Chitosan in a teabag? – National Deskfast Day in the US

Tea or coffee is certainly a philosophical question. What is the first thing you drink when you arrive at work? In all cases, it's about getting the day off to a good start. But is too much caffeine good? Can't you do something with chitosan? We looked around and found what we were looking for in South Korea. A new type of tea bag that decaffeinates the tea in the cup itself. An alginate-chitosan hydrogel was used for this.

 

 

Alginate/chitosan bi-layer hydrogel as a novel tea bag with in-cup decaffeination

Medhen W. Abebe, Richard Appiah Ntiamoah, Hern Kim, Alginate/chitosan bi-layer hydrogel as a novel tea bag with in-cup decaffeination, Reactive and Functional Polymers, Volume 170, 2022, 105128, ISSN 1381-5148,  https://doi.org/10.1016/j.reactfunctpolym.2021.105128.

Like coffee, green tea contains caffeine. In addition to caffeine, it contains substances such as polyphenols, catechins and theoflavins, which have anti-oxidative, anti-microbial and anti-obesity properties and are therefore beneficial to health. Caffeine, however, can have stimulating and antidepressant effects, but above a certain dose can lead to high blood pressure, sleep disorders, fetal growth disorders during pregnancy and other negative effects. The safe daily dose for caffeine is 4 mg/kg body weight (~200 mg/person). A cup of tea contains an average of 24-80 mg per cup, which means that the limit is very quickly exceeded. Decaffeinated tea is already available, but the industrial process is expensive and time-consuming. New methods are therefore needed to decaffeinate tea quickly and easily.

73% of tea drinkers use tea bags for their tea. The approximately 14.6 billion tea bags used every day are either made of paper or polymers such as nylon, PET, polypropylene or PVC. While polymer-based teabags are harmful to the environment and contain carcinogenic substances such as microplastics or antimony, paper teabags are largely biodegradable. Nevertheless, some of them are reinforced with thermoplastics or epichlorohydrin, which are also potentially carcinogenic. Therefore, in addition to an efficient method for decaffeination, innovations for a non-toxic and biodegradable tea bag are also necessary.

For this reason, an efficient, biodegradable, two-layer alginate-chitosan hydrogel tea bag capable of filtering out caffeine in the cup is to be produced in the study presented. Alginate is biodegradable, biocompatible and has mild gelling conditions, while chitosan is additionally able to absorb caffeine. To enhance this decaffeinating effect, activated carbon is also added. The tea is first encapsulated in an alginate matrix and then coated with a layer of chitosan-activated carbon. A chitosan with a degree of deacetylation of 75-80 % and a viscosity of 200 to 800 mPas was used. You can find comparable chitosans in our chitosan online shop. The properties of the produced tea bag should be improved under the following aspects: 1.) alginate concentration and degree of crosslinking, 2.) tea loading capacity, 3.) amount of activated carbon and 4.) tea release and decaffeination control.

RESULTS

• Successful encapsulation of tea and activated charcoal in alginate-chitosan hydrogel tea bags
• Safe and stable when infused with hot water
• 0,1 g/ml tea as optimum tea quantity→ best polyphenol release
• The higher the alginate concentration and degree of crosslinking, the less tea is released→ 2 % alginate as optimal, 1.5 % too unstable
• 1 mg activated carbon improves the absorption of caffeine and has a selective effect on polyphenols
• Caffeine and polyphenol release data best fits the Kosmeyer-Peppas model → Fick's diffusion-controlled release
• Production of a tea bag that releases 91% of polyphenols and ~40% of caffeine compared to conventional tea bag

Conclusions: In the presented study, a safe, environmentally friendly and in-cup decaffeinating tea bag was successfully produced by encapsulating tea with alginate, chitosan and activated carbon. This novel tea bag can be an alternative to conventional tea bags.

Link to article: https://doi.org/10.1016/j.reactfunctpolym.2021.105128