What is a flat pouch? Overview. A Flat Pouch is the perfect flexible packaging solutions for efficient and economical packaging. The simplicity of flat pouches ensures that minimal effort is required to package and seal pouches, which save more time and money. Flat pouches have no gussets or folds and can be side welded or bottom sealed. Are pouches safer than cans? Tuna pouches take up less space than cans and are more flexible, making them easier to store in cabinets or pantries and pack into lunch boxes. Cans are more solid, so they offer more protection for the product inside. Pouches are not reusable, while cans can be recycled, according to Weston. What is a barrier pouch? What Are Barrier Bags? Barrier bags are bags designed to protect their contents from moisture, dirt, and other contaminants. They are often made with heavy duty plastics, with puncture and smell proof properties. Some three side seal pouch are designed for a specific industry while others are broad enough for mass appeal.