Biscuits are a beloved food product around the world, varying widely in texture, flavor, and type, from crunchy cookies to softer, flaky varieties. While the basic ingredients remain similar (flour, fat, and sugar), their production is a highly technical and refined process designed to ensure consistency, quality, and efficiency. Here, we’ll dive into the detailed, step-by-step process of manufacturing biscuits at an industrial scale, covering everything from raw material selection to packaging.
1. Raw Material Selection
The quality of the final biscuit product depends heavily on the raw materials used. Key ingredients typically include:
- Flour: Usually wheat flour, although gluten-free flours like rice, sorghum, or corn flour may also be used.
- Sugar: Provides sweetness and can influence texture. Granulated sugar is common, but glucose syrup, honey, or other sweeteners may be used.
- Fats: Shortening, margarine, or butter gives biscuits their characteristic crumbly texture.
- Leavening Agents: Sodium bicarbonate (baking soda), ammonium bicarbonate, and baking powder are commonly used to create a light, porous structure.
- Water/Milk: Acts as a binding agent to bring the dough together.
- Salt and Flavorings: For taste; may include vanilla, cocoa, spices, or even savory additives like cheese.
- Emulsifiers: These help blend ingredients like fats and water, ensuring consistency.
- Preservatives: Added to prolong shelf life.
- Optional Ingredients: Eggs, nuts, chocolate chips, fruits, etc., to enhance the final product.
2. Pre-Mixing and Ingredient Handling
Before the main dough-making process begins, each ingredient must be weighed and prepared according to the specific recipe being used. Most factories rely on automated systems to precisely measure and dispense ingredients to ensure uniformity and quality control.
- Flour Sifting: Flour is sifted to remove impurities and aerate it for a finer dough texture.
- Sugar Milling: Depending on the recipe, granulated sugar may need to be milled into finer particles to ensure even distribution in the dough.
3. Mixing
The next step in biscuit manufacture is mixing, where ingredients are combined to form a dough or batter.
- Mixing Stages: Ingredients are mixed in stages to ensure a homogenous dough. First, dry ingredients (flour, sugar, salt, and leavening agents) are blended. Then fats are added, followed by water or milk, emulsifiers, and any additional ingredients like flavorings, fruit, or chocolate chips.
- Types of Mixers: Large-scale industrial mixers are used, including vertical mixers, horizontal mixers, or planetary mixers. The choice of mixer depends on the type of biscuit being produced.
- Mixing Time and Temperature: The time and speed of mixing can influence dough development and the final texture of the biscuit. Precise temperature control is crucial because excess heat during mixing can cause fats to melt prematurely.
4. Dough Forming and Sheeting
Once the dough is mixed, it must be shaped into the desired form for the biscuits.
- Dough Resting: Some doughs, especially for delicate or flaky biscuits, require resting to allow the gluten to relax and improve rolling and forming quality.
- Sheeting: For most biscuits, the dough is passed through rollers to form sheets of uniform thickness. Sheeting machines can be adjusted to different thicknesses based on the type of biscuit being made.
- Shaping: Mold stamping of a thin layer of dough creates the simplest shapes – usually biscuits. in this process, a fine crumb structure is produced by the action of rolling and sheeting. This is possible by coalescence of entrapped air bubbles with their redistribution throughout the dough structure. These will serve nucleation centres for gas bubble formation when baking later occurs.
- Shaping II: Less viscoelastic doughs are molded. The flattening operation occurs where a dough piece is rounded into spherical or cylindrical shapes (Patel & Campanella, 2014).
- Laminating: For biscuits like puff pastries or crackers, layers of fat are incorporated into the dough through a process called laminating, where the dough is repeatedly folded and rolled.
- Cutting: Once the dough is sheeted, it moves to a cutting section. Rotary cutters or stamping machines are used to cut the dough into various shapes. Cutting machines also imprint patterns or branding onto the biscuits.
- Depositing: For softer doughs or batters, such as those used for drop cookies, the dough is deposited directly onto baking trays using depositors that can dispense consistent portions.
5. Baking
Baking is one of the most critical stages in biscuit manufacturing, where dough is transformed into crisp, delicious biscuits.
- Ovens: Most biscuits are baked in long tunnel ovens or rotary ovens. Tunnel ovens use a conveyor belt system, and biscuits move through different temperature zones to ensure even baking.
- Temperature Control: Biscuit baking typically requires temperatures ranging from 150°C to 300°C, depending on the type and thickness of the biscuit. The baking process involves several stages—initial moisture loss, dough expansion due to the activation of leavening agents, followed by crust formation and browning due to the Maillard reaction and caramelization.
- Baking Time: This varies from a few minutes to up to 20 minutes, depending on the biscuit. The thickness, size, and moisture content determine the exact time and temperature needed for optimal baking.
6. Cooling
After baking, biscuits must be cooled properly to avoid moisture condensation, which could result in sogginess.
- Cooling Conveyor: The freshly baked biscuits exit the oven onto cooling conveyors, where they are exposed to ambient air or cooled with fans.
- Cooling Time: The cooling process usually takes between 5 and 15 minutes, depending on the biscuit’s size and moisture content. The goal is to reduce the biscuit’s internal temperature to a point where they can be safely packaged without risk of spoilage.
- Stress Management: Rapid cooling could cause cracking or breakage, so it’s important that the cooling is done gradually to minimize internal stresses in the biscuits.
7. Secondary Processing (Optional)
Many biscuits undergo secondary processes before packaging to add additional flavors, textures, or decorations.
- Coating: Biscuits may be coated with chocolate, yogurt, or icing. This typically involves passing the biscuits through a coating machine or enrober that applies the coating evenly.
- Filling: Sandwich biscuits, such as Oreos or cream-filled biscuits, go through a filling machine that deposits cream or other fillings between two biscuit halves.
- Toppings: Some biscuits may have toppings applied, such as sugar sprinkles, seeds, or nuts. This is typically done after baking but before the biscuits are fully cooled to help the toppings adhere.
8. Quality Control
Throughout the entire manufacturing process, rigorous quality control measures are in place to ensure that biscuits meet the desired standards for texture, taste, appearance, and safety.
- Ingredient Inspection: Raw materials are inspected upon arrival to ensure they meet predefined quality standards.
- Process Monitoring: During production, continuous monitoring of factors like temperature, dough consistency, baking time, and moisture content ensures that biscuits maintain uniform quality.
- Final Product Testing: Finished biscuits undergo testing for various attributes like size, weight, texture (e.g., hardness or crispness), moisture content, and flavor. These tests ensure that the product is consistent with specifications.
9. Packaging
Once biscuits have cooled and passed quality control checks, they are ready for packaging. The goal of packaging is to protect the biscuits from damage during transportation and from environmental factors like moisture, which could compromise texture and flavor.
- Types of Packaging: Biscuits are commonly packed in plastic trays, paperboard boxes, or flexible packaging like pouches and foil wraps. The choice depends on the type of biscuit and its shelf-life requirements.
- Sealing: Packaging machines often seal packages with heat-sealing methods to ensure that the contents remain fresh.
- Labeling: Product labeling is applied during this stage, providing critical information like ingredients, nutrition facts, expiration dates, and branding.
10. Distribution
After packaging, the biscuits are boxed and prepared for distribution. Distribution logistics are an essential part of the manufacturing process to ensure that biscuits reach consumers in perfect condition.
- Storage: Biscuits are typically stored in warehouses before distribution. Proper storage conditions (temperature and humidity control) are crucial to maintaining freshness.
- Transportation: Distribution may involve shipping biscuits by truck, train, ship, or plane, depending on the geographical reach of the product. Careful handling during transportation is necessary to avoid breakage.
Changes To Biscuit Structure And Texture During Oven baking
Throughout biscuit production, a variety of complex chemical changes occur which are brought on by the physical effects of processing. Heat is the main driver of any chemical changes. If yeast is used in biscuit production then fermentation during proofing is the most critical effected by temperature. The dough’s moisture content along with the humidity in the baking chamber of the oven are the two most critical elements.
Water hydrates gluten protein which changes conformation and behaviour which affects starch granules that swell and gelatinize during the actual baking process. The absorption of water by gluten is highly significant. When the temperature of either fermentation and especially oven baking occurs. the gluten structure throughout the biscuit dough swells and strengthens. The volume of the dough also expands as air and gas bubbles form. Visible swelling occurs between 30 and 50C. Gluten amongst other proteins then denatures above 50C. It eventually coagulates and partly precipitates above 70C. Above this temperature moisture is released from gluten along with starch hydration and gelatinization.
Air bubbles also start forming. They are saturated with water vapour. The rising temperature causes the air bubbles to increase further by 50%. Further expansion of the dough then occurs during oven baking.
Hydrated starch gelatinizes at temperatures between 50 and 60C. For biscuits, gelatinization is partial because not enough water is available for full starch gelatinization.
Moisture is evaporated from the surface of the dough. Free moisture removal occurs at 100C but when water is tightly bound then an oven temperature of 130C is required. This important element of oven baking is highly dependent on the type of oven and humidity in its chambers.
After baking and the driving away of moisture, the biscuits cool on a stripping conveyor. The moisture content of of the biscuits or cookies stabilizes and if baked correctly will mean correctly formed biscuits. If the moisture gradient was too high, the biscuits will crack and break during and after packing.
Challenges in Biscuit Manufacturing
- Ingredient Variability: Fluctuations in raw material quality can lead to inconsistency in the final product, so precise ingredient specifications and quality control are crucial.
- Moisture Control: Moisture is the enemy of crispy biscuits. Maintaining the right moisture levels during and after baking is a challenge, particularly in environments with high humidity.
- Uniformity: Ensuring uniform thickness, shape, and bake quality in mass production can be difficult, especially when producing large volumes.
The manufacture of biscuits is a complex and precise process involving numerous stages from ingredient selection to packaging. Each step requires careful control to ensure the final product meets the desired texture, flavor, and shelf life. Advances in automation and technology have enabled manufacturers to produce high volumes of biscuits consistently while maintaining high standards of quality and food safety.
From simple ingredients, biscuits are transformed into delicious treats through a well-orchestrated manufacturing process, making them one of the most popular and enduring snack foods in the world.
References
(2000). Technology of Biscuits, Crackers and Cookies. Cambridge , England : Woodhead Publishing Limited. 25 pp.
Patel, B., & Campanella, O. H. (2014). Dough Processing: Sheeting, Shaping, Flattening and Rolling. Conventional and Advanced Food Processing Technologies, pp. 51-74
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