Vacuum packaging is the process of packing various items without any air. This method of packaging increases the shelf-life of foods. It also reduces the bulk or space consumed in a storage area since air is eliminated or reduced. Vacuum sealing is widely used in the meat industry, hygroscopic powders, and other food items.
While vacuum packaging is an excellent way to preserve and store foods, not all bags or containers are suitable for this packing method. Some bags have a high oxygen transmission rate — the amount of air that leaks out of the bag after it is sealed.
Examples of bags with high oxygen transmittal rates are clear polyethylene and polypropylene bags. Both these bags are porous, and the vacuum will be gone within seconds after sealing.
Vacuum bags utilize an oxygen barrier embedded into the bag. This bag usually has a starting oxygen transmission rate of 10 cubic centimeters per 100 square inches per 24 hours. In the metric system, the unit of measurement is cubic centimeters per 100 square inches per 24 hours. The unit of measurement indicates the amount of air loss within 24 hours of sealing.
On the other hand, a standard LDPE bag has an oxygen transmittal rate of 450 cubic centimeters per 100 square inches per 24 hours. That is a significant difference in oxygen transmission rate, and some barrier bags can achieve an OTR much lower than ten cubic centimeters per 100 square inches per 24 hours. Below are the best vacuum seal bags you can find.
Co-Extruded Nylon/Poly Woven Bags
These bags are used for food and non-food products alike. Most co-extruded poly/nylon woven bags are transparent and used to package meats, cheeses, and other items. The usual thickness of co-extruded poly/nylon woven bags is three mils, equivalent to 0.003 inches or 0.07619 millimeters. Most bags have an OTR of 5 or less.
Co-extruded poly/nylon woven bags are ideal for storing food items in the freezer and long-term storage. After storage, expect that your food item is still fresh in texture and taste. Suppose a user still wants to make sure that they have the lowest possible oxygen penetration — in that case, a thicker bag is the next best option.
Co-Extruded Poly/Nylon With EVOH Bags
Ethylene vinyl alcohol or EVOH is an additive incorporated for additional barrier effect. Compared to the first type of bag, vacuum bags with EVOH appear to be grainier. It also has a lower oxygen transmission rate of 0.02 for a three mil bag. This low OTR is an excellent choice for products with compromised quality due to the high oxygen transmission rate.
Some of the products that will benefit from bags with EVOH are those that will not necessarily spoil but will have diminished sensory qualities upon air exposure. For institutional users, samples of hygroscopic ingredients are packed in a vacuum to ensure that clients receive unaltered and intact products. Sausage casings made from cellulose and collagen are also best transported in vacuum bags to prevent breakage and eliminate air and moisture.
Foil has a very low OTR of 0.0006 or less. Aside from being an oxygen barrier, foil also blocks light. This feature is handy for products that are prone to photooxidation. Products with high oil or fat content are susceptible to this type of spoilage.
Meanwhile, the polyethylene component allows the proper sealing of the bag. Foil/PET bags are usually 4 to 5 mil thick and are widely used in the coffee industry to preserve the aroma of the coffee beans. Foil/PET bags are also called metalized vacuum bags.
Some companies also employ an additional measure to flush nitrogen inside the foil/PET bag with its contents. Nitrogen gas replaces oxygen, thereby prolonging the shelf-life of food products.
Microorganisms require oxygen to live, and modifying the atmosphere kills them. Other elements used for this preservation method are the noble gases argon, krypton, helium, neon, and xenon.
Other applications of vacuum sealing
All the points discussed above pertain to the storage of materials in vacuum bags. There are, however, other uses of vacuum sealing.
For instance, the French cooking method sous vide — literally means under vacuum — involves vacuum sealing a food item then cooking it in a precise temperature water bath. This method ensures that you have consistent, restaurant-quality food every time.
Another food preparation method that can use vacuum seal bags is dry aging. This process is usually done in steaks to develop the flavor and texture of the meat. To prevent contamination, a vacuum seal bag is necessary. Dry-aged steak develops a nutty and buttery flavor that cannot be found in unaged beef.
Vacuum sealing can also be used for non-food items. It is always good to waterproof documents, emergency supplies (matches, lighters, batteries), and first aid kits (medicines and bandages). Sealing these items in a vacuum protects them from water and other elements that may damage other objects during calamities.
Lastly, there are vacuum bags that are specially formulated to contain electronics. These anti-static ESD vacuum bags have anti-electromagnetic interference features to ensure that the electronic chips are protected.
Not all bags or containers are suitable for use in vacuum packaging. A handful of materials that have a minimal oxygen transmission rate are readily available for this function.
Aside from the OTR, the bag’s thickness and composition also affect the oxygen barrier effect of your packaging. In recent years, other technologies such as Ziploc vacuum zipper bags, metalized vacuum packaging, and EMI-shielding also emerged.