MX2008007098A - Process for producing fructose-enriched syrups from agave plants - Google Patents

Abstract

The present invention describes a process for the manufactureof fructose-enriched syrups using a quick and continuous hydrolysis method in fructanes extracted from harvested agave plants. The aforementioned process allows the amount of carbohydrates contained in the final product to be controlled, thereby obtaining a syrup with agreeable organoleptic characteristics with a low glycemic index, which is perfect to be consumed by people having obesity or diabetic disorders.

Description

PROCESS FOR THE PRODUCTION OF RUSTY SYRUPS IN FRUCTOSE FROM AGAVE PLANTS TECHNICAL FIELD OF THE INVENTION The present investment refers to a process for the preparation of syrups rich in fructose from jelly pineapples of agave as a raw material, and in particular, to a combination of the acidification of the juice rich in fructans extracted from the agave plants, without the addition of inorganic acids and the heating of fructan-rich juice for a rapid and continuous hydrolysis of said fructans. The present invention also relates to the processes by which the distribution of carbohydrates in the final product can be controlled, using continuous processes.

STATE OF THE ART Agave syrup is a product rich in fructose obtained by the hydrolysis of fructans present in the agave and which can be used in the food and beverage industry. The hydrolysis process of these fructans can be achieved through thermal, chemical, and enzymatic processes. It is also possible to carry out a combination of some of these processes or up to the three to accelerate the reaction. In addition to the hydrolysis of agave fructans, it is advisable to remove both the remains of plant tissue and the aromas and flavors of the plant to obtain a high quality fructose syrup, free of these aromas and flavors and a light color.

The use of the thermal process as it is used in the tequila industry to obtain syrups rich in fructose, is widely recognized, and the operating cost is low, however, besides that the hydrolysis time is long, they come to present Millard's diverse reactions, which generate color and contaminants such as hydroxymethylfurfural (HMF) that can be toxic. Another conventional process is the use of the known acid hydrolysis for the production of fructose syrups. This process seeks to reduce the pH of the solution by the addition of some mineral acid such as hydrofluoric acid or sulfuric acid to favor the breakdown of the bonds present in fructans, where normally the reaction is carried out at temperatures above 60 ° C. Although the operating costs of the present process are low, yellowish or brown coloration still persists and the formation of small amounts of contaminants such as HMF. A third way for the hydrolysis of agave fructans is the use of enzymatic complexes. US Pat. No. 5,846,333 describes the use of commercial enzymes of the inulinase type capable of providing acceptable levels of hydrolysis for the preparation of fructose agave syrups. Unfortunately, this development involves a high cost of operation since the activity of the enzyme used for other batches is not recovered. However, through the use of enzymes, the presence of contaminants such as HMF is dramatically reduced, although the hydrolysis times are between 5 and 8 hours. A further disadvantage to the continuous use of enzymes of this method is the batch raw material processing.

US Pat. No. 4,138,272 describes a method for obtaining fructose and fructose-rich syrups from Xerophytes plants in which a combination of acidification of the juice is made, either by the addition of inorganic acids or by exchange columns ion and the heating of the juice at a temperature of around 85 ° C, however the time of the hydrolysis process is between 2.5 and 3 hours. All processes of the state of the art have disadvantages in relation to the quality and organoleptic characteristics of the product. In addition, its realization requires the processing in batches of the raw material, using minimum times of 3 to 8 hours for the hydrolysis of the fructans. Thus, there is still a need to detail a process for the hydrolysis of fructans that allows to work quickly and continuously, at low cost, and with a minimum generation of color and contaminants such as HMF, and which in turn is capable of ensuring that the concentration of the different carbohydrates present in the resulting syrup is always constant, allowing the quality to be determined freely of the agave syrup to be obtained and not subject to the characteristics of the raw material, as it happens today with any of the processes described above.

BRIEF DESCRIPTION OF THE FIGURES Figure 1. It is a schematic representation of the flow chart of the process for obtaining high fructose syrup from agave plants according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION For the process of the present invention, shredded agave pineapples are used to produce a concentrated fructose syrup with a minimum fructose: glucose ratio of 9: 1, by means of the flow chart of Figure 1. Carbohydrates of the agave are extracted from the tissue of the plant with a solvent, preferably water, which is administered countercurrently and at a temperature between 50 and 92 ° C (1). For this, it is necessary to increase the transfer area of the plant to facilitate the diffusion of carbohydrates to the solvent. This is achieved through a piece of plant where fragments of between 5 and 10 cm in length are produced using mill knives, and subsequently the plant undergoes a pulverization where a mixture of pulp and fiber is formed using a chain mill and / or hedgehogs. Water is used as a solvent at a temperature of 65 to 92 ° C in a proportion 0.5 to 2.5 times the amount of agave pulp that feeds the diffusion process. The outgoing pulp is squeezed in a mass mill and the juice obtained is mixed with the juice coming out of the diffusion process (4). Depending on the concentration of soluble carbohydrates present in the agave, and the amount of water used for the diffusion process, a concentration of sugars in the juice can be obtained from 5 to 33 ° Brix, having a concentration preferably of 18 ° Brix, at a temperature between 75 and 92 ° C. The resulting solution has remains of tissue of the plant that are undesirable in the process, so that these are removed in a first step by the action of a centrifugation and / or filtration to reduce the load of suspended solids present in the solution. Preferably, a filtration system with stainless steel mesh with a nominal pore size of 125 microns and which is suitable for working at temperatures between 75 and 92 ° C (5) is used. The prefiltered juice feeds a tangential flow microfiltration system with ceramic elements and with a nominal pore size of 0.45 microns (6). The juice is fed at a pressure of between 1809.99 to 3878 mmHg, preferably at 2843.8 mmHg, with a discharge of between 0 to 775.6 mmHg and at a temperature between 75 and 92 ° C. The filtering pressure is between 0 to 775.6 mmHg. With this, the diffuser juice passes from a turbidity of 500 Nephelometric Units of Turbidéz (UNT) to 0 UNT. There is a feedback to the feed tank (2) which in turn this line can feed other processes such as those for the production of tequila (3). The clarified juice is subjected to a demineralization process by passing it to a flow of between 2 and 5 bed volumes per hour, preferably at 3 and 5 bed volumes per hour, at a temperature between 50 and 85 ° C, a through a cation exchange resin, for example Dowex monosphere 88 in its H + form (7). This resin is a strong cationic resin of macroporous type and its matrix is of styrene-divinylbenzene, with a sulfonate functional group. The cations present in the juice are exchanged for protons which causes an acidification of the juice to obtain pH values between 1.5 and 3.0. The acidified juice is subjected to a hydrolysis process by raising the temperature between 110 and 145 ° C, for a period of between 15 sec and 15 minutes, depending on the temperature used (8). The juice is immediately cooled to a temperature between 40 and 75 ° C (9). If it is desired to obtain a lot rich in fructans, the hydrolysis system is omitted to continue with the process as described for acidified and hydrolyzed juices, where the fructans are then concentrated in the evaporator (13, 14, 15) and collected in the fructan receiving tank (29) to subsequently adjust the final concentration of this compound in the product (22). Acidified and hydrolyzed juice is subjected to a demineralization process by passing it to a flow of between 2 and 5 bed volumes per hour, at a temperature between 50 and 85 ° C, by an anion exchange resin using, as per example, dowex monosphere resin 77 in its OH "form. (10) This resin is a weak ammonic type of macroporous type and its matrix is of styrene-divinylbenzene, with a functional group of tertiary amine.The juice is again subjected to a anion exchange by passing it to a flow of between 2 and 5 bed volumes per hour, preferably to 3, and at a temperature of between 40 and 75, using for example, dowex resin 22 in its OH "form (11). This resin is of the strong anionic type of macroporous type and its matrix is of styrene-divinylbenzene, with a functional group of quaternary amine. With the exchange of anions, the pH of the demineralized and hydrolyzed juice becomes alkaline until reaching pH values between 8.5 and 13, so the juice is once again subjected to a step by the cationic resin to avoid any leakage of cations and regulate the pH between a value of 3 and 5 (12). The hydrolyzed and demineralized juice is concentrated until reaching a concentration between 50 and 70 ° Brix, preferably 65 ° Brix, either by a filtration system or in a conventional evaporator that works at a vacuum pressure, preferably the last one is used ( 13, 14, 15). The concentrated juice is subjected to a process of separation of fructose and glucose through affinity chromatography, using, for example, dowex monosphere 99 Ca350 resin, in a simulation system of bed moving (Simmulated Moving Bed, SMB by its acronym in English), where 2 to 8 columns are used, preferably 4 (16, 17, 18, 19). The concentrated juice is fed to the columns that are connected in series at a temperature of between 40 and 75 ° C, and each of them has its own supply of both eluent and concentrated juice. The concentration of sugars at the exit of each column is measured by a system of polarimetry and refractive index. The water used for the elution must be reverse osmosis quality. During the process, two fractions are generated, one rich in glucose (20), and the other rich in fructose (22). The two fractions are collected independently taking care that the fructose-rich fraction has a maximum glucose concentration of 3% of the total carbohydrates present in the solution. The fraction rich in glucose is collected and used in fermentation processes (21) and / or to adjust fructose / glucose concentration in honey between ranges of 70/30 to 98/2% fructose / glucose respectively of total carbohydrates , preferably using a ratio of 90/3 (the rest can be other carbohydrates such as fructans and sucrose; (22)). In the fructose / glucose separation process, there is a dilution of the juice. The color and some aromas resulting from the juice are regulated if necessary by passing the hydrolyzed and demineralized juice through a column packed with activated carbon or with a polymeric adsorbent resin at a temperature between 35 and 75 ° C, and using a flow of between 2 and 5 bed volumes per hour, preferably 3, as for example, dowex optipore resin SD-2 (23). This resin is macroporous with a matrix of styrene-divinylbenzene, and with a functional group of the tertiary amine type to increase its hydrophilicity.

The juice undergoes a filtration process through a pore membrane of 0.1 to 0.45 microns (24), and is preferably concentrated by a low pressure evaporation of 60 to 85 ° Brix (25, 26, 27). The product is sent to the container area (28).

EXAMPLE 1 500 liters of diffuser juice rich in agave fructans at a concentration of 8 ° Brix, are heated to a temperature of 85 ° C. The juice of the diffuser is then forced to pass through a stainless steel filter with nominal pore of 100 microns, to remove thick suspended solids. The filtered juice is then filtered in a ceramic tangential flow filter with a nominal pore size of 0.45 microns at a feed pressure of 2068.3 mmHg, without raising the pressure at the outlet of the system, maintaining it at a value of 0 mmHg. The juice is completely clarified with a characteristic color of the agave. The clarified juice is demineralized at a temperature of 80 ° C with a strong cationic resin such as Dowex monosphere 88 in its H + form, using a flow of 3 bed volumes per hour. The clarified and partially demineralized juice has a pH value of 2.25, and is at a temperature of 75 ° C. The juice is then heated to 121 ° C for 10 min and quickly cooled to a temperature of 65 ° C. The juice is then demineralized with anion exchange resins first of weak type at a flow of 3 bed volumes per hour, and subsequently with a strong anionic resin (Dowex monosphere 77 and Dowex 22 respectively). The juice acquires a pH of 10.5 so it is necessary to neutralize it, and this is achieved by passing demineralized juice through a cationic resin to a flow of 5 bed volumes per hour. At this point the juice has a pleasant flavor since it is free from the aromas of the plant itself. The juice is concentrated in a vacuum evaporator, until reaching a concentration of 60 ° Brix. The concentrated juice passes through an array of two dowex monosphere 99 Ca350 affinity columns placed in series, where by affinity to the polymer matrix, fructose elutes slower than glucose. For the system to work it is necessary to be free of air. Thus, the agave syrup feeds column # 1 to a flow of 3 bed volumes per hour, where at the end of the first column, we find that the first fraction has a high concentration of glucose. The syrup is allowed to continue to the second column but the syrup is now driven with water of reverse osmosis quality. At the end of column # 2, the first fraction is glucose only. Normally there is an increase in the concentration of sugar at the outlet of column # 2 corresponding to glucose. This profile generates a stationary phase or even a decrease in the concentration of sugars in the effluent, which means that the glucose fraction is ready to run out. Subsequently, a notable increase in the concentration of ° Brix of the effluent is observed, indicative that the fraction of interest must be collected. As this fraction is collected, fresh concentrated juice is injected again through column # 1, repeating the cycle. The concentration of sugars in both fractions is determined by HPLC, and the final concentration of agave syrup is regulated according to these measurements. Finally the syrup is again microfiltered now with a nominal pore of 0.2 microns, to guarantee that the syrup is free of microorganisms, and finally evaporated in vacuum until reaching a concentration of 75 ° Brix. The final product has a glucose concentration of less than 5% of the total carbohydrates present in the syrup, and a fructose concentration of at least 90% of the total sugars.

The product obtained by the process of the present invention has several advantages with respect to the products already on the market: The first advantage is the capacity given by the production process to control the quality and final composition of the product, especially in the distribution of carbohydrates. For the other syrups that are on the market, the distribution of carbohydrates depends on several factors where the main ones are the source of raw material or agave, in which factors such as the variety of the plant, its age and area of cultivation, that significantly influence the type of fructan present in the agave as well as its size (Mancilla-Margalli NA and López MG (2006) J Agrie Food Chem. 54: 7832-7839), and thus the final composition of fructose varies and glucose. The second advantage of the product obtained by the process of the present invention lies in the ratio Fructose: Glucose (F / G) thereof, which is the highest in relation to those already present in the market. This is of particular importance since the glycemic index (GI) of the syrup will be derived directly from the F / G value, where at values higher than 9 we will find the lowest GIs, even below 20 units. Low GI is very important because it makes this product susceptible for consumption by people with diabetes and / or obesity problems. The difference with commercial brands is demonstrated via HPLC analysis as shown below: Table 1.- Comparative chart of the properties of the syrup obtained by the present process and syrups that are already available in the market, determined by HPLC.

SPECIFICATION JARABE SYRUP JARABE COMMERCIAL PROCESS 1 COMMERCIAL 2 ° Brix 75 77 70 PH 4 3.8 CONTENT 87.12% + 1-2% 67.2-69.7% 73.39 FRUCTOSE CONTENT 4.76% 26.5-28.8% 23.40 GLUCOSE CONTENT OF 8.12% + / .-!% 2.93-3.4% 3.21 OTHER CH'S HUMIDITY 18.13% 16.5% 25.4% VISCOSITY 1100 cP 1000 cP 950 cP DENSITY 1384.5 (Kg / m3) The difference in the concentration or distribution of glucose is remarkable, as well as the increase in the distribution of fructose.

Claims (8)

1. CLAIMS 1.- A process for obtaining fructose-rich syrups from agave plants, characterized in that it comprises the steps of: a) Extract fructan-rich juice from the tissue of agave plants with water at a temperature between 50 and 95 ° C. b) Filter the obtained juice c) Hydrolyze the filtered agave juice by: a. Acidify the filtered juice by putting it in contact with a cation exchange resin until a pH value between 1.5 and 3. b. Heat the acidified juice at a temperature between 110 and 145 ° C. d) Cool the hydrolyzed juice at a temperature between 40 to 75 ° C. e) Demineralize the hydrolyzed juice by putting it in contact with anion exchange resins. f) Acidify the hydrolyzed and demineralized juice by putting it in contact with a cation exchange resin until a pH value between 3 and 5. g) Concentrate the demineralized and hydrolyzed juice to a concentration of between 50 and 70 ° Brix. h) Separate Fructose and Glucose from the hydrolyzed and demineralized juice by putting it in contact with affinity resins. i) Collect the fractions and mix them at a ratio between 70/30 to 98/2% of Fructose / Glucose respectively. j) Concentrate the high fructose syrup to a concentration between 60 and 85 ° Brix.
2. 2. - The process according to claim 1 further characterized in that the step (a) of extracting fructans comprises cutting the tissue of the plant into fragments of 5 to 10 cm in length.
3. 3. - The process according to claim 1 further characterized in that in step (a) of extracting fructans, the water is applied in countercurrent.
4. 4. - The process according to claim 1, further characterized in that the step (b) of filtration of the juice rich in fructans is made through a stainless steel filter with a nominal pore of 100 microns.
5. 5. - The process according to claim 1 further characterized in that step (c) of hydrolysis is carried out between 15 sec and 15 minutes.
6. 6. - The process according to claim 5 further characterized in that step (c) of hydrolysis is continuous.
7. 7. - A high fructose syrup obtained by the process according to claims 1 to 6, further characterized in that it has a fructose content of at least 90% and a glucose content of up to 5%.
8. 8. - The fructose-rich syrup according to claim 7, characterized in that it has a glycemic index of up to 9 units.