Method for preparing caramel pigment by taking psicose raffinate as raw material

Abstract

The invention belongs to the technical field of sugar alcohol preparation, and relates to a method for preparing caramel pigment by taking psicose raffinate as a raw material, which comprises the following steps: concentrating the psicose raffinate separated by a simulated moving bed, and evaporating and concentrating under the conditions of 80 DEG C and-0.1 MPa until the refractive index is 70% to obtain a psicose raffinate concentrated solution; a catalyst with the mass ratio being 15-25% is added into the weighed psicose raffinate concentrated solution, then sodium hydroxide with the concentration being 40% is added, the pH value of the mixed material is adjusted to be 6-8, and the catalyst is ammonium sulfite and sodium pyrosulfite with the mass ratio being 1: 1-1: 8; and adding the mixed material into a reaction kettle for reaction, controlling the reaction temperature to be 130-150 DEG C and the pH value to be 4-7, maintaining the pH to be stable in the reaction process, and reacting for 6-8 hours to obtain a caramel pigment product. By adopting a catalyst compounding process, the problems of low red index and poor salt tolerance of the product in the preparation process of the caramel pigment are solved, the cost is reduced, and the economic benefit is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sugar alcohol preparation, and particularly relates to a method for preparing caramel pigment by taking psicose raffinate as a raw material. Background Art

[0002] Caramel color, commonly known as sauce color, has a long production history. It is a brown product produced by various sugars alone or with certain additives through Maillard reaction and caramelization reaction under high temperature conditions. This product has good water solubility and is widely used in food, beverage, brewing and other food industries. It can not only make food present bright and beautiful colors and attractive aroma, but also serve as a mask for some unpleasant odors. The preparation process of caramel color is relatively complicated and the raw materials are diverse. Usually, sucrose, glucose, maltose, molasses, etc. are used as raw materials to produce caramel color. There are no reports on the preparation of caramel color using allulose raffinate as raw material.

[0003] From a cost perspective, most companies produce allulose using about 98% liquid fructose as raw material, and the remaining 2% is mainly glucose. Because the thermodynamic equilibrium conversion rate of fructose isomers of allulose is about 30%, in the subsequent production process, the industry can only use simulated moving beds to separate allulose isomers, and usually a certain proportion of extract and raffinate is obtained. Among them, the allulose purity of the extract is relatively high, and allulose crystals are obtained through refining processes such as decolorization, concentration, and crystallization, which can be directly used in the production of food additives. However, the raffinate contains a high concentration of fructose and allulose and a small amount of glucose. The industry can only use simulated moving beds to separate them again and reuse them. Not only are there many processes and high costs, but in the end, some of the mixed sugar liquid will still need to be treated with three wastes.

[0004] The invention patent with publication number CN118064508A discloses a process for preparing allitol from D-psicose mother liquor, wherein D-psicose mother liquor is used as a raw material, and crude allitol is obtained after the reaction of ribitol dehydrogenase and formate dehydrogenase, and then refined by filtration, concentration, separation, crystallization, etc. to obtain allitol crystals. This method is complex and time-consuming, and uses a combination of two enzymes, which has a high investment cost. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing caramel pigment using allulose raffinate as raw material, adopting a catalyst compounding process to solve the problems of poor red index and salt resistance of the product in the preparation process of caramel pigment, thereby reducing the high cost of simulated moving bed separation of allulose raffinate, alleviating the pressure of sewage treatment, avoiding pollution to the environment, and improving economic benefits.

[0006] The present invention is achieved by providing a method for preparing caramel pigment using psicose raffinate as a raw material, comprising the following steps: Step 1, concentrating the psicose raffinate obtained by simulated moving bed separation, evaporating and concentrating at 80° C. and −0.1 MPa to a refractive index of 70%, to obtain a psicose raffinate concentrate for standby use; Step 2: Add 15-25% by mass of a catalyst to the weighed allulose extract concentrate, and then add 40% sodium hydroxide to adjust the pH value of the mixture to 6-8, wherein the catalyst is at least one of ammonium sulfite and sodium pyrosulfite; Step 3: Add the mixed material into the reactor for reaction, control the reaction temperature at 130-150°C, the pH value of the reaction material at 4-7, monitor the pH value of the reaction material every half an hour during the reaction, and maintain the pH stable, and obtain the caramel pigment product after 6-8 hours of reaction.

[0007] Furthermore, in step 2, when ammonium sulfite and sodium pyrosulfite are used as catalysts at the same time, the addition ratio of ammonium sulfite and sodium pyrosulfite is 1:1 to 1:8.

[0008] Compared with the prior art, the method for preparing caramel pigment using psicose raffinate as raw material of the present invention has the following characteristics: 1. Significant environmental benefits: The present invention uses the allulose raffinate to prepare caramel pigment products, avoiding the sewage treatment pressure generated in the simulated moving bed separation process, and has significant environmental benefits.

[0009] 2. High resource utilization rate: The psicose raffinate contains high concentrations of psicose and fructose. If it is directly discharged, this valuable resource will be wasted. The present invention converts the psicose raffinate into a caramel pigment product, thereby achieving effective utilization of resources and improving resource utilization rate.

[0010] 3. Good economic benefits: Although allulose, fructose and glucose can be obtained after separation of the psicose raffinate, resource recovery can be achieved, the economic benefits are poor due to the high separation cost. The present invention converts the psicose raffinate into a caramel pigment product to obtain additional economic benefits, and has good economic benefits.

[0011] 4. Excellent product performance: The present invention optimizes the preparation process and selects a suitable catalyst ratio to prepare a caramel pigment product with a high red index and good acid and salt resistance, which can provide added value and improve the market competitiveness of the product. DETAILED DESCRIPTION

[0012] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0013] A preferred embodiment of the method for preparing caramel pigment using psicose raffinate as raw material of the present invention comprises the following steps: Step 1: Concentrate the psicose extract obtained by simulated moving bed separation, evaporate and concentrate it to a refractive index of 70% under the conditions of 80° C. and −0.1 MPa, and obtain a psicose extract concentrate for use.

[0014] Step 2: Add a catalyst in a mass ratio of 15-25% to the weighed allulose extract concentrate, then add sodium hydroxide with a concentration of 40%, and adjust the pH value of the mixture to 6-8, wherein the catalyst is ammonium sulfite and sodium pyrosulfite in a mass ratio of 1:1-1:8.

[0015] Step 3: Add the mixed material into the reactor for reaction, and control the reaction temperature to 130-150°C. Because the reaction system will produce acid, the pH will gradually decrease during the reaction. The pH value of the reaction material needs to be monitored every half hour and maintained stable between 4 and 7. After 6-8 hours of reaction, the caramel pigment product is obtained.

[0016] When the pH value of the reaction material drops below the lower limit of 4, 40% concentration of sodium hydroxide is added to control the pH value of the reaction system between 4-7 during the reaction.

[0017] The method for preparing caramel pigment using psicose raffinate as raw material of the present invention is further illustrated below by means of specific examples. Example 1

[0018] The first embodiment of the method for preparing caramel pigment using psicose raffinate as raw material of the present invention comprises the following steps: Step 11, evaporating and concentrating the psicose extract at 80° C. and −0.1 MPa to a refractive index of 70% to obtain a psicose extract concentrate for later use.

[0019] Step 12, weigh 500 g of allulose extract concentrate, add 15% by mass and 1:1 ammonium sulfite and sodium metabisulfite as catalysts; and adjust the pH of the mixture to 6 with sodium hydroxide.

[0020] Step 13, put the mixed material into a 1L reactor for reaction, control the reaction temperature to 130°C, monitor the pH value of the reaction material every half an hour, control the pH value of the reaction material to 4-6 during the reaction, add 40% concentration of sodium hydroxide when necessary, react for 6 hours and cool to room temperature, and obtain a caramel pigment product after the reaction is completed.

[0021] The absorbance and red index of the obtained caramel pigment product were analyzed according to the national standard, and the absorbance and red index of the caramel pigment product prepared in this example were obtained to be 0.081 and 6.3.

[0022] The caramel pigment product prepared in this embodiment is then subjected to an acid and salt resistance test according to the following method. Acid and salt resistance test method: Deionized water is prepared into a solution of pH 4.5 with lactic acid, 20% sodium chloride is added, 10 mL of the solution is measured, 3 drops of the caramel pigment sample to be tested are added using a pipette, and the solution is left to stand for 24 hours to observe whether there is precipitation. If precipitation is produced in the solution, it means that the acid and salt resistance test of the test sample is unqualified; if no precipitation is produced in the solution, it means that the acid and salt resistance test of the test sample is qualified.

[0023] The caramel pigment product prepared in this example was subjected to an acid and salt resistance test. The test solution was left standing for 24 hours without precipitation, indicating that the caramel pigment product passed the acid and salt resistance test. Example 2

[0024] A second embodiment of the method for preparing caramel pigment using psicose raffinate as raw material of the present invention comprises the following steps: Step 21, evaporating and concentrating the psicose extract at 80° C. and −0.1 MPa to a refractive index of 70% to obtain a psicose extract concentrate for later use.

[0025] Step 22, weigh 500 g of allulose extract concentrate, add 18% ammonium sulfite and 1:3 sodium metabisulfite as catalysts according to the mass ratio; and adjust the pH of the mixture to 6.5 with sodium hydroxide.

[0026] Step 23, put the mixed material into a 1L reactor for reaction, control the reaction temperature to 135°C, monitor the pH value of the reaction material every half an hour, control the pH value of the reaction material to 5-6 during the reaction, add 40% concentration of sodium hydroxide when necessary, react for 6 hours and cool to room temperature, and obtain a caramel pigment product after the reaction is completed.

[0027] The obtained caramel pigment product was analyzed for absorbance and red index according to the national standard, and the absorbance of the caramel pigment product prepared in this embodiment was 0.085 and the red index was 6.4. The caramel pigment product prepared in this embodiment was tested for acid and salt resistance according to the method of Example 1. The test solution was left to stand for 24 hours without precipitation, indicating that the acid and salt resistance test of the caramel pigment product was qualified. Example 3

[0028] A third embodiment of the method for preparing caramel pigment using psicose raffinate as raw material of the present invention comprises the following steps: Step 31, evaporating and concentrating the psicose extract at 80° C. and −0.1 MPa to a refractive index of 70% to obtain a psicose extract concentrate for later use.

[0029] Step 32, weigh 500 g of allulose extract concentrate, add 22% ammonium sulfite and 1:3 sodium metabisulfite as catalysts according to the mass ratio; and adjust the pH of the mixture to 7 with sodium hydroxide.

[0030] Step 33, put the mixed material into a 1L reactor for reaction, control the reaction temperature to 140°C, monitor the pH value of the reaction material every half an hour, control the pH value of the reaction material to 5.5-6.5 during the reaction, add 40% concentration of sodium hydroxide when necessary, react for 7 hours and cool to room temperature, and obtain a caramel pigment product after the reaction is completed.

[0031] The obtained caramel pigment product was analyzed for absorbance and red index according to the national standard, and the absorbance of the caramel pigment product prepared in this embodiment was 0.091 and the red index was 6.3. The caramel pigment product prepared in this embodiment was tested for acid and salt resistance according to the method of Example 1. The test solution was left to stand for 24 hours without precipitation, indicating that the acid and salt resistance test of the caramel pigment product was qualified. Example 4

[0032] A fourth embodiment of the method for preparing caramel pigment using psicose raffinate as a raw material of the present invention comprises the following steps: Step 41, evaporating and concentrating the psicose extract at 80° C. and −0.1 MPa to a refractive index of 70% to obtain a psicose extract concentrate for later use.

[0033] Step 42, weigh 500 g of allulose extract concentrate, add 22% ammonium sulfite and sodium metabisulfite in a mass ratio of 1:7 as catalysts; and adjust the pH of the mixture to 7.5 using sodium hydroxide.

[0034] Step 43, put the mixed material into a 1L reactor for reaction, control the reaction temperature to 145°C, monitor the pH value of the reaction material every half an hour, control the pH value of the reaction material to 5.5-6.5 during the reaction, add 40% concentration of sodium hydroxide when necessary, react for 8 hours and cool to room temperature, and obtain a caramel pigment product after the reaction is completed.

[0035] The obtained caramel pigment product was analyzed for absorbance and red index according to the national standard, and the absorbance of the caramel pigment product prepared in this embodiment was 0.095 and the red index was 6.2. The caramel pigment product prepared in this embodiment was tested for acid and salt resistance according to the method of Example 1. The test solution was left to stand for 24 hours without precipitation, indicating that the acid and salt resistance test of the caramel pigment product was qualified. Example 5

[0036] A fifth embodiment of the method for preparing caramel pigment using psicose raffinate as raw material of the present invention comprises the following steps: Step 51, evaporating and concentrating the psicose extract at 80° C. and −0.1 MPa to a refractive index of 70% to obtain a psicose extract concentrate for later use.

[0037] Step 52, weigh 500 g of allulose extract concentrate, add 25% ammonium sulfite and sodium metabisulfite in a mass ratio of 1:8 as catalysts; and adjust the pH of the mixture to 8 using sodium hydroxide.

[0038] Step 53, put the mixed material into a 1L reactor for reaction, control the reaction temperature to 150°C, monitor the pH value of the reaction material every half an hour, control the pH value of the reaction material to 5-7 during the reaction, add 40% concentration of sodium hydroxide when necessary, react for 6 hours and then cool to room temperature, and obtain a caramel pigment product after the reaction is completed.

[0039] The obtained caramel pigment product was analyzed for absorbance and red index according to the national standard, and the absorbance of the caramel pigment product prepared in this embodiment was 0.087 and the red index was 6.5. The caramel pigment product prepared in this embodiment was tested for acid and salt resistance according to the method of Example 1. The test solution was left to stand for 24 hours without precipitation, indicating that the acid and salt resistance test of the caramel pigment product was qualified.

[0040] Comparative Example 1 The steps for preparing caramel pigment in this comparative example are different from those in Example 1, except that in step 12, 15% of ammonium sulfite is added as a catalyst according to the mass ratio, and the other steps and conditions are the same as those in Example 1.

[0041] The obtained caramel pigment product was analyzed for absorbance and red index according to the national standard, and the absorbance of the caramel pigment product prepared in this comparative example was 0.085 and the red index was 5.5. The caramel pigment product prepared in this comparative example was tested for acid and salt resistance according to the method of Example 1, and a small amount of precipitate was precipitated after the test solution was left to stand for 24 hours, indicating that the caramel pigment product failed the acid and salt resistance test.

[0042] Comparative Example 2 The steps for preparing caramel pigment in this comparative example are different from those in Example 5, except that in step 52, 25% of ammonium sulfite is added as a catalyst according to the mass ratio, and the other steps and conditions are the same as those in Example 5.

[0043] The obtained caramel pigment product was analyzed for absorbance and red index according to the national standard, and the absorbance of the caramel pigment product prepared in this comparative example was 0.090 and the red index was 5.0. The caramel pigment product prepared in this comparative example was tested for acid and salt resistance according to the method of Example 1, and the test solution was left to stand for 24 hours without precipitation, indicating that the acid and salt resistance test of the caramel pigment product was qualified.

[0044] It can be seen from the above comparative examples that when using a single ammonium sulfite as a catalyst, the red index reaches about 5.0 under the condition of qualified acid and salt resistance, while when using the composite catalyst of ammonium sulfite and sodium pyrosulfite of the present invention, the acid and salt resistance are qualified and the red index is above 6.3.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing caramel pigment using psicose raffinate as raw material, characterized in that: The steps include: Step 1, concentrating the psicose raffinate obtained by simulated moving bed separation, evaporating and concentrating at 80° C. and −0.1 MPa to a refractive index of 70%, to obtain a psicose raffinate concentrate for standby use; Step 2: Add 15-25% by mass of a catalyst to the weighed allulose extract concentrate, and then add 40% sodium hydroxide to adjust the pH value of the mixture to 6-8, wherein the catalyst is ammonium sulfite and sodium pyrosulfite in a mass ratio of 1:1-1:8; Step 3: Add the mixed material into the reactor for reaction, control the reaction temperature at 130-150°C, the pH value of the reaction material at 4-7, monitor the pH value of the reaction material every half an hour during the reaction, and maintain the pH stable, and obtain the caramel pigment product after 6-8 hours of reaction.

2. The method for preparing caramel pigment using psicose raffinate as raw material according to claim 1, characterized in that: The steps include: Step 11, evaporating and concentrating the psicose raffinate at 80° C. and −0.1 MPa to a refractive index of 70%, to obtain a psicose raffinate concentrated solution for later use; Step 12, weighing 500 g of the allulose extract concentrate, adding 15% by mass and 1:1 ammonium sulfite and sodium metabisulfite as catalysts; adjusting the pH of the mixture to 6 with sodium hydroxide; Step 13, put the mixed material into a 1L reactor for reaction, control the reaction temperature to 130°C, monitor the pH value of the reaction material every half an hour, control the pH value of the reaction material to 4-5.5 during the reaction, add 40% concentration of sodium hydroxide when necessary, react for 6 hours and cool to room temperature, and obtain a caramel pigment product after the reaction is completed.

3. The method for preparing caramel pigment using psicose raffinate as raw material according to claim 1, characterized in that: The steps include: Step 21, evaporating and concentrating the psicose raffinate at 80° C. and −0.1 MPa to a refractive index of 70% to obtain a psicose raffinate concentrated solution for later use; Step 22, weighing 500 g of the D-psicose extract concentrate, adding 18% ammonium sulfite and 1:3 sodium pyrosulfite as catalysts according to a mass ratio; adjusting the pH of the mixture to 6.5 with sodium hydroxide; Step 23, put the mixed material into a 1L reactor for reaction, control the reaction temperature to 150°C, monitor the pH value of the reaction material every half hour, control the pH value of the reaction material to 5-6 during the reaction, add 40% concentration of sodium hydroxide when necessary, react for 6 hours and cool to room temperature, and obtain a caramel pigment product after the reaction is completed.

4. The method for preparing caramel pigment using psicose raffinate as raw material according to claim 1, characterized in that: The steps include: Step 31, evaporating and concentrating the psicose raffinate at 80° C. and −0.1 MPa to a refractive index of 70%, to obtain a psicose raffinate concentrated solution for standby use; Step 32, weighing 500 g of the D-psicose extract concentrate, adding 22% ammonium sulfite and 1:3 sodium pyrosulfite as catalysts according to a mass ratio; adjusting the pH of the mixture to 7 with sodium hydroxide; Step 33, put the mixed material into a 1L reactor for reaction, control the reaction temperature to 140°C, monitor the pH value of the reaction material every half an hour, control the pH value of the reaction material to 5.5-6.5 during the reaction, add 40% concentration of sodium hydroxide when necessary, react for 7 hours and cool to room temperature, and obtain a caramel pigment product after the reaction is completed.

5. The method for preparing caramel pigment using psicose raffinate as raw material according to claim 1, characterized in that: The steps include: Step 41, evaporating and concentrating the psicose raffinate at 80° C. and −0.1 MPa to a refractive index of 70% to obtain a psicose raffinate concentrated solution for later use; Step 42, weighing 500 g of the D-psicose extract concentrate, adding 18% ammonium sulfite and 1:7 sodium pyrosulfite as catalysts according to a mass ratio; adjusting the pH of the mixture to 7.5 with sodium hydroxide; Step 43, put the mixed material into a 1L reactor for reaction, control the reaction temperature to 145°C, monitor the pH value of the reaction material every half an hour, control the pH value of the reaction material to 5.5-6.5 during the reaction, add 40% concentration of sodium hydroxide when necessary, react for 7 hours and cool to room temperature, and obtain a caramel pigment product after the reaction is completed.

6. The method for preparing caramel pigment using psicose raffinate as raw material according to claim 1, characterized in that: The steps include: Step 51, evaporating and concentrating the psicose raffinate at 80° C. and −0.1 MPa to a refractive index of 70%, to obtain a psicose raffinate concentrated solution for later use; Step 52, weighing 500 g of the D-psicose extract concentrate, adding 25% ammonium sulfite and sodium metabisulfite in a mass ratio of 1:8 as catalysts; adjusting the pH of the mixture to 8 with sodium hydroxide; Step 53, put the mixed material into a 1L reactor for reaction, control the reaction temperature to 150°C, monitor the pH value of the reaction material every half an hour, control the pH value of the reaction material to 5-7 during the reaction, add 40% concentration of sodium hydroxide when necessary, react for 6 hours and then cool to room temperature, and obtain a caramel pigment product after the reaction is completed.