Luzio, Gary (18 Berley Court Newark, DE, 19702, US)
Soederberg, Joergen (Fuglehavevej 52 Ballerup, DK-2750, DK)
Taytelbaum, Maurits P. (50 Rockford Road Wilmington, DE, 19805, US)
|1.||A process for producing pectin from plant starting material comprising, a) in a first extraction step, contacting said plant starting material with a weakly acidic solution at a temperature and for a time to sufficiently remove a noncalcium sensitive pectin (NCSP) fraction, and b) separating the extract juice from the plant starting material.|
|2.||The process of producing pectin from plant starting material comprising, a) treating said plant starting material with a strong acidic solution at a temperature and for a sufficient time to form an aqueous phase rich in a calcium sensitive pectin (CSP) fraction, and b) separating the extract juice from the plant starting material.|
|3.||A process for producing pectin from plant starting material comprising: a) contacting said plant starting material in a first extraction step with an aqueous weakly acidic solution at a temperature and for a time to sufficiently to remove a noncalcium sensitive pectin (NCSP) aqueous extract fraction, b) separating the aqueous extract fraction from the plant starting material, and c) contacting the separated plant starting material with an aqueous acid solution stronger than in step (a) at a temperature and for a time sufficient to remove a calcium sensitive pectin (CSP) fraction.|
|4.||The process of claim 3, wherein the CSP fraction is separated from the plant starting material.|
|5.||The process of claims 34, wherein the sufficient time has an upper limit of 5.0 hours.|
|6.||The process of claims 35, wherein the stronger acid solution of step c has a pH upper limit of 2.2 and a lower limit of 1.5.|
|7.||The process of claims 35, wherein the process is a countercurrent flow extraction process.|
|8.||The process of claim 7, wherein the process is a moving fixed bed countercurrent flow process.|
|9.||The process of claim 8, wherein the process is a multistage countercurrent flow extraction process.|
|10.||The process of claim 9, wherein the process is a rotary multistage countercurrent flow extraction process.|
|11.||The process of claims 1 and 310, wherein the weakly acidic solution has a pH upper limit of 4.0 and a lower 2.5.|
|12.||The process of claim 11, wherein the weakly acidic solution has a pH upper limit of 3.3.|
|13.||The process of claim 12 wherein the weakly acidic solution has a pH lower limit of 2.7.|
|14.||The process of claims 1113, wherein the weakly acidic solution has a pH lower limit of 3.0.|
|15.||The process of claim 14, wherein the weakly acidic solution has a pH lower limit of 2.8.|
|16.||The process of claims 2 and 315, wherein the strong acidic solution pH upper limit of 2.2 and a lower limit of 1.5.|
|17.||The process of claim 16, wherein the strong acidic solution pH upper limit of 2.1.|
|18.||The process of claim 17, wherein the strong acidic solution pH lower limit is 1.6.|
|19.||The process of claim 18, wherein the strong acidic solution pH upper limit is 2.0.|
|20.||The process of claim 19, wherein the strong acidic solution pH lower limit is 1.7.|
|21.||The process of any of the preceding claims, wherein the temperature has an upper limit of 90°C and a lower limit of 70°C.|
|22.||The process of claim 21, wherein the temperature has an upper limit of 80°C.|
|23.||The process of claims 2122, wherein the temperature has a lower limit of 71°C.|
|24.||The process of claim 23, wherein the temperature has an upper limit of 75°C.|
|25.||The process of claim 24, wherein the temperature has a lower limit of 72°C.|
|26.||The process of any of the preceding claims, wherein the sufficient time has an upper limit of 5.0 hours.|
|27.||The process of claim 26, wherein the sufficient time has an upper limit of 4.0 hours.|
|28.||The process of claim 2 and 1620, wherein the sufficient time has an upper limit of 5.0 hours and a lower limit of 0.5 hour.|
|29.||The process of claim 27, wherein the sufficient time has an upper limit of 3.0 hours.|
|30.||The process of any of claims 2729, wherein the sufficient time has a lower limit of 0.75 hour.|
|31.||The process of claim 30, wherein the sufficient time has a lower limit of 1.0 hour.|
|32.||The process of any of the preceding claims, wherein the calcium content level in the solution is less than 1500 ppm on a dry weight basis.|
|33.||The process of any of the preceding claims, wherein the upper limit of the degree of esterification of the NCSP fraction is 80% and the lower limit is 70%.|
|34.||The process of claims 233 wherein the upper limit of the degree of esterification of the CSP fraction is 70% and the lower limit is 60%.|
|35.||The process of any of the preceding claims, wherein the plant starting material is selected from the group consisting of citrus fruit, apple, sunflower and sugar beet.|
|36.||The process of claim 35, wherein the plant starting material is citrus peel byproduct from juice manufacture.|
|37.||The process of any of the preceding claims, wherein said acid is an inorganic acid.|
|38.||The process of claim 37, wherein said acid is nitric acid.|
|39.||The process of any of the preceding claims, wherein said weakly acidic solution contains additional amounts of multivalent cation from salt of same.|
|40.||The process of claim 39, wherein said multivalent cation is selected from the group consisting of calcium, magnesium, iron, copper, and aluminum.|
|41.||The process of claim 40, wherein said multivalent cation is calcium ion.|
|42.||The process of claim 41, wherein said calcium salt is selected from the group consisting of calcium nitrate, calcium hydroxide, calcium acetate, calcium propionate, calcium oxide, calcium carbonate, calcium gluconate, calcium lactate.|
|43.||The process of claim 42, wherein said calcium salt is calcium carbonate.|
|44.||The process of claims 3943, wherein concentration of said additional multivalent cation is 150 millimolar in solution.|
|45.||The process of claim 44, wherein concentration of said additional multivalent cation is 525 millimolar in solution.|
|46.||The process of claims 1 and 345, wherein said NCSP has a calcium sensitivity value (CS) of less than 20 cps.|
|47.||The process of claim 46, wherein said NCSP has a calcium sensitivity value (CS) of less than 10 cps.|
|48.||The process of claims 247 wherein said CSP has a YOG value greater than 150.|
|49.||The process of claims 248 wherein said CSP has a calcium sensitivity value (CS) greater than 100 cps.|
|50.||An aqueous composition comprising a non calcium sensitive pectin (NCSP) having a pH greater than 2.5 containing less than 2% by weight of alcool.|
|51.||The aqueous composition of claim 50, wherein the upper limit of the pH is 4.0.|
|52.||The aqueous composition of claims 5051, wherein the NCSP has a DE upper limit of 80.|
|53.||The aqueous composition of claims 5052, wherein the NCSP has a DE lower limit of 70.|
|54.||An aqueous composition comprising a calcium sensitive pectin (CSP) having a pH less than 2.2 containing less than 2% by weight of alcool.|
|55.||The aqueous composition of claim 54, wherein the lower limit of the pH is 1.5.|
|56.||The aqueous composition of claims 5455, wherein the CSP has a DE upper limit of 70.|
|57.||The aqueous composition of claim 5456, wherein the CSP has a DE lower limit of 60.|
|58.||A peel composition comprising a peel in which the ratio of CSP to the sum of CSP and NCSP is enriched.|
There are many processes for extraction of pectin in the art, and there are many uses for these products. A typical pectin process comprises the steps of: (1) aqueous extraction from plant starting material, (2) purification of the liquid extract, and (3) isolation of the extracted pectin from the liquid.
In the acid pectin extraction process, plant material is typically treated with dilute acids such as nitric-, sulfuric-, hydrochloric-or other inorganic or organic acids at somewhat elevated temperatures (70-90°C is specified) to remove the pectin from the cellulose components of the plant starting material. Commonly used plant starting materials are citrus peels left over from juice production and apple pomace left over from apple juice and cider production. Extraction conditions are selected such that a major part of the pectin molecules contained in the plant starting material is transferred from the cell walls of the plant starting material to the extraction medium.
After the acid extraction step, a mixture of solid plant material and liquid that contains the pectin remains. This mixture is then separated by filtration, centrifugation or other conventional separation steps known to those skilled in the art. The wet solids cake can be re-extracted or neutralized and sold as cattle feed. Re-extractions can be done in another stage or multi-stage or continuous countercurrent extractors common to the art. The extract juice is treated to precipitate pectin by addition of an appropriate alcool. This renders the pectin insoluble in the resulting
mixture of an alcohol and water. The insolubilized pectin is separated from the alcohol/water mixture by appropriate means such as filtration, centrifugation, etc. The resulting pectin cake is dried and milled to the desired particle size.
Industrially produced pectins are made up primarily of polygalacturonic acid chains in which rhamnose may be found. Neutral sugars may be attached to the rhamnose units. To qualify as pectin the anhydrogalacturonic acid must make up at least 65% of the ash-free dry matter in commercial type pectins. The galacturonic acid units in the pectin are naturally partly esterified with methyl alcool. According to convention, pectins with more than 50% of the carboxylic acid groups esterified with methyl alcohol are referred to as high methoxyl pectins; whereas, pectins with less than 50% of the carboxylic acid groups esterified with methyl alcohol are called low methoxyl pectins.
The extract as obtained by the commercial production is composed of those molecules that are soluble under the conditions of pH, temperature, and time used during the extraction. The extract is composed of a mixture of molecules which differ according to molecular weight, distribution of molecular weight, and degree of esterification. In most instances, the extract is composed of high methoxyl pectins.
Additional processing of the extract to further de-esterify the molecule is required to produce low methoxyl pectins.
The properties of these high methoxyl pectins are very much dependent on the specific mixture of molecular configurations present in the isolated pectin. This mixture of molecules can be controlled only to a certain degree by the pectin manufacturer by selection of raw materials and extraction conditions. For this reason, variation in pectin properties is seen from extract to extract, from manufacturer to manufacturer, and normalization of the properties is generally necessary. This may be
accomplished by blending different extracts and diluting with acceptable diluent such as sugar, dextrose, fructose, etc., but control of specific pectin properties is limited by this approach.
To those skilled in the art, high methoxyl pectin is not a well-defined molecule but is actually a complex mixture of different types of pectin molecules. Individual types of high methoxyl pectins can have very useful properties. One of the main functional variations between high methoxyl pectins is their sensitivity to the presence of varying concentration of polyvalent cations such as calcium ions. Sensitivity to the presence of calcium ion is defined here as calcium sensitivity. It is known to those skilled in the art that calcium sensitivity is also a strong indicator of sensitivity to other polyvalent cations. Commercially extracted, high- methoxyl pectins contain a mixture of both calcium sensitive and non- calcium sensitive pectins.
US Patent No. 5,567,462 discloses a process for preparing a pecto- cellulose composition from a pectin-containing plant raw material by treating comminuted citrus peel in an acidified aqueous solution to solubilize pectin. The pectin is then recovered in the cellulosic matrix of the citrus peel by adjusting the pH of the solution and dried. The resulting pecto-cellulose product is incorporated in food and other products.
International Publication No PCT/WO 97/03574 discloses a process where a high ester pectin starting material is treated in an acidic environment with at least one protein and a recombinant enzyme.
None of the prior art discloses the instant invention. A need still exists in the pectin industry for a simpler, economical, safer, and more efficient process for producing separated calcium-sensitive pectin (CSP) and a non-calcium sensitive pectin (NCSP) pectin fractions.
SUMMARY OF INVENTION The present invention is related to a two-step process for extraction of different pectin fractions directly from plant starting material, typically citrus peel. In this invention extraction is done by a sequential two-step process using different pH conditions in each extraction step. In a first extraction step, mild pH conditions are used to extract a pectin fraction having a low level of calcium sensitivity. This first fraction is known as non-calcium sensitive pectin or NCSP. In a second extraction step, more acidic conditions are used to extract a pectin fraction having a high level of calcium sensitivity. This second fraction is known as calcium sensitive pectin, or CSP.
More specifically, this invention is directed to a process comprising treating pectin starting material under conditions sufficient to form an aqueous phase rich in NCSP. This invention also comprehends an aqueous composition comprising a non calcium sensitive pectin having a pH greater than 2.5 containing less than 2% by weight of alcool.
Further, this invention relates to a process comprising (1) treating pectin starting material under conditions sufficient to form modified pectin material rich in CSP and (2) treating the modified pectin material under conditions sufficient to form an aqueous phase rich in CSP. An aqueous composition is also provided comprising a calcium sensitive pectin having a pH less than 2.5 containing less than 2% by weight of alcool. A peel composition is also embraced by this invention comprising a peel in which the ratio of CSP to the sum of CSP and NCSP is enriched.
The process of this invention does not require isopropyl alcohol (IPA) during the separation of the pectin fractions and only uses process equipment typically used to extract pectin. Additionally, it has been found sometimes advantageous to add a small amount of soluble calcium salt to the NCSP extraction, particularly when acid conditions are more
aggressive than normal. This invention is simpler, relatively easy to implement, more efficient, and more economical than other methods used to separate CSP and NCSP pectin fractions.
BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a block diagram of the process of the invention.
Fig. 2 shows an embodiment of the present invention using a single extractor.
Fig. 3 shows a multi-stage, multi-celled, countercurrent flow process embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION It has been surprisingly found that CSP can be extracted from NCSP from a source of pectin starting material using only a simple process based on differential pH acidities. In other words, by using different pH ranges, CSP and NCSP can be extracted directly from the pectin starting material in-situ, thus eliminating the need for first removing both fractions together in a solution and then using isopropyl alcohol and a source of cation for separating and then using filtering equipment. The fractional extraction process of the present invention uses two solvents in sequence to extract the pectin fractions from the pectin starting material. The first solvent contains a relatively weak acid solution and optionally may contain a small amount of a cation salt under certain conditions for extracting the NCSP while fixing the CSP in place. The second solvent is a relatively strong acid solution which then extracts the remaining CSP. It has been found that the weak and strong acid solvents have pH ranges greater than 2.5 for the weak acid and less than 2.5 for the strong acid.
The present invention relates to a process of sequentially extracting two kinds of pectin, distinguished by their calcium sensitivity in solution,
from the same plant starting material. The invention described herein is a two-step extraction process, which uses a different pH in each step.
Pectins are generally extracted on an industrial scale using only a single step process. In the two step process of this invention, the first step is performed under mild acid pH conditions greater than pH 2.5 and the second step is performed under strong acid pH conditions less than pH 2.5. Any inorganic acid can be used. The preferred acid is nitric acid.
Organic acids can be used also, if they are capable of the pH requirements of the invention. The low pH required for the second step extraction of the present invention rules out most organic acids for this step.
The first step has been found to extract a non-calcium sensitive pectin or NCSP which exhibits a calcium sensitivity of 0 to 20 cps in a 0.5 weight percent (wt%) solution at 25° C. It is more preferred that the NCSP has a calcium sensitivity of 0 to 10 cps. The second step has been found to extract a calcium sensitive pectin or CSP which exhibits a calcium sensitivity of greater than 20 cps in a 0.5 wt% solution at 25° C. CSP with calcium sensitivities of between 100 and 1000 cps as measured by calcium sensitivity test defined hereinafter is particularly useful.
As used herein,"calcium sensitivity"is intended to mean that property of a pectin product related to an increase in the viscosity of a solution of the pectin product under appropriate conditions using the procedure as described below in the section labeled"Analytical Procedures."Since calcium sensitivity is a strong indicator of sensitivity to other multi-valent cations, the present invention covers sensitivity to such other cations also, for example, magnesium, copper, iron, zinc, aluminum, manganese, and barium.
Another important property of CSP and NCSP is the degree of esterification. As used herein,"degree of esterification"is intended to mean the extent to which free carboxylic acid groups contained in the
polygalacturonic acid chain have been esterified (e. g., by methylation) or in other ways rendered non-acidic (e. g., by amidation). The degree of esterification of pectin fractions produced by the fractional extraction technique of the present invention varies from about 60% to about 80%.
The NCSP has typically higher DE than the CSP material. For example, NCSP has DE of 70-80%, whereas CSP has a DE of 60-70%.
The calcium content in the NCSP and CSP fractions of the present invention has been found to be important for their use in acid-milk stabilization properties of the pectin. The preferred calcium level in the CSP pectin especially is less than 1500 ppm on a weight basis. It is preferred to have the calcium content tess than 750 ppm, and more preferred less than 500 ppm. This is achieved by means common to the art, for example, ion exchange. If conversion of NCSP to low DE pectins is desired then the preferred calcium content of NCSP should also be less than 1500 ppm, preferred less than 750 ppm, and more preferred less than 500 ppm.
As indicated above, processes in accordance with the present invention comprise the treatment of plant starting material containing extractable pectin. This typically includes citrus peel such as lemon, orange, grapefruit, lime, but could also include other fruits such as apple, or other vegetable matter such as sugar beets or sunflower heads.
FIRST STEP EXTRACTION In the first step peel, water and acid are charged to a reactor.
Sufficient acid is added to the reactor in the first step to adjust the pH to a value of 2.5 to 4.0. The pH of the reaction medium influences the rate at which pectin can be extracted as well as the amount. It is clear from this invention that pH also influences the type or fraction of pectin extracted.
Although pectin can be extracted under any acidic conditions from plant
starting material, from pH 0-7, NCSP can only be extracted at pH in the range of and at temperatures in the range of 70° C to 90°C. Above 3.3 NCSP yields are lessened, and at pH 2.7 or lower small amounts of CSP start to be extracted in the first step. Thus, it is preferred that the lower limit of the pH range be 2.7, more preferably 2.8. The preferred upper limit of the pH range is 3.0 with the most preferred pH being 3.3.
The resident time of extraction in the first step has a lower limit of 0.5 hour, preferably 0.75 hour, with the most preferred time being 1.0 hour.
The upper limit of the resident time for extraction is 5.0 hours, preferably 4.0 hours, more preferably 3.0 hours.
When the pH is less aggressive, for example 3.0 or higher, in the first step, no calcium addition is necessary to prevent extraction of CSP.
When, however, calcium ion is not added, the most preferred pH range is 3.0 to 3.3.
In situations where the first step extraction is done under more aggressive acid conditions of pH 2.5 up to 3.0, or at more elevated temperatures than usual, for example, temperatures of 75 to 90°C, it is advantageous to add a small amount of the preferred calcium salt to the acid mixture used for the extraction. The addition of calcium under more aggressive extraction conditions has been found to inhibit the release of CSP in this step. The divalent cation concentration can be varied over a relatively narrow range in the first step extraction, for example from 1 to 50 millimolar (mM) concentration of calcium ion in the acid solution. The preferred lower limit of this range is 3 mM with the most preferred lower limit being 5 mM. The preferred upper limit of this range is 33 mM with a more preferred upper limit being 25 mM and the most preferred upper limit being 20 mM. This added calcium is above that which naturally is in the plant starting material, which can be, typically, about 1 % of dry weight basis. The optimal amounts of calcium ion or other divalent cation depend
on pH and temperature and are a matter of simple optimization within defined parameters. For a specific example, the pH of the first step extraction can be as low as 2.5, in which case a calcium ion concentration in the acid added to the vegetable starting material of about 20 mM was found to be advantageous. When calcium ion is added, the most preferred pH range is from 2.7 to 3.0.
Calcium salts which could be used in the first step extraction under aggressive conditions include calcium hydroxide, calcium chloride and calcium oxide. The more preferred salts are calcium nitrate, calcium acetate, calcium propionate, calcium gluconate and calcium lactate. The most preferred calcium salt is calcium carbonate. Lime can also be used as a source of calcium carbonate.
Examples of other calcium salts which could be used in the practice of the present invention, provided they are reasonably soluble during the extraction, include calcium acid phosphate, calcium citrate, calcium oxalate, calcium dihydrogen phosphate, calcium formate, calcium glutamate, calcium glycerate, calcium glycerophosphate, calcium glycinate, calcium hydrogen phosphate, calcium iodide, calcium lactophosphate, calcium magnesium carbonate, calcium magnesium inositol hexaphosphate, calcium phosphate tribasic, calcium-o-phosphate, calcium pyrophosphate, calcium succinate, calcium sucrate, calcium sulfite, and calcium tetraphosphate.
Salts of other polyvalent cations, such as iron, barium, magnesium, copper and aluminum in particular, can also be used.
The temperature of the first step reaction is also an important variable. Pectin must be extracted at temperatures between 70 and 90°C in order to be labeled pectin. Extractions could be performed at lower temperatures, for example, 50-70°C, but the products cannot be called pectin. It is advantageous and most economical to extract the pectin at a
temperature of 70°C normally. Extraction at higher temperature can hasten the release of pectin from vegetable starting material, and thus shorten the process time. However, at elevated temperatures, extraction of undesirable CSP in the first step extraction can occur, and this must be guarded against in such an operation. Extraction at elevated temperatures also has a deleterious effect on the molecular weight of the pectin. The most preferred temperature range is 70 to 75° C for the first step extraction.
Following the first step extraction the juice containing the NCSP is separated from the peel which still contains CSP. The separation of the peel and juice is done by vacuum filtration or other such means well known in the art. The aqueous composition that is separated is a NCSP pectin solution having a pH greater than 2.5 containing less than 2% by weight of alcool. It should be understood that although no alcohol is used in this simple process, minor amounts could be in the system either as a contaminant or could be formed during the extraction; therefore, to cover these extrinsic amounts of alcool, the term less than 2% by weight is used. The juice from the first step extraction, which contains NCSP is processed under conditions normally and conventionally used for pectin isolation.
The remaining peel after the removal of the NCSP is CSP enriched peel that possibly can be used where a source of fiber and CSP is required. Notwithstanding, this CSP peel is typically sent to the second stage reaction vessel for further processing.
SECOND STEP EXTRACTION Following the first step extraction and separation, the peel is charged into a second step reactor and more water and acid are added for the second step extraction.
The second step extraction is performed under more acidic conditions. The major difference is that the NCSP has been removed from the peel and the pectin extracted in the second step is relatively pure CSP.
Sufficient acid is added in the second step extraction to adjust the pH to a value of between 1.5 and 2.2. For the second step extraction, it is preferred to extract the CSP at a lower limit of pH 1.6, with a pH of 1.7 being more preferred. The preferred upper limit of the pH range is 2.1 with the more preferred pH being 2.0.
Various temperatures may be used for the second extraction step ranging from 70 to 90° C, but the preferred temperature range for this second step is 70 to 75° C with no calcium added for the second step. It would be counterproductive to add calcium to this second step, where extraction of CSP is desired, because calcium has the effect of gelling or binding the CSP in the peel. Extractions could be performed at lower temperatures, for example, 50-70 C, but the products cannot be labeled as pectin.
The resident time of extraction in the second step has a lower limit of 0.5 hour, preferably 0.75 hour, with the most preferred time being 1.0 hour.
The upper limit of the resident time for extraction is 5.0 hours, preferably 4.0 hours, more preferably 3.0 hours After the second step extraction, peel and liquid are separated by filtration or other means common to the art. The CSP fraction is then precipitated from aqueous solution by addition of isopropyl alcohol (IPA).
The CSP is then dried, milled and standardized for sale. The NCSP fraction can be treated in the same way, which is conventional in the art, or can be used as aqueous solution for other processing, for example amidation or total de-esterification to produce low methoxyl grades of pectin. Converting the pectin fractions to solid form and readying them for sale is carried out by conventional techniques. Drying is accomplished by
conventional techniques, e. g., atmospheric or reduced-pressure ovens, to a moisture content of preferably less than 10%. The drying temperature should be maintained below the temperature at which the pectin starts to lose its properties, e. g., color, molecular weight, etc. Milling techniques are well known and any known technique can be used to mill the pectin product to the desired particle size. It is most preferred that the final product be in dry, powder form, with a moisture content of 10% or less.
Dry, powder form is intended to mean that the product be pourable without substantial caking. This is preferred for ease of use.
In accordance with the present invention, any type of conventional equipment can be used in the present invention. Although the process of the instant invention is a two-step process, each of the steps can be multiple steps; this means that the two steps of this invention only refer to the two different distinct acidity pH ranges required for removing the different fractions of the pectin. The equipment can be a fixed bed that moves between the stages or a fixed reactor that is stirred for intimate contact or a fixed bed that percolates the solvent through the bed. The only requirement is that the stages be so designed so that intimate contact is made in a sufficient time period in order to make the separation.
Therefore, a multistage process can be used because the more stages, the more thorough the contact and separation. Processes in accordance with the present invention could be either continuous or batch, with continuous being preferred.
Fig. 1 shows a block diagram of the invention in its broadest sense for illustration purposes to demonstrate the simplicity of the instant invention. Fig. 1 shows that water, acid, and optional cation salt is added to vessel (1) that is operated at a temperature of about 70°C for at least one hour for extracting NCSP from citrus fruit peel that has been chopped up into small pieces for this process. During the extraction, NCSP solution
with other products that are normally present in citrus fruit peel is removed and is sent to an ion exchanger (2) so that the cation is removed to an amount below 1500 ppm. The NCSP solution is then sent to an evaporator (3) for removing the water from the NCSP; this evaporator can be distille at normal distillation temperatures either under vacuum or at atmospheric pressure. The NCSP is then precipitated with a cation in vessel (4) and this precipitate is sent to a drier (5) and grinding apparatus (6) where the NCSP is then dried into particles and ground to the desired sizes and the particulate product is then bagged for use.
After the NCSP is substantially removed from the peel (that can be ascertained by sampling), the CSP enriched citrus peel is then sent to the second stage (7) for CSP extraction. The extracted solution containing the CSP and other side products is then sent to an ion exchanger (8) so that the cation is removed to an amount below 1500 ppm. The CSP solution is then sent to an evaporator (9) for removing the water from the CSP. This evaporator can be distille at normal distillation temperatures either under vacuum or at atmospheric pressure. The CSP is then precipitated in vessel (10) with a cation and this precipitate is sent to a drier (11) and grinding apparatus (12) and the particulate product is then bagged for use.
The spent solid citrus peel removed from the second stage (7) is then removed and disposed of by conventional disposa means; normally, it is sold to farmers for use as animal feed such as for cattle or hogs.
Fig. 2 illustrates a more detailed embodiment of the present invention using a single, jacketed (15), cylindrical vessel (extractor) (10) having a removable top and a porous support (11) for supporting a peel bed (12) positioned near the bottom of the vessel and a distributor (13) for distributing over the bed of peel the extraction fluid for percolating through the bed; both stages of the extraction takes place in extractor (10). The extraction solvent, or extractant fluid, is then pumped through an insulated
line (14) from a first receiver (20) via a peristaltic pump (17) to the extractor vessel (10) and back to the receiver vessel (20) for a time sufficient to achieve the first extraction. The liquid passes over the distributor (13) and drains through the bed (12) and back into the first receiver (20). The recirculation loop is continued until it is indicated that substantially all of the fraction has been extracted. At the completion of the extraction, the bed can be drained by opening the drain line as indicated by line (6). Valves V1 and V4 are open while valves V2, V3, V5, V6 and V7 are closed for the first extraction; valves V2 and V3 are open while the other valves are closed for the second extraction. In this way, the bed of vegetable material can be extracted in sequence. During the second extraction, the second receiver (30) receives the CSP fraction.
At the beginning of the process, the extraction solvent is introduced to the system through receiver (20) or (30) depending on the cycle. This is done to make sure that the extraction fluid is at the correct temperature before going to the extractor so that the system operates more efficiently.
The temperatures of the extractor (10) during both of the extractions are controlled by the circulation of an ethylene glycol/water mixture through the jacket (15) by way of the jacket heater and recirculator (16). The jacket valves, J1, J2, J3, and J4, control the flow of the heating fluid. The flow is parallel to the receivers and in series with the extractor. The temperature can be carefully monitored with probes (not shown) located in all vessels (10), (20), and (30). The pressure drop across the bed of vegetable material can be controlled by the liquid level above the bed. All vessels are vented to the atmosphere. During the first cycle for extracting NCSP, valves J1 and J4 are closed while valves J2 and J3 are opened for circulating and recirculating the heating fluid. During the second cycle for extracting CSP, valves J1 and J4 are opened and J2 and J3 are closed.
The receiver and the extractor for each of the cycles are maintained at the
same temperature during that cycle.
In a commercial process, countercurrent extractors are preferred because they recover more of the available pectin that is hydrolyzed from the vegetable material. The preferred embodiment of the invention is a continuous countercurrent process equipment typical of the art. For example, a horizontal extractor in which the solids move along a conveyor belt is common geometry, or a rotary countercurrent extractor such as a Rotacele extractor can be used. In any case, the extraction battery must be adapted for introduction of two different solvents in sequence, and provision made to draw off the appropriate product. These modifications can be done within the equipment itself by modifications easily accomplished by a skilled artisan in the art or by using a second unit for the second extraction.
Fig. 3 shows a countercurrent flow extractor (100) having two stages, the first (101) for extracting NCSP and the second (102) for extracting CSP. As discussed above, different extraction fluids are used in the different stages. Each stage is divided into cells (a, b, c, d, e, f, g, h, i, j) (or segments); the number of cells will depend on the design of the equipment and the desired effect that would be designed into the unit by artisan in the art. This design permit for a more thorough removal of all of the NCSP from the first stage (101) and CSP from the second stage (102). In this fixed bed percolation process, fillers can be used with the vegetable material to increase the rate of flow of the extracting fluid through the bed (105) or (106) as it moves along perforated the conveyor belt (103) or (104). The filler material is inert to the extraction fluid adding support to the bed and creating voids for liquid percolation. Natural materials such as peanut hulls, sunflower hulls, wood fiber, or mixtures thereof, are the preferred filles. Non-corrosive packing material, such as Rashig rings, wire coils or the like can also be used.
In each of the stages, the fixed bed travels on a perforated conveyor belt (103) or (104) while the extracting fluid (111 or 112) moves through the bed in the opposite direction. As shown in the drawing, the fluid is removed along with the extracted materials and are used as the extracting fluid for a porous cell in each of the stages. The extracted materials along with the extractant fluid after moving through series of cells in each stage are removed from each stage at the bottom of cell a or f via lines 107 or 108. The extracting fluid and extracted materials are moved countercurrent to the bed (105 or 106) by pumps (109 or 110) and introduced to a proceding stage by springer means (113 or 114).
Although this embodiment has been illustrated as a bed moving on a linear conveyor belt, it could also be in the form of a rotary multistage system such as a Rotacel percolation extractor or any form well known in the art. A main consideration in this system is that the beds remain substantially fixed throughout the process in each of the stages during the extraction process so as to enable intimate contact between the extracting fluid and vegetable material with minimal disturbance of the bed so that no or substantially less particulate materials are in the extract.
In accordance with the invention, the compositions described herein offer unique performance characteristics heretofore not obtained. High methoxyl CSP has the ability to imbibe more water than a corresponding material of lower degree of esterification because it has a more open structure. This results in a softer, more deformable gel which is important for many applications in food, cosmetics, etc. The gel is easily reduced to desirable small particles, and its improved deformability results in better mouth feel and creaminess. Although the products of this invention can be used as a fat substitute because of their fat-like organoleptic properties, they can also be added to foods that normally do not contain fat just to impart the fat-like organoleptic properties.
Current low methoxyl commercial pectins, which have a degree of esterification less than about 50%, have more sites for calcium crosslinking and, therefore, a denser structure with less ability to absorb water. Pectins with lower degree of esterification than about 50% form firmer gels with calcium, resulting in less palatale products.
The present invention has advantages over the prior art. For example, as compared to a non-separated pectin product, CSP composition according to the present invention is more efficient in many applications, for example, up to two times more efficient in stabilizer applications for acidified protein systems, such as acidified milk drinks and yoghurt products. As a measure of stabilizing power of the pectin a YOG assay (as described in the analytical section hereinafter) is performed.
Non-fractionated pectins typically have YOG values of from about 100 to about 140. In the present invention, the CSP fraction of the pectin has a YOG value of greater than 150, preferably greater than 160, more preferably greater than 180, and most preferably greater than 200. The higher the YOG value the greater the stabilizing power of the pectin in the final product.
Also, for example, NCSP compositions according to the present invention provide better performance in those applications requiring pectin that is not reactive with cations. The NCSP, according to the present invention, has the advantage that it will not form gels in the presence of calcium, can be readily dissolved in solutions below 10°C, and can be dissolved in solutions containing calcium ion. These attributes have advantages in many end- use applications.
Products of the present invention are particularly applicable to meat, poultry, fish products, dairy products such as milk, ice cream, yoghurt,
cheese, pudding, and flavored dairy drinks, baked foods such as bread, cake, cookies, crackers, biscuits, pies, donuts, pretzels, and potato chips, non-dairy spreads, mayonnaise, soups, sauces, dips, dressings, frozen confections, fruit preparations, jams and jellies, beverages, water gels, confectionery jelly, and low fat spreads.
The present invention is also applicable to be used in disposable diapers, wound dressings, tampons and incontinent devices. Additionally, pectins produced by process of the present invention are applicable to sun tan lotions, sun screen compositions, creams which include emollients such as isopropylmyristate, silicone oils, mineral oils, and vegetable oils which give rise to a tactile response in the form of an increase in skin lubricity, and skin coolants such as menthol, menthyl lactate, menthyl pyrrolidone carboxylate N-ethyl-p-menthane-3-carboxamide and other derivatives of menthol, all of which give rise to a tactile response in the form of a cooling sensation on the skin, perfumes, deodorants other than perfumes, whose function is to reduce the level of, or eliminate microflora at the skin surface, especially those responsible for the development of body odor, antiperspirant actives, whose function is to reduce or eliminate the appearance of perspiration at the skin surface, and anticholinergic actives, whose function is to inhibit the generation of perspiration before it reaches the skin surface.
ANALYTICAL PROCEDURES Determination of Calcium Sensitivity (CS) of Pectin Samples A pectin solution of desired concentration is prepared in distille water and pH adjusted to 1.5 with 1 M HCI. The pectin sample must be in acid or monovalent salt forms. The initial pectin concentration is 0.60 wt%.
Portions measuring 145 g of this pectin solution are added into viscosity glasses.
Five (5) ml of a solution containing 250 mM calcium chloride is added to the 145 g pectin solution to give a final concentration of 8.3 mM calcium.
With efficient stirring with a magnetic stirrer 25 ml of an acetate buffer containing 1 M of acetate ions and a pH of 4.75 is added to the pectin solution to bring pH to 4.2. This brings the final pectin concentration to about 0.5 wt% The magnet is taken out, and the glass is left at room temperature (25 C) until the next day, when the viscosity is measured at 25 C with a Brookfield viscometer.
While the method is most suitable for pectin samples having a viscosity not higher than 100, viscosity up to 200 Brookfield units can be measured with good reproducibility. Pectin samples with higher viscosity tend to gelify, resulting in less reproducible results. The method, however, gives a fair indication of the relative calcium sensitivity of samples.
When the viscosity of the same pectin samples is measured without the addition of calcium chloride-diluting with distille water instead, the contribution by the calcium ions to the viscosity of the calcium containing solution can be calculated by subtracting the value for the calcium free solution or CS-from the value for the calcium containing solution or CS+.
This value is called the CS value (in the table it is referred to as delta CS).
For pectin samples with very low calcium sensitivity (CS), this difference is typically less than 20 cps.
The results reported in the examples are the difference between measured viscosity with and without the addition of calcium. If the difference in viscosity is less than 20 cps then this is classified as a non- calcium sensitive pectin or NCSP. If the difference in viscosity is greater than 20 cps then this is classified as a calcium sensitive pectin or CSP.
Viscosities of CSP types typically are greater than 100 cps.
Determination of Galacturonic Acid and Degree of Esterification Weigh 5 g of the sample to the nearest 0.1 mg and transfer to a suitable beaker. Stir for 10 minutes with a mixture of 5 mi of hydrochloric acid TS (TS NEEDS TO BE DEFINED) and 100 ml of 60% ethanol.
Transfer to a fitted glass filter tube (30 to 60 ml capacity) and wash with six 15 ml portions of the HCI-60% ethanol mixture, followed by 60% ethanol until the filtrate is free of chlorides. Finally wash with 20 ml of ethanol, dry for 2.5 hours in an oven at 105 C, cool and weigh. Transfer exactly one- tenth of the total net weight of the dried sample (representing 0.5 g of the original unwashed sample) to a 250 mi conical flask and moisten the sample with 2 ml of ethanol TS. Add 100 ml of recently boiled and cooled distille water stopper and swirl occasionally until a complete solution is formed. Add 5 drops of phenolphthalein TS, titrate with 0.1 N sodium hydroxide TS and record the results as the initial titre (V,).
Add exactly 20 mi of 0.5 N sodium hydroxide TS, stopper, shake vigorously and let stand for 15 minutes. Add exactly 20 ml of 0.5 h1 hydrochloric acid TS and shake until the pink color disappears. After adding three drops of phenolphthalein TS, titrate with 0.1 N sodium hydroxide TS to a faint pink color which persists after vigorous shaking; record this value as the saponification titre (V2).
Quantitatively transfer the contents of the conical flask into a 500-ml distillation flask fitted with a Kjeldahl trap and a water-cooled condenser, the delivery tube of which extends well beneath the surface of a mixture of 150 mi of carbon dioxide-free water and 20.0 mi of 0.1 N hydrochloric acid TS in a receiving flask. To the distillation flask add 20 ml of a 1-in-10 sodium hydroxide solution, seal the connections, and then begin heating carefully to avoid excessive foaming. Continue heating until 80-120 mi of distillate has been collected. Add a few drops of methyl red TS to the receiving flask, and titrate the excess acid with 0.1 N sodium hydroxide TS,
recording the volume required, in ml, as S. Perform a blank determination on 20.0 mi of 0.1 N hydrochloric acid TS, and record the volume required, in ml, as B. Record the amide titre (B-S) as V3.
Calculate degree of esterification (as % of total carboxyl groups) by the formula: 100 x V2 V, +V2+V3 And calculate mg of galacturonic acid by the formula: 19.41 x (V1 +V2+V3) The mg of galacturonic acid obtained in this way is the content of one-tenth of the weight of the washed and dried sample. To calculate % galacturonic acid on a moisture-and-ash-free basis, multiply the number of mg obtained by 1000/x, x being the weight in mg of the washed and dried sample.
Determination of Stabilizing power-8.5% milk solids non-fat (MSNF)- grade YOG analysis Principe Solutions of pectin with different concentrations are mixed with yoghurt, homogenized and heat treated at 70°C for 10 minutes. The amount of sediment and the viscosity are measured after cooling to 5°C.
The performance of the unknown batch is compared to that of a standard batch.
Apparatus 1. Balance (2 dec.) 2. Balance (3 dec.) 3. Incubator, Hetotherm, type 102 A 923, or similar type 4. Water bath, thermostaticaily controlled at 5°C 5. Water batch, thermostatically controlled at 75°C 6. Mixer, Silverson or similar type 7. Homogenizer, APV Rannie Lab. Homogenizer, model MINI-LAB, type 8.30 H, or similar type 8. Magnet stirrer, JK Ika-Combimag Reo or similar type 9. Beakers, 1500,600 and 400 mi 10. Test tubes, 15 ml 11. Centrifuge, Hereaus Christ, type GL, or similar type 12. Brookfield Viscosimeter LVT 13. Viscosimiter glasses (inner diameter: 50 mm, inner length: 110 mm) 14. pH-meter 15. Automatic dispenser, Fill-Master, type 311 Process Preparation of yoghurt, 17% Milk Solids Not-F (MSNF) Reference is made to Control Method 708, Yoghurt production-17% MSNF.
Determination of Stabilizing Power 1. Prepare an X% pectin solution in deionized water using a Silverson mixer. Mix for 5 min. Heat to 70°C for 10 min. for dissolution of the pectin, cool and adjust for evaporated water. Calculate X as: X= 100 grade YOG % __ ; imated grade YOG Examples: If 100 grade YOG is expected, a 1 % solution is prepared.
If 200 grade YOG is expected, an 0.5% solution is prepared.
The standard YOG-8.5-STD2 which per definition has a YOG grade of 100 is run in parallel with the unknown pectin batch.
2. Weight pectin solution and water into a series of 600 ml beakers and mix for 30 sec., according to the table below.
Pectin X% pectin Deionized 17% MSNF concentration, Solution, Water, yoghurt end product, % g g g 0.000 0 200 200 0.100 x X 40 160 200 0.125 x X 50 150 200 0.150 x X 60 140 200 0.175 x X 70 130 200 0.200 x X 80 120 200 0.250 x X 100 100 200 0.300 x X 120 80 200 0.350 x X 140 60 200 3. While stirring with a magnet stirrer, add 200 g yoghurt (17% MSNF) to the pectin solutions using an automatic dispenser. Continue stirring until the solution is homogeneous. The end product will be 8.5% MSNF yoghurt. Final weight: 400 g.
4. Homogenize at 150-180 bar.
5. Heat to above 70°C in a 75°C water bath for 10 min.
6. Determine the amount of sediment as follows: a) Record the weight of the centrifugal tubes (2 for each pectin concentration applied with 3 decimals. b) Fill the centrifugal tubes (2 for each pectin concentration) to approx.
1 cm from the rind.
c) Weigh all centrifugal tubes including sample. Record the weight with 3 decimals. d) Centrifuge samples for 20 min. at 4500 rpm (approx. 3000 x g). e) Decant supernatant and place the tubes upside down for 30 min. to drain remaining liquid. f) Wipe with a Kleenex tissue and weigh the tube. Record the weight with 3 decimals. g) Calculate the weight of sediment as a percentage of the weight of the sample centrifuged, as follows: weight of tube incl. sediment-weight of empty tube x 100 = % sediment weight of tub incl. sample-weight empty tube h) A weight attached to a computer with calculation program may be used with advantage.
7. Determine viscosity as follow: a) Fill one viscosity glass with each concentration and leave untouched for 18-24 hours at 5°C. b) Measure viscosity with Brookfield Viscosimeter type LVT at 60 rpm.
Read the viscosity after 1 min.'s rotation.
Calculation 1. Plot the results for the standard batch and the unknown batch into a diagram with pectin concentration as the x-axis and percent sediment as the y-axis. Draw two curves, one for the standard and one for the unknown, by connecting neighboring data points with straight lines.
2. Delimit an interval of pectin concentrations as follows: Lower End: The lowest pectin concentration of the STANDARD which yields half of the largest sediment recorded for the standard.
Higher end: The lowest pectin concentration of the STANDARD which yields 1.25 times the lowest sediment recorded for the standard.
3. Shift the position of all the data points for the UNKNOWN by multiplying the distances to the y-axis with a constant, k. Choose k by trial and error until the two curves superimpose to the greatest possible extent within the above interval.
4. The YOG grade of the unknown is now 100 x k.
5. State the result as grade YOG-8.5C.
EXAMPLES The general experimental procedure used for the examples is described below. Each example differs only in experimental conditions or peel source. For Example #1 various experimental conditions were used with one peel source. In Example #2 the same experimental conditions were used with different peel sources. The results for both examples are shown in Table 1.
All experiments were carried out using a 12-liter, jacketed glass reaction vessel. Hot liquid circulated in the jacket to maintain reaction
temperature at 70C, which was measured by a thermocouple. The reactor was provided with a stirrer which operated at mild stirring conditions sufficient to lift the peel to the surface. Acid solution of the proper concentration was prepared in the reactor and heated to temperature.
Nitric acid was used in these experiments. Peel was received in shredded, dried form and contained about 12% moisture. The peel was then charged and the extraction allowed to proceed for a pre-determined time. Peel weight was typically 400 g. The pH was measured and adjusted during the time period, since the peel has buffering action. After the reaction was complete, the reactor contents were drained into a bucket and filtered in a large Buechner funnel or crock using filter cloth and vacuum. The wet peel was then either placed back into the reactor for the second step extraction under different pH conditions or re-extracted in a large beaker adapted for stirring and temperature control (hot plate) under the same pH conditions or with water to increase the yield of the first fraction. The extract was ion- exchanged, evaporated to concentrate the liquor, and then precipitated with IPA. The precipitate was washed with IPA/water solution and dried in a vacuum oven with nitrogen sweep. The resulting pectin material was then ground to pass through an 80 (US) Mesh screen and sent for analyses and further testing.
Example 1 Several extractions are described in this example. All experiments in this example used a single peel source designated A. In runs 4A and 11A no additional calcium was added to the reactor. Increasing levels of calcium were added in runs 5A and 8A. Calcium was added as calcium nitrate salt. Runs 4A and 5A show similar results, both having high calcium sensitivity numbers over 600 cps for the CSP fraction and very low delta CS for the NCSP fraction. A low delta CS for the NCSP fraction
indicates there is no CSP in that fraction. The overall yields and molecular weights of each fraction are similar, but the split is somewhat different.
Run 8A done under more aggressive acid but increased calcium addition showed similar results in some instances to runs 4A and 5A, except the calcium sensitivity of the CSP fraction was significantly less, below 600, and the split was somewhat more even. The amount of NCSP in the extracted pectin varies with peel source, among other things, but the expected maximum is about 45% of the total pectin. Run 11A done under aggressive acid conditions but no added calcium shows a split higher than 40%, but also show a high delta CS for the NCSP fraction. This indicates bleed through of the CSP into the NCSP fraction, and therefore indicates undesirable run conditions. Thus runs 8A and 11A are not preferred conditions, whereas runs 4A and 5A are.
The galacturonic acid content of all extracted pectin samples are typical, between 70 and 80%. The degree of esterification is higher for the NCSP fraction (74-77%) than for the CSP fraction (64-68%). The dilution ratios are on the basis of peel charged, for example 20 indicates 20 times as much liquid as peel on a weight basis, thus for 100 g of dried peel charged, 2 liters of liquid would be used. Additional acid solution was used in the re-extracts at a 10/1 basis.
Exampfe 2 In this example different peel sources were used to extract fractionated pectins under the same conditions. From Table 1, it is clear that the results are similar, with the splits being somewhat different, as might be expected. All peel sources were from citrus fruit (dried lemon peel) from South America.
These examples show the preferred conditions, especially pH. The preferred pH of the second extraction is between 1.7 and 2.0, which is very
typical of normal acid extraction of pectin anyway. The preferred pH range for the first extraction is between 2.9 and 3.3, although this could be extended to 2.7-3.5 in our judgment. A pH of 1.5 is too aggressive for the second stage, and a pH of 2.5 is too aggressive for the first stage, even though its effects can be countered by adding additional calcium, it is not preferred to do so.
This process uses batch extraction equipment typically found in a pectin plant rather than elaborate stagewise extraction equipment and therefore should be easy to implement. Because of its relative simplicity, this process should be more cost effective than alternative methods used to extract non- calcium and calcium sensitive pectin fractions. Table 1. Results of Fractional Extraction Experiments for Examples 1 (4-11 A) and 2 (4C and4Y). Conditions and #4A #5A #8A #11A #4C #4Y Results STEP 1 _ _ _ Dilution/pH/time 20/3. 3/3h 17/2.9/2h 20/2. 5/3h 14/2. 5/1 h 20/3. 3/3h 20/3. 3/3h Calcium added 0 22.5 mM 45 mM 0 0 0 NCSP yield, g 23. 18 16. 31 30. 00 32. 58 21. 92 36.28 Mol. Wt. 122,000 124, 000 158, 000 184,000 CS-, cP 13. 5 15 14. 5 18 18 16 CS+, cp 16. 5 20. 5 17 218 24. 5 16. 5 Delta CS, cP 3 5. 5 2. 5 200 6. 5 0. 5 GA 76. 6 75. 4 78. 9 77. 6 74. 5 77. 5 DE 74. 6 76. 9 76. 2 74. 7 77. 9 78. 5 Calcium content, ppm 586 1500 4650 730 STEP 2 _ _ _ _ _ _ Dilution/pH/time 17. 5/2. 0/ 17. 5/1. 75/ 17. 5/1. 5/ 17. 5/1. 5/ 17. 5/2. 0/ 17. 5/2. 0/ 0.75h 1.5h 0.75h 0.75h 0.75h 0.75h CSP yield, g 47. 85 56. 93 49. 68 43. 44 56. 07 56.63 Mol. Wt. 149,000 174, 000 177, 000 195,000 CS-, cP 16. 5 15. 5 13.5 15.5 12 11 CS+, cP 888 650 556 472 568 366 Delta CS, cP 871. 5 634. 5 542. 5 456.5 556 355 GA 70. 7 80. 7 76. 9 72. 7 72. 0 68. 9 DE 64. 8 67. 4 66. 3 65. 9 69. 7 68. 1 Calcium content, ppm 195 229 401 222 YOG 215 202 172 169 NCSP/CSP/O Split 33/67 22/78 38/62 43/57 22/78 39/61