Method for reducing impurity content in high-concentration white granulated sugar syrup

Abstract

The invention discloses a method for reducing the content of impurities in high-concentration white granulated sugar syrup, and relates to the technical field of sugar manufacturing processes. Lime milk and phosphoric acid are adopted as clarifying agents, and the ash content and the sulfur dioxide content in the syrup can be effectively reduced by utilizing a method of combining alkaline floating after phosphoric acid and stoving neutralization with acidic floating of phosphoric acid; the color value and the turbidity of the syrup can be reduced, so that the decolorizing effect of the syrup is improved; moreover, the cleaning process sequentially passes through an alkaline pH value and a neutral pH value, so that the clarifying agent can react completely, the cleaning effect is enhanced, and the decolorizing effect can be further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sugar-making processes, and more particularly to a method for reducing the impurity content in high-concentration white granulated sugar syrup. Background Art

[0002] White granulated sugar is processed from plants such as sugarcane or sugar beet, and is the main product of sugar factories. Its main component is sucrose, which is an important daily condiment and is widely used in industries such as food processing, beverages, and pharmaceuticals. The traditional and mature processing methods for producing white granulated sugar in China mainly include the sulfite method and the carbonation method. Compared with the carbonation method, the sulfite method has relatively simple process equipment, less usage of clarifying agents, lower energy consumption, and lower cost, but it removes relatively fewer non-sugar impurities, has a relatively lower boiling and recovery rate, the quality of white granulated sugar is unstable, it will discolor during long-term storage, and the residual sulfur dioxide content is relatively high.

[0003] The traditional carbonation clarification process uses sugarcane as the raw material, including crushing, pressing, heating, carbon dioxide saturation, second heating, filtration, carbon dioxide saturation, third heating, filtration, sulfur dioxide bleaching, fourth heating, five-effect evaporation, sulfur dioxide bleaching, crystallization separation, and finally obtaining white granulated sugar. Since sulfur dioxide is introduced twice for bleaching in the process, and only precipitates mainly composed of calcium carbonate are used to remove various non-sugars, the impurity removal effect is not good, resulting in part of the sulfur dioxide remaining in the clarified syrup and finally remaining in the finished white granulated sugar during sugar boiling and crystallization, making the sulfur dioxide content of the white granulated sugar on the high side and affecting the product quality.

[0004] Therefore, how to provide a method that can effectively reduce the impurity content in white granulated sugar syrup is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a method for reducing the impurity content in high-concentration white granulated sugar syrup In order to achieve the above object, the present invention adopts the following technical solutions: A method for reducing the impurity content in high-concentration white granulated sugar syrup, comprising the following steps: (1) Dissolve white granulated sugar in distilled water to form a solution of 50 - 60 °Bx, and heat to obtain syrup; (2) Add lime milk and phosphoric acid to the syrup in step (1), stir evenly, adjust the pH value, and then perform sulfur fumigation neutralization and ultrasonic treatment to obtain a mixed solution; (3) Charge CO2 into the mixed solution in step (2), add a flocculant, stir evenly, then transport it to a syrup floating device, perform heating and floating separation in the floating device, and skim off the scum formed on the upper layer to obtain a floating clarified syrup; (4) Add phosphoric acid to the first floating clear syrup in step (3) to neutralize the pH value, charge CO2, add a flocculant, stir evenly, and then transport it to the syrup floating device again. Heat and float separation are carried out in the floating device, and the scum formed on the upper layer is skimmed off to obtain the second floating clear syrup; (5) Perform secondary sulfur fumigation and neutralization on the second floating clear syrup in step (4), and after centrifugation, clear syrup without impurities can be obtained.

[0006] Further, in step (1), the heating temperature is 60 - 65 °C.

[0007] Further, in step (2), the addition amount of the lime milk is 100 - 200 mg added to 1 kg of syrup; the addition amount of the phosphoric acid is 300 - 400 mg added to 1 kg of syrup; the pH value is 8.2 - 8.8; the sulfur fumigation intensity is 8 - 12 mL, and the sulfur fumigation and neutralization pH value is 8.5 - 8.8; the ultrasonic intensity is 0.5 W / cm 2 - 10 W / cm 2 , and the ultrasonic time is 100 - 300 s.

[0008] Further, in step (3), the charging amount of CO2 is 0.1 - 0.5% of the mass of the mixed solution; the addition amount of the flocculant is 15 - 20 mg added to 1 kg of syrup.

[0009] Further, in step (4), the addition amount of the phosphoric acid is 100 - 200 mg added to 1 kg of syrup; the pH value is adjusted to 7.0 - 7.2; the charging amount of CO2 is 0.1 - 0.5% of the mass of the first floating clear syrup; the addition amount of the flocculant is 15 - 20 mg added to 1 kg of syrup.

[0010] Further, in steps (3) - (4), the flocculant is one or several of polyacrylamide, chitosan, and magnesium hydroxide.

[0011] Further, in steps (3) - (4), the heating temperature of the floating device is 80 - 85 °C.

[0012] Further, in step (5), the sulfur fumigation intensity is 6 - 10 mL, and the sulfur fumigation and neutralization pH value is 6.4 - 6.8; the centrifugation is carried out at 1500 - 2000 rpm for 10 - 20 min.

[0013] As an invention concept identical to the above technical solution, the present invention also claims protection for a white granulated sugar syrup without impurities prepared by the above method.

[0014] As an invention concept identical to the above technical solution, the present invention also claims protection for the application of the above white granulated sugar syrup without impurities in the preparation of foods, pharmaceuticals, and health products.

[0015] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a method for reducing the impurity content in high-concentration white granulated sugar syrup, and the beneficial effects are as follows: By using lime milk and phosphoric acid as clarifying agents, and adopting a treatment method combining the alkaline floating after sulfur fumigation neutralization and the acidic floating with phosphoric acid addition, the ash content and sulfur dioxide content in the syrup can be reduced, and the color value and turbidity of the syrup can also be reduced, thereby improving the decolorization effect of the syrup.

[0016] Moreover, the clarification process of the present invention passes through two pH values of alkaline and neutral in sequence. The pH value of the syrup before pre-liming and the first floating is controlled to be alkaline, which can make the clarifying agent react completely and enhance the clarification effect; the second is neutral. The added phosphoric acid reacts with the remaining CaO in the syrup after the first floating and clarification, and the generated calcium phosphate can not only play a decolorizing role but also reduce the Ca 2+ content in the syrup. Specific embodiments

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0018] The lime milk used in the embodiments can be used only after adding water to slake calcium oxide to form lime milk with a concentration of 10-20 ºBe. Example 1

[0019] A method for reducing the impurity content in high-concentration white granulated sugar syrup includes the following steps: (1) Dissolve white granulated sugar in distilled water to form a 60°Bx solution, and heat it at 60°C to obtain syrup; (2) Add 100 mg (the addition amount per 1 kg of syrup) of 10ºBe lime milk and 300 mg of phosphoric acid (the addition amount per 1 kg of syrup) to the syrup in step (1), stir evenly, adjust the pH value to 8.5, and then perform sulfur fumigation neutralization under the condition of a sulfur fumigation intensity of 8 mL. The pH value after neutralization is 8.8; then perform ultrasonic treatment at a strength of 0.5 W / cm 2 for 300 s to obtain a mixed solution; (3) Charge 0.3% of the mass of the mixed solution of CO2 into the mixed solution in step (2), add 15 mg of polyacrylamide (the addition amount per 1 kg of syrup), stir evenly, then transport it to a syrup floating device, and perform heating and floating separation in the floating device at 80°C, and skim off the scum formed on the upper layer to obtain a once-floated and clarified syrup; (4) Add 200 mg of phosphoric acid (added amount per 1 kg of syrup) to the first floating clarified syrup in step (3) to neutralize the pH value to 7.0, and introduce CO₂ with a mass of 0.5% of the first floating clarified syrup. Add 15 mg of polyacrylamide, stir evenly, and then transport it to the syrup floating separator again. Perform heating and floating separation in the floating separator at 80 °C, and skim off the scum formed on the upper layer to obtain the second floating clarified syrup; (5) Perform secondary sulfur fumigation on the second floating clarified syrup in step (4) under the condition of a sulfur fumigation intensity of 6 mL to neutralize the pH value to 6.8, and centrifuge at 1500 rpm for 20 min to obtain impurity-free clarified syrup. Example 2

[0020] A method for reducing the impurity content in high-concentration white granulated sugar syrup, comprising the following steps: (1) Dissolve white granulated sugar in distilled water to form a solution with a Bx of 55°, and heat it at 65 °C to obtain syrup; (2) Add 150 mg of 15 ºBe lime milk (added amount per 1 kg of syrup) and 400 mg of phosphoric acid (added amount per 1 kg of syrup) to the syrup in step (1), stir evenly, adjust the pH value to 8.8, and then perform sulfur fumigation and neutralization under the condition of a sulfur fumigation intensity of 10 mL. The neutralized pH value is 9.0; then perform ultrasonic treatment at a strength of 10 W / cm 2 for 100 s to obtain a mixed solution; (3) Introduce CO₂ with a mass of 0.1% of the mixed solution into the mixed solution in step (2), add 10 mg of chitosan (added amount per 1 kg of syrup) and 10 mg of magnesium hydroxide (added amount per 1 kg of syrup), stir evenly, transport it to the syrup floating separator, perform heating and floating separation in the floating separator at 83 °C, and skim off the scum formed on the upper layer to obtain the first floating clarified syrup; (4) Add 100 mg of phosphoric acid (added amount per 1 kg of syrup) to the first floating clarified syrup in step (3) again to neutralize the pH value to 7.2, and introduce CO₂ with a mass of 0.3% of the first floating clarified syrup. Add 10 mg of chitosan (added amount per 1 kg of syrup) and 10 mg of magnesium hydroxide (added amount per 1 kg of syrup), stir evenly, transport it to the syrup floating separator again, perform heating and floating separation in the floating separator at 83 °C, and skim off the scum formed on the upper layer to obtain the second floating clarified syrup; (5) Perform secondary sulfur fumigation on the second floating clarified syrup in step (4) under the condition of a sulfur fumigation intensity of 8 mL to neutralize the pH value to 6.4, and centrifuge at 1800 rpm for 15 min to obtain impurity-free clarified syrup. Example 3

[0021] A method for reducing the impurity content in high-concentration white granulated sugar syrup, comprising the following steps: (1) Dissolve white sugar in distilled water to form a 50° Bx solution, and heat at 63°C to obtain a syrup; (2) Add 200 mg 20°Be lime milk (the amount added to 1 kg of syrup) and 350 mg phosphoric acid (the amount added to 1 kg of syrup) to the syrup in step (1), stir evenly, adjust the pH value to 8.2, and then carry out sulfur fumigation neutralization under the condition of sulfur fumigation intensity of 12 mL. The pH value after neutralization is 8.5. Then, carry out sulfur fumigation at 5.5 W / cm 2 Ultrasonic treatment was performed at an intensity of 200 s to obtain a mixed solution; (3) 0.5% CO2 by mass of the mixed solution is charged into the mixed solution of step (2), 17 mg of chitosan (the amount added in 1 kg of syrup) is added, and after stirring evenly, the mixture is transferred to a syrup floater, heated and floated in the floater at 85°C for separation, and the scum formed on the upper layer is skimmed off to obtain a floating clear syrup; (4) 150 mg of phosphoric acid (the amount added to 1 kg of syrup) is again added to the first floating clear syrup of step (3) to neutralize the pH value to 7.1, and 0.1% of CO2 by mass of the first floating clear syrup is charged, and 17 mg of chitosan (the amount added to 1 kg of syrup) is added. After stirring evenly, the mixture is transferred to the syrup floater again, heated and floated in the floater at 85° C. for separation, and the scum formed on the upper layer is skimmed off to obtain a second floating clear syrup; (5) The double-floated clear syrup of step (4) is subjected to a second sulfur fumigation at a sulfur fumigation intensity of 10 mL to neutralize the pH value to 6.6, and then centrifuged at 2000 rpm for 10 min to obtain a clear syrup without impurities.

[0022] Comparative Example 1 The difference from Example 2 is that the ultrasonic treatment in step (2) is removed, and the rest is the same.

[0023] Comparative Example 2 The difference from Example 2 is that the alkaline flotation process in step (3) is removed, and the rest is the same.

[0024] Comparative Example 3 The difference from Example 2 is that the phosphoric acid-adding acid flotation process in step (4) is removed, and the rest is the same.

[0025] Comparative Example 4 The difference from Example 2 is that hydrochloric acid (30 wt %) is used to replace the phosphoric acid in step (2), and sodium carbonate is used to replace the lime milk in step (2). The specific amounts are the same as those in Example 2.

[0026] Test Example 1 The conductivity ash, color value and turbidity of the clear sugar syrups of Examples 1-3 and Comparative Examples 1-2 were measured according to GB / T 35887-2018 “Test Method for White Sugar”. The measurement results are shown in Table 1.

[0027] Table 1 Determination results of conductivity ash, color value and turbidity in different clear sugar syrups

[0028] As shown in Table 1, the conductivity ash, color value and turbidity of the clear syrup prepared in Examples 1-3 of the present invention are 0.08-0.10%, 102.69-111.55 and 47.05-49.12 respectively, and the effect of Example 2 is more significant; in Comparative Example 1, ultrasonic treatment is removed, and the conductivity ash, color value and turbidity of the clear syrup prepared therein are significantly higher than those of the present invention, because the present invention adopts ultrasonic treatment after sulfur fumigation neutralization to increase the neutralization reaction speed and reaction degree of the syrup, so that sulfur dioxide is completely consumed and the decolorization effect is improved; compared with Comparative Examples 2-3, the alkaline flotation process and phosphoric acid addition are removed. The conductivity ash, color value and turbidity of the clear sugar syrup prepared by the alkaline and acidic flotation process are significantly higher than those of the present invention. It can be seen that the flotation process combining alkalinity and acidity has a good effect on reducing turbidity. Among them, the alkaline flotation process can make the clarifier react completely, thereby enhancing the purification effect. The acidic flotation process can form larger flocs under the action of the flocculant after the calcium phosphate formed by adding phosphoric acid adsorbs impurities, and can float well under the action of bubbles, which can achieve a good effect on reducing the turbidity of the sugar solution. The clarifier was replaced in Comparative Example 4. Although it can also reduce the ash content, color value and turbidity, the reduction effect is far lower than that of the present invention.

[0029] Test Example 2 The clear syrups of Examples 1-3 and Comparative Examples 1-2 were respectively used to determine the content of sulfur dioxide in the samples according to GB 5009.34-2016 “National Food Safety Standard Determination of Sulfur Dioxide in Foods”. The results are shown in Table 2.

[0030] Table 2 Determination results of sulfur dioxide content in different clear sugar syrups

[0031] As shown in Table 1, the sulfur dioxide content in the clear sugar syrup prepared in Examples 1-3 of the present invention can reach as low as 0.54 mg / kg; the sulfur dioxide content in the clear sugar syrup prepared in Comparative Example 1 is increased by 92.45% compared with Example 2 by removing the ultrasonic treatment, and the present invention generates shock waves and jets in a very small space and a very short time in the sulfur fumigation neutralization reaction system under the action of the ultrasonic field, thereby reducing the SO3 2-Content; In Comparative Examples 2-3, the alkaline floating process and the phosphoric acid acid floating process were removed, and the sulfur dioxide content in the prepared clear syrup was also much higher than that of the present invention. This shows that the treatment method combining sulfur fumigation neutralization and phosphoric acid acid floating in the present invention can effectively remove sulfur dioxide; while in Comparative Example 4, sulfurous acid was used as a clarifying agent, which can reduce the turbidity of the syrup, but will increase the residual amount of sulfur dioxide in the syrup.

[0032] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0033] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for reducing the impurity content in high-concentration white sugar syrup, characterized in that: The following steps are involved: (1) Dissolve white sugar in distilled water to a solution of 50-60° Bx, and heat to obtain syrup; (2) adding lime milk and phosphoric acid to the syrup of step (1) and stirring evenly, adjusting the pH value, fumigating with sulfur, and performing ultrasonic treatment to obtain a mixed solution; (3) CO2 is charged into the mixed solution of step (2), a flocculant is added, and after being stirred evenly, the mixed solution is transported to a syrup floater, where it is heated and floated for separation, and the scum formed on the upper layer is skimmed off to obtain a floating clear syrup; (4) phosphoric acid is added again to the first floating clear syrup of step (3) to neutralize the pH value, and CO2 is charged, a flocculant is added, and after being stirred evenly, it is transported to the syrup floater again, heated and floated in the floater for separation, and the scum formed on the upper layer is skimmed off to obtain a second floating clear syrup; (5) The double-floating clear syrup of step (4) is subjected to secondary sulfur fumigation neutralization and centrifugation to obtain clear syrup without impurities.

2. The method according to claim 1, characterized in that In step (1), the heating temperature is 60-65°C.

3. The method according to claim 1, characterized in that: In step (2), the amount of lime milk added is 100-200 mg per 1 kg of syrup; the amount of phosphoric acid added is 300-400 mg per 1 kg of syrup; the pH value is 8.2-8.8; the sulfur fumigation intensity is 8-12 mL, and the sulfur fumigation neutralization pH value is 8.5-8.8; the ultrasonic intensity is 0.5 W / cm 2 -10W / cm 2 , ultrasonic time is 100-300s.

4. The method according to claim 1, characterized in that: In step (3), the amount of CO2 charged is 0.1-0.5% of the mass of the mixed solution; the amount of flocculant added is 15-20 mg per 1 kg of syrup.

5. The method according to claim 1, characterized in that In step (4), the amount of phosphoric acid added is 100-200 mg per 1 kg of syrup; the pH value is adjusted to 7.0-7.2; the amount of CO2 charged is 0.1-0.5% of the mass of the floating syrup; and the amount of flocculant added is 15-20 mg per 1 kg of syrup.

6. The method according to claim 1, characterized in that In steps (3)-(4), the flocculant is one or more of polyacrylamide, chitosan, and magnesium hydroxide.

7. The method according to claim 1, characterized in that In steps (3) and (4), the heating temperature of the floater is 80-85°C.

8. The method according to claim 1, characterized in that In step (5), the sulfur fumigation intensity is 6-10 mL, and the sulfur fumigation neutralization pH value is 6.4-6.8; and the centrifugation is performed at 1500-2000 rpm for 10-20 min.

9. An impurity-free white sugar syrup prepared by the method according to any one of claims 1 to 8.

10. Use of the impurity-free white sugar syrup according to claim 9 in the preparation of foods, medicines and health products.

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