Multistage processes for the enriching saponin concentration in hesperaloe extracts

Abstract

A process for enriching saponins in aHesperaloe extract may include purifying a Hesperaloe crude extract by flocculation, centrifugation, foam fractionation, solvent extraction, or any combination thereof, to produce aHesperaloe processed extract comprising saponins; and filtering the Hesperaloe processed extract through one or more membranes to produce a Hesperaloe saponin-enriched extract. The one or more membranes include a first membrane with a pore size sufficient to allow saponin retention. A saponin concentration on a dry basis in the saponin-enriched retentate may be greater than a saponin concentration on a dry basis in the Hesperaloe processed extract.

Description

MULTISTAGE PROCESSES FOR THE ENRICHING SAPONIN CONCENTRATION IN HESPERALOE EXTRACTSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 519.147, filed August 11. 2023. and entitled ‘"MULTISTAGE PROCESSES FOR ENHANCING SAPONIN CONCENTRATION IN HESPERALOE EXTRACTS”, the content of which is hereby incorporated by reference in its entirety for all intents and purposes.FIELD

[0002] The present disclosure relates to processes for enriching saponins in a Hesperaloe extract and the resultant saponin-enriched Hesperaloe extracts.BACKGROUND

[0003] Plants produce a vast and diverse assortment of organic compounds, the great majority of which do not appear to participate directly in their growth and development. These substances, traditionally referred to as secondary metabolites or plant natural products, often are distributed among limited taxonomic groups within the plant kingdom. The functions of secondary metabolites remain largely unknown, although a number of compounds have been associated with attributes useful to the plants, for example, as protection against herbivores and protection against microbial infection, as attractants for pollinators and seed-dispersing animals, and as compounds that influence competition among plant species (allelochemicals). There is a growing interest in plant natural products, since these products often have a wide range of applications in different kinds of industries, including pharmaceutical industries, cosmetic industries, food industries, detergent industries, and the like.

[0004] A particular group of plant secondary metabolites of interest are saponins. Saponins are glycosylated compounds classified as either triterpenoids, steroids, or steroidal glycoalkaloids. Saponins consist of one or two sugar moieties which are coupled to the aglycon (mono- and bisdesmosides, respectively). Saponins can be hydrolyzed to produce sapogenins and sugar moieties by acid hydrolysis or enzy matic methods. Saponins aregenerally water-soluble high molecular weight compounds with molecular weights ranging from 600 Daltons to more than 2,000 Daltons.

[0005] The asymmetric distribution of hydrophobic (aglycone) and hydrophilic (sugar) moieties in saponins confers an amphipathic character, which is largely responsible for their detergent-like properties. The ability to lower surface tension makes saponins potentially well-suited for use in the cosmetic and in the detergent industries.

[0006] Saponins also have the ability to form insoluble complexes with cholesterol, which makes some of them suitable for use in the pharmaceutical industry as cholesterol lowering agents. Other saponins are associated with formation of immunostimulating complexes that are useful in vaccine strategies.

[0007] Currently , a major limitation to the broad exploitation of saponins is the fact that commercially available saponins are relatively expensive. The expense is due in large part to the limited number of plant extracts having significant amounts of saponins. Currently, commercially available plant extracts containing saponins include Saponaria officinalis, Quillaia bark and stem, Castanea sativa seeds, and extracts of various Yucca species.

[0008] Plant extracts containing saponins are thus of general interest within a wide range of different industries. There is therefore a growing need in the art for alternative sources of saponin extracts and these plant sources preferably should be cheap and easy to obtain, and the saponin content should be relatively high.SUMMARY

[0009] The present disclosure relates to multistage processes that use filtration (e g., membrane filtration) for enriching a concentration of saponin in Hesperaloe extracts and the resultant Hesperaloe saponin-enriched extracts.

[0010] In some embodiments, the present disclosure relates to a process for enriching saponins in a Hesperaloe extract, the process comprising: purifying a Hesperaloe crude extract by flocculation, centrifugation, foam fractionation, solvent extraction, or any combination thereof, to produce a Hesperaloe processed extract comprising saponins; and filtering the Hesperaloe processed extract through one or more membranes to produce a Hesperaloe saponin-enriched extract, wherein the one or more membranes comprise a first membrane with a pore size sufficient to allow saponin retention, wherein a saponin concentration on a dry basis in a saponin-enriched retentate is greater than a saponin concentration on a dry basis in the Hesperaloe processed extract.

[0011] In some embodiments, the present disclosure relates to a process for enriching saponins in a Hesperaloe extract, the process comprising: heating a Hesperaloe crude extract obtained from a Hesperaloe biomass to increase a temperature of the Hesperaloe crude extract by about 15 °C or more within about 5 minutes or less; centrifuging the heated Hesperaloe crude extract to produce a supernatant that is a Hesperaloe processed extract; and filtering the Hesperaloe processed extract through one or more membranes to produce a Hesperaloe saponin-enriched extract, wherein the one or more membranes comprise a first membrane with a pore size sufficient to allow saponin retention, wherein a saponin concentration on a dry basis in the saponin-enriched retentate is greater than a saponin concentration on a dry' basis in the Hesperaloe processed extract.

[0012] In some embodiments, the present disclosure relates to a process for enriching saponins in a Hesperaloe extract, the process comprising: foam fractionating a Hesperaloe crude extract to produce a foam comprising saponins; collecting the foam and, optionally, further processing the foam, thereby yielding a Hesperaloe processed extract; and filtering the Hesperaloe processed extract through one or more membranes to produce a Hesperaloe saponin-enriched extract, wherein the one or more membranes comprise a first membrane with a pore size sufficient to allow saponin retention, wherein a saponin concentration on a dry' basis in the saponin-enriched retentate is greater than a saponin concentration on a dry' basis in the Hesperaloe processed extract.DESCRIPTION OF THE DRAWINGS

[0013] FIGS. 1 A and IB show a triterpenoid saponin structure and a steroidal saponin structure, respectively.

[0014] FIG. 2 provides a schematic flow diagram for a multistage process for enriching saponins in a Hesperaloe extract according to some embodiments of the present invention.

[0015] FIG. 3 provides a schematic flow diagram for example multistage processes for enriching saponins in a Hesperaloe extract according to some embodiments of the present invention.

[0016] FIG. 4 provides a graph of the UV -visible absorption spectrum for the filtered samples produced during multistage processes according to some embodiments of the present invention.DEFINITIONS

[0017] As used herein, the term “biomass” generally refers to whole plants and plant organs (i.e., leaves, stems, flowers, roots, etc.) of the genus Hesperaloe including, for example, Hesperaloe funlfera. Hesperaloe nocturna. Hesperaloe parviflora. and Hesperaloe chiangii. In particularly preferred instances, water-soluble solids may be prepared from biomass consisting essentially of the above ground portion of the Hesperaloe plant, and more particularly the portion of the Hesperaloe plant above the crown, and still more preferable the leaves of the Hesperaloe plant.

[0018] As used herein, the term “bagasse” generally refers to biomass that has been subjected to an extraction process such as, for example, continuous solvent extraction or milling, so that the resulting solids have less water-soluble solids than the biomass from which it is derived. In certain preferred embodiments bagasse is prepared by subjecting biomass to high pressure, such as by milling. High pressure may be achieved by using compression pressure, such as that provided by machines such one or more opposed counterrotating rolls, a mechanical press, a screw press as well as by direct hydraulic pressure and other processes to apply pressure to the biomass and remove intercellular and intracellular liquid.

[0019] As used herein, the term “milling” generally refers to the application of sufficient pressure to force intercellular and intracellular liquid from the biomass.

[0020] As used herein, the term “saccharide” is used interchangeably with the terms “polysaccharide,” “oligosaccharide,” and “sugar,” the definitions of which are well known to those skilled in the art of carbohydrate chemistry. It should be noted that saccharides can be in the form of mono-, oligo-, and / or polysaccharides. Preferably saccharides are water- soluble and do not include cellulose, hemicellulose or mono-, oligo-, and / or polysaccharides bound to other compounds, such as glycosides (arabinose, glucose, galactose, xylose, and glucuronic acid) bound to a triterpenoid to form a saponin.

[0021] As used herein, the term “saponin” generally refers to a glycoside comprising a sugar component referred to as a glycone and a non-sugar component referred to as an aglycone. Depending on the structure of the aglycone, the saponin may be classified as a triterpenoid saponin, illustrated in FIG. 1A, or as a steroidal saponin, illustrated in FIG. IB. The aglycone portion of the saponin may be either a pentacyclic triterpenoid or a tetracyclic triterpenoid, both of which contain 30 carbon atoms. Whether steroidal or triterpenoid, saponins may be mono, bi, or tridesmodic. Monodesmodic saponins have a single saccharide, normally atached at C-3. Bidesmodic saponins have two saccharides, often withone attached through an ether linkage at C-3 and the other either attached through an ester linkage at C-28 or through an ether linkage at C-20 (pentacyclic and tetracyclic triterpene saponins, respectively), or through an ether linkage at C-26 (furostane saponins). In certain instances, Hesperaloe biomass may comprise at least about 5 wt. % of total saponins, such as from about 5 to about 15 wt. %, such as from about 8 to about 12 wt. %, based upon the dry weight of the biomass. Total saponins may be determined as described in the Test Methods section below.

[0022] As used herein, the term '‘water-soluble solids” generally refers to dry matter which remains after an extract has been centrifuged, filtered and all water is evaporated. The procedure for measuring water-soluble solids of a biomass extract of the present invention is described in detail in the Test Methods section below. Water-soluble solids may be expressed on a percentage basis relative to the mass of dry biomass.

[0023] As used herein, the term “water-insoluble solids” generally refers to the fraction of extract that is removed by centrifugation and filtration in the course of extracting water- soluble solids, as described in the Test Methods section below.DETAILED DESCRIPTION

[0024] The present disclosure relates to multistage processes for enriching a concentration of saponin in Hesperaloe extracts and the resultant Hesperaloe saponin-enriched extracts. Hesperaloe extracts may be recovered from non-woody plants and more particularly the non-woody plants of the genus Hesperaloe^ for example, Hesperaloe funifera, Hesperaloe nociurna. Hesperaloe parviflora, and Hesperaloe chiangii.

[0025] Hesperaloe fibers (or bagasse) are useful as a wood fiber alternative. Generally, Hesperaloe fibers are isolated from Hesperaloe biomass by grinding, cutting, pressing, crushing, and / or mechanical abrasion (e.g., milling, depithing, or a combination thereof). The solvent, typically water, can be used in the process to extract a variety7of substances from the Hesperaloe biomass. The water with extracted substances is a Hesperaloe crude extract. The extracted substances may include, for example, fats, proteins, saccharides, polysaccharides, saponins, sapogenins, minerals (also referred to as inorganic salts), and organic acids. The extracted substances may also include water-insoluble components that are suspended in the Hesperaloe crude extract. The present disclosure provides a method for producing a Hesperaloe extract with increased saponin concentration (also referred to hereinas Hesperaloe saponin-enriched extract) from the Hesperaloe crude extract using a multistage process that includes membrane filtration.

[0026] FIG. 2 illustrates an example multistage process 200 for increased saponin concentration in a Hesperaloe extract according to some embodiments of the present disclosure. In the illustrated multistage process 200, a Hesperaloe crude extract 202 produced from Hesperaloe biomass is purified 204 to remove at least a portion of the fats, proteins, saccharides, polysaccharides, and / or water-insoluble components. The resulting Hesperaloe processed extract 206 is then filtered 208 through one or more membranes to produce a Hesperaloe saponin-enriched extract 210. At least one of the one or more membranes has a pore size sufficient to allow saponin retention, which is described in more detail herein.

[0027] The Hesperaloe crude extract 202 may be produced, for example, by milling (and optionally imbibition and / or depithing) Hesperaloe biomass in the presence of a solvent. Generally, processing Hesperaloe biomass removes at least about 25% of the water-soluble solids from the biomass, more preferably at least about 50%, still more preferably at least about 75%, such as from about 25% to about 98%, such as from about 50% to about 90%, such as from about 75% to about 90%. Examples of useful solvents may include, but are not limited to, acetic acid, acetone, acetonitrile, benzene, 1 -butanol, 2-butanol, 2-butanone, t- butyl alcohol, carbon tetrachloride, chlorobenzene, chloroform, cyclohexane, 1,2- dichloroethane, di ethylene glycol, diethyl ether, diglyme, 1,2-dimethoxy ethane, dimethylformamide, dimethylsulfoxide. 1,4-di oxane, ethanol, ethyl acetate, ethylene glycol, glycerin, heptane, hexamethylphosphoramide, hexamethylphosphorous triamide, hexane, methanol, methyl-t-butyl ether, methylene chloride, N-methyl-2-pyrrolidinone, pentane, perchloroethylene, petroleum ether, 1 -propanol. 2-propanol, pyridine, tetrahydrofuran, toluene, triethylamine, trifluorotoluene, water, xylene, the like, and any combination thereof.

[0028] In one example, the process for producing a Hesperaloe crude extract 202 may comprise contacting a Hesperaloe biomass with a solvent comprising water and separating the water-soluble fraction from the insoluble biomass fraction. In another example, the extractant solution may comprise, in addition to water, a surfactant, another solvent, and / or Hesperaloe crude extract. The Hesperaloe crude extract can come from, for example, an earlier extraction step or an earlier milling step. In yet another example, a Hesperaloe crude extract 202 may also be produced with a first extraction using acetone or diethyl ether to remove lipids and pigments followed by a second extraction using methanol as a solvent, ora mixture of methanol and water. In another example, the solvent may be a 4: 1 ethanol-water solvent.

[0029] Additional details of milling and other processes used to produce the Hesperaloe crude extract 202 produced from the Hesperaloe biomass are described in US Patent App. Pub. No. 2023 / 0233644, which is incorporated herein by reference for all intents and purposes.

[0030] The amount of water-insoluble solids recovered from a biomass will vary depending on the extraction efficiency; however, in certain instances from about 1 gram to about 100 grams of water-soluble solids may be extracted per kilogram of dry biomass, such as from about 1 gram to about 30 grams per kilogram, or such as from about 10 grams to about 50 grams per kilogram.

[0031] The amount of water-soluble solids recovered from a biomass will vary depending on the extraction efficiency; however, in certain instances from about 100 grams to about 400 grams of water-soluble solids may be extracted per kilogram of dry' biomass, such as from about 120 grams to about 350 grams per kilogram, or such as from about 150 grams to about 300 grams per kilogram.

[0032] A Hesperaloe crude extract 202 may have a water-soluble solids concentration of about 5% to about 90%, such as about 5% to about 30%, such as about 25% to about 60%, or such as about 50% to about 90%, based on a total weight of the Hesperaloe crude extract 202. The Hesperaloe crude extract 202 may comprise saccharides and polysaccharides at a concentration of at least about 1 wt. %, such as from about 1 wt. % to about 15 wt. %, such as from about 2 wt. % to about 10 wt. %, based upon the total weight of water-soluble solids. The Hesperaloe crude extract 202 may comprise saponins and sapogenins at a concentration of at least about 0.5 wt. %, such as at least 1 wt. %, such as at least 5 wt. %, such as from about 0.5 wt. % to about 40 wt. %, such as from about 1 wt. % to about 20 wt. %, such as from about 5 wt. % to about 30 wt. %, based upon the total weight of water-soluble solids. The Hesperaloe crude extract 202 may comprise proteins at a concentration of at least about 1 wt. %, such as from about 1 wt. % to about 30 wt. %, such as from about 5 wt. % to about 25 wt. %, based upon the total weight of water-soluble solids. The Hesperaloe crude extract 202 may comprise fats at a concentration of about 0 wt. % to about 25 wt. %, such as about 1 wt. % to about 20 wt. %, such as about 5 wt. % to about 15 wt. %, based upon the total weight of water-soluble solids. The Hesperaloe crude extract 202 may comprise inorganic salts, cumulatively, at a concentration of about 5 wt. % to about 35 wt. %, such as about 5wt. % to about 30 wt. %, such as about 7 wt. % to about 20 wt. %, based upon the total weight of water-soluble solids.

[0033] The Hesperaloe crude extract 202 is purified 204 by one or more treatment steps to remove at least a portion of the fats, proteins, saccharides, polysaccharides, and / or waterinsoluble components and produce the Hesperaloe processed extract 206. Examples of treatments may include, but are not limited to, flocculation, centrifugation, foam fractionation or filtration, solvent extraction, the like, and any combination thereof. For example, the Hesperaloe crude extract 202 may be purified 204 by flocculation followed by centrifugation to facilitate removal of the flocculants. In this example, the resulting supernatant is the Hesperaloe processed extract 206. Alternatively, additional treatments (e.g., solvent extraction or foam fractionation) may be performed on the supernatant to produce the Hesperaloe processed extract 206.

[0034] Flocculation may be achieved by heating, changing the pH, changing the ionic strength, or any combination thereof of the Hesperaloe crude extract 202. The foregoing may cause one or more of fats, proteins (e.g., cause protein denaturing and precipitation), saccharides, polysaccharides, and / or water-insoluble components to flocculate where, after settling, the supernatant may be the Hesperaloe processed extract 206 or may be further purified to produce the Hesperaloe processed extract 206.

[0035] In some embodiments, heating to cause flocculation may include heating to a temperature below, at, or above the boiling point of the solvent present in the Hesperaloe crude extract 202. Advantageously, heating above the boiling point of the solvent may cause solvent evaporation, thereby concentrating the components therein while also causing flocculation. Heating may be to a temperature of about 40°C or more, such as about 50°C or more, about 60°C or more, about 70°C or more, about 80°C or more, from about 40°C to about 120°C, from about 40°C to about 95°C. from about 60°C to about 105°C, or from about 70°C to about 120°C. Heating to cause flocculation may be at any heating rate. Rapid heating may advantageously increase flocculation. Rapid heating may include increasing the temperature by about 15°C or more within about 5 minutes or less, such as increasing temperature by from about 15°C to about 80°C within from about 0.5 minutes to about 5 minutes, increasing temperature by from about 30°C to about 80°C within from about 0.5 minutes to about 3 minutes, or increasing temperature by from about 40°C to about 80°C within from about 0.5 minutes to about 2 minutes.

[0036] Changing the pH to cause flocculation may include increasing or decreasing the pH. After changing the pH, the pH of the Hesperaloe crude extract 202 may be from about 3 toabout 12, such as from about 3 to about 7, from about 5 to about 9, or from about 7 to about 12.

[0037] Changing the ionic strength to cause flocculation may include adding salt to the Hesperaloe crude extract 202. Examples of useful salts may include, but are not limited to, sodium salts, potassium salts, magnesium salts, calcium salts, aluminum salts, and the like with counterions of chloride, bromide, sulfate, nitrite, nitrate, and the like. Combinations of the foregoing may be used to change the ionic strength of the Hesperaloe crude extract 202.

[0038] Centrifugation may be used to remove higher density substances from the Hesperaloe processed extract 206 and, when used in combination with flocculation, to remove flocculants from the Hesperaloe processed extract 206. Suitable rpm to achieve a desired g-force that removes the foregoing may be determined by one of ordinary skill in the art without undue experimentation. After centrifugation, the supernatant may be the Hesperaloe processed extract 206, or the supernatant may be further purified 204 to produce the Hesperaloe processed extract 206. Centrifugation and flocculation followed by centrifugation may be preferred to minimize the amount of solvent needed when purified 204 to remove at least a portion of the fats, proteins, saccharides, polysaccharides, and / or water-insoluble components.

[0039] When centrifugation follows flocculation, an amount of time between initiating flocculation and starting centrifugation may be about 30 minutes or less, such as about 15 minutes or less, such as about 5 minutes or less, such as about 1 minute or less, such as about 10 seconds or less to about 30 minutes, such as about 10 seconds to about 15 minutes, such as about 10 second to about 5 minutes.

[0040] Foam fractionation is a separation process where gas is passed through (e.g., bubbled through) a fluid, typically contained in a column, to produce a foam at the top of the fluid. The foam is collected and optionally broken to produce a liquid. The collected fluid (e.g., the foam and / or liquid from a broken foam) typically has higher concentrations of surface-active agents (e.g., surfactants, emulsifiers, detergents, lipids, and the like) compared to the prefoamed fluid. The collected fluid may also include substances solubilized by the surfaceactive agents (e.g.. inorganic salts and organic acids). In a foam fractionation process, the collected fluid may be the Hesperaloe processed extract 206 or may be further purified 204 to produce the Hesperaloe processed extract 206.

[0041] Solvent extraction may use one or more solvents, optionally in series, to remove at least a portion of the fats, proteins, saccharides, polysaccharides, and / or water-insoluble components. For example, the Hesperaloe crude extract 202 may be defatted using non-polar solvents like hexane. In another example, hot water may be used to increase the solubility of saponins as compared to other components like polysaccharides. Examples of solvent extraction in conjunction with Hesperaloe are described in US Patent App. No. 2023 / 0233644, which is incorporated herein by reference. The fluid produced in solvent extraction processes that has a higher saponin concentration on a dry basis than the Hesperaloe crude extract 202 may be the Hesperaloe processed extract 206 or may be further purified 204 to produce the Hesperaloe processed extract 206.

[0042] The gas environment during any of the purification treatments (in the purification step 204) may be ambient air or have a reduced-oxygen concentrations. To reduce oxidation of saponins, the gas environment in which any of the purification treatments are performed may have a reduced oxygen concentration as compared to air. This may be especially useful in foam fractionation where higher amounts of gas are used. In a reduced-oxy gen environment, the gas environment may have an oxygen concentration of about 20 vol% or less, such as about 0 vol% to about 20 vol%, such as about 0 vol% to about 15 vol%, such as about 0 vol% to about 10 vol%, such as about 0 vol% to about 5 vol%.

[0043] Again, one or more treatments may be used to remove at least a portion of the fats, proteins, saccharides, polysaccharides, and / or water-insoluble components from of the Hesperaloe crude extract 202 to produce the Hesperaloe processed extract 206.

[0044] The amount of water-soluble solids recovered from the Hesperaloe crude extract 202 will vary depending on the treatment and its efficiency. The Hesperaloe processed extract 206 may have a water-soluble solids concentration of from about 5% to about 90%, such as from about 5% to about 30%, from about 25% to about 60%, or from about 50% to about 90%, based on a total weight of the Hesperaloe processed extract 206. The Hesperaloe processed extract 206 may comprise saccharides and polysaccharides at a concentration of at least about 1 wt. %, such as from about 1 wt. % to about 15 wt. %, from about 2 wt. % to about 10 wt. %, based upon the total weight of water-soluble solids. The Hesperaloe processed extract 206 may comprise saponins at a concentration of at least about 0.5 wt. %, such as at least 1 wt. %, at least 5 wt. %, from about 0.5 wt. % to about 40 wt. %, from about 1 wt. % to about 20 wt. %, or from about 5 wt. % to about 30 wt. %, based upon the total weight of water-soluble solids. The Hesperaloe processed extract 206 may comprise sapogenins at a concentration of at least about 0.5 wt. %, such as at least 1 wt. %, at least 5 wt. %, from about 0.5 wt. % to about 40 wt. %, from about 1 wt. % to about 20 wt. %, or from about 5 w t. % to about 30 wt. %, based upon the total weight of water-soluble solids. The Hesperaloe processed extract 206 may comprise proteins at a concentration of at leastabout 1 wt. %, such as from about 1 wt. % to about 20 wt. %, or from about 5 wt. % to about 15 wt. %, based upon the total weight of water-soluble solids. The Hesperaloe processed extract 206 may comprise fats at a concentration of from about 0 wt. % to about 20 wt. %. such as from about 1 wt. % to about 15 wt. %, or from about 3 wt. % to about 10 wt. %, based upon the total weight of water-soluble solids. The Hesperaloe processed extract 206 may comprise inorganic salts, cumulatively, at a concentration of from about 5 wt. % to about 35 wt. %, such as from about 5 wt. % to about 30 wt. %, or from about 7 wt. % to about 20 wt. %, based upon the total weight of water-soluble solids. For example, the Hesperaloe processed extract 206 may comprise at least about 1 wt. % saccharides and polysaccharides, at least about 0.5 wt. % saponins, at least about 0.5 wt. % sapogenins, at least about 1 wt. % proteins, from about 0 wt. % to about 20 wt. % fats, and from about 5 wt. % to about 35 wt. % inorganic salts, each based upon a total weight of water-soluble solids of the Hesperaloe processed extract 206.

[0045] The Hesperaloe processed extract 206 may be filtered 208 through one or more membranes to produce a Hesperaloe saponin-enriched extract 210. The one or more membranes includes at least one membrane with a pore size sufficient to enrich a saponin concentration on a dry basis in a retentate relative to a saponin concentration on a dry basis in the Hesperaloe processed extract 206. Stated another way, at least one of the membranes has a pore size sufficient to allow saponin retention. It should be noted that 100% saponin retention is not implied, but saponin retention is preferably at least 50 wt. %, and more preferably at least 80 wt. %. Said membrane may have a pore size characterized by a distance measurement (e.g., nm or pm) or a nominal molecular weight limit (NMWL). For example, the membrane that allows saponin retention may have a pore size of about 5 nm or less, such as from about 0.5 nm to about 5 nm, or from about 0.5 nm to about 3 nm. If the pore size is characterized by NMWL, the membrane that allows saponin retention may have a pore size (or NMWL) of about 600 Da or less, such as from about 100 Da to about 600 Da, from about 100 Da to about 500 Da, or from about 300 Da to about 500 Da.

[0046] The one or more membranes may include a second membrane having the same pore size as the membrane that allows saponin retention. That is, the filtration process may include filtering through two or more membranes that allows saponin retention. Optionally, filtering through one or more membranes of different pore sizes may occur between said flitrations.

[0047] The one or more membranes may include a second membrane having a pore size larger than the membrane that allows saponin retention. The second membrane may bereferred to as a membrane with a pore size sufficient to allow saponin permeation (at least 50 wt. % permeation, and more preferably at least 80 wt. % permeation) or a membrane that allows saponin permeation. For example, the membrane that allows saponin permeation may have a pore size of about 2 nm or greater, such as about 2 nm to about 20 nm, such as about 2 nm to about 1 nm, such as about 2 nm to about 5 nm. If the pore size is characterized by NMWL, the membrane that allows saponin permeation may have a pore size (or NMWL) of about 600 Da or greater, such as from about 600 Da to about 1200 Da, such as from about 600 Da to about 1000 Da, or from about 600 Da to about 800 Da.

[0048] The one or more membranes may include a second membrane having the same pore size as the membrane that allows saponin retention.

[0049] When using two or more membranes with different sizes, the membranes can be used in any order. For example, filtering may include (i) filtering the Hesperaloe processed extract 206 through a membrane that allows saponin retention (e.g., pore size of about 5 nm or less or about 600 Da or less) to produce a retentate then (ii) filtering the retentate through a membrane that allows saponin permeation (e.g.. pore size of about 2 nm or greater or about 600 Da or greater) where a permeate after the second filtering is the Hesperaloe saponin- enriched extract 210. In another example, filtering may include (i) filtering the Hesperaloe processed extract 206 through a membrane that allows saponin permeation (e.g., pore size of about 2 nm or greater or about 600 Da or greater) to produce a permeate then (ii) filtering the permeate through a membrane that allows saponin retention (e.g., pore size of about 5 nm or less or about 600 Da or less) where a retentate after the second filtering is the Hesperaloe saponin-enriched extract 210.

[0050] The filtration process may, for example, include a filtration process other than membrane filtration. Such filtration processes may include, but are not limited to, gravity filtration, vacuum filtration, crossflow filtration, centrifugal filtration, the like, and any combination thereof. For example, filtration through larger pore membranes may be gravity filtration, and filtration through smaller pore size membranes (e.g., the membrane that allows saponin retention) may be membrane filtration. In another example, the filtration process may include two or more flitrations with all filtrations being membrane filtrations.

[0051] Similar to the processes in the one or more purification treatment at the purification step 204, the gas environment during any of the filtrations may be ambient air or have a reduced-oxygen concentrations.

[0052] The amount of water-soluble solids recovered from the Hesperaloe processed extract 206 will van’ depending on the treatment and its efficiency. The Hesperaloe saponin-enriched extract 210 may have a water-soluble solids concentration of from about 5% to about 90%, such as from about 5% to about 30%, from about 25% to about 60%, or from about 50% to about 90%, based on a total weight of the Hesperaloe saponin-enriched extract 210. The Hesperaloe saponin-enriched extract 210 may comprise saccharides and polysaccharides at a concentration of about 10 wt. % or less, such as from about 0 wt. % to about 10 wt. %, or from about 1 wt. % to about 5 wt. %, based upon the total weight of water-soluble solids. The Hesperaloe saponin-enriched extract 210 may comprise saponins at a concentration of at least about 0.8 wt. %, such as at least 1 wt. %, at least 5 wt. %, from about 0.8 wt. % to about 40 wt. %, from about 1 wt. % to about 20 wt. %, or from about 5 wt. % to about 30 wt. %, based upon the total weight of water-soluble solids. The Hesperaloe saponin-enriched extract 210 may comprise sapogenins at a concentration of at least about 0.8 wt. %, such as at least 1 wt. %, at least 5 wt. %, from about 0.8 wt. % to about 40 wt. %, from about 1 wt. % to about 20 wt. %, or from about 5 wt. % to about 30 wt. %, based upon the total w eight of w ater-soluble solids. The Hesperaloe saponin-enriched extract 210 may comprise proteins at a concentration of about 15 wt. % or less, such as from about 0 wt. % to about 15 wt. %, or from about 1 wt. % to about 10 wt. %, based upon the total weight of w ater-soluble solids. The Hesperaloe saponin-enriched extract 210 may comprise fats at a concentration of about 10 wt. % or less, such as from about 1 wt. % to about 15 wt. %, or from about 3 wt. % to about 10 wt. %, based upon the total weight of water-soluble solids. The Hesperaloe saponin-enriched extract 210 may comprise inorganic salts, cumulatively, at a concentration of about 35 wt. % or less, such as from about 0 wt. % to about 35 wt. %, from about 5 wt. % to about 30 wt. %, or from about 7 wt. % to about 20 wt. %, based upon the total w eight of water-soluble solids. For example, the Hesperaloe saponin-enriched extract 210 may comprise about 10 wt. % or less saccharides and polysaccharides, at least about 0.8 wt. % saponins, at least about 0.8 wt. % sapogenins, about 15 wt. % or less proteins, about 10 wt. % or less fats, and about 35 wt. % or less inorganic salts, each based upon a total weight of w ater-soluble solids of the Hesperaloe saponin- enriched extract 210.

[0053] To quantify a concentration increase or decrease for a specific substance (e.g., saponin, proteins, fat, and the like) from the Hesperaloe processed extract 206 to the Hesperaloe saponin-enriched extract 210, the percent change can be calculated dividing the difference betw een the substance concentration in the Hesperaloe saponin-enriched extract 210 ([sub2io]) and the substance concentration in the Hesperaloe processed extract 206 ([sub2os]) by the substance concentration in the Hesperaloe processed extract 206, reportedin % (see below formula), where a positive value is an increase and a negative value is a decrease.

[0054] For example, a saponin percent change from the Hesperaloe processed extract 206 to the Hesperaloe saponin-enriched extract 210 can be calculated per the following formula.where [sap2oe] is a concentration of saponin in the Hesperaloe processed extract 206 on a drybasis and [sap2io] is a concentration of saponin in the Hesperaloe saponin-enriched extract 210 on a dry basis.

[0055] The saponin percent change from the Hesperaloe processed extract 206 to the Hesperaloe saponin-enriched extract 210 may be an increase by about 5% or greater, such as, about 50% or greater, about 100% or greater, about 200% or greater, from about 5% to about 1000% or more, from about 5% to about 50%, from about 25% to about 150%, from about 100% to about 400%, from about 250% to about 500%, from about 400% to about 800%, from about 500% to about 1000% or more. The sapogenin percent change may be used as a measure of the saponin percent change.Illustrations

[0056] Illustration 1. A process for enriching saponins in & Hesperaloe extract, the process comprising: purifying Hesperaloe crude extract by flocculation, centrifugation, foam fractionation, solvent extraction, or any combination thereof, to produce a Hesperaloe processed extract comprising saponins; and filtering the Hesperaloe processed extract through one or more membranes to produce a Hesperaloe saponin-enriched extract, wherein the one or more membranes comprise a first membrane with a pore size sufficient to allow saponin retention, wherein a saponin concentration on a dry basis in the saponin-enriched retentate is greater than a saponin concentration on a dry basis in the Hesperaloe processed extract.

[0057] Illustration 2. The process of Illustration 1, wherein the one or more membranes further comprises a second membrane having a pore size sufficient to allow saponin permeation.

[0058] Illustration 3. The process of Illustration 2, wherein the filtering of the Hesperaloe processed extract through the one or more membranes comprises either (i) filtering theHesperaloe processed extract through the first membrane to produce the saponin-enriched retentate. then filtering the saponin-enriched retentate through the second membrane to produce a permeate that is the Hesperaloe saponin-enriched extract or (ii) filtering the Hesperaloe processed extract through the second membrane to produce a saponin-containing permeate then filtering the saponin-containing permeate through the first membrane to produce a saponin-enriched retentate that is the Hesperaloe saponin-enriched extract.

[0059] Illustration 4. The process of any of Illustrations 1-3. wherein the saponin concentration on the dry basis in the saponin-enriched retentate is increased by at least about 5% relative to the Hesperaloe processed extract.

[0060] Illustration 5. The process of any of Illustrations 1-4, wherein the saponin concentration on the dry basis in the Hesperaloe saponin-enriched extract is at least about 0.8 wt. % based upon the total weight of water-soluble solids.

[0061] Illustration 6. The process of any of Illustrations 1-5, wherein the Hesperaloe processed extract comprises at least about 1 wt. % saccharides and polysaccharides, at least about 0.5 wt. % saponins, at least about 0.5 wt. % sapogenins, at least about 1 wt. % proteins, from about 0 wt. % to about 20 wt. % fats, and from about 5 wt. % to about 35 wt. % inorganic salts, each based upon a total weight of water-soluble solids of the Hesperaloe processed extract; and wherein the Hesperaloe saponin-enriched extract comprises about 10 wt. % or less saccharides and polysaccharides, at least about 0.8 wt. % saponins, at least about 0.8 wt. % sapogenins, about 15 wt. % or less proteins, about 10 wt. % or less fats, and about 35 wt. % or less inorganic salts, each based upon a total weight of water-soluble solids of the Hesperaloe saponin-enriched extract.

[0062] Illustration 7. The process of any of Illustrations 1-6, w herein the purifying of the Hesperaloe crude extract comprises the flocculation, wherein the flocculation comprises heating the Hesperaloe crude extract by about 15°C or more within about 5 minutes or less.

[0063] Illustration 8. The process of any of Illustrations 1-7, wherein the purifying of the Hesperaloe crude extract comprises the flocculation followed by the centrifugation, and wherein the centrifugation produces a supernatant that is the Hesperaloe processed extract.

[0064] Illustration 9. The process of any of Illustrations 1-8. wherein the purifying of the Hesperaloe crude extract comprises milling a biomass derived from a non-woody plant of the genus Hesperaloe.

[0065] Illustration 10. The process of any of Illustrations 1-9, w herein the purifying of the Hesperaloe crude extract comprises milling and depithing a biomass derived from a non- woody plant of the genus Hesperaloe.

[0066] Illustration 11. A process for enriching saponins in a Hesperaloe extract, the process comprising: heating a Hesperaloe crude extract obtained from a Hesperaloe biomass to increase a temperature of the Hesperaloe crude extract by about 15°C or more within about 5 minutes or less; centrifuging the heated Hesperaloe crude extract to produce a supernatant that is a Hesperaloe processed extract; and filtering the Hesperaloe processed extract through one or more membranes to produce a Hesperaloe saponin-enriched extract, wherein the one or more membranes comprise a first membrane with a pore size sufficient to allow saponin retention, wherein a saponin concentration on a dry basis in the saponin-enriched retentate is greater than a saponin concentration on a dry basis in the Hesperaloe processed extract.

[0067] Illustration 12. The process of Illustration 11, wherein the one or more membranes further comprises a second membrane having a pore size sufficient to allow saponin permeation.

[0068] Illustration 13. The process of Illustration 12, wherein the filtering of the Hesperaloe processed extract through the one or more membranes comprises either (i) filtering the Hesperaloe processed extract through the first membrane to produce the saponin-enriched retentate, then filtering the saponin-enriched retentate through the second membrane to produce a permeate that is the Hesperaloe saponin-enriched extract or (ii) filtering the Hesperaloe processed extract through the second membrane to produce a saponin-containing permeate then filtering the saponin-containing permeate through the first membrane to produce a saponin-enriched retentate that is the Hesperaloe saponin-enriched extract.

[0069] Illustration 14. The process of any of Illustrations 11-13, wherein the saponin concentration on the dry basis in the saponin-enriched retentate is at least about 5% higher than the saponin concentration on the dry basis in the Hesperaloe processed extract.

[0070] Illustration 15. The process of any of Illustrations 11-14, wherein the saponin concentration on the dry basis in the Hesperaloe saponin-enriched extract is at least about 0.8 wt. % based upon the total weight of water-soluble solids.

[0071] Illustration 16. The process of any of Illustrations 11-15, wherein the heating increases the temperature of the Hesperaloe crude extract by from about 30°C to about 80°C within from about 0.5 minutes to about 3 minutes.

[0072] Illustration 17. A process for enriching saponins in a Hesperaloe extract, the process comprising: foam fractionating a Hesperaloe crude extract to produce a foam comprising saponins; collecting the foam and. optionally, further processing the foam, thereby yielding a Hesperaloe processed extract; and filtering the Hesperaloe processed extract through one ormore membranes to produce a Hesperaloe saponin-enriched extract, wherein the one or more membranes comprise a first membrane with a pore size sufficient to allow saponin retention, wherein a saponin concentration on a dry basis in the saponin-enriched retentate is greater than a saponin concentration on a dry basis in the Hesperaloe processed extract.

[0073] Illustration 18. The process of Illustration 17, wherein the one or more membranes further comprises a second membrane having a pore size sufficient to allow saponin permeation.

[0074] Illustration 19. The process of Illustration 18, wherein the filtering of the Hesperaloe processed extract through the one or more membranes comprises either (i) filtering the Hesperaloe processed extract through the first membrane to produce the saponin-enriched retentate, then filtering the saponin-enriched retentate through the second membrane to produce a permeate that is the Hesperaloe saponin-enriched extract or (ii) filtering the Hesperaloe processed extract through the second membrane to produce a saponin-containing permeate then filtering the saponin-containing permeate through the first membrane to produce a saponin-enriched retentate that is the Hesperaloe saponin-enriched extract.

[0075] Illustration 20. The process of any of Illustrations 17-19, wherein the saponin concentration on the dry basis in the saponin-enriched retentate is at least about 5% higher than the saponin concentration on the dry basis in the Hesperaloe processed extract.TEST METHODSWater-soluble Solids

[0076] Total biomass water-soluble solids may be determined using an Accelerated Solvent Extraction system (ASE) such as a DIONEX™ ASE™ 350 (Thermo Fisher Scientific. Waltham, MA). Approximately 10 grams of harvested biomass is dried to a constant weight in an oven, typically 4 hours at 125°C. After drying 1.5 - 2.0 grams of the dry biomass is accurately weighed and the weight (Wb) recorded to the nearest 0.001 gram. Using water as the solvent, biomass is extracted using the conditions set forth in the Table 1 below. The ratio of biomass to solvent is generally 21 : 1 and five consecutive water extraction cycles are performed. At the end of each extraction cycle, the liquid phase is collected, dried under vacuum at approximately 40°C and the w eight of the dried material (Wi) is recorded to the nearest 0.001 grams. The total w eight of water-soluble solids (We) is calculated by summing the weight of solids recovered from each extraction cycle (Wi). Total water-soluble solids as a percentage of dry biomass is then determined using the following equation: Water-soluble Solids (wt. %) = We / Wb *100.Table 1

[0077] The total water-soluble solids in biomass extract may be determined by withdrawing an appropriate aliquot, typically about 10-50 mL, transferring to clean, dry, centrifuge tube. The tube is centrifuged at 7000 rpm for 20 minutes. The weight of extract (Wi) is calculated. An aliquot of the supernatant is then transferred to clean, pre-weighed beaker (Do), and weighed. The beaker and sample are then weighed to the nearest 0.001 g and the weight (D2) recorded. The beaker containing the sample is then placed at 140°C in a hot air oven for overnight drying. The beaker is removed from the oven and desiccated to cool to room temperature then weighed to the nearest 0.001 gram (Di). The weight percentage of soluble solids, based upon the weight of the extract, is determined using the formula below: ) % ioo — —L>o)Di= mass of empty beaker + dried soluble solids, Do = mass of empty beaker, D2 = mass of biomass extract and empty beaker.Total Sapogenin

[0078] Total sapogenins were measured according to the following. As described above, the concentration of sapogenins may provide an indicator of the saponin concentration.

[0079] Diosgenin standard solutions (diosgenin, >99%, Alfa-Aesar J60976-15, or equivalent) were prepared according to Table 2 where the stock solution was 0. 1 grams diosgenin in 100 mL of ethyl acetate.Table 2

[0080] About 1.0000 g of yucca extract was differentially weighed into a 50 mL conical tube and dissolved in about 30 mL of room temperature deionized water. After dissolution, the extract was rested with no significant motion (i.e., no stirring or shaking) for about 45 minutes. Then, the rested extract was centrifuged for 13 minutes at 4000 rpm (or the equivalent until a pellet formed). Then, about 5 mL to 10 mL of the supernatant was added to a 200 mL volumetric flask and diluted with deionized water to a total of 200 mL. After sufficient mixing to produce a homogeneous solution, about 1.00 mL of the diluted extract was placed in a 15 mm culture tube and evaporated to dryness in a heating block held at 98 °C under an air stream. After allowing the tube to dry, about 2.00 mL of ethyl acetate was added to the tube. Then, about 2.00 mL of each of the diosgenin standard solutions from Table 2 was placed in separate 15 mm culture tubes. For the extract and standard solutions, about 1.00 mL of 0.5% p-anisaldehyde in ethyl acetate and about 1.00 mL of concentrated sulfuric acid was added to each tube. After vortex mixing each, the tubes of extract and standard solutions were allowed to rest for about 60 minutes. After resting, about 3.00 mL of ethyl acetate was added to each tube and mixed well using vortex mixer. Then, the absorbance intensity was measured at 430 nm using an empty cuvette at the blank. The standard solutions provide a linear regression to compare the extract to when deriving the concentration of diosgenin and taking into account the final dilution factor.EXAMPLES

[0081] FIG. 3 illustrates the method and samples collected. Hesperaloe funifera was milled and pressed 302 to produce a crude extract 304. Samples of the crude extract were (i) centrifuged 306 at room temperature to produce supernatant 308 (or Hesperaloe processed extract 308), (ii) heated to 60°C in 2 minutes then centrifuged 310 to produce supernatant 312 (ox Hesperaloe processed extract 312), or (iii) heated to 80°C in 2 minutes then centrifuged 314 to produce supernatant 316 (or Hesperaloe processed extract 316) and solids 318. The quick heating facilitated flocculation of fiber components from the crude extract 304. Each centrifugation was at 5000 rpm for 20 minutes.

[0082] The supernatant 316 (ox Hesperaloe processed extract 316) was then either (i) filtered 320 through a 600-800 Dalton membrane filter (NFG (600-800 Da) Sanitary Nanofiltration Spiral-Wound Element, available from Synder Filtration) or (ii) filtered 324 through a 300-500 Dalton membrane filter (NFW (300-500 Da) Nanofiltration TFC Spiral-Wound Element, available from Synder Filtration). For the 600-800 Da membrane filter, almost all of the supernatant passed through the membrane producing a permeate 322 with a clear and light yellow appearance that foamed upon shaking. For the 300-500 Dalton membrane filter, a retentate 326 was separated from a permeate 328. The retentate 326 was a clear and dark brown in appearance and foamed upon shaking. The permeate 328 was clear and colorless in appearance and did not foam upon shaking.

[0083] Various samples in this example were dried and the concentration of various components were measured on a dry basis. Table 3 provide the percent change that a specific step provided. For example, a percent change in the listed substances in the 304 - 316 row corresponds to the percent change for said substance from the crude extract 304 to the supernatant 316 after performing the step of heating and centrifugation 314.Table 3* Saponin percent changes are believed to be commensurate with sapogenin percent changes. N.M. is not measured.

[0084] Regarding the flocculation by heating then centrifugation, heating to 80 °C mitigated the amount of sapogenins (and by extension the amount of saponins) that was lost tocentrifugation. In the same comparison, the fat is extracted to a greater extent with the centrifugation and no heating.

[0085] Regarding filtration, membrane filtration with the 300-500 Dalton membrane concentrates the sapogenins and saponin in the retentate 326 as well as the magnesium- containing and calcium-containing minerals.

[0086] Further, the UV-visible absorption spectrum (FIG. 4) was taken for the membrane filtered samples. These spectra confirmed the observational results that the permeate 322 and the retentate 326 that foamed included sapogenins (UV-visible peak absorption around 365 nm to 370 nm) to a greater extent than the permeate 328, which did not foam. As illustrated in the results above, the permeate 322 and the retentate 326 include other components, which may contribute to additional absorption below 350 nm.

Claims

WHAT IS CLAIMED IS:

1. A process for enriching saponins in a Hesperaloe extract, the process comprising: purifying a Hesperaloe crude extract by flocculation, centrifugation, foam fractionation, solvent extraction, or any combination thereof, to produce a Hesperaloe processed extract comprising saponins; and filtering the Hesperaloe processed extract through one or more membranes to produce a Hesperaloe saponin-enriched extract, wherein the one or more membranes comprise a first membrane with a pore size sufficient to allow saponin retention, wherein a saponin concentration on a dry basis in the saponin-enriched retentate is greater than a saponin concentration on a dry basis in the Hesperaloe processed extract.

2. The process of claim 1 , wherein the one or more membranes further comprises a second membrane having a pore size sufficient to allow saponin permeation.

3. The process of claim 2, wherein the filtering of the Hesperaloe processed extract through the one or more membranes comprises either (i) filtering the Hesperaloe processed extract through the first membrane to produce the saponin-enriched retentate, then filtering the saponin-enriched retentate through the second membrane to produce a permeate that is the Hesperaloe saponin-enriched extract or (ii) filtering the Hesperaloe processed extract through the second membrane to produce a saponin-containing permeate then filtering the saponin-containing permeate through the first membrane to produce a saponin-enriched retentate that is the Hesperaloe saponin-enriched extract.

4. The process of claim 1, wherein the saponin concentration on the dry basis in the saponin-enriched retentate is increased by at least about 5% relative to the Hesperaloe processed extract.

5. The process of claim 1, wherein the saponin concentration on the dry basis in the Hesperaloe saponin-enriched extract is at least about 0.8 wt. % based upon the total weight of water-soluble solids.

6. The process of claim 1, wherein the Hesperaloe processed extract comprises at least about 1 wt. % saccharides and polysaccharides, at least about 0.5 wt. % saponins, at leastabout 0.5 wt. % sapogenins, at least about 1 wt. % proteins, from about 0 wt. % to about 20 wt. % fats, and from about 5 wt. % to about 35 wt. % inorganic salts, each based upon a total weight of water-soluble solids of the Hesperaloe processed extract; and wherein the Hesperaloe saponin-enriched extract comprises about 10 wt. % or less saccharides and polysaccharides, at least about 0.8 wt. % saponins, at least about 0.8 wt. % sapogenins, about 15 wt. % or less proteins, about 10 wt. % or less fats, and about 35 wt. % or less inorganic salts, each based upon a total weight of water-soluble solids of the Hesperaloe saponin- enriched extract.

7. The process of claim 1, wherein the purifying of the Hesperaloe crude extract comprises the flocculation, wherein the flocculation comprises heating the Hesperaloe crude extract by about 15°C or more within about 5 minutes or less.

8. The process of claim 1, wherein the purify ing of the Hesperaloe crude extract comprises the flocculation followed by the centrifugation, and wherein the centrifugation produces a supernatant that is the Hesperaloe processed extract.

9. The process of claim 1, wherein the purify ing of the Hesperaloe crude extract comprises milling a biomass derived from a non-woody plant of the genus Hesperaloe.

10. The process of claim 1, wherein the purifying of the Hesperaloe crude extract comprises milling and depithing a biomass derived from a non-woody plant of the genus Hesperaloe.

11. A process for enriching saponins in a Hesperaloe extract, the process comprising: heating a Hesperaloe crude extract obtained from a Hesperaloe biomass to increase a temperature of the Hesperaloe crude extract by about 15 °C or more within about 5 minutes or less; centrifuging the heated Hesperaloe crude extract to produce a supernatant that is a Hesperaloe processed extract; and filtering the Hesperaloe processed extract through one or more membranes to produce a Hesperaloe saponin-enriched extract, wherein the one or more membranes comprise a first membrane with a pore size sufficient to allow saponin retention, wherein asaponin concentration on a dry basis in the saponin-enriched retentate is greater than a saponin concentration on a dry basis in the Hesperctloe processed extract.

12. The process of claim 11, wherein the one or more membranes further comprises a second membrane having a pore size sufficient to allow saponin permeation.

13. The process of claim 12. wherein the filtering of the Hesperctloe processed extract through the one or more membranes comprises either (i) filtering the Hesperaloe processed extract through the first membrane to produce the saponin-enriched retentate, then filtering the saponin-enriched retentate through the second membrane to produce a permeate that is the Hesperaloe saponin-enriched extract or (ii) filtering the Hesperaloe processed extract through the second membrane to produce a saponin-containing permeate then filtering the saponin-containing permeate through the first membrane to produce a saponin-enriched retentate that is the Hesperaloe saponin-enriched extract.

14. The process of claim 11. wherein the saponin concentration on the dry basis in the saponin-enriched retentate is at least about 5% higher than the saponin concentration on the dry basis in the Hesperaloe processed extract.

15. The process of claim 11. wherein the saponin concentration on the dry basis in the Hesperaloe saponin-enriched extract is at least about 0.8 wt. % based upon the total weight of water-soluble solids.

16. The process of claim 11, wherein the heating increases the temperature of the Hesperaloe crude extract by from about 30°C to about 80°C within from about 0.5 minutes to about 3 minutes.

17. A process for enriching saponins in ^Hesperaloe extract, the process comprising: foam fractionating a Hesperaloe crude extract to produce a foam comprising saponins; collecting the foam and, optionally, further processing the foam, thereby yielding a Hesperaloe processed extract; and filtering the Hesperaloe processed extract through one or more membranes to produce a Hesperaloe saponin-enriched extract, wherein the one or more membranescomprise a first membrane with a pore size sufficient to allow saponin retention, wherein a saponin concentration on a dry basis in the saponin-enriched retentate is greater than a saponin concentration on a dry basis in the Hesperaloe processed extract.

18. The process of claim 17, wherein the one or more membranes further comprises a second membrane having a pore size sufficient to allow saponin permeation.

19. The process of claim 18, wherein the filtering of the Hesperaloe processed extract through the one or more membranes comprises either (i) filtering the Hesperaloe processed extract through the first membrane to produce the saponin-enriched retentate, then filtering the saponin-enriched retentate through the second membrane to produce a permeate that is the Hesperaloe saponin-enriched extract or (ii) filtering the Hesperaloe processed extract through the second membrane to produce a saponin-containing permeate then filtering the saponin-containing permeate through the first membrane to produce a saponin-enriched retentate that is the Hesperaloe saponin-enriched extract.

20. The process of claim 17, wherein the saponin concentration on the dry basis in the saponin-enriched retentate is at least about 5% higher than the saponin concentration on the dry basis in the Hesperaloe processed extract.

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