You may recall that you were shopping for tea products. Apart from personal taste preferences and price factors, you would always choose a nice packet with a longer shelf life and the nearest production date. Isn’t it?
Under the influence of the COVID-19 pandemic, people have to reduce their shopping trips. Shoppers are more likely to want their tea leaves products to be fresh and last longer.
As the growing trends of a globalized market, tea producers should supply longer shelf life products. In this way, merchants can have a longer time to sell their products. Fresh, preservative-free, but with a longer shelf life. It seems to be a paradox in the food packaging field. In fact, this is exactly what we have been trying to achieve.
So what Technical means can keep the freshness of tea products and extend their shelf life in mass production. Let’s get started.
Factors Affecting tea product Shelf Life
Understanding the causes of tea deterioration is critical in selecting the appropriate package to maximize shelf life. Usually, these factors bring changes in aroma, taste, color, and texture until they are unacceptable.
Intrinsic factors of the raw product
- Initial quality- Using untested ingredients, it will easily lead to deterioration. For instance, the damp tea leaf can result in mildew.
- Inherent nature of the product- The product is rich in active ingredients. Green tea, for example, has a shelf life of only one year at room temperature.
Only the tea products with guaranteed quality are worth protecting and prolonging their shelf life.
Packaging is an external factor that affects shelf life.
Under natural conditions, loose tea will slowly deteriorate for various factors。
- Oxygen– Oxygen is the top killers of tea products freshness. Tea leaves would oxidize over time with exposure to the air. With the loss of polyphenols and vitamins, the quality of products will be greatly reduced.
- Moisture– The finished tea is hygroscopic. It will absorb moisture from the air. As a result, the tea leaves release its flavor in vain.
- Light– It’s no secret that light induced damage on tea. The plant pigments or lipids in tea leaf will oxidize through light-induced reaction quickly. Without light protection, it will cause a metallic flavor.
- Odors– From a microscopic point of view, tea is a loose and porous structure. It will absorb the Peculiar molecules around it. Tea is easily polluted in contact with unpleasant odors!
- Heat– The higher the temperature, the faster the quality of tea changes. This is mainly reflected in the storage conditions.
It is necessary to create an oxygen-free, dry, shaded airtight packaging space for tea leaves for all these factors. Meanwhile, keep the temperature low during transportation and storage. In this way, the aroma and taste of tea can be maintained for a long time.
Choosing the suitable packing material
After understanding the causes of the tea deterioration, we know that a good package acts as a physical barrier to oxygen, moisture, microorganisms for tea. The performance of the bag determines whether the tea can have a long shelf life.
Besides the fact that the packing material should be able to block the light, a good barrier rate is an important reference factor in choosing a bag. As we all know, Molecular motion is everywhere. Usually, we use permeability to describe this indicator.
- Glass and metal packaging materials own the lowest permeability. It is difficult for low molecular weight compounds to pass through. But， it is not a valid packaging material for the high cost.
- For paper-based materials, it’s too permeable. Its barrier is in vain in front of small molecules.
- The polymers, such as low-density polyethylene (LDPE), polyvinylchloride (PVC) or polypropylene (PP) can provide a wide range of permeability. We can flexibly choose the corresponding grade of materials as packaging materials according to our needs. The low packaging difficulty and material cost make the polymers become the first choice of tea packaging.
What are the feasible packaging solutions to extend the shelf life of tea?
Regardless of the packaging technology employed, the key to protect tea against deteriorative effects is to avoid the tea from exposure to oxygen, moisture, odors, and light. Today the efforts to extend the shelf life focus on removing or modifying the atmosphere surrounding the tea within a package.
Vacuum tea packaging refers to the technique of removing air from a teabag prior to sealing. By creating a near-vacuum inside the tea bag, it insulates the outside from air, moisture, and microbes.
Oolong tea with a massive shape is a typical example of vacuum packaging. This method ensures the tea leaves are safe for a long time. However, under the condition of vacuum packaging, the pressure on tea is greater. Some fragile tea leaves are not applicable.
Modified atmosphere packaging(MAP) refers to changing the atmosphere surrounding food products inside a pack for food preservation. In general, the MAP can be divided into two different categories, Active MAP and Passive MAP.
- Active MAP can be defined as replacing the original gases in the package with a desired mixture of gases.
- Passive MAP means that the product is packed with a certain film type. The bag’s atmosphere is the natural result of product respiration and the diffusion of gases through the film. No need for gas replacement.
When applied in tea packaging, MAP seems to be an ideal method for its wider range of applications. Tea producers just need to modify the gases in each package. The appropriate level of gas barrier would reduce the tea oxidation. As a result, the shelf life of tea has been extended.
What are the MAP packaging types in the field of tea packaging?
Depending on your tea products and their own specifications, appropriate technology is crucial to extending the shelf life of tea. Below are the most popular:
1. Nitrogen flushing
It is a common active MAP packaging method. During a nitrogen flush process, the inert gas is injected into the bag to replace the oxygen. After the bag is sealed, the tea product is in an oxygen-free dry space and the shelf life could be extended.
As nitrogen is harmless and rich in sources, nitrogen flushing has become the most popular MAP packaging technology for tea products. Commonly used in the packaging of double chamber tea bags and bulk tea bags.
2. Desiccant packs
Unlike gas flushing, this MAP packaging method is adding a small sachet with oxygen scavenger or desiccant to your packet. This small sachet usually contains a mixture of iron powder, activated carbon, or quicklime. These ingredients can absorb moisture, oxygen, and odor inside the bag. The atmosphere in the bag was modified after the bag was sealed.
You’ve probably seen these inside snack bags. It is commonly used to prolong the shelf life of coffee bags and bulk tea bags.
As its name implies, the one-way valve allows the gas in the bag to escape from the valve but prevents external air from entering. This valve is usually done to relieve the pressure of excess gas in the bag to prevent the bag from bursting.
Usually, the one-way valves MAP is mainly used in coffee packaging fields. According to the report 2018 report in the Journal of Agricultural and Food Chemistry. The roasted coffee beans would release carbon dioxide all the time for several days. When carbon dioxide continues to accumulate, the bag will burst. Therefore, Excess carbon dioxide must be considered when packing the roasted coffee beans.
One-way valves are usually installed in pre-fabricated bags or roll films. It is usually a small piece of plastic affixed to a coffee package. One-way valves do not hinder packaging graphics or functions.
4. Barrier packaging films
It is a typical passive MAP packaging technology. The specific packaging films help prevent contact with oxygen, carbon dioxide, or moisture. No need to change the atmosphere in the bag.
In general, barrier films are made up of single or multiple layers of flexible films. Even can be coated with special resins to protect against ultraviolet rays as needed. With the advancement of material technology, Barrier films will bring more smart applications.
When applied in tea packaging, it Provides an excellent aroma barrier and extends the shelf-life.
Need a packaging machine to deffeat tea freshness killers?
Tea producers should have sufficient market sensitivity with the increasing demand for preservative-free, fresh, and natural tea products. The few disadvantages are related to the need for equipment and proper packaging materials. But with the benefits of extended shelf life and long-term sales, who cares?
If you want to gain more market share through high-quality tea products and longer shelf life. Let’s talk about it.