Description:FIELD OF THE INVENTION
[0001] The present invention relates generally to food waste valorization, and more particularly to a process for extracting hemicellulose from Brassica-derived waste materials.
BACKGROUND
[0002] Disposal of plant wastes, including stems, leaves, and other processing by-products, is a common outcome of large-scale agricultural and food-processing operations. Such plant waste streams represent an underutilized resource rich in structural polysaccharides, particularly hemicellulose, which holds substantial potential for use in food, pharmaceutical, and bio-based material industries. Conventional recovery techniques often rely on harsh chemical treatments, prolonged processing, and complex separation steps, leading to low efficiency, reduced yield, and adverse environmental impact.
[0003] For instance, One US patent prior art 13/937,855 discloses, conventional hemicellulose extraction from agriculture residues such as wheat straw, corn stover, and bagasse predominantly relies on acidic, alkaline, steam explosion, or Organosolv pretreatments. The process discloses sulfuric acid, sodium hydroxide, or organic solvents, leading to high chemical residue, the need for neutralization, and generation of wastewater.
[0004] Existing solutions are typically energy-intensive, with prolonged processing times, and demonstrate low selectivity for hemicellulose, frequently co-extracting or degrading cellulose and lignin. The environmental impact is significant, including air, water, and soil contamination, while scalability is hindered by equipment corrosion, complex operational controls, and reagent-intensive workflows.
[0005] Further, the processes generate undesirable by-products such as lignin sludge and inhibitory compounds, pose health and safety risks in handling corrosive or toxic reagents, and often lack systematic optimization beyond trial-and-error approaches. Conventional systems generally focus on a single pretreatment technique without integrated innovation, resulting in outputs primarily suited for composting or energy conversion, offering limited contribution toward Sustainable Development Goals (SDGs).
[0006] While such limitations are observed across a wide range of agricultural residues, they become particularly significant in certain crop wastes where unique chemical compositions present additional processing challenges.
[0007] Brassica crop waste, including stems, leaves, and seed husks from cabbage, broccoli, mustard, and related species, contains abundant lignocellulose, low lignin content but also high levels of sulfur compounds (e.g., glucosinolates) and phenolics that hinder downstream processing. With over 60% of Brassica waste biomass being inedible and discarded post-harvest presents a significant challenge and opportunity for value-added utilization.
[0008] Therefore, there is a need to develop a process to overcome above mentioned disadvantages by specifically extracting hemicellulose from the Brassica waste using ecofriendly process.

SUMMARY
[0009] The primary objective of the invention is to is to develop an efficient, and chemical-free process for extracting hemicellulose from Brassica waste.
[0010] Another objective of the invention is to provide a process for enhanced production of hemicellulose extracted from Brassica waste.
[0011] Yet another objective of the invention is to convert Brassica waste to a valuable source of xylose-rich hemicellulose, thereby promoting circular bioeconomy practices and reducing landfill waste.
[0012] Still another objective of the invention is to achieve non-catalytic, energy-based cell wall disruption for enhanced hemicellulose recovery, with targeted release of xylose from hemicellulose while minimizing the degradation of cellulose and lignin, thereby producing a sugar-rich extract suitable for high-value applications.
[0013] According to an aspect of the invention, there is provided a process for extracting hemicellulose from Brassica waste. The process involves subjecting preprocessed Brassica waste powder to an aqueous solvent treatment to form an aqueous slurry. The aqueous slurry is then subjected to either a pretreatment using microwave irradiation or a pretreatment using ultrasound under a different condition. These pretreatments disrupt the cell wall structure of the Brassica waste, thereby facilitating the release of hemicellulose. The released hemicellulose is then separated and collected from the treated slurry.
[0014] According to another aspect of the invention, the preprocessing step comprises washing the Brassica waste to remove impurities, followed by drying the washed material at a temperature of 50–60 °C for 10–12 hours to remove moisture. The dried Brassica waste is then ground, and sieved to obtain a fine powder suitable for subsequent processing.
[0015] According to one embodiment of the invention, the energy-based pretreatment in the form of microwave-assisted processing, wherein microwave energy is applied under controlled conditions to promote disruption of the lignocellulosic structure of the Brassica waste and enhance hemicellulose liberation.
[0016] In another embodiment of the invention, the energy-based pretreatment is ultrasound-assisted, in which ultrasonic energy generates cavitation effects and shear forces within the aqueous slurry, thereby facilitating the release of hemicellulose. The hemicellulose obtained through such processes may be enriched in xylose and may be suitable for a variety of industrial applications, including but not limited to food, pharmaceutical, and bio-based material sectors.
[0017] According to another aspect of the invention, the Brassica waste utilized in the process comprises material derived from Brassica oleracea var. botrytis, which may include stems, leaves, florets, or other by-products generated during agricultural harvesting or food-processing operations. These embodiments may be applied individually or in combination with additional processing steps to optimize yield, purity, and downstream functionality of the recovered hemicellulose.

BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The foregoing and other features and advantages of the invention will be more fully understood from the following description made with reference to the drawings.
[0019] FIG. 1 depicts a flow diagram of the process for extracting hemicellulose from Brassica-derived waste materials in accordance with the present invention.
[0020] FIG. 2 demonstrates 2D contour plots and 3D response surface plots for reducing sugar (xylose) in the hemicellulose fraction of cauliflower waste after microwave pretreatment in accordance with the present invention.
[0021] FIG.3 illustrates plots and 3D response surface plots for reducing sugar (xylose) in the hemicellulose fraction of cauliflower waste after ultrasound pretreatment in accordance with the present invention.
[0022] FIG. 4 shows SEM images of (a-b) CWP, (c-d) CWP-US-PT, (e-f) CWP-MW-PT in accordance with the present invention.
[0023] FIG. 5 represents FTIR spectra of untreated cauliflower waste powder (CWP) and pretreated samples in accordance with the present invention.
[0024] FIG. 6 depicts XRD patterns of structural and crystallinity changes in CWP after pretreatment in accordance with the present invention.
[0025] FIG. 7 illustrates TGA thermograms for CWP, CWP-US-PT and CWP-MW-PT in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION
[0026] Aspects of the present invention are best understood by reference to the description set forth herein. All the aspects described herein will be better appreciated and understood when considered in conjunction with the following descriptions. It should be understood, however, that the following descriptions, while indicating preferred aspects and numerous specific details thereof, are given by way of illustration only and should not be treated as limitations. Changes and modifications may be made within the scope herein without departing from the spirit and scope thereof, and the present invention herein includes all such modifications.
[0027] Several aspects of the present invention are disclosed herein. It is to be understood that these aspects may or may not overlap with one another. Thus, part of one aspect may fall within the scope of another aspect, and vice versa. Each aspect is illustrated by a number of embodiments, each of which in turn, can include one or more specific embodiments. It is to be understood that the embodiments may or may not overlap with each other. Thus, part of one embodiment, or specific embodiments thereof, may or may not fall within the ambit of another, or specific embodiments thereof, and vice versa.
[0028] A broad framework of the principles will be presented by describing various embodiments of this invention using exemplary aspects. The terms "one embodiment" or "an embodiment" means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. For clarity and ease of description, each aspect includes only a few embodiments. Different embodiments from different aspects may be combined or practiced separately, to design a customized process or product depending upon application requirements. Many different combinations and sub-combinations of a few representative processes or structures shown within the broad framework of this invention, which may be apparent to those skilled in the art but not explicitly shown or described, should not be construed as precluded.
[0029] The present invention provides an eco-friendly, chemical free solution to extract hemicellulose from Brassica derived waste.
[0030] The present invention provides a process for extracting hemicellulose from the Brassica waste. The process comprises a preprocessing step for preparing Brassica waste to an energy based treatment. The preprocessing step involves washing the Brassica waste to remove impurities. The washing step is performed using water, optionally at ambient temperature, to eliminate physical contaminants such as soil, dust, and debris, as well as to reduce chemical residues.
[0031] The washing step is carried out in a batch or continuous mode, employing mechanical agitation, spray nozzles, or a combination thereof, to ensure thorough cleaning of the Brassica waste prior to further processing.
[0032] The washed Brassica waste is dried at a temperature in the range of 50 °C to 60 °C for a duration of 10 to 12 hours using any one of the drying equipment selected from tray dryer, cabinet dryer, tunnel dryer, belt conveyor dryer, static fluidized bed dryer, vibrating fluidized bed dryer, rotary drum dryer, cascade dryer, vacuum tray dryer, rotary vacuum dryer, hybrid microwave-hot air dryer, spray dryer or equivalent controlled-temperature drying apparatus.
[0033] The selected temperature range and duration are adapted to reduce the moisture content of the Brassica waste to a level suitable for long-term storage, while preserving heat-sensitive bioactive components present in the Brassica waste.
[0034] Further, the dried Brassica waste is subjected to grinding to obtain a particulate material. The grinding instrument is selected from a hammer mill, pin mill, or other comminution equipment capable of producing particles of a size suitable for subsequent sieving. Furthermore, grinding facilitates uniformity in particle size and improves the handling characteristics of the processed material.
[0035] The preprocessing step further comprises sieving the ground Brassica waste to obtain a fine Brassica waste powder. The sieving may be performed using a mesh of predetermined aperture size to achieve a uniform particle size distribution. Oversized particles retained on the sieve may be reprocessed through the grinding apparatus until the desired fineness is achieved.
[0036] The sequential execution of the washing, drying, grinding, and sieving steps produces a fine Brassica waste powder of consistent quality, reduced microbial load, and extended shelf life, rendering it suitable for incorporation into nutraceutical compositions, functional food products, or other value-added applications.
[0037] The preprocessed Brassica waste is further processed by a process 100, illustrated in FIG. 1 to extract hemicellulose.
[0038] At step 110, the process comprising subjecting a preprocessed Brassica waste powder to an aqueous solvent treatment to form an aqueous slurry. The aqueous solvent comprises water, which functions as a medium to convert the preprocessed Brassica waste powder into an aqueous slurry, thereby facilitating dissolution and extraction of water-soluble constituents including, soluble proteins. The addition of water promotes swelling and softening of plant cellular structures, thereby enhancing permeability and release of intracellular components, while enabling uniform mixing and mass transfer between solid and liquid phases. Furthermore, the aqueous medium serves to activate or inactivate endogenous enzymes, depending on the applied process conditions, and provides efficient heat distribution when thermal treatment is employed, thereby improving the overall efficiency of the extraction process.
[0039] At step 120, the preprocessed aqueous slurry is treated with energy-assisted pretreatment under predetermined conditions so as to effect disruption of the cell wall matrix of the Brassica waste material.
[0040] In one exemplary embodiment of the present invention, energy-assisted pretreatment involving microwave irradiation. The microwave pretreatment may be performed with a power output ranging from 180 W to 540 W, depending on the batch size and desired treatment intensity. The irradiation time may range from 5 minutes to 15 minutes, applied either continuously or in pulsed intervals to prevent excessive heating. The pretreatment may further include solid-to-liquid ratio, wherein the solid-to-liquid ratio selected from 1:20 to 1:60. Microwave energy penetrates the slurry, causing rapid volumetric heating of water molecules and polar functional groups within the cell wall, resulting in softening, rupture, and partial hydrolysis of the polysaccharide matrix. This disruption increases porosity and enhances solvent accessibility to hemicellulose-rich regions of the Brassica cell wall. Agitation during irradiation may be provided to promote uniform heating and prevent localized overheating.
[0041] In another exemplary embodiment of the present invention, the aqueous slurry is subjected to an energy based pretreatment using ultrasound. The ultrasound pretreatment may be carried out for a treatment duration of 5 to 30 minutes, depending on slurry volume and composition. The ultrasonic probe or bath may be configured to produce high-intensity acoustic cavitation, wherein the rapid formation and collapse of microscopic bubbles generate localized hotspots, microjets, and shear forces. The physical effects are capable of breaking down the lignocellulosic network and disrupting middle lamellae, thus liberating hemicellulose from the plant cell wall matrix. The ultrasound assisted treatment may also include temperature regulation, maintaining the slurry between 65 °C and 95°C to balance cavitation efficiency with hemicellulose integrity. The pretreatment may further include solid-to-liquid ratio, wherein the solid-to-liquid ratio is selected from 1:20 to 1:60.
[0042] The choice between the microwave irradiation and ultrasound is made based on processing requirements, including target yield, desired molecular weight distribution of the extracted hemicellulose, energy efficiency, and scalability. Microwave pretreatment may be preferred for rapid, high-throughput operations requiring significant cell wall softening, whereas ultrasound pretreatment may be advantageous for more selective extraction where control over molecular fragmentation is desired.
[0043] The process parameters, including solvent composition, pH, solid-to-liquid ratio, microwave power, ultrasound frequency, and treatment durations, may be optimized through empirical or computational methods to maximize hemicellulose yield and purity while minimizing degradation of other valuable polysaccharides or co-extracted compounds. The process is adaptable to various forms of Brassica waste, including leaves, stems, stalks, seed husks, and processing by-products from cabbage, broccoli, cauliflower, kale, mustard, and related species within the Brassicaceae family.
[0044] At step 130, the process includes a separation step following either the microwave or ultrasound pretreatment explained in step 120.
[0045] The separation step comprises, but is not limited to, one or more of: filtration, centrifugation, sedimentation, decantation, pressing, membrane-based separation techniques or combinations thereof. The method selected may depend on the viscosity, particle size distribution, and solids content of the slurry etc.
The treated slurry is subjected to gravity-driven filtration through filter cloths, mesh screens, or membrane filters, wherein the pore size is selected to retain solid plant residues while permitting the passage of hemicellulose-containing liquid. In certain embodiments, the separation is carried out by vacuum-assisted filtration employing a Buchner funnel, thereby facilitating enhanced removal of the liquid phase and improving filtration efficiency.
[0046] The separation step comprises centrifugation at a relative centrifugal force (RCF) between about 5,000 × g and about 15,000 × g, optionally in a continuous-feed industrial centrifuge, to sediment insoluble particles and recover a clarified supernatant enriched in dissolved hemicellulose. For example, in one embodiment, centrifugation at approximately 10,000 × g for 20 minutes at 25 °C yields a clear, straw-colored liquid containing greater than 80% of the soluble hemicellulose fraction.
[0047] In one embodiment, the type of centrifuge is selected based on the properties of the slurry and specific processing requirements. Suitable examples include, without limitation, decanter centrifuges for continuous removal of large volumes of solids, disc-stack centrifuges for high-speed separation of fine particles, and tubular-bowl centrifuges for eliminating very small or colloidal solids. Where the hemicellulose is obtained as a solid cake following precipitation, basket or peeler centrifuges may be employed. For small-scale batches or experimental trials, laboratory high-speed centrifuges equipped with fixed-angle or swing-bucket rotors can be used. The selection may be guided by factors such as slurry viscosity, particle size distribution, solids content, and the desired mode of operation, whether batch or continuous.
[0048] In certain embodiments, the separation step includes a multi-stage approach, wherein coarse filtration through a woven cloth or metal mesh is performed prior to ultrafiltration or diafiltration to further concentrate and partially purify the hemicellulose fraction. In one embodiment, ultrafiltration membranes.
[0049] In yet other embodiments, tangential flow filtration (TFF) is employed to process high-solid slurries without excessive clogging, wherein the feed is recirculated across the membrane surface under controlled transmembrane pressure. This method enables continuous operation and efficient recovery of the target hemicellulose fraction.
[0050] In some embodiments, sedimentation tanks or clarifiers may be employed as a low-energy alternative to centrifugation.
[0051] In industrial-scale embodiments, screw presses, belt presses, or hydraulic presses may be used to mechanically separate solids from the hemicellulose-rich liquid phase, optionally in combination with filter aids such as diatomaceous earth, perlite, or cellulose fibers to improve throughput and clarity.
[0052] In certain embodiments, chemical flocculation or coagulant addition may be used to aggregate fine particles prior to filtration or centrifugation, thereby improving separation efficiency.
[0053] In some embodiments, the separated hemicellulose fraction may undergo a concentration stage prior to further purification or drying to enhance product yield and reduce downstream processing time. Concentration may be achieved through various techniques, including evaporation under reduced pressure, rotary evaporation, falling-film or thin-film evaporation, and membrane-based concentration processes such as ultrafiltration or nanofiltration. Reduced-pressure evaporation can lower the boiling point of the aqueous medium, thereby minimizing thermal degradation of the hemicellulose. Rotary evaporators are particularly suited for laboratory or pilot-scale operations, allowing efficient solvent removal with gentle agitation. In larger-scale operations, falling-film or thin-film evaporators can provide high heat-transfer efficiency with short residence times, which is advantageous for heat-sensitive polysaccharides. Membrane concentration methods, such as ultrafiltration, enable selective removal of water and low-molecular-weight impurities while retaining high-molecular-weight hemicellulose. The choice of concentration method may depend on factors such as target purity, product stability, available utilities, and scale of operation. In certain embodiments, two or more of the aforementioned concentration methods may be employed sequentially to achieve the desired solids content prior to purification, precipitation, or drying.
[0054] The isolated hemicellulose may optionally be dried using spray drying, freeze drying, drum drying, or vacuum oven drying to produce a stable, free-flowing.
[0055] In yet another embodiment, the separation step is integrated directly into a continuous processing line, wherein microwave or ultrasound pretreatment is followed by on-line clarification, membrane concentration, and drying in a single automated system, thereby reducing processing time and minimizing degradation of hemicellulose.
[0056] The separation conditions (e.g., filter pore size, centrifugation speed, membrane MWCO, and drying method) are optimized according to the specific plant feedstock used, such as corn stover, wheat straw, sugarcane bagasse, hardwood chips, or rice husk, to maximize recovery yield and purity of hemicellulose.
[0057] The present invention is further applicable to other plant-based wastes, including, but not limited to, sugarcane bagasse, rice husk, wheat bran, corn stover, barley straw, oat hulls, peanut shells, soybean hulls, coconut husk, banana peels, mango peels, potato peels, tomato pomace, apple pomace, citrus peels, pineapple peels, coffee husks, tea waste, palm kernel cake, and cassava peels etc.
[0058] Example 1: Process for Extracting Hemicellulose from Brassica Waste Using Microwave-Assisted Pretreatment
[0059] The process for extracting hemicellulose from Brassica waste includes the following steps:
[0060] The Brassica waste is subjected to a preprocessing step comprising washing the Brassica waste to remove surface impurities and extraneous matter, drying the washed material at a temperature in the range of 50–60 °C for a period of 10–12 hours to reduce moisture content preferably 60 °C for 12 hours, and subsequently grinding and sieving the dried material to obtain a fine Brassica waste powder.
[0061] The preprocessed Brassica waste powder is mixed with 80 mL water to prepare an aqueous slurry, wherein the solid-to-liquid ratio is selected from a range of 1:20.
[0062] Further the aqueous slurry is subjected to microwave-assisted pretreatment under defined conditions effective to disrupt the cell wall structure of the Brassica waste, thereby facilitating the release of hemicellulose wherein, the microwave pretreatment is conducted at a power level in the range of 180 W microwave power for 10 minutes at a solid-to-liquid ratio of 1:20.
[0063] Example 2: Process for Extracting Hemicellulose from Brassica Waste Using Ultrasound Pretreatment
[0064] The process for extracting hemicellulose from Brassica waste comprises the steps of washing the Brassica waste to remove impurities, drying the washed Brassica waste at a temperature in the range of 50–60 °C for 10–12 hours to remove moisture preferably 60 °C for 12 hours, and grinding and sieving the dried Brassica waste to obtain a fine Brassica waste powder. The Brassica waste powder is mixed with 80 mL water to prepare an aqueous slurry, wherein the solid-to-liquid ratio is selected from a range of 1:40. Further, the aqueous slurry is pretreated using ultrasound assisted pretreatment, by applying ultrasound at a temperature of 95 °C for 10 minutes at a solid-to-liquid ratio of 1:30.
[0065] Box-Behnken Design:
[0066] FIG. 2 shows a graph indicating the process parameters for the extraction of reducing sugar (xylose) in the hemicellulose fraction of cauliflower waste were optimized using a Box–Behnken Design, and the experimental results were represented through 2D contour plots and 3D response surface plots. The 2D contour plots and corresponding 3D response surface plots were generated to illustrate the interaction effects of process variables on the xylose yield obtained from the hemicellulose fraction of cauliflower waste after microwave pretreatment, wherein the plots depict the variation in xylose concentration as a function of the selected operational parameters
[0067] FIG. 3 shows the 2D contour plots and corresponding 3D response surface plots, representing the interaction effects of process variables on the xylose yield obtained from the hemicellulose fraction of cauliflower waste after ultrasound pretreatment, wherein the plots demonstrate the influence of defined treatment conditions on the resulting xylose concentration.
[0068] FIG. 2 and FIG. 3 represents Box–Behnken Design analysis in both microwave and ultrasound pretreatment, which provide a visual correlation between the selected process parameters and the measured xylose yield, thereby enabling identification of the optimal operational conditions for maximum recovery of hemicellulose-derived reducing sugars.
Characterization
[0069] Monomeric Sugar Analysis by HPLC
[0070] The monosaccharides extraction by ultrasonic and microwave pretreatment of the hemicellulose fraction of Cauliflower waste powder (CWP) was determined by High-performance liquid chromatography (HPLC). The liquid fractions as collected under conditions (as optimized by RSM and further DNS method testing) were used for HPLC analysis i.e. for Cauliflower waste powder-microwave-pretreatment (CWP-MW-PT), microwave power 180 W, duration10 min, and 1:20 S: L ratio and for Cauliflower waste powder-ultrasound-pretreatment (CWP-US-PT),1:40 S: L ratio, temperature 95°C and duration of 30 min were used. Xylose was the dominant monomeric sugar component in hemicelluloses extracted from biomass by both pretreatments. The xylose content as determined in pretreated CWP by HPLC analysis was 5.7 mg/mL for CWP-MW-PT and 5.12 mg/mL for CWP-US-PT. The results inferred that the microwave pretreated biomass yielded a significant amount of xylose (57%), along with galactose (12.1 mg/mL). For US-PT pretreated biomass, 51.2% xylose was extracted successfully. The galactose yield was 14.4 mg/mL. The CWP-MW-PT yielded higher xylose than CWP-US-PT, as per HPLC results. High xylose conversion efficiency. Under the optimized set of conditions, CWP-MW-PT and CWP-US-PT gave almost the same xylose yield as determined by the DNS method; a comparison of results obtained by HPLC is important. Comparing the optimized experimental conditions for CWP-MW-PT and CWP-US-PT and xylose content in CWP biomass quantified by HPLC, higher content of xylose is successfully extracted by microwave pretreatment. In addition, the high yield is obtained in an ambient set of conditions for microwave pretreatment as compared to ultrasound (with high temperature and prolonged exposure). Thus, CWP-MW-PT offers viable and more sustainable green technology for xylose extraction from cauliflower waste by pretreatment, which paves the way for further food applications.
[0071] Analytical Analysis
[0072] SEM analysis
[0073] Further, the surface morphology of CWP (raw and pretreated) was examined by obtaining SEM micrographs, as seen in FIG. 4. The surface structure of raw CWP, FIG. 4 (a, b), was tight and smooth with dense layering. Before pretreatment, the cellulose chains are deemed to be oriented and cemented together by components as hemicellulose, forming a more complex structure with a relatively smooth texture. The SEM images of CWP after CWP-US-PT and CWP-MW-PT pretreatments are shown in FIG. 4 (c, d) and (e, f), respectively. After pretreatment by both CWP-US-PT and CWP-MW-PT, the CWP sample was eroded, which possibly happened because of damage to the secondary cell wall layer. As can be seen, the surface is rougher and relatively looser because of the stripping of hemicellulose. When compared to CWP-MW-PT, the CWP-US-PT has a more pronounced effect on surface morphology. This may be because of cavitation, i.e. mechanical effect of ultrasound radiation, which leads to more breakdown in addition to the effects of temperature and pressure.
[0074] FTIR
[0075] The FTIR spectra of untreated cauliflower waste powder (CWP) and pretreated samples, i.e. CWP-US-PT and CWP-MW-PT, are presented in FIG. 5. The broad bands observed from 3000 to 3400 cm−1 correspond to OH stretching vibrations, corresponding to intermolecular hydrogen bonding and are observed in all three samples. The peak near 2920 cm-1 corresponds to methylene (-CH2) symmetric stretching vibrations for cellulose and hemicellulose in CWP. The peak that appears at 1650 cm−1 is because of water present in cellulose molecules. A characteristic peak at 1100 cm-1 is attributed to C-O-C stretching vibrations. In addition, two characteristic peaks at 1740 and 1250 cm-1 in CWP correspond to -COOH and ester groups of hemicellulose, respectively. The disappearance of both these peaks in pretreated CWP samples (after CWP-MW-PT and CWP-US-PT) implies that the hemicellulose was successfully removed. The functional group changes in the FTIR confirmed that CWP was deconstructed via both the CWP-US-PT and CWP-MW-PT conditions.
[0076] XRD
[0077] X-ray diffraction (XRD) was utilized to evaluate the structural and crystallinity changes in CWP after pretreatment. FIG. 6 shows the characteristic peaks at 2θ=16.2° and 22.5° corresponding to (100) and (002) planes of cellulose I. The pretreated samples also show these characteristic diffraction peaks with crystallinity changes and minor shifts in 2θ values. The CrI (crystallinity index) as calculated for CWP was 29.3%, which increased to 30.5% for microwave pretreated CWP and 32.9% for CWP-US-PT samples. This increase is because of the removal of amorphous hemicellulose (by pretreatment), which exposed more crystalline cellulose. As compared to the CWP-US-PT, CWP-MW-PT has slightly lower crystallinity because thermal agitations during microwave may sometimes also remove some part of the crystalline cellulose. The changes in CrI on pretreatment also support the successful extraction of hemicellulose on CWP-US-PT and CWP-MW-PT.
[0078] TGA
[0079] The thermogravimetric analysis of CWP provides important insights into thermal decomposition patterns of various constituents, which makes it easier to track the changes occurring during deconstruction by pretreatment. The pyrolysis process of untreated and pretreated CWP, as seen from TGA curves (FIG. 6), can be divided into three major stages: moisture removal (25–125°C), i.e. 5-9% weight loss; breakdown of hemicellulose (180–330 °C); and the cellulose decomposition phase (330–400°C). The higher stages (the flat section), i.e. above 500 °C, represent the non-combustible fraction of CWP biomass. It can be observed that when CWP was subjected to CWP-US-PT and CWP-MW-PT, the hemicellulose part was extracted, and the residual material shows changes in TGA patterns. FIG. 7 shows that the peaks corresponding to the combustion region, i.e. cellulose, get shifted to a higher temperature (350°C) for pretreated samples as compared to raw CWP and more flattened higher temperature sections. In addition, the section of the curve which corresponds to the hemicellulose degradation is flattened as hemicellulose has been removed by pretreatments. Additionally, some minerals in the biomass can act as catalysts during the thermochemical conversion, and hence biomass shows more resistance to thermal decomposition. Thus, the TGA findings also support the successful extraction of the hemicellulose fraction from CWP by US-PT and MW-PT.
[0080] Comparative example 1
[0081] In a reported process, cauliflower waste dried at 80 °C was subjected to dilute acid pretreatment using 2% (v/v) sulfuric acid, resulting in a total sugar release of approximately 26.05 g/L of slurry. While such acid pretreatment facilitated the solubilization of structural carbohydrates, the process necessitated the use of chemical reagents, required subsequent neutralization steps, and generated acidic effluents, thereby introducing additional operational and environmental challenges. (Khedkar et al., 2017)
RESULTS AND DISCUSSION:
[0082] A comparative analysis of Example 1 and Example 2 demonstrates that, under otherwise substantially similar preprocessing conditions the use of microwave-assisted pretreatment at 180 W for 10 minutes with a solid-to-liquid ratio of 1:20 (Example 1) yields 78.09 mg/g xylose, whereas the use of ultrasound-assisted pretreatment at 95 °C for 10 minutes with a solid-to-liquid ratio of 1:30 (Example 2) yields 79.33 mg/g xylose, the latter representing an increase of approximately 1.6% in yield, albeit with higher solvent volume and thermal energy requirements.
[0083] According to the comparative example, the yield obtained from cauliflower waste is reported as 26.05 g/L (Khedkar et al., 2017). In contrast, in accordance with the present invention, microwave-assisted pretreatment at 180 W for 10 minutes with a solid-to-liquid ratio of 1:20 (Example 1) provides a yield of 78.09 mg/g xylose, whereas ultrasound-assisted pretreatment at 95 °C for 10 minutes with a solid-to-liquid ratio of 1:30 (Example 2) provides a yield of 79.33 mg/g xylose, the latter representing an increase of approximately 1.6% relative to the former. Accordingly, the pretreatment methods of the present invention demonstrate significantly improved efficiency over previously reported alkali-based pretreatment processes.
[0084] The results inferred that while both methods could effectively facilitated hemicellulose extraction, the microwave-assisted pretreatment provided comparatively better results under more ambient conditions i.e shorter processing time with lower overall energy consumption. - include this somewhere near results and discussion & advantages.
[0085] Thus, the advantages of the present invention offer a green, sustainable, and highly efficient process for extracting xylose-rich hemicellulose from cauliflower (Brassica oleracea var. botrytis) waste. The exclusive use of water as a solvent eliminates the need for corrosive acids, alkalis, or organic solvents, thereby preventing secondary pollution, avoiding neutralization steps, and ensuring the production of food-grade extracts free from chemical residues.
[0086] According to one embodiment the microwave-assisted pretreatment enables rapid, localized heating that disrupts biomass cell walls efficiently, significantly reducing processing time, energy consumption, and operational costs, while maintaining high extraction yields.
[0087] According to another embodiment, ultrasound-assisted pretreatment employs cavitation to mechanically rupture biomass structures, achieving selective hemicellulose release without degrading cellulose or lignin. This process operates at moderate temperatures, avoids inhibitor formation, reduces power requirements, and eliminates the need for corrosion-resistant equipment.
[0088] The integration of microwave and ultrasound pretreatments, optimized via statistical methods such as the Box–Behnken Design, provides flexibility in process selection, enables adaptation to diverse lignocellulosic feedstocks, and allows hybrid operation for synergistic yield improvements.
[0089] The invention further delivers environmental and socio-economic benefits by valorizing high-waste-index cauliflower residues, reducing landfill volumes, minimizing greenhouse gas emissions, and preventing leachate contamination. The scalable, safe-to-operate process supports multiple downstream industries, including nutraceuticals, biofuels, bioplastics, and prebiotics, while promoting circular bioeconomy principles and sustainable industrial development.
[0090] The process enables rapid processing cycles, allowing higher throughput per unit time and reducing plant footprint requirements. Controlled microwave energy application minimizes non-uniform heating, thereby improving extraction reproducibility between batches. The process reduces mechanical wear on equipment compared to grinding-intensive processes and is adaptable to continuous-flow microwave systems for industrial-scale deployment. It also supports selective hemicellulose recovery with minimal co-extraction of lignin, improving downstream purification efficiency.
[0091] The process allows extraction at lower operational pressures, reducing both safety risks and infrastructure costs. The cavitation effect enhances solvent penetration at the microstructural level, improving extraction efficiency even with low biomass-to-solvent ratios. It operates effectively without pre-drying biomass, thus lowering pre-processing energy requirements. The gentle processing environment preserves thermo-sensitive bioactive compounds, enabling co-recovery of other value-added components if desired.
[0092] The independent operation of each method allows localized technology adoption based on resource availability and energy pricing, enabling regional customization of processing strategies. Both methods generate minimal solid waste, which remains free of hazardous residues and can be valorized further, for example, as animal feed or compost. The processes provide a low-barrier entry point for small and medium enterprises due to modest capital investment requirements compared to conventional chemical extraction plants. The resulting sugar-rich extract meets regulatory standards for direct application in functional food, nutraceutical, and fermentation industries without additional chemical treatment.
[0093] The present invention achieves a significant increase in hemicellulose extraction yield by employing controlled energy-based pretreatments that selectively disrupt the lignocellulosic matrix of cauliflower (Brassica oleracea var. botrytis) waste without degrading the target polysaccharides. In the microwave-assisted embodiment, rapid volumetric heating generates uniform internal steam pressure, enhancing cell wall rupture and solvent penetration, thereby releasing higher quantities of xylose-rich hemicellulose in reduced time. In the ultrasound-assisted embodiment, acoustic cavitation produces intense microturbulence and localized shear forces that loosen hemicellulose bonds while preserving sugar integrity, resulting in improved solubilization and recovery efficiency. The optimized processing parameters, determined through statistical design, ensure maximum yield per unit biomass while minimizing energy input, thereby making the process both economically and environmentally advantageous.
[0094] As per the present invention, both microwave and ultrasound pretreatments minimize sugar degradation compared to chemical hydrolysis, ensuring a higher proportion of intact xylose suitable for high-value applications such as prebiotics (XOS).
[0095] Microwave penetration and ultrasound cavitation can effectively process biomass particles with slight size variation, reducing milling energy requirements.
[0096] Short, high-temperature microwave bursts and cavitation effects in ultrasound reduce microbial load in biomass, improving storage stability of extracts.
[0097] The invention significantly reduces pre- and post-processing costs by eliminating acid or alkali neutralization steps, thereby cutting labor, time, and chemical expenses. Both microwave and ultrasound pretreatments can be operated in batch or continuous modes, offering flexibility for small- and large-scale applications. The use of non-corrosive, water-only processes extends equipment lifespan, minimizes maintenance requirements, and reduces downtime. Furthermore, ultrasound systems can be configured as modular, portable units for on-site processing near agricultural sources, lowering transport costs and preserving biomass quality.
[0098] The embodiments of the present invention disclosed herein are intended to be illustrative and not limiting. Other embodiments are possible, and modifications may be made to the embodiments without departing from the spirit and scope of the invention. As such, these embodiments are only illustrative of the inventive concepts contained herein.
, Claims:1. A process for extracting hemicellulose from Brassica waste, comprising:
subjecting a preprocessed Brassica waste powder to a water based treatment to form an aqueous slurry;
subjecting the aqueous slurry to an energy based pretreatment under defined conditions to disrupt cell wall structure of the Brassica waste thereby facilitating release of hemicellulose; and
separating, and collecting the released hemicellulose from the treated aqueous slurry.
2. The process as claimed in claim 1, wherein the preprocessing comprises steps of,
washing Brassica waste to remove impurities;
drying the washed Brassica waste at 50-60 °C for 10-12 hours to remove moisture; and
grinding and sieving the dried Brassica waste to obtain a fine Brassica waste powder.
3. The process as claimed in claim 1, wherein the energy based pretreatment is microwave assisted.
4. The process as claimed in claim 3, wherein the defined conditions under microwave assisted pretreatment comprises applying microwave in a range of 180 to 540 W for 5 to 15 minutes, with a solid-to-liquid ratio selected from 1:20 to 1:60.
5. The process as claimed in claim 1, wherein the energy-based pretreatment is ultrasound assisted.
6. The process as claimed in claim 5, wherein the defined conditions under ultrasound assisted pretreatment comprises applying ultrasound at a temperature in a range of 65 °C to 95 °C for a duration of 5 to 30 minutes with a solid-to-liquid ratio selected from 1:20 to 1:60.
7. The process as claimed in claim 1, wherein the hemicellulose is xylose rich hemicellulose.
8. The process as claimed in claim 1, wherein the Brassica waste comprises Brassica oleracea var. botrytis.