption phenomenon during impregnation are discarded.

[0017] Therefore, there is a lack of information on the use of supercritical impregnation to incorporate phenolic compounds, which have a polar nature, into starch aerogels.

[0018] Therefore, the present invention presents methods and formulations related to the supercritical impregnation of phenolic compounds in starch aerogels. The present invention represents an improvement of the techniques commonly used, since the invention does not require the use of organic solvents, has high diffusion rates, promotes the incorporation of compounds through adsorption and precipitation. In addition, the method of the present invention presents ease of scale-up, modulation of the loading of the compounds from the operational parameters, so that it represents an improvement of what is commonly used in the industry. BRIEF DESCRIPTION OF THE INVENTION

[0019] Firstly, it should be noted that the following description is based on the preferred embodiments of the invention, without being limited by them.

[0020] The present invention aims to develop a system for releasing bioactive compounds that does not use solvents and that promotes the incorporation of compounds through adsorption and precipitation. Thus, the present invention provides methods for incorporating phenolic compounds into starch aerogels, in which the incorporation of phenolic compounds occurs through supercritical impregnation technology. In addition, the present invention discloses the aerogel incorporated with phenolic compounds obtained by the method of the present invention.

[0021] Thus, in one embodiment of the present invention, the phenolic compounds to be incorporated into the aerogel are phenolic compounds obtained from the residue of a vegetable, preferably, in which the polar phenolic compounds are obtained from the extract of yellow passion fruit bagasse.

[0022] In one embodiment of the invention, the aerogel to be incorporated is starch aerogel, preferably wherein the aerogel is cornstarch aerogel. In a further embodiment of the invention, the aerogel is in the form of aerogel particles.

[0023] Furthermore, since phenolic compounds come from passion fruit bagasse and aerogels are produced from corn starch, the present invention has application in the development of functional foods.

[0024] Thus, the present invention provides methods for incorporating phenolic compounds into an aerogel matrix comprising the steps of (i) extraction of phenolic compounds from plant residue; (ii) formulation of the aerogel; and (iii) incorporation of the extracted phenolic compounds into the aerogel; wherein the incorporation occurs using supercritical CO2 technology. Additionally, the present invention provides starch aerogel formulations incorporated with phenolic compounds obtained by said incorporation method. BRIEF DESCRIPTION OF THE FIGURES

[0025] For a better understanding of the nature and objectives of the present invention, in order to assist in identifying the main characteristics of the composition of the present invention and its technical results and effects, the figures to which reference is made are presented as follows:

[0026] Figure 1 represents a graph showing values ​​for the oxygen radical absorption capacity (ORAC), iron reducing power (FRAP) and total phenolic content (TPC) of passion fruit bagasse compounds impregnated in cornstarch aerogels by supercritical fluid impregnation (SFI) at different pressures (22.5, 30.0 and 37.5 MPa) and temperatures (45, 55 and 65 °C).

[0027] Figure 2 shows the values ​​of the ORAC / TPC and FRAP / TPC ratio of the defatted passion fruit bagasse extract (DPFB extract) and aerogel impregnated by SFI at 37.5 MPa and 65 °C.

[0028] Figure 3 presents the adsorption (dotted red line) and desorption (dotted blue line) isotherms for cornstarch.

[0029] Figure 4 shows the surface morphology images of cornstarch (a and b), pure cornstarch aerogel (ced) and cornstarch aerogels impregnated with defatted yellow passion fruit extract (eef) obtained by SFI at 37.5 MPa, 65 °C.

[0030] Figure 5 shows the influence of impregnation on the color of the aerogel (SFI at 65 °C and 37.5 MPa).

[0031] Figure 6(A) shows the X-ray diffraction pattern.

[0032] Figure 6(B) shows differential scanning calorimetry (DSC) thermograms of cornstarch, unimpregnated cornstarch aerogel and impregnated cornstarch aerogel under impregnation conditions: 37.5 MPa and 65°C. DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention discloses methods and compositions related to the incorporation of phenolic compounds into starch aerogels, in which the incorporation of the phenolic compounds occurs through impregnation with supercritical CO2.

[0034] The present invention proposes a method for incorporating phenolic compounds into biopolymers through the supercritical fluid impregnation (SEI) technique or supercritical impregnation.

[0035] The supercritical impregnation technique can be divided into three steps: First, the target compounds are dissolved in a supercritical fluid. The fluid used is usually carbon dioxide (CO2), since it is a non-toxic, generally recognized as safe (GRAS), environmentally sustainable solvent with moderate critical temperature and pressure. In the second step, mass transfer from the mixture (target compounds + solvent) to the solid material (adsorbent) occurs. Finally, the process is completed by depressurizing the system and removing the CO2 and non-impregnated compounds.

[0036] Furthermore, the use of CO2 in the supercritical state allows phenolic compounds to be incorporated selectively, with the participation of the adsorption phenomenon and the use of high diffusion rates, which represents an advantage compared to commonly used techniques. Furthermore, the present invention allows the modulation of the compounds of interest to occur based on adjustments in the operational parameters.

[0037] Furthermore, the present invention presents the advantage of using natural extracts from agro-industrial waste as sources of phenolic compounds, so that the present invention provides a more sustainable alternative, by representing a way of reusing material that would otherwise be discarded.

[0038] Thus, in one embodiment of the invention, the phenolic compounds to be incorporated into the aerogel biopolymer matrix are phenolic compounds obtained from the residue of a vegetable. In an additional embodiment of the invention, the phenolic compounds are obtained from the residue of strawberry, blackberry, plum, grape, jabuticaba, apple, pomegranate, cherry, raspberry, blueberry, passion fruit and yellow passion fruit, without limiting the scope of the invention. In a preferred embodiment of the present invention, the phenolic compounds are obtained from the extract of yellow passion fruit bagasse.

[0039] The bioactive compounds extracted from yellow passion fruit bagasse (Passiflora edulis Sims) (PFB) represent a potential source of phenolic compounds and antioxidants. Thus, in one embodiment of the invention, the step of obtaining the passion fruit bagasse extract is carried out.

[0040] The passion fruit bagasse extract of the present invention is obtained by dehydrating the yellow passion fruit bagasse in an oven at approximately 105 °C, until the bagasse has a constant weight. The yellow passion fruit bagasse is then ground and stored under refrigeration, protected from light. Subsequently, the supercritical fluid extraction (SEE) step is performed, with the aim of removing the fat from the yellow passion fruit bagasse. The supercritical fluid extraction occurs at a temperature of 35 ± 0.5 °C and a pressure of 40 ± 1 MPa.

[0041] To obtain passion fruit bagasse extract, a mass of defatted passion fruit bagasse is compacted in a stainless steel cell and coupled to the pressurized liquid extraction (PLE) unit. The extraction is carried out from the initial contact between the defatted passion fruit bagasse and the solvent (water and ethanol) at a pressure of 10 ± 1 MPa and a temperature of 75.0 ± 0.5 °C, in which the solvent has a water: ethanol mass ratio of approximately 1:1 to approximately 1:10; preferably at a ratio of 1:3; and, with a static time of 5 to 20 minutes, preferably 10 minutes. After the static time, the extract is collected for a period of 120 minutes. Subsequently, the total volume of the extract obtained is rotary evaporated, lyophilized and resuspended in ethanol (99%).

[0042] Thus, after obtaining the yellow passion fruit bagasse extract, the extract is stored in dark bottles, protected from light, for later use.

[0043] Furthermore, in one embodiment of the present invention, the aerogel is starch aerogel. In a further embodiment of the invention, the aerogel is selected from: potato, rice, cassava, pea, wheat or corn starch aerogel, without limiting the scope of the invention. In a preferred embodiment of the invention, the aerogel is corn starch aerogel.

[0044] Thus, in one embodiment of the present invention, a step of formulating the cornstarch aerogel is disclosed. The formulation of the cornstarch aerogel occurs from the steps of (1) preparation of the hydrogel; (2) exchange of solvents; and (3) supercritical drying.

[0045] Thus, the hydrogel preparation step occurs from two solutions. The first solution, solution I, is an aqueous suspension of starch (15% w / w) prepared with the aid of a magnetic stirrer (200 rpm, 25 °C, 15 min). In turn, solution II is obtained by mixing soybean oil and a nonionic surfactant, at a ratio of 2% w / w surfactant and 98% oil, in which the nonionic surfactant used can be sorbitan monooleate. The ratio between solution I and solution II is approximately 1:1, 1:2, 1:3, 1:4, 1:5, preferably where the mass ratio between solution I and solution II is 1:3.

[0046] The emulsion gelation process is initiated by slowly pouring solution II over solution I at a temperature of about 75 °C and rotation of about 600 rpm. After 120 min, stirring is stopped and the emulsion is kept at rest for approximately 90 min at 75.0 ± 0.5°C. In order to allow retrogradation of the cornstarch hydrogel, the emulsion is kept at 4.0 ± 0.5°C for 72 h. A volume of ethanol:water (30% v / v) is added to the retrograded solution and the mixture is transferred to a separatory funnel to remove the oil phase, followed by vacuum filtration through filter paper to remove excess water.

[0047] Solvent exchange is performed by immersing the hydrogel particles in ethanol / water mixtures (30, 60, 90, and 100%, v / v) with a ratio of 1:5 (particles / liquid mass) and an exchange frequency of 24 h.

[0048] The supercritical drying step is performed by transferring a mass of alcohol gel particles to a stainless steel container. The container is then closed and coupled to the SEE unit, where a temperature of 40.0 ± 1.0 °C is maintained for 5 min to stabilize the system. The system is then pressurized with CO2 until it reaches 12.0 ± 0.5 MPa, keeping this condition constant for a static time of 5 min. The CO2 output is regulated by macro and micrometric valves at a rate of approximately 10.0 g / min, and drying is completed when S / F 25 is reached, where S / F represents the mass of CO2 consumed over the mass of alcohol gel particles. Finally, the system is depressurized at a rate of approximately 1.5 MPa / min at approximately 40 °C until atmospheric pressure is reached. After depressurization, the starch aerogel particles are collected and stored until further use. Thus, in a further embodiment of the invention, the aerogel is in the form of aerogel particles. In a preferred embodiment of the invention, the aerogel particles have an average diameter of 10 to 30 micrometres, more preferably, the aerogel particles have an average diameter of 20 micrometres.

[0049] Furthermore, the present invention discloses impregnation of phenolic compounds in starch aerogel. Thus, in one embodiment of the present invention, supercritical impregnation steps using CO2 as supercritical fluid are disclosed.

[0050] In the present invention, supercritical impregnation is performed by placing a container containing aerogel inside a stainless steel cell coupled to the impregnation unit. Then, the extract containing phenolic compounds obtained from the vegetable residue is placed in contact with the walls of the stainless steel cell, so as to prevent contact of the extract with the aerogel. Prior contact between the extract and the aerogel must be prevented, so as to enable supercritical impregnation. In the present invention, the aerogel is present in a proportion of 0.01 g to 0.10 g of aerogel for 1 mL of extract containing phenolic compounds, preferably, the aerogel is present in a proportion of 0.05 g of aerogel for each mL of extract containing phenolic compounds. The impregnation cell is closed, previously heated (45 to 65°C) and pressurized (22 at 31.5 MPa), and the impregnation system is kept under static conditions for a period of approximately 120 minutes. After this time, the system is depressurized at an average fixed rate of approximately 1.3 MPa / min. After the system is depressurized, the particles impregnated with phenolic compounds are collected and stored away from light.

[0051] Impregnated aerogel particles have the advantage of facilitating the release of impregnated compounds, as well as simpler storage and stockpiling. Examples of implementation

[0052] In order to evaluate the supercritical impregnation of the present invention, tests were carried out to evaluate the effects of pressure and temperature on the impregnation of phenolic compounds from passion fruit bagasse in cornstarch aerogels. For this, the method was investigated considering three temperatures (45 °C, 55 °C and 65 °C) and three pressures (22.5 MPa, 30 MPa and 31.5 MPa), based on the results of total reducing capacity (TRC) and antioxidant capacity from the ferric ion reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) methods.

[0053] Furthermore, the physical characterization of aerogels impregnated with phenolic compounds was also carried out, in order to evaluate their potential use as controlled release systems for bioactive compounds.

[0054] The results were statistically evaluated and One-way analysis of variance (ANOVA) was performed using Tukey's test to assess significant differences at the 5% level. Example 1 - Obtaining phenolic compounds

[0055] Yellow passion fruit bagasse was dehydrated in an oven at 105 °C until constant weight, ground and stored under refrigeration, away from light. Subsequently, the supercritical fluid extraction (SEE) step was performed to remove fat from the yellow passion fruit bagasse at a temperature of 35 ± 0.5 °C and 40 ± 1 MPa. Then, 10 g of the defatted passion fruit bagasse was compacted in a stainless steel cell and coupled to the pressurized liquid extraction (PLE) unit. The extraction was performed from the initial contact between the defatted passion fruit bagasse and the solvent (1 / 3; water / ethanol) for a static time of 10 minutes, using a pressure of 10 MPa and a temperature of 75 °C. After the static time, the extract began to be collected in amber glass vials for a period of 120 minutes. Subsequently, the total volume of the extract obtained was rotary evaporated, lyophilized and resuspended in ethanol (99%).Finally, the extract was stored in dark bottles, protected from light, for later use. Example 2 - Aerogel Preparation

[0056] Initially, the cornstarch hydrogel was prepared from two solutions. Solution I, an aqueous suspension of starch (15% w / w) was prepared with the aid of a magnetic stirrer (200 rpm, 25 °C, 15 min) and solution II was obtained by mixing soybean oil and the nonionic surfactant Span® 80 (2% w / w). The ratio between solution I and solution II was 1:3. The emulsion gelation process was initiated by slowly pouring solution II over solution I at 75 °C and 600 rpm. After 120 minutes, the stirring was stopped, the emulsion was left to rest for 90 minutes and was stored at 4 °C for 72 h to allow retrogradation of the cornstarch hydrogel. 500 mL of ethanol / water (30% v / v) was added to the retrograded solution and the mixture was transferred to a separatory funnel to remove the oil phase, followed by vacuum filtration through filter paper to remove excess water.

[0057] The solvent exchange was performed by immersing the particles in ethanol / water mixtures (30, 60, 90, and 100%, v / v) with a ratio of 1:5 (particles / liquid mass) and an exchange frequency of 24 h. The last solvent exchange was repeated three times, keeping the particles in ethanol to perform supercritical drying and obtain the aerogel.

[0058] Finally, for supercritical drying, 25.0 g of alcohol gel particles, packaged in paper bags, were transferred to a 54.37 mL stainless steel container. The container was closed, coupled to the SFE unit, and the temperature of 40.0 ± 1.0 °C was maintained for 5 min to stabilize the system. Subsequently, the system was pressurized with CO2 until reaching 12.0 ± 0.5 MPa, keeping this condition constant for a static time of 5 min. The CO2 output was regulated by macro and micrometric valves. at a rate of 10.0 g / min and drying was completed when reaching S / F (mass of CO2 consumed / mass of alcohol gel particles) 25. Finally, the system was depressurized at a rate of 1.5 MPa / min at 40 °C until atmospheric pressure was reached. The aerogel particles were collected, packaged in airtight vials and stored in desiccators until further use. The prepared aerogel particles have an average diameter of 10 to 30 micrometers, preferably, the aerogel particles have an average diameter of 20 micrometers. Example 3 - Supercritical impregnation

[0059] Approximately 0.15 g of cornstarch aerogel was placed in a glass beaker (25 mm in diameter and 40 mm in height) and transferred into a stainless steel cell coupled to the impregnation unit. Soon after, 3 ml of defatted yellow passion fruit bagasse extract was placed on the cell walls, avoiding direct contact between the extract and the aerogel. In this example, the ratio between the amount of aerogel and the amount of extract was 0.05 g of aerogel / 1 mL of extract. The impregnation cell was closed, previously heated and pressurized, and the system was kept under static conditions for a period of 120 minutes. Subsequently, the depressurization step was started at an average fixed rate of 1.3 MPa / min, and finally, the impregnated particles were collected and stored away from light until further analysis. Effect of pressure and temperature on the impregnation of phenolic compounds from passion fruit bagasse in cornstarch aerogels.

[0060] The effect of temperature (45 °C, 55 °C and 65 °C) and pressure (22.5 MPa, 30 MPa and 31.5 MPa) used in supercritical impregnation was evaluated from the results of total reducing capacity (TRC) and antioxidant capacity from the methods of ferric ion reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC).

[0061] For this purpose, an extraction step was performed to recover the phenolic compounds impregnated in the aerogels. This step involved immersing the impregnated aerogel in 50% ethanol, in a ratio of 0.05:1 (w / v), homogenizing in a magnetic stirrer for 15 minutes and using a filter to remove the aerogel particles. Finally, the impregnated aerogel extract was used in the TPC, ORAC and FRAP analyses.

[0062] The effects of pressure and temperature are presented in Figure 1. The pressure and temperature ranges were chosen to ensure the possible presence of heat-sensitive phenolic compounds, while also respecting the unit's safety pressure limits (40 MPa). Regarding pressure, it was identified that an isothermal increase from 22.5 to 37.5 MPa at 65 °C increased the TPC, ORAC and FRAP values. On the other hand, this trend was not observed at 45 and 55 °C. The positive effect of pressure on TPC, FRAP and ORAC is related to the concentration of phenolic compounds in supercritical CO2 (SC-CO2), that is, to the partition coefficient. Higher pressure increases the partition coefficient for the aerogel, favoring the impregnation of phenolic compounds in the aerogel. At higher pressures, the solubility of these compounds increases, and the diffusion of the active compound is facilitated due to the swelling of the pores of the polymer matrix.

[0063] However, an opposite behavior was observed in the TPC and FRAP results at 45 °C, in which the pressure increased from 22.5 to 30.0 MPa and from 30.0 to 37.5 MPa. This behavior may have two reasons: the first is the decrease in CO2 diffusivity caused by the increase in pressure; and the second is given by the interactions between all agents involved in the SEI. If the interaction between SC-CO2 and target compounds is stronger than that between target compounds and matrix, the target compounds will be dragged in the final step of the process and will not be impregnated in the matrix.

[0064] Under isobaric conditions (37.5 MPa), TPC and FRAP increased with temperature, although ORAC remained stable when the temperature increased from 45 to 55 °C. Opposite behaviors were observed for TPC at a pressure of 22.5 MPa when increasing the temperature from 45 to 55 °C. For this same temperature range, FRAP increased in the isobaric condition of 30.0 MPa. A possible explanation for such different behaviors is the presence of crossover regions, in which above this region, the temperature affects positively affects the solubility of the active compound, which is driven by vapor pressure, suppressing the impact of the decrease in SC-CO2 density. Likewise, below this region, the effect of the decrease in density given by the increase in temperature prevails. In the example of the present invention, the temperature / pressure combination at 65 °C / 37.5 MPa provided the best impregnation, with values ​​of 0.462 mg EAG / g for TPC, 0.687 ± 0.030 mg TE / g for FRAP and 0.564 mg TE / g for ORAC. These results suggest that the experiments were performed above the crossover region.

[0065] Thus, the results found reveal the importance of evaluating the SEI variables in the adsorption / precipitation efficiency of active compounds with low affinity for SC-CO2, such as phenolic compounds from yellow passion fruit bagasse. The study of parameters such as pressure and temperature allows the selection of conditions that provide improved results so that the compounds of interest are impregnated in the aerogel matrix.

[0066] Comparing the values ​​obtained under the worst and best impregnation conditions, there was an increase of 270.6% in the TPC content, 328.6% in the FRAP antioxidant capacity and 655.8% in the ORAC antioxidant capacity.

[0067] In order to verify whether the antioxidant capacity of the impregnated aerogel extract remains the same as that of the defatted yellow passion fruit bagasse extract, the relationship between the hydrophilic ORAC (h-ORAC) / TPC and FRAP / TPC values, calculated for the aerogels impregnated at 65 °C and 37.5 MPa (the best condition obtained for impregnation) and for the defatted yellow passion fruit bagasse extract. The h-ORAC / TPC and FRAP / TPC ratios are quantitative strategies to evaluate the maintenance of the antioxidant capacity of the phenolic compounds impregnated in the aerogel compared to the phenolic compounds present in the extract. For this, we divided the value obtained in the ORAC analysis by the value of the TPC analysis and similarly for the FRAP / TPC.

[0068] Thus, the results presented in Figure 2 indicate that SFI (65 °C, 37.5 MPa) did not decrease the antioxidant capacity, reinforcing that SFI was effective in maintaining the antioxidant capacity of the extract in cornstarch aerogels. The observed antioxidant capacity is probably related to several phenolic compounds present in passion fruit bagasse, such as phenolic acids, flavonoids, stilbenes, carboxylic acids, and phenolic aldehydes.

[0069] However, among the identified phenolic compounds, the stilbene piceatannol deserves to be highlighted, since, in addition to having several biological activities, it has a fundamental contribution to the antioxidant capacity of the passion fruit bagasse extract. Physical Characterization

[0070] The physical characterization was performed on cornstarch, raw aerogel and impregnated aerogel, which obtained the best result according to the analyses of total reducing capacity and antioxidant capacity (37.5 MPa, 65 °C).

[0071] Nitrogen adsorption / desorption measurements were performed using 100 mg of sample. Prior to analysis, the samples were heated at 60 °C under vacuum for 15 h. Nitrogen adsorption / desorption isotherms were performed at 77.3 K. The BET model (Brunauer, Emmett, and Teller - Stephen Brunauer, P. H. Emmett, and Edward Teller Journal of the American Chemical Society 1938 60 (2) , 309–319 DOI: 10.1021 / j a01269a023 ) was used to calculate the specific surface area using a multipoint model (relative pressure range 0.05–0.3). The BJH model (Barrett, Joyner and Halenda - Elliott P. Barrett, Leslie G. Joyner, and Paul P. Halenda Journal of the American Chemical Society 1951 73 (1) , 373-380 DOI: 10.1021 / j aOl 145al26 ) was used to calculate the pore size distribution (relative pressure less than 0.3).

[0072] The surface area, pore volume and mean pore diameter calculated from nitrogen adsorption / desorption measurements of cornstarch before and after aerogel preparation are shown in Table 1. Table 1: Surface properties of aerogels Pore ​​Area Volume Average Surface Pore Diameter (m 2 / g) (cm 3 / g) (nm) Cornstarch 9.873 0.016 not determined Unimpregnated aerogel 63.621 0.285 8.976 Impregnated cornstarch aerogel „ 1 OQ (65°C / 37.5 MPa) 51 ' 662 °' 129 4 ' 788

[0073] As can be seen, the production of aerogel from raw cornstarch revealed a 6.4-fold increase in surface area and 17.8-fold increase in pore volumes. The increase in surface area and pore volume of the aerogel demonstrates the potential use of aerogel as a carrier for bioactive compounds using SFI.

[0074] Furthermore, adsorption / desorption analysis revealed that supercritical impregnation of phenolic compounds from yellow passion fruit bagasse was obtained (Table 1). The decreases in surface area (from 63,621 to 51,662 m 2 / g), volume (from 0.285 to 0.129 cm 3 / g) and mean pore diameter (from 8.976 to 4.788 nm) of the particles indicate the loading of phenolic compounds into the mesopores of the cornstarch aerogel by SFI. Furthermore, the similarity of the hysteresis loop shapes of the aerogel before and after the SFI process (Figure 3) did not indicate a drastic change in the pore channel during the impregnation of phenolics from the defatted yellow passion fruit bagasse extract.

[0075] It is important to note that the applied conditions confirmed the success of SFI in loading phenolic compounds from DPFB extract into the aerogels.

[0076] The samples were also characterized by Scanning Electron Microscopy (SEM). The morphological analysis by SEM of the raw starch and starch aerogel before and after impregnation at 37.5 MPa and 65 °C is shown in Figure 4. As seen in Figure 4, the aerogel particles have an average diameter of 10 to 30 micrometers, preferably the aerogel particles have an average diameter of 20 micrometers. Thus, as can be seen, the granular and irregular structure of the starch remained after the aerogel and SFI production processes, suggesting that the main modifications occur inside the particles, as indicated by the increase in pore size and surface area. Furthermore, the impregnation process did not alter the overall morphology of the aerogel.

[0077] However, as can be seen in Figure 5, a visible change occurred in the color of the impregnated aerogel, which highlights, as well as the results discussed in the previous sections, the incorporation of phenolic compounds from the defatted yellow passion fruit bagasse extract into the aerogel.

[0078] The samples were also characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC), in which the presence of yellow passion fruit bagasse extract from SFI (65 °C, 37.5 MPa) was also verified.

[0079] The XRD patterns of cornstarch, unimpregnated aerogel, and impregnated aerogel are shown in Figure 6(A). The peaks for cornstarch showed a profile characteristic of type A starches, with clear peaks at 15°, 17°, 18°, 23° (20). Preparation of the aerogel caused the disappearance of the peak at 18° (20), a decrease in the intensity of the peaks at 15° and 17° (20), and the appearance of the peak at 20° (20). The disappearance or decrease of the The intensity of the peaks is possibly related to starch gelatinization, which promotes crystal dissolution and granule rupture. The appearance of the characteristic 20° peak (20) is related to the formation of the amylose-lipid complex and crystallites from retrogradation.

[0080] Considering that the present invention uses the water-in-oil emulsion technique for the formation of aerogels, the residual oil phase possibly formed a complex with amylose, promoting the appearance of the 20° peak (20). After SFI of the defatted yellow passion fruit bagasse extract, the peak at 15° (20) decreases moderately. This slight decrease in crystallinity can be attributed to the presence of phenolic compounds from the DPFB extract in the aerogel, which would be preventive, since this decrease indicates prevention of crystallization by the presence of the active compound. Furthermore, the DSC thermograms of the cornstarch, aerogel and impregnated aerogel samples are presented in Figure 6 (B). The samples presented similar behavior in the heat flow profile with increasing temperature, with endothermic peaks around 139° for starch and 125°C for non-impregnated aerogel and impregnated aerogel. It was possibly related to the dehydration and gelatinization of the starch.

Claims

CLAIMS 1. Method for incorporating phenolic compounds into an aerogel matrix characterized by the fact that it comprises the steps of (i) extraction of phenolic compounds from plant residue; (ii) formulation of the aerogel; and (iii) incorporation of the extracted phenolic compounds into the aerogel; in which the incorporation occurs through impregnation with supercritical CO2.

2. Method according to claim 1, characterized in that step (iii) incorporating extracted phenolic compounds into the aerogel comprises: a) placing a container containing aerogel inside a stainless steel cell, wherein the stainless steel cell is coupled to the supercritical impregnation unit; b) contacting the extract containing phenolic compounds with the walls of the stainless steel cell, wherein the aerogel is present in a proportion of 0.01 g to 0.10 g of aerogel for 1 mL of extract containing phenolic compounds, preferably wherein the aerogel is present in a proportion of 0.05 g of aerogel for 1 mL of extract containing phenolic compounds; c) closing the impregnation cell, wherein the impregnation cell is previously heated to a temperature of 45 to 65 °C; and wherein the impregnation cell is pressurized to a pressure of 22.5 to 31.5 MPa; d) maintain the impregnation cell in static conditions for 120 min; e) depressurization at an average fine rate of 1.3 MPa / min; and in which, after depressurization, the particles impregnated with phenolic compounds are collected.

3. Method according to claim 1 or 2, characterized in that the phenolic compounds are obtained from the residue of a vegetable.

4. Method according to any one of claims 1 to 3, characterized in that the phenolic compounds are phenolic compounds obtained from residue of strawberry, blackberry, plum, grape, jabuticaba, apple, pomegranate, cherry, raspberry, blueberry, passion fruit and yellow passion fruit, preferably, in which the phenolic compounds are obtained from the yellow passion fruit residue.

5. Method according to any one of claims 1 to 4, characterized in that the phenolic compounds are polar phenolic compounds.

6. Method according to any one of claims 1 to 5, characterized in that the phenolic compounds are selected from the group comprising phenolic acids, flavonoids, stilbenes, carboxylic acids and phenolic aldehydes.

7. Method, according to any of the claims 1 to 6, characterized in that the aerogel is starch aerogel.

8. Aerogel characterized by the fact that it is incorporated with phenolic compounds, in which the incorporation occurs through the method as defined in any one of claims 1 to 7.

9. Aerogel according to claim 8, characterized in that the aerogel is starch aerogel.

10. Aerogel, according to claim 8 or 9, characterized by the fact that the phenolic compounds incorporated in the aerogel are phenolic compounds obtained from the residue of a vegetable.

11. Aerogel, according to any one of claims 8 to 10, characterized by the fact that the incorporated phenolic compounds are phenolic compounds obtained from residue of strawberry, blackberry, plum, grape, jabuticaba, apple, pomegranate, cherry, raspberry, blueberry, passion fruit and yellow passion fruit, preferably, in which the phenolic compounds are obtained from the yellow passion fruit residue.

12. Aerogel according to any one of claims 8 to 11, characterized in that the incorporated phenolic compounds are polar phenolic compounds.

13. Aerogel according to any one of claims 8 to 12, characterized in that the incorporated phenolic compounds are phenolic compounds selected from the group comprising phenolic acids, flavonoids, stilbenes, carboxylic acids and phenolic aldehydes.

14. Aerogel according to any one of claims 8 to 13, characterized in that the phenolic compounds are incorporated into the aerogel through supercritical impregnation using supercritical CO2.

15. Aerogel according to any one of claims 8 to 14, characterized in that the aerogel is in the form of aerogel particles.

16. Aerogel according to any one of claims 1 to 15, characterized in that the aerogel has an average diameter of 10 to 30 micrometers, more preferably, the aerogel particles have an average diameter of 20 micrometers.

17. Aerogel according to any one of claims 8 to 16, characterized in that the aerogel is capable of transporting and releasing bioactive compounds.

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