Classifications

• • C—CHEMISTRY; METALLURGY
  • C13—SUGAR INDUSTRY
  • C13B—PRODUCTION OF SUCROSE; APPARATUS SPECIALLY ADAPTED THEREFOR
  • C13B20/00—Purification of sugar juices
  • C13B20/08—Purification of sugar juices by oxidation or reduction

Definitions

• the present invention relates to a process for bleaching sweet juice in the extraction of sugar contained in plants such as beet or cane, more particularly a process for bleaching such a juice which uses hydrogen peroxide.
• Sugar extraction commonly involves four main operations: - the formation of a raw juice, for example by crushing the plant as in the case of sugar cane or by diffusion of the plant's sugar in water as in the case of sugar beet, - the purification or purification of the raw juice by the action of lime, called liming, followed by carbonation then by sulfitation and possibly decalcification to provide a purified juice which, compared to the raw juice, contains a quantity impurities, the "non-sugars", usually reduced by at least half, the concentration of the purified juice, by evaporation of water, to provide a concentrated juice, or dense juice, syrupy liquid generally containing around 70% sugar, from which the sugar can be separated by crystallization, - the crystallization of the dense juice, followed by drying, to provide commercial white sugar and a molasses as a residue.
• liming the purification or purification of the raw juice by the action of lime, called liming
• carbonation then by sulfitation and possibly decalc
• SO2 is the commonly used sulfiting agent.
• the peroxide hydrogen is not substitutable for a sulphiting agent like SO2 in the treatment of a juice which must undergo a concentration by evaporation of water and which is designated in all that follows by diluted juice.
• the present invention consists of a process for extracting the sugar contained in plants such as sugar beet or sugar cane, a process in which a diluted juice is concentrated by evaporation of water to yield a juice from which the sugar can be separated by crystallization, characterized in that a concentration by evaporation of water relates to a diluted juice added with hydrogen peroxide, whose pH, addition made of hydrogen peroxide, is between 8 and 9.5.
• the quantity of hydrogen peroxide to which the diluted juice is added can vary within fairly wide limits, but a significant result is generally not obtained when less than 30 g are added. around hydrogen peroxide counted as 100% per tonne of raw material, such as beet or cane, presented for extraction to form the raw juice as said above.
• the amount of hydrogen peroxide added to the diluted juice to form the diluted juice supplemented with hydrogen peroxide is counted as stated just above. It is preferably between 50 g./T. and 100 g./T.
• the hydrogen peroxide is added to the diluted juice to be concentrated, normally in the form of a commercial aqueous solution such as for example a 35% or 50% by weight solution of hydrogen peroxide.
• the diluted juice, with added hydrogen peroxide is at a temperature which can be between approximately 20 ° C and 150 ° C but which is preferably in the range of temperatures at which the concentration of the diluted juice is carried out by evaporation of water, for example between about 40 ° C and 120 ° C, preferably between about 60 ° C and 100 ° C.
• the diluted juice, with added hydrogen peroxide is at a pressure which can depend on the chosen temperature and which is normally between atmospheric pressure and a pressure less than about 0.08 bar, most often between the pressure atmospheric and about 0.1 bar.
• the pH of the diluted juice, addition of hydrogen peroxide is preferably between approximately 8.5 and 9.
• the dense juice obtained is clearly more colored than that resulting from the concentration by evaporation of water of the same diluted juice not added with hydrogen peroxide but subjected to sulfitation before concentration.
• the diluted juice addition of hydrogen peroxide, has a pH of less than 8 when it is subjected to a concentration by evaporation of water, the crystallization of sugar from the dense juice is made difficult.
• the diluted juice to which hydrogen peroxide is added most often contains about 10% to 50% sugar by weight.
• the diluted juice to which the invention applies can in fact be a diluted juice which has not yet been subjected to a concentration by evaporation of water and / or a juice which has already been partially concentrated in this way during its transformation into dense juice from which the sugar is separated by crystallization.
• the result targeted by the present invention is normally achieved in a period between the time when the hydrogen peroxide is used and that at which the diluted juice is found in the form of dense juice, which does not exceed about twenty minutes . Most often this duration is of the order of 5 to 15 minutes.
• the equipment for carrying out the present invention from the use of hydrogen peroxide to obtaining the dense juice, is designed like that known today to be suitable for the concentration by evaporation of water of a diluted juice. into a dense juice.
• the material chosen must be suitable for the conditions of execution of the process and the requirements of the food sector. Stainless steel meets this double requirement.
• the coloration of the juices is determined by measuring the absorbance at 420 nm using a refractometer on the various juices concerned filtered through a porous membrane. This method is known to those skilled in the art. It is based on the protocol established at the level of the European Communities and is described for example in 1984 by the IRIS-Research Institute of the Sugar Industry.
• the value 100 is assigned to the coloring of the dense juice obtained from the diluted juice to which the present invention is applied.
• a color value greater than 100 means for the diluted juice or for a juice derived therefrom other than the dense juice obtained according to the invention, a darker coloration than that of said dense juice.
• a coloring value of less than 100 translated for the diluted juice or for a juice derived therefrom other than the dense juice obtained according to the invention a coloration whiter than that of said dense juice.
• the starting juices used in all the examples are diluted industrial juices. They contain, next to water and impurities, 14% to 15% sugar by weight.
• the hydrogen peroxide is used in the form of a commercial aqueous solution containing 35% of hydrogen peroxide by weight.
• the values of the committed quantities of hydrogen peroxide are expressed in grams of 100% hydrogen peroxide per tonne of raw material presented for extraction to form the raw juice, g./T., As was said earlier in this text.
• the raw material here is sugar beet.
• the starting diluted juice whose pH is equal to 9.3 and the color value equal to 90, is supplemented with hydrogen peroxide at a rate of 73.5 g./T.
• the temperature of the juice is equal to a value maintained between 90 ° C and 100 ° C.
• Pressure is atmospheric pressure.
• the juice is then concentrated by evaporation of water, at atmospheric pressure, so that the dense juice collected contains, by weight, 68 of sugar.
• the value of its coloring is equal to 100 as agreed.
• the coloring of the dense juice obtained which always contains, by weight, 68% sugar, is equal to 205.
• Example 1 which incorporates the invention, is followed by leaving the diluted juice, addition made of hydrogen peroxide, at pH 9.2 naturally reached by the very fact of this addition.
• the dense juice obtained has a coloration whose value is practically equal to that of the dense juice obtained in Example 1 from the sulphited juice.
• An industrial diluted juice other than that used in Examples 1 and 2 has a color value of 108.5. It is loaded into an evaporator operating at a pressure below atmospheric pressure and equal to about 0.1 bar so that the temperature of the juice during its concentration by evaporation of water remains between 65 ° C and 75 ° C.
• the dense juice obtained contains, by weight, 70.5% of sugar and the value of its coloring is equal to 100 as agreed.
• White sugar obtained by crystallization according to the process adopted industrially from the various juices dense resulting in the examples of the application of the invention, satisfies each time the criteria of coloring as besides those of sucrose content, ash content and obviously sulfur content, which its marketing imposes.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Biochemistry (AREA)
• Organic Chemistry (AREA)
• Non-Alcoholic Beverages (AREA)

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Citations (4)

• 1989
  • 1989-09-21 FR FR8912615A patent/FR2652093B1/fr not_active Expired - Lifetime
• 1990
  • 1990-09-19 DE DE1990618180 patent/DE69018180T2/de not_active Expired - Fee Related
  • 1990-09-19 EP EP90420412A patent/EP0419384B1/de not_active Expired - Lifetime

Patent Citations (4)

Non-Patent Citations (1)

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