However, the researchers pointed out that more detailed analysis is needed before it can be used in skincare products.
The study team, from Indonesia and Iran, argued that solid waste from the coffee pulping process threatens the environment because it produces organic pollutants.
On the other hand, evidence suggests that coffee by-products may provide added value due to their potential as a source of antioxidants.
They therefore conducted a systematic review aimed at evaluating the antioxidant activity of coffee by-products obtained from the pulp of arabica and robusta, and their processing methods.
A study in the review comparing robusta and arabica coffee pulp with aqueous extraction found higher antioxidant capacity in that of the arabica variant.
However, a different result was shown by another study comparing the coffee silver peel antioxidant activities of the two variants.
“The study found that the silver skin of the robusta variant coffee has higher antioxidant activity, as suggested by DPPH, ABTS and FRAP tests,they wrote.
“Higher antioxidant efficacies of the robusta variant were also revealed by a study using green coffee extract.”
They also found that antioxidant activities could be affected not only by the variant, but also by the method of extraction or brewing.
The data suggests that aqueous extract was found to be the most commonly used processing method to obtain the antioxidant from various coffee by-products, followed by methanol and ethanol extract.
Additionally, each coffee by-product could have different levels of antioxidant activity, with the coffee silver skin having the highest value.
In terms of potential in cosmetics, they highlighted a study that showed the use of a coffee by-product in the topical formulation had been reported.
The study in question added coffee pulp extract powder to a skin lotion formulation (at 0.125%, 0.25%, 0.5% and 1% by mass), and evaluated the content of phenolic compounds, antioxidant activity and stability.
“All coffee pulp skin lotions were found to have good physical stability and significantly higher antioxidant activity (IC50: 5,805 ppm – 55,776 ppm) compared to commercial lotions (IC50: 505,018ppm – 557,218ppm)”,the study noted.
This latest review concluded“Coffee by-products contain bioactive compounds with antioxidant properties that could be used as additives in foods, beverages and cosmetics. In particular, their benefits in skin care products require further investigation.
Source: F1000 Search
“Coffee By-Products as a Source of Antioxidants: A Systematic Review”
Authors:Kartini Hasballah, et al.