Embalagens Celulósicas - Aula 3

Summary

This lesson delves into cellulose-based packaging for food, focusing on the types of paper and cardboard used for food packaging. It covers the properties of cellulose, its production process, and the differences between long and short fibers. The lecture also highlights important regulations, like RDC 88/2016 and 89/2016, that govern materials in contact with food. Key materials such as Kraft paper, coated paper, and cellophane are discussed, alongside their benefits and drawbacks. The importance of quality control in manufacturing and the pros and cons of using cellulose for packaging are also explored.

Takeaways

• 😀 The lesson focuses on cellulosic packaging for food, including paper and cardboard materials.
• 😀 Cellulose is a polymer of glucose and the main structural polysaccharide in plants and trees, with about 50% of wood being cellulose.
• 😀 The paper is made from cellulose fibers, and its strength depends on the size, arrangement, and resistance of these fibers.
• 😀 Paper fibers are classified into long (2-5 mm) and short (0.5-1.5 mm) fibers, with long fibers providing strength and short fibers improving printing quality.
• 😀 Key physical properties of paper include weight (grammage), thickness (affecting print quality), and flexibility (impacting folding and curling).
• 😀 The process of making paper involves mechanical or chemical methods, including pulping, bleaching, and final paper formation.
• 😀 Paperboard production uses a corrugating machine to create the wavy layers of cardboard, which is then glued together and processed for packaging.
• 😀 Legislation regulating food packaging includes RDC 88/2016, 89/2016, and 90/2016, which set standards for materials in contact with food, including cellulosic materials.
• 😀 Cellulosic packaging materials include kraft paper, which is strong and used for food packaging, and coated paper, which has a smooth finish and is used for labels and promotional materials.
• 😀 Some key advantages of using cellulosic materials for packaging include low cost, biodegradability, and ease of production, while disadvantages include poor barriers to moisture and odors.

Q & A

What is cellulose and why is it important in the context of food packaging?

Cellulose is a polymer made of glucose units linked by β-1,4-glycosidic bonds. It is the primary structural polysaccharide found in plants and trees, constituting about 50% of wood. In food packaging, cellulose is crucial because it is the main material used in the production of paper and cardboard, which are commonly used for food packaging due to their physical properties.

What are the two main types of fibers used in paper production, and how do they affect the properties of the paper?

The two main types of fibers are long fibers (2-5 mm) from coniferous trees and short fibers (0.5-1.5 mm) from hardwood trees. Long fibers provide mechanical strength and are used in products like corrugated cardboard and multi-ply sacks. Short fibers are more suited for high-quality printing and smooth surfaces, commonly used in packaging for products like flour or snacks.

What is the significance of the physical properties of paper such as grammage and thickness?

Grammage refers to the weight per unit area (grams per square meter) and influences the paper's mechanical properties and barrier effectiveness. Thickness (or caliper) affects the material's printability, flexibility, and durability. These properties are essential when designing packaging materials that must meet specific functional and aesthetic requirements.

How is paper made, and what are the main steps in the process?

Paper is made from wood that undergoes mechanical or chemical processing to extract cellulose. The wood is cooked in chemicals to break it down and form cellulose fibers. The pulp is then bleached to create white paper (if necessary), and it is dried to form sheets. The same process is used for food packaging materials such as paperboard and corrugated cardboard.

What are the main regulatory standards for cellulosic packaging materials in contact with food?

Key regulations include RDC No. 88/2016, which outlines technical standards for materials that come into contact with food, and RDC No. 89/2016, which focuses on materials used for cooking and hot filtration, like coffee filters. RDC No. 90/2016 applies to materials that contact food during cooking or heating, such as food trays used for lasagna or other pre-cooked meals.

What are the different types of cellulose-based materials used in food packaging, and how do they differ?

There are several types of cellulose-based materials used in food packaging, such as Kraft paper (strong and used in heavy-duty packaging), coated paper (for high-quality printing), and cellophane (a transparent, biodegradable material used for wrapping items like baked goods and sweets). The differences arise from the type of cellulose used, the paper's thickness, and whether it is coated or not.

How do different types of Kraft paper vary in terms of strength and application?

Kraft paper comes in different weights and grades, with higher grammage offering greater strength. For example, heavy-duty Kraft paper (up to 300 g/m²) is used for industrial applications like cement sacks, while lighter grades (80-90 g/m²) are used for products like grains or flour. The paper can be either natural (brown) or bleached (white).

What is the purpose of paper coating, and how does it affect food packaging?

Coating paper adds a layer of material that makes the surface smooth and enhances printability. This is especially important in food packaging for branding and aesthetic appeal. Coated papers are used for packaging products like snack bags, where high-quality printing is important, and they can also offer some barrier properties to protect the contents.

What are the advantages and disadvantages of using cellulose-based materials for food packaging?

Advantages include low cost, biodegradability, ease of production, and excellent printability. These materials also provide a good barrier to light. However, they have poor resistance to moisture, odors, and puncturing. They may also require combination with other materials (e.g., plastic) to improve their barrier properties and functionality.

What role does paperboard play in food packaging, and how is it produced?

Paperboard is a thicker and stronger form of paper used primarily for packaging products like pizza boxes, fast food containers, and ice cream cartons. It is made by combining layers of paper pulp, often including different types of fiber for strength. Paperboard may be coated or layered to improve its resistance to moisture and impact, making it ideal for secondary and tertiary packaging.