Revolutionizing Starch Production: How Screw Extrusion is Producing Pre-Gelatinized (Modified) Starch

Production of Pre-Gelatinized (Modified) Starch by Screw Extrusion

Raw material formula: such as potato starch. Production process: starch → starch milk → gelatinization → drying → crushing → packaging

Extrusion method: This is a method that uses a screw extrusion puffing machine to produce pregelatinized starch based on the principle of extrusion and puffing. Add the pre-adjusted wet starch with a moisture content of 15-20% into the extruder. The starch is extruded by friction with the spiral shaft to generate heat and gelatinizes. Then it is extruded through a small hole with a diameter of 1-10 mm at high pressure. The materials entering the atmosphere are instantly expanded and dried, and pregelatinized starch is obtained after crushing and screening. Due to the high shear force, the viscosity of the product decreases and the solubility of the product increases. Since there is basically no need to add water during the manufacturing process, internal friction heat can be used to maintain a temperature of 120-160°C.

The production of physically pregelatinized starch does not require the addition of any additives. The characteristics of physically modified starch are to destroy molecular bonds, increase the affinity between starch and water, and increase the viscosity. This modification is often used as food additives such as thickening, thickening, etc. It is sticky and easy to bond various raw materials. It is then used in industry such as drilling. It is added to oil wells to speed up the bonding of the well walls during drilling. Then it is used in various industries and has a wide range of applications.

Raw materials: Different varieties of starch have a greater impact on pregelatinized starch. The different ratios of amylose and amylopectin in starch are the main factors causing this impact. In addition, the size of starch granules and starch composition also affect gelatinization. Slurry concentration: Generally, as the slurry concentration increases, the gelatinization degree of the product decreases. Drying temperature: When the output is constant, the higher the drying temperature, the higher the gelatinization degree of the product. Serous film thickness: When the thickness of the serous film is too large, gelatinization will be difficult and uneven, and sandwiching will easily occur. Additives: Sodium bicarbonate and sodium hydroxide can reduce the degree of polymerization of starch, making starch easy to gelatinize. Glyceryl monostearate and the like can fit into the helical structure of amylose to inhibit starch aging and are also beneficial to starch gelatinization.

Pregelatinized starch is generally used in food, feed, oil fields, building materials, pellet adhesion, coatings and other industries.

Application in food: Fast dissolution and adhesiveness are the main properties of pregelatinized starch, so it can be used in some occasions that have strict time requirements. In the food industry, it can be used to save heat treatment and require thickening and shape retention. In other aspects, it can improve the quality of pastries and stabilize the internal structure of frozen foods. Pregelatinized starch is mainly used in the food industry to make soft puddings, gravy fillings, slurries, dehydrated soups, seasonings and fruit juice candies.

Application in eel farming: Usually eel feed is in granular form, which is composed of feed powder rich in vitamins and other nutrients, a certain proportion of binders, oils, etc. The binder must have the following characteristics: ① non-toxic, Easy to digest and nutritious; ② transparent; ③ maintains the overall shape of the particles until the eel is eaten; ④ not dissolved by solutes in the water; ⑤ non-stick equipment. Pregelatinized potato starch is the best eel feed binder, and the general addition amount is 20%.

Application in cosmetics industry: Talcum powder is a commonly used skin care product, generally made of talc, starch and other auxiliary materials. Nowadays, gelatinized starch is used abroad to replace talcum powder and starch to produce new talcum powder. In addition to the characteristics of ordinary talcum powder, it also has the characteristics of good skin affinity and strong water absorption.

Application in the pharmaceutical industry: Generally, Western medicine tablets are composed of medicinal ingredients, starch binders, lubricants, etc. The starch mainly plays a role in material balance. The new tablets are composed of medicinal ingredients, pregelatinized lake, and lubricants. The gelatinized starch not only plays a material balance role, but also acts as a binder. This reduces unnecessary side effects caused by adding other adhesives. In addition to meeting medical requirements, the tablets produced by this new formula also have the characteristics of high strength after molding, easy digestion and dissolution after taking, and no toxic side effects.

Application in other industries: Pregelatinized starch quickly dissolves in cold water to form a high-viscosity starch paste, which makes it successfully used in many aspects. For example, it is used as a sand binder in metal casting; it is widely used as a sizing agent in the textile industry; it is used as a water-quality coating in the construction industry; it is used in oil well drilling mud in the petroleum industry to increase water storage and viscosity;

In addition, it can also be used as a raw material for further denaturation treatment. For example, in the preparation of lake graft copolymers, the starch raw material is pre-gelatinized before undergoing the grafting reaction, which can significantly increase the average molecular weight of the grafted branched polymer, while the grafting frequency can be greatly reduced.

Application of pregelatinized starch in food industry

(1) During the pregelatinization process, water molecules destroy the hydrogen bonds of starch molecules, thereby destroying the crystal structure of starch granules, making them swell and dissolve in water, so they are easily acted upon by amylase, which is beneficial to human body digestion and absorption. This property of pregelatinized starch can be used in the production of food for the elderly and infants.

(2) Pregelatinized starch has certain application advantages in traditional foods. Potato pregelatinized starch has good viscoelasticity and can replace gluten in flour. Better steamed buns can be made by adding 8% of flour weight to wheat starch. Adding amylose-containing pregelatinized starch to dough can improve its morphological properties. In addition, adding an appropriate amount of pregelatinized starch to noodles can reduce noodle breakage and cook quickly. In particular, cassava phosphate cross-linked starch has the best effect, with an added amount of 10%.

(3) Pregelatinized starch has strong water retention and can be used to improve the quality of baked goods. When making cakes, add a certain amount of pregelatinized starch. It is easy to form a dough when mixing the flour. Moreover, because the pregelatinized starch increases water absorption and gas production capacity, the cake has a good volume and can increase the freshness of the finished product.

and structural uniformity, making the product soft and taste good. Zhang Youbai believes that pregelatinized starch is used in baked goods to make cakes soft, and can control the low-temperature fluidity and grease viscosity of dough during the bread mixing, dough manipulation, extrusion, extrusion, and molding processes. It can also Delay aging. T0098 modified starch (pregelatinized starch) has a good effect on the sensory quality of bread. Scanning electron microscopy shows that pregelatinized starch can effectively extend the shelf life of bread. The optimal addition amount is 2% of flour quality. Pregelatinized starch is used in the production of fruit cakes. It wraps the fruit and suspends it on the cake to ensure that the fruit is evenly distributed in the cake during processing. In industrial production, 2% special pregelatinized waxy corn starch is added to the cake. , which can not only increase the volume of the cake, but also preserve the product characteristics. Adding 4% phosphate starch by flour mass to the cake can increase the volume of the cake, delay the aging of the cake, and significantly improve the foam holding performance of the cake foaming system. Adding cassava pregelatinized starch can promote the moisture binding method of the bread, form a stable state of combined water, and improve the bread holding performance. Water-based; but the growth rate will slow down after adding more than 5%. In addition, because pregelatinized starch can inhibit sucrose crystallization, it can be used as a moisturizing agent for Western-style pastry surface frosting.

(4) Pregelatinized starch has good freezing stability and can be used to stabilize the internal structure of frozen foods. Adding an appropriate amount of pregelatinized starch to quick-frozen foods can prevent the product from cracking during the quick-freezing process, improve the yield, and thus reduce production costs. In this regard, some people have conducted a series of studies on frozen glutinous rice dumpling wrappers. Using pregelatinized starch in quick-frozen glutinous rice dumpling wrappers can improve the process and improve stability. The dough can be directly mixed with cold water instead of the hot noodle process, making it easier to control the dough quality and ensure uniform product quality. In addition, pregelatinized starch has good viscoelasticity and shape retention, which can enhance the elasticity of glutinous rice balls and maintain the shape of glutinous rice balls to help avoid collapse of glutinous rice balls.

(5) Pregelatinized starch is a good raw material for snack foods such as rice crackers and crackers, and is better than ordinary starch. The reason is that when pregelatinized starch is used to make the mixed dough, part of the starch has absorbed water. During baking, the water escapes from the starch granules, causing expansion. Moreover, sometimes in order to achieve better results, modified pregelatinized starch is also used.

(6) Pregelatinized starch can swell and dissolve in cold water to form a paste with a certain viscosity, good dispersion, thickening and stabilizing effect, and easy to use, so it is widely used in various convenience foods. It eliminates the need for cooking and heating when eating, and also has the effects of thickening and improving taste; it is also used in various nutritional pastes, instant soups, jams and apple pie fillings. For example, pregelatinized starch is used to prepare instant oatmeal, almond paste, chicken essence, etc., which can be consumed with warm water. Generally, the dosage is 5% to 10% in jams and cookie fillings. Pregelatinized starch gel has a certain strength and can be used as a substitute for pudding gel. In Europe and the United States, instant pudding powder made from pregelatinized starch as the base material and adding a certain amount of starch sugar, nutritional enhancers, flavorings, etc. is very popular. instant food.

(7) Pregelatinized starch has strong water absorption, high gelatinization degree and viscoelasticity. It can also be used in surimi series products, ham, sausages and other foods to enhance elasticity, improve formability, and prevent water loss. For example, adding a certain proportion of pregelatinized starch when making fish balls can not only be used as an adhesive, but also prevent the fish balls from sticking together. It can also greatly improve the structure, color, taste and texture of the fish balls, making the product plump. Smooth and tender; but the dosage should be 10%~40%. If it is too much, it will age easily. According to US patent reports, adding solid flavoring materials to pregelatinized starch and adding water to cover the surface of the product can not only increase the flavor, but also increase the weight of the product by 0.05% to 20%, which will bring unexpected economic benefits.

Pregelatinized starch has the characteristics of instant cold water solubility, high viscosity and high swelling property.

Applications in the metallurgical industry

In beneficiation process, starch is mainly used as flocculant of minerals and inhibitor of iron minerals in flotation process. Due to the OH group in the monoglucose structure, starch polymerized molecules have strong hydrophilicity and are commonly used as flotation inhibitors. In addition, through the bridging effect in the solution, starch is also the flocculant of fine particles of minerals. Corn starch can be converted to dextrin by heat treatment, acid hydrolysis or enzymatic action. Dextrin retains the proportion of straight chain and branched chain structure in the original starch molecule, but the polymerization degree n value of glucose unit is greatly reduced, although it is still hydrophilic, but the structural chain is too short to form a bridge between the particles, and it is only used when the particles are required to have a high dispersion in the pulp. There are many types of iron ore equipment, and we often hear iron ore processing equipment and iron ore crushing equipment. Modified starch is the product of some changes in the structure of starch. Due to the change in structure and the introduction of some groups, it has a wider use than starch. The main uses of starch and modified starch in mineral processing are as follows: (1) inhibitor of iron oxide minerals in iron ore reverse flotation process. Flotation of quartz and silicate minerals with amine collectors; As an inhibitor of carbonate and other iron-bearing minerals in phosphate separation process using fatty acid as collector; As an inhibitor of silicate minerals of iron and magnesium in copper sulfide flotation; In quartzite type iron ore flotation process, quartz is activated by calcium oxide and then collected by sodium oleate, and starch is used as the inhibitor of hematite. (2) Starch inhibitors can also be used to inhibit talc, mica, natural sulfur, carbonaceous gangue, sulfide minerals, barite, etc. (3) It can also be used as an inhibitor in reverse flotation of other oxidized ores. For example, as an inhibitor of molybdenite in the separation of copper and molybdenum. It is also used in the flotation separation of aluminum-silicon minerals, the separation of calcite and fluorite, and the separation of calcite and apatite.

Physically modified starch is a high-temperature and high-pressure modified starch that is processed without adding any chemical raw materials.

Chemical modification is to graft chemical agents onto starch molecular groups to modify the modified starch.