Process for purifying beet juice

Abstract

The present invention relates to a process for purifying beet sugar juice and more particularly sugar juice obtained by pressing beets. It also relates to the purified juice and to the uses thereof, in particular as a fermentation substrate and for preparing granulated sugar. The purification process according to the invention comprises a step of passing the juice to be treated through a cellulose-fibre-based pre-layer. This process can be improved when the juice to be treated comprises between 0.1% and 4% of cellulose fibres.

Claims

1. A process for purifying beet sugar juice comprising: (a) combining the beet sugar juice and cellulose fibers at a content of between 0.1% and 4% by weight; and, (b) passing the beet sugar juice and cellulose fiber combination through a filtration precoat which consists of 100% of cellulose fibers.

2. The process as claimed in claim 1, wherein the cellulose fiber content is preferentially between 0.2% and 3% by weight.

3. The process as claimed in claim 1, wherein the filtration is carried out by means of a scraped precoat rotary filter.

4. The process as claimed in claim 1, wherein the filtration is frontal.

5. The process as claimed in claim 1, wherein the filtration step is preceded by a centrifugation step.

Description

EXAMPLES

(1) 1. Determination of the Sludge Level:

(2) The sludge level is evaluated by centrifugation according to the following protocol: weight out 65 g of JBT AE and add 20 ml of water, adjust the pH to 6.5, add 100 ml of demineralized water, heat to 100° C. and maintain at boiling for 2 to 3 minutes, cool and then centrifuge for 15 minutes at 3700 rpm in 15 ml tubes.

(3) The sludge content, expressed in ml/100 g, is calculated as follows:

(4) ml lus×100×100/15×65.

(5) 2. Filtration of the JBT AE on a Scraped Precoat Rotary Filter

(6) Two tests were carried out with two types of precoats: a. Potato starch to which 10% of corn starch has been added; b. Cellulose fibers known under the trade names ARBOCEL (Grade BER40) and VITACEL (Grade L600).

(7) Since cellulose is temperature-resistant, unlike starch, the use of this raw material enables hot-filtration of the syrups.

(8) Under our test conditions and in order to avoid dilution of the JBT AE filtrate with the water constituting the liquid ring of the vacuum pump of the filter, a filtrate recycling system was put in place. The filtrate could then be used as service liquid and thus eliminate the dilution with water.

(9) After having filtered close to 80 to 100 liters of JBT AE, the tests were stopped and the filtrates were concentrated on a rotary evaporator. The sludge levels of the JBTs thus reconstituted were measured and are collated in the following table I. These JBTs were compared to a control corresponding to the JBT AE thawed and concentrated directly without any prior treatment.

(10) TABLE-US-00001 TABLE I Level of deposit measured on the JBTs that were concentrated after filtration of the JBT AE on a precoat Precoat type Sludge level Observation Nonfiltered JBT AE control 8% to 12% Concentrated directly Precoat consisting of 90%   4% Very rapid clogging of the Alimentamyl modified precoat requiring regular potato starch + 10% corn scraping starch Precoat based on cellulose <1% No clogging observed, no fiber: scraping 50% BER40 + 50% L600

(11) The use of a precoat consisting of starch is not envisionable since the filtration of 100 kg of JBT AE led to the consumption of close to 3 kg of starch, i.e. a ratio of close to 10% W/W of starch per kg of JBT produced.

(12) The use of cellulose appears, on the other hand, to be particularly advantageous since no scraping of the precoat was required, while the deposit measured on JBT was brought back from approximately 10% (control without treatment) to less than 1%.

(13) 3. Frontal Filtration of the JBT AE with Addition (Topping Up) of Cellulose Fibers

(14) Since the use of cellulose on the precoat filter made it possible to obtain a good reduction of the deposit present in the JBT AE, the tests consisting in topping up the JBT AE with cellulose were continued under various frontal filtration conditions.

(15) This is because, since the use of the JBT AE on a rotary filter was difficult to manage, it was decided to work using frontal filtration with a cellulose precoat (Grade BER40) and topping up (2% W/W relative to juice) in order to simplify the implementation of the tests and thus to accelerate the rate thereof.

(16) Three series of tests were carried out in order to estimate the advantage of a filtration of the JBT AE on a cellulose precoat.

(17) The results of the various tests carried out are collated in table II hereinafter. The results should be compared to the internal control (JBT concentrated to L without any other treatment) and to the “Attin” controls (JBT produced at Attin from the same JBT AE).

(18) Various test conditions were tested by varying: the pH of the juice to be filtered; the use of a flocculant (ALOES Alopolym 637) used at 10 ppm.

(19) TABLE-US-00002 TABLE II Tests of frontal filtration of various non-concentrated beet juices resulting from the ECOSAF pilot Flocculant Duration Filtration Cellulose top (Alopolym concentration Level of Test Sample ref. pH up 637) & final Brix deposit Observation S1.4 JBT AE 10.0 no no 20 min, 62° Bx 18%  Internal control S1.6 JBT AE 4.0 2% no 20 min, 62° Bx 9% Reduction of the deposit via low pH and cellulose S2.2 JBT AE 10.5 2% no 20 min, 67° Bx 4 to 5% Reduction of the deposit via cellulose S2.3 JBT AE 10.5 2% 10 ppm 20 min, 67° Bx 2% S2.4 JBT AE 4.2 2% no 20 min, 66° Bx 1% S2.5 JBT AE 4.2 2% 10 ppm 20 min, 62° Bx 2% S3.2 JBT AE 9.2 no no 20 min, 64° Bx 8% Internal control S3.3 JBT AE 9.2 2% 10 ppm 20 min, 65° Bx 0% Reduction of the deposit via cellulose A cellulose precoat is deposited on the filter, the juice to be filtered being topped up with 2% of cellulose (Grade BER 40). After filtration, the filtrates were alkalinized if necessary to pH 10 and then concentrated on a rotary evaporator until a Brix close to 65% was obtained. The level of deposit was then measured.

(20) The use of cellulose as an addition enabled a significant reduction in the level of sludge, said reduction being between 50% and approximately 90% of the initial deposit.

(21) The monitoring of the filtration kinetics shows that the filtrations of the acidified JBT AEs prove to be more difficult than those of the alkaline JBT AEs.

(22) These observations tend to show that the acidification of the JBT AE and/or the addition of flocculant cause(s) a loss of permeability of the filtration cake. This greater resistance to filtration perhaps also reflects a greater retention of impurities. The deposit levels measured in the filtered juices which have been acidified or to which flocculant has been added are effectively lower (1% to 2%) than in the case of filtration of the JBT AE at pH 10.5 without the addition of flocculant (deposit level approximately 4% to 5%).

(23) The filtration on a cellulose precoat therefore clearly makes it possible to retain the deposit present in the JBT; the topping up of the JBT AE with cellulose makes it possible to facilitate the filtration by improving the filtration flow rates.

(24) While this technique for purifying the JBT AE was retained, it was, however, advisable to continue the tests in order to specify the type of filter to be used and the top up parameters. The choice of the grade of cellulose fibers to be used could then be validated.

(25) 4. Centrifugation of the JBT AE with or without Cellulose Fiber Top Up

(26) Various conditions for centrifugation of the JBT AE (C10) were studied on the Pilot floor-standing centrifuge (JOUAN KR4/22, RP6 6-bucket rotor, 0.8 kg of juice centrifuged per bucket).

(27) The cellulose fibers (Grade BER 40) could be used for topping up the juices before centrifugation at an incorporation ratio ranging between 0.5% and 2% W/W. The contact time before centrifugation was set at a few minutes, which was the time for preparing the preparations.

(28) The pH of the juice was not readjusted before use.

(29) For each test, the supernatant of the juice centrifuged was carefully recovered so as not to resuspend the centrifugation pellet, and was then concentrated on a Pilot rotary evaporator.

(30) It was possible to apply two supernatant concentration kinetics during these tests, namely: rapid and controlling kinetics resulting in a short residence time in the concentration balloon flask, close to 20 min. The concentration is entirely carried out under reduced pressure (25 mbar), bath temperature close to 90° C., product temperature close to 80° C. and vapor temperature close to 70° C.; slow kinetics resulting in a residence time in the concentration balloon flask close to 60 minutes. The concentration is only partially carried out under vacuum according to the following sequence (15 minutes without vacuum, bath and product temperature close to 90° C., little evaporation during this period; then 10 minutes at 500 mbar, bath and product temperature close to 90° C., little evaporation; then 10 minutes at 200 mbar, bath temperature 90° C.; then 25 mbar until the desired concentration is reached).

(31) The results of the JBT AE centrifugation tests are collated in table III hereinafter.

(32) TABLE-US-00003 TABLE III Tests of centrifugation of various JBT AE-type beet juices resulting from the ECOSAF pilot Duration Sample Centrifuge BER 40 concentration & Level of Obser- Test nature acceleration/time cellulose final Brix deposit vation S4.1 JBT AE no no 20 min, 64° Bx 13%  Internal control S4.2 JBT AE 2700 g/5 min no 20 min, 62° Bx 2% Reduction in the S4.3 JBT AE 2700 g/5 min 0.5%   20 min, 65° Bx 2% sludge level S4.4 JBT AE 2700 g/5 min 1% 20 min, 66° Bx 2% with or without S4.5 JBT AE 2700 g/5 min 2% 20 min, 63° Bx 1% cellulose S4.6 JBT AE 4500 g/5 min no 20 min, 67° Bx 2% Reduction in the S4.7 JBT AE 4500 g/5 min 0.5%   20 min, 63° Bx 1% sludge level S4.8 JBT AE 4500 g/5 min 1% 20 min, 67° Bx 1% with or without S4.9 JBT AE 4500 g/5 min 2% 20 min, 62° Bx 1% cellulose S5.1 JBT AE no no 20 min, 63° Bx 21%  Internal control S5.2 JBT AE 2700 g/5 min no 20 min, 63° Bx <0.5%     Reduction in the S5.3 JBT AE 2700 g/5 min 0.5%   20 min, 64° Bx <0.5%     sludge level S5.4 JBT AE 2700 g/5 min 1% 20 min, 64° Bx <0.5%     with or without S5.5 JBT AE 2700 g/5 min 2% 20 min, 65° Bx 1% cellulose S5.6 JBT AE 4500 g/5 min no 20 min, 66° Bx <0.5%     Reduction in the S5.7 JBT AE 4500 g/5 min 0.5%   20 min, 68° Bx <0.5%     sludge level S5.8 JBT AE 4500 g/5 min 1% 20 min, 65° Bx <0.5%     with or without S5.9 JBT AE 4500 g/5 min 2% 20 min, 66° Bx <0.5%     cellulose S6.1 JBT AE no no 60 min, 66° Bx 14%  Internal control S6.2 JBT AE 1000 g/1 min no 60 min, 65° Bx 1% Reduction in the S6.3 JBT AE 1000 g/1 min 0.5%   60 min, 64° Bx 1% sludge level S6.4 JBT AE 1000 g/5 min no 60 min, 69° Bx <0.5%     with or without S6.5 JBT AE 1000 g/5 min 0.5%   60 min, 68° Bx <0.5%     cellulose S6.6 JBT AE 3000 g/1 min no 60 min, 68° Bx <0.5%     Reduction in the S6.7 JBT AE 3000 g/1 min 0.5%   60 min, 65° Bx <0.5%     sludge level S6.8 JBT AE 3000 g/5 min no 60 min, 65° Bx <0.5%     with or without S6.9 JBT AE 3000 g/5 min 0.5%   60 min, 65° Bx <0.5%     cellulose The juices were centrifuged on a JOUAN KR4/22 centrifuge + RP6 rotor. The juice to be centrifuged can be topped up with JRS BER 40 cellulose fibers according to a ratio of 0.5% to 2% W/W. After centrifugation, the supernatants were concentrated on a rotary evaporator until a Brix close to 65% was obtained. The level of deposit was then measured according to the protocol of example 1.

(33) The JBT AE centrifugation tests clearly show that all the conditions tested in the Pilot: acceleration ranging from 1000 to 4500 g; for a period of 1 to 5 minutes; with or without use of cellulose; followed by a more or less long concentration treatment; sampling of JBT AE on ECOSAF pilot on three different days,

(34) result in total reduction of the level of deposit present in the JBT AE.