WO2018029500A1

WO2018029500A1 - New components to clarify sugar cane juice in a process for producing crystal or raw sugar

Info

Publication number: WO2018029500A1
Application number: PCT/IB2016/001095
Authority: WO
Inventors: Sergio Teixeira; Neimar Jose GIROTTO; Cinthia NAKAMURA; Lidiane DE OLIVEIRA
Original assignee: Rhodia Poliamida E Especialidades S.A.
Priority date: 2016-08-08
Filing date: 2016-08-08
Publication date: 2018-02-15
Also published as: CN109563552A; BR112019002528A2; WO2018029519A1; BR112019002528B1; EP3497248A1

Abstract

The present invention generally relates to the use of a quaternary ammonium salt and a cationic (co)polymer to clarify sugar cane juice during the production of crystal or raw sugar. The invention also refers to a new process for producing crystal or raw sugar from sugar cane juice. More specifically, the present invention describes a process for improving the clarification of crystal or raw sugar by adding a quaternary ammonium salt and a cationic (co)polymer before, during or just after the clarification step.

Description

NEW COMPONENTS TO CLARIFY SUGAR CANE JUICE IN A PROCESS FOR

PRODUCING CRYSTAL OR RAW SUGAR

FIELD OF THE INVENTION

BACKGROUND OF THE INVENTION

According to Food and Agriculture Organization of the United Nations (FAO, 2015), world sugar production is estimated to reach 181 million tons in 2014/2015, a modest 0.2 percent increase over the 2013/2014 season but still the second largest harvest in history and Brazil remains the largest producer with a production estimated at 37.5 million tons.

Sugar cane is the main sugar producing crop, with a world sugar production approximately six times bigger than from sugar beet, the other major source of sugar. Sugar cane is one of the several species of tall perennial true grasses, with an established agricultural field crop, in all tropical and subtropical countries of the world, and being put into progressively improved sugar production processes.

Currently, in the sugar cane milling industry, there has been substantial interest to find effective technologies to be applied in the removal of impurities from sugar cane juice during the manufacture. These efforts reflect the increasing demand for food products that contain minimal amounts of chemicals and, as a consequence, emphasis has been placed on improving the quality of the sugar, providing a white crystalline substance. Since color is one of the most important sugar quality criteria, this aspect has come under evaluation and new methods has been investigated to reduce the sugar color without a trace of chemicals in the final product. The conventional process for producing crystal and raw sugar from sugar cane involves the extraction of sugar cane juice from the harvested sugar cane. The sugar cane juice is submitted to purification, also commonly known as clarification, resulting in crystal sugar or raw sugar. The raw sugar can be remelted to give sugar syrups or sugar liquors, which are the raw material used to produce the refined sugar.

At the beginning of the sugar production process, the sugar cane juice clarification is the most important step to supply sugar of optimum quality to the market. During the 1950s a sugar cane juice clarification technology, called sulphitation, was developed in India for the production of sugar. This usual process of clarification involves the addition of sulphur dioxide (S0₂) to the juice in order to separate non-sugar constituents, including colored materials. The sugar produced by this process may contain about 20 ppm or more of sulphur and this contaminant causes health and environmental problems and became difficult to be accepted in food and beverages markets. Many chemical additives have been suggested to precipitate impurities during the purification of sugars. But these initiatives have been developed mainly in the refining steps of the sugar industry, for example, the US Patent 3,698,951, as well as WO 2011/060168 and US Patent ^Q 5,865,899 describe a sugar refining processes wherein sugar syrups and liquors are decolorized by adding dialkyldimethyl quaternary surfactants.

The main approaches have thus been made to optimize the refining processes, through the clarification process so as to reduce the sugar color from sugar syrups and liquors that have already been clarified in the previous steps of producing raw sugar or crystal sugar and thus that present less impurities and a lower degree of initial coloration. Indeed there is a difference between sugar syrups or liquors and sugar cane juice, sugar syrups and liquors are melted raw sugars, they are more concentrated and with less impurities, which were removed in the previews steps of the sugar refining process, on the other hand, sugar cane juice is the juice extracted directly from crushing whole or peeled sugar cane in a mill.

Dimethylamine-epichlorohydrin copolymer (DMA-Epi) is known from the Food and Drug Administration, HHS, 21 CFR Ch.l (4-1-12 Edition), paragraph 173.60 to be a food additive used as a decolorizing agent and/or flocculant in the clarification of refinery sugar liquors and juices. It is added only at the defecation/clarification stage of sugar liquor refining at a concentration not to exceed 150 parts per million of copolymer by weight of sugar solids. However, a good performance in sugar cane juice clarification in the process to produce crystal or raw sugar is achieved for quantities which exceed the regulation limitations.

In view df the above, up to now there is no solution for improving clarification process of sugar cane juice to obtain crystal or raw sugar. Therefore, the present invention aims to an optimized solution for clarifying sugar cane juice when producing crystal or raw sugar.

A further object of the invention is to propose an improved process to produce crystal or raw sugar with a low degree of coloration and thus, acceptable by the food, pharmaceutical and beverage industries.

Another objective of the present invention is to propose a more efficient process, with fewer chemicals consumed, less corrosion and easier to control. SUMMARY OF THE INVENTION

The invention thus proposes the use of a quaternary ammonium salt and a cationic (co)polymer to clarify sugar cane juice during the production of crystal or raw sugar.

The present invention also provides a process for producing crystal or raw sugar comprising the following steps:

a) Extraction of sugar cane juice from sugar cane;

b) Clarification of sugar cane juice; c) Evaporation of clarified sugar cane juice;

d) Crystallization of clarified sugar cane juice;

e) Centrifugation and drying.

wherein a quaternary ammonium salt and a cationic (co)polymer are added before, during or just after the clarification step.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

The term "sugar cane juice" in the sense of the present invention is any juice containing sugar and extracted by shredding and crushing whole or peeled sugar cane in a mill.

The term "crystal sugar", also known as plantation white sugar, according to the invention is a sugar produced directly from sugar cane juice obtained from sugar cane, basically by the processes of extraction, clarification, evaporation and crystallization. Examples of crystal sugar may include those with sucrose crystals with an average size of 0.4 to 0.8 mm, preferably 0.5 to 0.7mm, with a degree of coloration between 50 to 400 ICUMSA units, preferably 90 to 150 ICUMSA units and notably used for domestic and industrial purposes. The term "raw sugar", also known as a VHP (Very High Polarization) sugar, according to the invention is a minimally processed cane sugar. Examples of raw sugar may include those with a degree of coloration between 400 to 1200 ICUMSA units, preferably 700 to 900 ICUMSA units and generally used as feedstock for the refining process to obtain refined sugar.

The term "a", for example used below in the text as follows: "a quaternary ammonium salt" or "a cationic (co)polymer" is a generic plural. It means that it has to be interpreted as "one or more" or "at least one". Use of a quaternary ammonium salt and a cationic (co)polymer

- The quaternary ammonium salt

The quaternary ammonium salt is advantageously a compound having the formula (I):

wherein:

Ri and R₂, independently from one another, are selected in the group consisting of Cg to C₃₆ linear or branched, saturated or unsaturated aliphatic groups, optionally containing a heteroatom or an ester or amide group;

R₃ and R₄, independently from one another, are selected in the group consisting of Ci to Ci₈ linear or branched, saturated or unsaturated aliphatic groups, optionally containing a heteroatom or an ester or amide group;

X is an anion, for example selected from halide, nitrate, phosphate or acetate; preferably X is a halide; more preferably X is chloride.

In one embodiment, Ri and R₂, independently from one another, are selected in the group consisting of C₁₂ to C₂₀ linear or branched, saturated or unsaturated aliphatic groups, optionally containing a heteroatom or an ester or amide group, preferably Ci6 to C₁₈ linear alkyl groups.

In another embodiment, that can be combined with the previous one, R₃ and R₄, independently from one another, are selected in the group consisting of Ci to C_i2 linear or branched, saturated or unsaturated aliphatic groups, optionally containing a heteroatom or an ester or amide group, preferably Ci to C₄ linear alkyl groups.

In a preferred embodiment, the quaternary ammonium salt is dimethyl- dioctadecylammonium chloride. The quaternary ammonium salt according to the present invention can be derived from plants or animals or can be synthesized by a reaction between trialkylamines and haloalkanes, under well-known classical conditions. In a preferred embodiment, the dimethyldioctadecylammonium chloride, is a reaction between methyldioctadecylamine and methyl chloride. The quaternary ammonium salt can be present in an amount of from 10 ppm to 160 ppm, preferably from 20 ppm to 100 ppm, more preferably from 20 to 40 ppm by weight based on the solid amount weight in the sugar cane juice. The quaternary ammonium salt can be added in the form of an aqueous solution or an alcoholic solution or a hydro-alcoholic solution. A preferred embodiment is the use of a solution containing ethanol and/or isopropanol as solvents for the quaternary ammonium salt, and also water. - The cationic (co)polymer

The cationic (co)polymer can either be a cationic homopolymer or copolymer.

Advantageously, it can be selected from the group consisting of: polyquaternary ammonium salts preferably a homopolymer of dimethylaminoethyl acrylate methyl chloride quaternary and/or a homopolymer of diallyl dimethyl ammonium chloride (PolyDADMAC), cationic copolymers of dialkylamines and epichlorohydrin, and mixtures thereof.

According to a first embodiment, the cationic (co)polymer is a cationic copolymer of dialkylamine and epichlorohydrin, wherein the alkyl part is a linear or branched alkyl comprising from 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. The preferred cationic copolymer is a cationic copolymer of dimethylamine and epichlorohydrin (DMA-Epi). The preferred copolymer of dimethylamine and epichlorohydrin, of CAS Reg. No. 25988-97-0, can have not more than 5 mole% of dimethylamine that may be replaced by an equimolar amount of ethylenediamine, and its mole ratio of total amine to epichlorohydrin is preferably about 1:1. Advantageously, the nitrogen content of the copolymer of dimethylamine and epichlorohydrin is 9.4 to 10.8 weight percent on a dry basis. DMA-Epi suitable molar mass can vary from 6,500 to 30,000 g/mol, preferably from 7,000 to 25,000. Cationic copolymer of dimethylamine and epichlorohydrin can be prepared by the step- reaction synthesis of 2-hydroxy-3-dimethylaminopropyl, a monomer formed by the reaction of epichlorhydrin and dimethylamine, as disclosed in Water Science and Technology: Water Supply Vol 1 Nol pp 43-50, IWA Publishing 2001. It is also available under the commercial names: Glokill PQ60 from Solvay S.A., and Barquat PQ from Lonza Group AG.

According to another embodiment, the cationic (co)polymer is polydiallyl dimethyl ammonium chloride (PolyDADMAC). The molecular weight of the polydiallyl dimethyl ammonium chloride (PolyDADMAC) can vary from 100000 to 200000 g/mol, preferably from 140000 to 180000 g/mol and more preferably around 160000 g/mol.

PolyDADMAC can be prepared by radical polymerization of diallyldimethylammonium chloride (DADMAC), more precisely by free radical addition polymerisation of diallyldimethylammonium chloride (DADMAC) using persulfate or an organic peroxide as initiator. It is also available under the commercial names: Mirapol 100 from Solvay S.A., Percol 1697 from Allied Colloids Ltd, and Merquat 100 from Lubrizol Corporation.

The cationic (co)polymer is advantageously present in an amount of from 10 ppm to 70 ppm, preferably 15 ppm to 40 ppm by weight based on the solid amount weight in the sugar cane juice.

The cationic (co)polymer can be added in the form of an aqueous solution. - Additional components

A phosphorus source is preferably also added during the production of crystal or raw sugar, preferably before, during or just after the clarification step. In this case, it is preferably selected from the group consisting of any salt containing a phosphate anion, selected preferably from hydrogen phosphites (HP0₃ ^2~), dihydrogen phosphates (H₂P0^4~), orthophosphates (P0₄ ³~, HP0 ²~, H₂P0₄ ^"), hypophosphates (H₂P₂0₆ ^2~), metaphosphates (P0₃~) or pyrophosphates (P₂0₇ ^4~), and a cation, preferably selected from ammonium, such as R₄N⁺, R₃NH⁺, R₂NH₂ ⁺, RNH₃ ⁺, NH₄ ⁺, wherein R is generally a linear or branched Ci to C₆ alkyl group, sodium (Na⁺) or calcium (Ca²⁺).

In a preferred embodiment, the phosphorus source is phosphoric acid. Advantageously, the phosphoric acid is used as an aqueous solution, usually at a concentration by weight of between 50 and 95%, preferably at 70 to 85% by weight.

The phosphorus source can be added together with the quaternary ammonium salt and/or together with the cationic copolymer and/or separately from the quaternary ammonium salt and the cationic copolymer. We prefer adding the phosphorus source together with the quaternary ammonium salt and together with the cationic copolymer and optionally also separately from the quaternary ammonium salt and the cationic copolymer. The total amount of phosphorus source is advantageously from 50 % to 400 %, preferably from 100 % to 200% by weight of the total weight of the quaternary ammonium salt and cationic copolymer. When phosphorus source, in particular phosphoric acid is added together with the cationic polymer, notably DMA-Epi, the relative quantities of DMA-Epi and Phosphorus source is about 20-30% by weight of DMA-Epi and 35-50% by weight of phosphorus source, the rest being water.

When phosphorus source, in particular phosphoric acid is added together with the quaternary ammonium salt, notably DHT, the relative quantities of DHT and Phosphorus source is about 30-60% by weight of DHT and 15-25% by weight of phosphorus source, the rest being water and/or alcohols like ethanol or isopropanol.

When phosphorus source, in particular phosphoric acid is added separately from the quaternary ammonium salt and the cationic copolymer, it is in the form of an aqueous solution of phosphoric acid at 50 and 95%, preferably at 70 to 85% by weight.

A particularly preferred embodiment consists in the use of 2 or 3 solutions:

- An hydro-alcoholic solution of quaternary ammonium salt with a phosphorus source, preferably an aqueous solution of DHT with phosphoric acid,

- An aqueous solution of cationic (co)polymer with a phosphorus source, preferably an aqueous solution of DMA-Epi with phosphoric acid,

Optionally, an aqueous solution of phosphorus source, preferably phosphoric acid, to clarify sugar cane juice during the production of crystal or raw sugar. According to this particularly preferred embodiment the quantities of each of the 2 or 3 solutions are the following:

- From 20 to 100 ppm, preferably from 50 to 95 ppm of a hydro-alcoholic solution of quaternary ammonium salt with a phosphorus source, preferably a hydro-alcoholic solution of DHT with phosphoric acid,

- From 50 to 150 ppm, preferably from 75 to 125 ppm of an aqueous solution of cationic (co)polymer with a phosphorus source, preferably an aqueous solution of DMA-Epi with phosphoric acid, Optionally from 20 to 100 ppm, preferably from 50 to 95 ppm of an aqueous solution of phosphorus source, preferably phosphoric acid.

According to this particularly preferred embodiment the concentrations of each of the 2 or 3 solutions are the following:

an hydro-alcoholic solution comprising from 30 to 60% of quaternary ammonium salt with 10 to 30% of a phosphorus source, preferably 40-60% of a hydro-alcoholic solution of DHT with 10 to 30% of an aqueous solution of phosphoric acid at a concentration by weight of between 50 and 95% by weight,

- an aqueous solution comprising from 40 to 60% of an aqueous solution of cationic

(co)polymer at a concentration by weight of between 50 and 70%, with 40 to 60% of a phosphorus source, preferably an aqueous solution of 40-60% of DMA-Epi at a concentration of 50-70% with 40 to 60% of an aqueous solution of phosphoric acid at a concentration by weight of between 50 and 95%,

- optionally an aqueous solution of phosphorus source, preferably an aqueous solution of phosphoric acid at a concentration by weight of between 50 and 95%, preferably at 70 to 85% by weight.

The most preferred embodiment of the invention is when the 2 or 3 solutions are used in the following concentrations and quantities:

From 20 to 100 ppm, preferably from 50 to 95 ppm of a hydro-alcoholic solution comprising from 30 to 60% of quaternary ammonium salt with 10 to 30% of a phosphorus source, preferably 30-60% of a hydro-alcoholic solution of DHT with 10 to 30% of an aqueous solution of phosphoric acid at a concentration by weight of between 50 and 95% by weight,

From 50 to 150 ppm, preferably from 75 to 125 ppm of an aqueous solution comprising from 40 to 60% of an aqueous solution of cationic (co)polymer at a concentration by weight of between 50 and 70%, with 40 to 60% of a phosphorus source, preferably an aqueous solution of 40-60% of DMA-Epi at a concentration of 50-70% with 40 to 60% of an aqueous solution of phosphoric acid at a concentration by weight of between 50 and 95%, - Optionally, from 20 to 100 ppm, preferably from 50 to 95 ppm of an aqueous solution of phosphorus source, preferably an aqueous solution of phosphoric acid at a concentration by weight of between 50 and 95%, preferably at 70 to 85% by weight.

Preferably, the 3 solutions above are used. Process for producing crystal or raw sugar

The invention provides a process for producing crystal or raw sugar from sugar cane juice comprising the following steps:

a) Extraction of sugar cane juice from sugar cane;

b) Clarification of sugar cane juice;

c) Evaporation of clarified sugar cane juice;

d) Crystallization of clarified sugar cane juice;

e) Centrifugation and drying.

Initially, it is preferable to select the most appropriate variety of sugar cane. The overall quality of the crystal or raw sugar is dependent on several aspects of the sugar cane selected, as agronomic practices, maturity stages and climate changes. It is preferable to select extremely sweet, soft and flavorful varieties of sugar cane which have substantially no acidic content, from 13% to 22% of sucrose and from 0.1% to 1.0% of glucose. In particular, it is preferred that the sugar cane chosen for processing yields a sucrose level of at least 20 percent.

Sugar cane is harvested either by hand or mechanized cutting, both with positive aspects. Mechanical harvesting equipment is capable of either cutting the intact cane stalk or chopping the cane. On the other hand, the manually cutting avoids the introduction of foreign matter commonly carried into the processing mill along with the sugar cane. The foreign matter, often comprising ten percent or more of the sugar cane weight, primarily consists of soil, sludge, ash, leaves, minerals and cane tops. The introduction of the foreign matter has the undesirable effect of altering the natural flavor of subsequently extracted sugar cane juice.

Extraction of sugar cane juice from sugar cane

In step (a), the cut sugar cane stalks can be subjected to a standard washing step to remove the foreign matter mentioned above and to reduce impurities on the surface of the stalks. Subsequently, the sugar cane stalks are generally reduced into smaller individual pieces either with the use of rotating knives or hammer mill shredders and leaves and nodes are advantageously removed.

The sugar cane juice extraction includes any conventional extraction means suitable for breaking sugar cane cells, these means being well known by a person skilled in the art, such as crushing by tandem mills and extraction by diffusion. A tandem mill is a special type of modern rolling mill where rolling is done in one pass and there are several stands (sets of rolls). In a traditional extraction, the sugar cane stalks are conveyed through a standard rolling mill to extract the sugar cane juice, as is well known to those skilled in the art, at a temperature from 30°C to 90°C, more preferably from 60°C to 85°C.

In a preferred embodiment, the sugar cane juice obtained by the extraction step (a) described above has a pH level between 4 and 6, 10 to 30 % by weight of sucrose, 60 to 80 % by weight of water and 5 to 20 % by of insoluble materials and 10 to 30 % by weight of soluble solids.

In a more preferred embodiment, the sugar cane juice obtained by the extraction step (a) described above has a pH level between 4.5 and 5.5, 13 to 22 % by weight of sucrose, 68 to 76 % by weight of water and 8 to 16% by of insoluble materials and 18 to 25 % by weight of soluble solids.

Clarification of sugar cane juice

According to the invention, the process for producing crystal or raw sugar from sugar cane juice comprises a clarification of sugar cane juice wherein a quaternary ammonium salt and a cationic (co)polymer are added before, during or just after the clarification step (b). The quaternary ammonium salt is advantageously as described above according to the various embodiments. The quaternary ammonium salt is advantageously solubilized or dispersed in water or in an organic solvent, preferably ethanol or isopropanol, before its addition in the clarification step (b). The quaternary ammonium salt can be added in the amount described above.

The cationic (co)polymer is as described above according to the various embodiments.

The cationic (co)polymer can be added in the amounts described above.

In a particularly preferred embodiment, a phosphorus source is also added before, during or just after the clarification step. The phosphorus source is as described above according to the various embodiments.

The phosphorus source can be added in the amounts described above.

In a particularly embodiment of the present invention, the quaternary ammonium salt, the cationic (co)polymer and optionally the phosphorus source are added either as a homogeneous blend, or separately but simultaneously, or separately and at different stages before, during or just after the clarification step (b). We prefer adding the quaternary ammonium salt and the cationic (co)polymer separately but simultaneously for solubility reasons. When added, it is preferred that a fraction of the phosphorous source is added with the quaternary ammonium salt, that another fraction is added with the cationic (co)polymer and optionally the remaining fraction is added separately but simultaneously before, during or just after the clarification step (b).

As very preferred embodiment, from 3 to 25 % of the total amount of phosphorous source is added with the quaternary ammonium salt, from 10 to 70 % of the total amount of phosphorous source is added with the cationic (co)polymer and from 0 to 80 % of the total amount of phosphorous source is added separately but simultaneously before, during or just after the clarification step (b). In one embodiment of the present invention, the clarification step (b) comprises pre-heating (bl), pH correction (b2) and heating (b3) steps.

In step (bl), the sugar cane juice is pre-heated preferably at a temperature from 40 °C to 75 °C, more preferably from 60 °C to 70 °C.

While pre-heating is conducted, in order to facilitate the following chemical reactions and to improve the precipitation of colloids and finely dispersed matter from the clarified sugar cane juice, the juice is advantageously subjected to the pH correction step (b2). The standard procedure in sugar mills is to add any source of lime, but calcium oxide, also referred to as lime milk, is preferred. The addition of lime raises the pH and has the purpose of forming calcium phosphate precipitate, which upon sedimentation carries with it the impurities present in the juice. In step (b2), calcium oxide or lime milk is advantageously added to the sugar cane juice in a sufficient amount to bring the pH level of the juice to 6.0 to 8.0, preferably 6.8 to 7.4. The amount of calcium oxide used in the present invention is reduced when compared with existing processes. Minimizing the quantity of additives, such as calcium oxide, during the clarification, is essential for maintaining the natural flavor of the sugar cane juice and consequently in the final product.

Then, according to step (b3) the sugar cane juice is heated, in a second heating stage, preferably at a temperature from 90 °C to 120 °C, more preferably from 98 °C to 110 °C. Steps (bl) and (b3) are performed using standard heating equipment, as it is well known in the sugar mill industry.

In one embodiment of the present invention, the quaternary ammonium salt, the cationic (co)polymer and optionally the phosphorus source are added during the steps bl, b2 and/or b3. In a preferred embodiment, the quaternary ammonium salt, the cationic (co)polymer and optionally the phosphorus source are added between steps b2 and b3 and even more preferably during step b3.

Evaporation

Once the sugar cane juice has been substantially clarified, the juice is subjected to evaporation step (c) to concentrate the juice. The clarified juice is generally transferred to standard evaporators and preferably heated at a temperature from 60 °C to 95 °C, more preferably from 80 °C to 85 °C. Preferably, the juice is subsequently extracted from the evaporators at a soluble solid content of 50 to 70 °Brix, preferably at 55 to 65 "Brix.

Crystallization

Following the evaporation step (c), the clarified sugar cane juice is directed to the subsequent crystallization step (d), which is generally carried out in a vacuum pan to form solid crystals. Then, in the crystallization step, the juice is boiled preferably at a temperature from 50 °C to 90 °C , more preferably from 60 °C to 75 °C and under vacuum which causes the development and growth of solid crystals and the outcome called "massecuite" (mixture of crystals and mother liquor, also called molasses, resulting from the crystallization).

Centrifugation and drying

Then, according to step (e), the crystal or raw sugar and molasses obtained from the crystallization are then separated after a centrifugation and dried preferably at a temperature from 65 °C to 95 °C, more preferably from 70 °C to 80 °C.

In a preferred embodiment of the present invention, the process for producing crystal or raw sugar consists in the following steps:

a) Extraction of sugar cane juice from sugar cane;

b) Clarification of sugar cane juice;

bl) Pre-heating

b2) pH correction

b3) Heating

c) Evaporation of clarified sugar cane juice;

d) Crystallization of clarified sugar cane juice; e) Centrifugation and drying,

wherein a quaternary ammonium salt, a cationic copolymer and optionally a phosphorous source are added before, during or just after the clarification step.

All the steps a) to e) and their preferred embodiments are detailed above.

In a preferred embodiment, the process according to the invention is sulfur free, which means that no sulfur compound or derivative is added during the process.

The resulting crystal sugar obtained according to the invention has a degree of coloration between 50 and 400 ICUMSA units, preferably 90 to 150 ICUMSA units.

The resulting raw sugar obtained according to the invention has a degree of coloration between 400 and 1200 ICUMSA units, preferably 700 to 900 ICUMSA units. The present invention provides advantages over existing processes to obtain crystal or raw sugar. The invention proposes an improved sugar cane juice clarification process by adding a quaternary ammonium salt and a cationic (co)polymer at the beginning of the process. This process presents an increased decolorizing performance, reducing the sugar color leaving no trace of chemicals in the final product. Crystal and raw sugars produced using the process according to the invention has a low degree of coloration and it is acceptable in food, pharmaceutical and beverage industries.

Other details or advantages of the invention will become more clearly apparent in the light of the examples given below.

EXAMPLES

Methods of measure

For the examples below, the tests have been performed with compositions comprising from 20 % to 50 % of a quaternary ammonium salt and/or 10 % to 50 % of a cationic (co)polymer. Color and Turbidity were measured to control the clarification.

The ICUMSA color was determined by measuring absorbance of the juice solutions at 420 nm, and calculated by the equation below: A x 100,000

Color =

b x C

wherein A is the absorbance measured at 420 nm, b is the cell length, C represents the concentration (g/100 mL) of the solution.

The juice turbidity was expressed as the difference between the measurements at 720 nm before and after the sample filtration through the 0.45 μηι membrane. Turbidity before and after filtration was calculated by the equation below:

- log T

Turbidity = x 1000

b x 0,05089

wherein T is the transmittance measured at 720 nm, and b is the cell length.

Tests and results

The clarification performance was verified by clarification tests in order to evaluate the efficiency of the sugar cane juice treatment. Three compositions were dosed in a fresh mixed juice after the pre-heating step. Subsequently, phosphoric acid was added, in a way that the total amount was the same for all treatments.

The composition named herein "DHT Blend" is a solution comprising 53.3 % by weight of dimethyldioctadecylammonium chloride ("DHT"), solubilized in ethanol (75/25), 25.9 % by weight of an aqueous solution of phosphoric acid at a concentration of 85 % by weight, 7.2 % by weight of isopropanol and 13.6 % by weight of anhydrous ethanol. The ratio between the dimethyldioctadecylammonium chloride and the phosphoric acid should be around 1.5 to 2.

The composition named herein "DMA-Epi Mix" is a solution comprising 50 % by weight of a 50 % by weight aqueous solution of dimethylamine-epichlorohydrin copolymer, and 50 % by weight of an aqueous solution of phosphoric acid at a concentration of 85 % by weight. The ratio between the dimethylamine-epichlorohydrin copolymer and the phosphoric acid should be around 0.3 to 1.

Lime was added to the mixed juice in a sufficient amount to bring the pH to 6.8 - 7.2 and the mixture was heated at a temperature from 98 °C to 105 °C for 30 seconds.

Anionic polyacrylamides of high molecular weight ("Polymer") were also added to the mixture and then the treated juice was stored for 10 minutes. After that a sample of the supernatant was withdrawn for analysis.

The color and turbidity were measured and compared between all the compositions tested. Mixed juice color must be below 10,000 IU in a well succeeded treatment. Concerning the turbidity values, the lower the better. Table 1. Clarification tests results.

As seen in Table 1, the addition of 175 ppm of DHT Blend (trial #2) led to a color reduction of 26 %. In this case, the color of the treated juice was worse than the obtained with sulphitation (control; trial #5).

Treatment with DMA-Epi Mix (trial #3) produced a clarified juice with 9780 IU, representing a color reduction of 46 %. The combination of 75 ppm of DHT blend and 100 ppm of DMA- Epi Mix (trial #4) also led to a good clarification, comparable with results obtained with 175 ppm of DMA-Epi Mix alone. Both trials led to a better clarification in comparison with the control.

Turbidity values for clarified juices treated with DHT Blend and/or DMA-Epi Mix were better than the one obtained with sulphitation. Conclusion

The above results show that the process described in this invention improves the quality of juices produced in the clarification step during the process for producing crystal or raw sugar from sugar cane juice. The treatment proposed in trial #4 led to a color reduction of 45 % and turbidity reduction of 87 %, which is considerably better than 38 % and 67 % observed, respectively, for sulphitation.

Claims

Use of a quaternary ammonium salt and a cationic (co)polymer to clarify sugar cane juice during the production of crystal or raw sugar.

Use according to claim 1, wherein the quaternary ammonium salt is a compound having the formula (I):

wherein:

Ri and R₂, independently from one another, are selected in the group consisting of C₈ to C36 linear or branched, saturated or unsaturated aliphatic groups, optionally containing a heteroatom or an ester or amide group;

R₃ and R₄, independently from one another, are selected in the group consisting of Ci to Ci8 linear or branched, saturated or unsaturated aliphatic groups, optionally containing a heteroatom or an ester or amide group;

X is an anion selected from halide, nitrate, phosphate or acetate; preferably X is a halide; more preferably X is chloride.

Use according to claim 2, wherein Ri and R₂, independently from one another, are selected in the group consisting of C_i2 to C₂₀ linear or branched, saturated or unsaturated aliphatic groups, preferably Ci6 to Ci₈ linear alkyl groups, and R₃ and R₄, independently from one another, are selected in the group consisting of Ci to Ci₂ linear or branched, saturated or unsaturated aliphatic groups, preferably Ci to C₄ linear alkyl groups.

Use according to claim 1 to 3, wherein the quaternary ammonium salt is dimethyldioctadecylammonium chloride.

5. Use according to claims 1 to 4, wherein the quaternary ammonium salt is present in an amount of from 10 ppm to 160 ppm, preferably 20 ppm to 100 ppm by weight based on the solid amount weight in the sugar cane juice.

6. Use according to anyone of claims 1 to 5, wherein the cationic (co)polymer is a cationic copolymer of dialkylamine and epichlorohydrin, wherein the alkyl part is a linear or branched alkyl comprising from 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, more preferably a cationic copolymer of dimethylamine and epichlorohydrin. 7. Use according to anyone of claims 1 to 5, wherein the cationic (co)polymer is Polydiallyldimethylammonium chloride (PolyDADMAC).

8. Use according to claims 1 to 7, wherein the cationic (co)polymer is present in an amount of from 10 ppm to 70 ppm, preferably 15 ppm to 40 ppm by weight based on the solid amount weight in the sugar cane juice.

9. Use according to anyone of claims 1 to 8, wherein a phosphorus source is also added during the production of crystal or raw sugar. 10. Use according to anyone of claims 1 to 9, wherein the phosphorus source is selected from the group consisting of any salt containing a phosphate anion, preferably hydrogen phosphites (HP0₃ ^2~), dihydrogen phosphates (H₂P0^4~), orthophosphates (P0₄ ^3~, HP0₄ ²~, H₂P0₄ ^~), hypophosphates (H₂P₂0₆ ^2~), metaphosphates (P0₃ ^~) or pyrophosphates (P₂0₇ ^4~), and a cation, preferably ammonium, sodium or calcium, more preferably phosphoric acid.

11. Use according to anyone of claims 9 or 10, wherein the phosphorus source is present in a total amount of from 50% to 400%, preferably from 100% to 200% by weight of the total weight of the quaternary ammonium salt and cationic (co)polymer.

12. Process for producing crystal or raw sugar comprising the following steps:

a) Extraction of sugar cane juice from sugar cane; b) Clarification of sugar cane juice;

c) Evaporation of clarified sugar cane juice;

d) Crystallization of clarified sugar cane juice;

e) Centrifugation and drying.

13. Process according to claim 12, wherein the quaternary ammonium salt has the formula (I):

wherein:

R3 and R₄, independently from one another, are selected in the group consisting of Ci to Ci8 linear or branched, saturated or unsaturated aliphatic groups, optionally containing a heteroatom or an ester or amide group;

14. Process according to claim 13, wherein Ri and R₂, independently from one another, are selected in the group consisting of C_i2 to C₂o linear or branched, saturated or unsaturated aliphatic groups, preferably Ci₆ to Ci₈ linear alkyl groups, and R₃ and R₄, independently from one another, are selected in the group consisting of Ci to C₁₂ linear or branched, saturated or unsaturated aliphatic groups, preferably C_x to C₄ linear alkyl groups.

15. Process according to anyone of claims 12 to 14, wherein the quaternary ammonium salt is dimethyldioctadecylammonium chloride.

16. Process according to anyone of claims 12 to 15, wherein the quaternary ammonium salt is present in an amount of from 10 ppm to 160 ppm, preferably 20 ppm to 100 ppm by weight based on the solid amount weight in the sugar cane juice. 17. Process according to anyone of claims 12 to 16, wherein the cationic (co)polymer is a cationic copolymer of dialkylamine and epichlorohydrin, wherein the alkyl part is a linear or branched alkyl comprising from 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, more preferably a cationic copolymer of dimethylamine and epichlorohydrin. 18. Process according to anyone of claims 12 to 16, wherein the cationic (co)polymer is Polydiallyldimethylammonium chloride (PolyDADMAC).

19. Process according to anyone of claims 12 to 18, wherein the cationic (co)polymer is present in an amount of from 10 ppm to 70 ppm, preferably 15 ppm to 40 ppm by weight based on the solid amount weight in the sugar cane juice.

20. Process according to anyone of claims 12 to 19, wherein a phosphorus source is also added before, during or just after the clarification step. 21. Process according to anyone of claims 20, wherein the phosphorus source is selected from the group consisting of any salt containing a phosphate anion, preferably hydrogen phosphites (HP0₃ ^2~), dihydrogen phosphates (H₂P0^4~), orthophosphates (P0 ^3~, HP0₄ ^2~, H₂P0 ^"), hypophosphates (H₂P₂0₆ ^2~), metaphosphates (P0₃ ^") or pyrophosphates (P₂0₇ ^4~), and a cation, preferably ammonium, sodium or calcium, more preferably the phosphorus source is phosphoric acid.

22. Process according to anyone of claims 20 or 21, wherein the phosphorus source is present in a total amount of from 50% to 400%, preferably from 100% to 200% by weight of the total weight of the quaternary ammonium salt and cationic (co)polymer.

23. Process according to anyone of claims 12 to 22, wherein the clarification step (b) comprises pre-heating (bl), pH correction (b2) and heating (b3) steps, the quaternary ammonium salt, the cationic (co)polymer and optionally the phosphorus source being added during steps bl, b2 and/or b3.

24. Process according to claim 23, wherein the quaternary ammonium salt, the cationic (co)polymer and optionally the phosphorus source are added between the steps b2 and b3 and even more preferably during step b3.

25. Process according to anyone of claims 12 to 24, wherein the quaternary ammonium salt, the cationic (co)polymer and optionally the phosphorus source are added either as a homogeneous blend, or separately but simultaneously, or separately and at different stages before, during or just after the clarification step.

26. Process according to anyone of claims 23 to 25, wherein calcium oxide or lime milk is added during the step b2 in a sufficient amount to bring the pH of the juice to 6.0 to 8.0, preferably 6.8 to 7.4.

27. Process according to anyone of claims 12 to 26 wherein this process is sulfur free.