Glucoamylase, also known as glucamylase, is an exoenzyme. Just like a skilled craftsman, it starts from the non-reducing end of liquefied starch, precisely cleaving the α-1,4-glucosidic bonds, and gradually decomposes the starch molecules to produce glucose molecules one by one. However, when it comes to the more complex α-1,6-glucosidic bonds in amylopectin, glucoamylase is somewhat inadequate and cannot cleave them quickly and effectively.
To overcome the limitation of glucoamylase in dealing with amylopectin, compound glucoamylase has been developed. Compound glucoamylase is like a professional "saccharification team", which is carefully prepared by enzyme preparation manufacturers by blending glucoamylase activity and pullulanase activity in an appropriate ratio.
Pullulanase can specifically hydrolyze the α-1,6-D-glucosidic bonds in liquefied starch to produce linear polysaccharides containing 1,4-α-D-glucosidic bonds. When working synergistically with glucoamylase, it acts like a capable assistant to the craftsman, helping to solve the problem of amylopectin and greatly improving the efficiency of the saccharification reaction.
In addition to the efficient synergistic effect, compound glucoamylase also has the advantage of low miscellaneous enzyme activity. The lower the activity of miscellaneous enzymes such as transglycosylase, the less likely the composite reaction will occur, thereby improving the purity and sugar yield of glucose. This is similar to a team where each member performs their own duties without unnecessary interfering factors, resulting in better work efficiency and outcomes.
Among the numerous compound glucoamylase products on the market, high-performance compound glucoamylase from well-known brands is favored by the industry due to its excellent performance. They excel in saccharification speed, glucose yield, and reverse reaction control, providing enterprises with better-quality and more efficient saccharification solutions.
In the industrial production of glucose through starch hydrolysis, the control of substrate concentration is like walking a tightrope. A precise balancing point must be found to ensure efficient production and high-quality products. Substrate concentration, a seemingly simple parameter, has a profound impact on the saccharification reaction. It is not only related to production costs but also directly determines the effect of saccharification and the quality of glucose.
3.1 Disadvantages of Too Low Concentration
When the substrate concentration is too low, it is like a battle with insufficient troops. Although the battle can proceed, the efficiency and results will be greatly reduced. In the saccharification reaction, an excessively low substrate concentration will lead to a significant increase in steam consumption in the subsequent process section. This is because a large amount of water needs to be evaporated during the subsequent sugar solution concentration process, and the evaporation of this water consumes a large amount of steam.
Imagine a factory that could originally process a large amount of starch in one saccharification reaction to obtain a high-concentration sugar solution, and only a small amount of steam is needed to concentrate it to the required concentration. However, if the substrate concentration is too low, it means that the sugar solution obtained from each saccharification reaction has a very low concentration. To achieve the same product concentration, more water needs to be evaporated, which will undoubtedly greatly increase the amount of steam used, leading to a sharp rise in production costs. This will not only reduce the profit margin of the enterprise but also may put the enterprise at a disadvantage in market competition.
3.2 Problems of Too High Concentration
Contrary to the situation of too low substrate concentration, when the substrate concentration is too high, a series of other problems will arise. An excessively high substrate concentration will intensify the reverse reaction of glucoamylase, just like a machine that was originally operating smoothly suddenly being stuffed with too many raw materials, causing the machine to operate unsmoothly or even break down.
In the process of glucoamylase catalyzing the hydrolysis of starch to produce glucose, there is also a reverse reaction, that is, glucose will recombine to form complex carbohydrates such as isomaltose. When the substrate concentration is too high, the glucose concentration in the reaction system will also increase accordingly, which provides more favorable conditions for the reverse reaction and makes the reverse reaction more likely to occur. The intensification of the reverse reaction will directly reduce the saccharification level, decrease the yield of glucose, and affect the quality of the product and production efficiency. Moreover, the high-concentration substrate will increase the viscosity of the reaction solution, leading to difficulties in mass transfer and heat transfer, which further affects the progress of the saccharification reaction.
3.3 Optimal Concentration Range
After years of factory practice and research, most factories generally control the substrate concentration during starch liquefaction within the range of 30% - 35% (mass fraction). This range is like the Goldilocks Zone, which is just right. Within this concentration range, it can not only ensure that the saccharification reaction has sufficient substrates for the reaction but also effectively control the steam consumption and the occurrence of reverse reactions. When the substrate concentration is 30% - 35%, glucoamylase can give full play to its catalytic role, efficiently converting starch into glucose, while avoiding the steam waste caused by too low substrate concentration and the reverse reaction problems caused by too high substrate concentration.
At present, the highest saccharification substrate concentration in the industry should not exceed 38% (mass fraction). Once this limit is exceeded, the impact of the reverse reaction will become difficult to control, the saccharification level will decrease significantly, and the product quality will be difficult to guarantee. Therefore, in actual production, strictly controlling the substrate concentration within an appropriate range is one of the keys to ensuring the smooth progress of the industrial production of glucose through starch hydrolysis.
In the industrial production of glucose through starch hydrolysis, enzyme dosage and reaction time are like the rhythm control in a sweet movement. Their accuracy directly affects the effect of the saccharification reaction and the quality of the final product. These two factors are interrelated and interact with each other, jointly determining the efficiency and benefit of production.
4.1 Impact of Enzyme Dosage
Enzyme dosage is like the "catalyst dose" in this sweet conversion, which has a crucial impact on the saccharification reaction. Increasing the enzyme dosage, on the surface, seems to inject a "cardiotonic" into the saccharification reaction, which can shorten the reaction time and increase the output. When the factory's equipment capacity is limited but the market demand continues to grow, and it is necessary to increase the output, increasing the enzyme dosage can allow the saccharification reaction to complete more conversions in a shorter time, thereby improving production efficiency.
However, there are some problems that cannot be ignored behind this. Increasing the enzyme dosage will reduce the final DE value (dextrose equivalent value) of saccharification, directly affecting the saccharification yield. This is because in the process of glucoamylase catalyzing the hydrolysis of starch to produce glucose, in addition to the positive hydrolysis reaction, there is also a reverse reaction. When the enzyme dosage is too high, the reaction speed accelerates, and the glucose concentration in the system increases rapidly, which provides more favorable conditions for the reverse reaction. The intensification of the reverse reaction will cause glucose to recombine to form complex carbohydrates such as isomaltose, thereby reducing the purity and yield of glucose.
4.2 Selection of Reaction Time
Reaction time is like the "timeline" in this sweet conversion, and its length also has a profound impact on the saccharification reaction. The reaction time for glucose production and saccharification is generally recommended to be 40 - 60 hours, which is the optimal time range obtained through a large number of practices and studies. Within this time range, the enzyme can give full play to its catalytic role, converting starch into glucose gradually and effectively. If the reaction time is too short, the starch may not be completely hydrolyzed, resulting in incomplete saccharification, low glucose yield, and difficulty in ensuring product quality. On the other hand, if the reaction time is too long, it will not only increase the production cost but also may trigger some side reactions, such as the decomposition of glucose and the darkening of color, which will also affect the product quality.
Choosing an appropriate reaction time can also reduce the enzyme cost. Because within the appropriate time, the enzyme can complete the catalytic task efficiently without additional enzyme dosage to increase the reaction speed. This not only saves the cost of enzyme preparations but also avoids a series of problems caused by excessive enzyme dosage. An appropriate reaction time can also ensure the saccharification quality, making the produced glucose have high purity and good quality, meeting the strict requirements of different industries for glucose.