WO2014030030A1

WO2014030030A1 - Method of producing a sugar product from fruit

Info

Publication number: WO2014030030A1
Application number: PCT/IB2012/054210
Authority: WO
Inventors: Fabio Foraci; Veronica Vallini
Original assignee: NATURALIA INGREDIENTS Srl
Current assignee: NATURALIA INGREDIENTS Srl
Priority date: 2012-08-20
Filing date: 2012-08-20
Publication date: 2014-02-27
Anticipated expiration: 2015-02-20
Also published as: CA2882522A1; IN2015DN01415A; CN104837376A; HK1213440A1; KR20150070097A; CA2882522C; AR092175A1; JP2015527356A

Description

METHOD OF PRODUCING A SUGAR PRODUCT FROM FRUIT

TECHNICAL FIELD

The present invention relates to a method of producing a liquid or solid sugar product, in particular glucose and fructose, from fruit.

BACKGROUND ART

Producing sugar, such as glucose and fructose, from fruit juice, in particular grape juice, is known.

The juice, obtained for example by pressing the fruit, is normally processed first to eliminate non- sugar components, and then by chromatography to separate the sugars, mainly glucose from fructose. The resulting products, in liquid form or later crystallized, are normally used in the food industry or consumed as they are, ^"for example, as sweeteners.

EP1734108 and EP2425723 describe a method of producing sugar products from grapes, in which a concentrated rectified must solution is chromatography processed to obtain a glucose solution and a fructose solution, which are then crystallized.

Prior to the chromatography stage, the juice obtained from crushing the grapes is clarified and demineralized, and then concentrated to the right concentration for chromatography processing. The EP1734108 and EP2425723 method, however, has the drawback of including no treatment to reduce the colour of the sugar solutions, and no control of the hydroxymethylfurfurol (HMF) content, which has crystallization inhibiting properties. Also, the chromatography process fails to provide for complete, satisfactory separation, and more specifically for correct, uniform extraction, of the glucose and fructose. Demand therefore exists for a method of separating sugars, particularly glucose and fructose, from fruit juices, designed to eliminate the above drawbacks, and which, in particular, provides for controlling hydroxymethylfurfurol levels; correct, uniform extraction of sugars from fruit, while at the same time safeguarding the integrity of the sugars; and low energy consumption.

DESCRIPTION OF THE INVENTION

It is an object of the present invention to provide a method of producing a sugar product from fruit, designed to permit hydroxymethylfurfurol level control; correct uniform sugar extraction from fruit, while at the same time safeguarding the integrity of the sugars; lower energy consumption than known methods; and product purity comparable with that of known methods.

According to the present invention, there is provided a method as claimed in Claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS A non- limiting embodiment of the invention will be described by way of example, with particular reference to grapes and to the attached drawing, in which :

Figure 1 shows a chromatography system for separating a glucose solution and fructose solution in accordance with the present invention.

BEST WAY OF IMPLEMENTING THE INVENTION

In the present invention, the term ^juice' refers to grape juice, and in particular to juice obtained from crushing grapes .

After being filtered to remove any remaining solids, the juice so formed is clarified, e.g. by adding gelatine, bentonite and carbon, and demineralized, e.g. on ion resins. Alternatively, clarification and demineralization may be performed as described in EP2425723.

This stage produces a clarified, demineralized fruit juice with a sugar, in particular glucose and fructose, percentage of over 98%, e.g. 98.5%, with reference to the dry substance.

Next, the clarified, demineralized fruit juice is concentrated to reduce its water content, but without altering the composition of its solid portion. The obtained concentrated juice, also known as rectified concentrated must, is a colourless solution containing over 98%, with reference to the dry substance, of fructose and glucose, and the rest of which is made up of components such as alcohol, flavonoids and other polyphenols .

The concentrated concentrated rectified must is then heated to a temperature of 50-70°C, in particular 57-65°C, e.g. 60°C. Advantageously, at these temperatures, the concentrated concentrated rectified must has a viscosity (<10 mPa*s) allowing an uniform leading front during chromatography process.

At these temperatures, the glucose and fructose in the juice can be separated effectively with no need for a high-pressure eluent, and above all without altering the stability of the sugars and/or deteriorating the chromatography resins.

So, despite operating at higher than the ambient temperature of known methods, improved sugar separation allows a considerable reduction in total energy consumption of the method according to the invention as a whole .

The concentrated concentrated rectified must is then subjected to chromatographic separation, in particular on ion-exchange resins, more specifically on cation resins, and preferably on styrene-divinylbenzene resins derivatized with sulphone groups. The resins used may have the characteristics described in EP2425723.

Chromatographic separation is performed in a simulated fluid-bed system as shown in Figure 1.

The Figure 1 system comprises four columns : a, b, c and d, each with a pump (P, Pab, Pbc, Pcd) for pumping the circulating fluid, i.e. the eluent, through the columns .

The four columns are filled with a cation resin, preferably styrene-divinylbenzene resin derivatized with sulphone groups .

The outlet of column a is connected to the inlet of column b by a line Cab fitted with pump Pab; the outlet of column b is connected to the inlet of column c by a line Cbc fitted with pump Pbc; the outlet of column c is connected to the inlet of column d by a line Ccd fitted with pump Pcd; the outlet of column d is connected to the inlet of pump P by a line C₂; and the outlet of pump P is connected to the inlet of column a by a line C_x. Columns a-d, lines C_x, C₂, Cab, Cbc, Ccd and pumps P, Pab, Pbc, Pcd thus form a separation circuit FC, through which the circulating fluid, i.e. the eluent, e.g. deionized water, circulates in the direction of the arrows in Figure 1.

Eluent feed lines Da-Dd and concentrated rectified must feed lines Fa-Fd into separation circuit FC are connected to separation circuit FC close to the respective inlets of columns a-d.

Glucose extraction lines Ea-Ed, for extracting a glucose-enriched fraction from separation circuit FC, and fructose extraction lines Ra-Rd, for extracting a fructose-enriched fraction from separation circuit FC, are connected to separation circuit FC close to the respective outlets of columns a-d.

Eluent feed lines Da-Dd branch off from an eluent feed pipe D connected at one end to an eluent pump P_D; and concentrated rectified must feed lines Fa-Fd branch off from a concentrated rectified must feed pipe F connected at one end to a concentrated rectified must pump P_K.

Open-close valves VDa-VDd are installed along respective eluent feed lines Da-Dd; and open-close valves VFa-VFd are installed along respective concentrated rectified must feed lines Fa-Fd.

Open-close valves VEa-VEd are installed along respective glucose extraction lines Ea-Ed; and open- close valves VRa-VRd are installed along respective fructose extraction lines Ra-Rd.

Glucose extraction lines Ea-Ed are connected to a glucose extraction pipe E.

Fructose extraction lines Ra-Rd are connected to a fructose extraction pipe R.

The Figure 1 system operates as follows.

After initiating the system by filling it with eluent - preferably deionized water or at any rate water with a low calcium content, which acts as the circulating fluid - one of eluent feed lines Da-Dd, one of glucose extraction lines Ea-Ed, one of concentrated rectified must feed lines Fa-Fd and one of fructose extraction lines Ra-Rd are connected so as to be positioned in the following order: eluent feed line, glucose extraction line, concentrated rectified must feed line, fructose extraction line along the direction of the circulation fluid in the separation circuit FC, through opening and closing of valves VDa-VDd, VEa-VEd, VFa-VFd and VRa-VRd.

For example, eluent feed line Da, glucose extraction line Ea, concentrated rectified must feed line Fc and fructose extraction line Rc are connected to separation circuit FC by opening valves VDa, VEa, VFc, VRc and closing all the other valves.

This results in the formation of an elution zone IV in column a, between eluent feed line Da and glucose extraction line Ea; a concentration zone III in column b, between glucose extraction line Ea and concentrated rectified must feed line Fc; a refining zone II in column c, between concentrated rectified must feed line Fc and fructose extraction line Rc ; and an adsorption zone I in column d, between fructose extraction line Rc and eluent feed line Da.

In column a containing the elution zone, the resin- retained glucose is eluted by the eluent from line Da, and is transferred to the circulating fluid in separation circuit FC. At the inlet of column a, the circulating fluid therefore contains roughly no glucose. This concentration increases as the circulating fluid flows through column a, and, at the outlet of column a, the circulating fluid contains a large amount of glucose (glucose-enriched fraction) , part of which is extracted from the separation circuit by glucose extraction line Ea and collected in a glucose tank, and the rest of which is fed into column b.

In column b containing concentration zone III, the glucose in the circulating fluid from column a is retained by the resin as the circulating fluid flows through column b. In the meantime, the fructose in column b, retained by the resin to a lesser degree than the glucose, is transferred to the circulating fluid, so the glucose concentration in the circulating fluid flowing through column b decreases, while the fructose concentration increases. The circulating fluid from column b is then fed into column c together with a portion of concentrated rectified must from line Fc .

In column c containing refining zone II, the glucose in the concentrated rectified must from line Fc and in the circulating fluid is retained by the resin, and the fructose previously retained by the resin in column c is transferred to the circulating fluid. At the inlet of column c, the circulating fluid therefore contains roughly no glucose, whereas the fructose concentration increases as the circulating fluid flows through column c. The circulating fluid from column c and containing a large amount of fructose ( fructose - enriched fraction) is partly extracted by fructose extraction line Rc and collected in a fructose tank, and partly fed into column d.

In column d containing adsorption zone I, the large amount of fructose in the circulating fluid from column c is retained by the resin, so, at the outlet of column d, the circulating fluid contains practically no glucose and no fructose, and is fed back into column a along lines Ci and C₂.

After a given time interval (6.5 minutes) , valves VDa, VEa, VFc, VRc are closed and valves VDb, VEb, VFd, VRd are opened. Opening and closing the valves above determines a transfer of the elution zone IV from column a to column b, of the concentration zone III from column b to column c, of the refining zone II from column c to column d, and of the adsorption zone I from column d to column a.

In column b, the resin- retained glucose is therefore eluted by the eluent from line Db; and the circulating fluid from column b (glucose-enriched fraction) is partly extracted by glucose extraction line Eb and collected in a glucose tank, and the rest fed into column c along line Cbc .

In column c, the glucose in the circulating fluid from column b is retained by the resin, and the fructose, retained by the resin to a lesser degree, is transferred to the circulating fluid, so the glucose concentration in the circulating fluid decreases, while the fructose concentration increases as the circulating fluid flows through column c.

The circulating fluid from column c is fed into column d together with the concentrated rectified must from concentrated rectified must feed line Fd. In column d, the glucose in the concentrated rectified must and in the circulating fluid is retained by the resin, and the fructose is transferred to the circulating fluid. And, at the outlet of column d, part of the circulating fluid (fructose-enriched fraction) is extracted by fructose extraction line Rd and collected in a fructose tank, and the rest is fed into column a.

In column a, the glucose and fructose in the circulating fluid are retained by the resin, so the circulating fluid from column a has no glucose and no fructose, and is fed back into column b.

After a given time interval (6.5 minutes), valves

VDb, VEb, VFd, VRd are closed and valves VDc, VEc, VFa, VRa are opened. Opening and closing the valves above determines a transfer of the elution zone IV from column b to column c, of the concentration zone III from column c to column d, of the refining zone II from column d to column a, and of the adsorption zone I from column a to column b; and the process is repeated as described above .

Chromatographic separation is performed at a temperature of 50-70°C, and more specifically of 57- 65°C, e.g. 60°C.

On the other hand, these temperatures greatly increase the amount of hydroxymethylfurfurol (HMF) derived from thermal decomposition of the sugars.

In the production method according to the invention, the concentrated rectified must and the sugars in it are kept several days in the system. Before it is crystallized, the sugar molecule remains in the process solutions in the system for a period of 5-10 days, and at temperatures of 70-28°C, so a certain amount of HMF, however small, is inevitably produced. excessive amounts of hydroxymethylfurfurol may render the crystallization stage ineffective and greatly reduce crystallization efficiency. In fact, hydroxymethylfurfurol is a known fructose crystallization inhibitor.

Excessive amounts of hydroxymethyIfurfurol have the following effect on fructose crystallization :

20 ppm of HMF in the fructose syrup - 60% crystallization efficiency

50 ppm of HMF in the fructose syrup - 55% crystallization efficiency

200 ppm of HMF in the fructose syrup - 45% crystallization efficiency

The chromatographic separation stage is therefore followed by a filtration stage using carbon filters (e.g. active-carbon - 3 micron filtration BECODISC Filters ^®) which, in addition to reducing the colour of the chromatography eluate, also retains the HMF contained in it, to achieve a high degree of crystallization efficiency.

Temperature is preferably maintained constant at both the chromatographic and filtration stages.

The post-filtration fructose- and glucose-enriched fractions are then concentrated, e.g. in steam concentrators, to the Brix required to produce liquid sugar products for consumption or crystallization roughly 88° Brix for fructose and 75° Brix for glucose. After chromatography and filtration, the glucose- enriched fraction is over 86% pure, and the fructose- enriched fraction over 96% pure.

Chromatographic separation, filtration and concentration are performed at a preferably constant temperature of 50-70°C, and more specifically 57-65°C, e.g. 60°C.

The liquid sugar products obtained may then be crystallized by cooling - and possibly inseminating fructose or glucose crystals - from a temperature of 50- 70°C to a temperature of 25-30°C. These crystallization temperatures, as opposed to the 12-13°C temperatures used in known methods , have the advantage of improving sugar crystallization efficiency and greatly reducing energy consumption.

The crystallized end products obtained are over 99% pure .

All the documents mentioned in the above disclosure are incorporated by way of reference.

Claims

1) A method of producing a sugar product from fruit, the method comprising the steps of :

a) providing a fruit juice comprising glucose and fructose ;

b) demineralizing and decolouring said fruit juice to obtain a clarified, demineralized fruit juice;

c) concentrating said clarified, demineralized fruit juice to obtain a concentrated clarified, demineralized fruit juice; and

d) separating said concentrated demineralized, clarified fruit juice by chromatography to obtain at least a glucose-enriched fraction and at least a fructose-enriched fraction;

the method being characterized by comprising, after said step d) , a step e) of filtering said glucose- enriched fraction and said fructose-enriched fraction on a carbon filter; and in that said steps d) and e) are performed at a temperature of 50-70°C.

2) A method as claimed in Claim 1, characterized in that said temperature is between 57 °C and 65 °C.

3) A method as claimed in Claim 1 or 2, characterized in that said temperature—is maintained constant at steps d) and e) .

4) A method as claimed in any one of Claims 1 to 3 , characterized by comprising, after step e) , a step f ) of crystallizing said glucose-enriched fraction and said fructose-enriched fraction.

5) A method as claimed in Claim 4, characterized in that said crystallization step f) is performed with a temperature gradient of 70 to 25°C.

6) A method as claimed in any one of Claims 1 to 5, characterized in that said chromatographic separation step d) is performed on ion-exchange resins.

7) A method as claimed in Claim 6, characterized in that said ion-exchange resins are cation resins.

8) A method as claimed in Claim 7, characterized in that said cation resins are styrene-divinylbenzene resins derivatized with sulphone groups.