Roasted Roselle Seeds Show Real Potential as a Caffeine-Free Coffee Alternative With High Antioxidant Levels

Roselle seeds, a by-product that usually gets tossed aside during the harvesting of Hibiscus sabdariffa, are now attracting attention for a surprising reason: when roasted for the right amount of time, they can produce a coffee-like beverage with notable antioxidant benefits and a flavor profile that comes strikingly close to actual coffee. A new study published in the International Journal of Food Safety, Nutrition and Public Health explores this potential in detail, and the findings are genuinely interesting for anyone curious about new caffeine-free drinks, sustainable food use, or plant-based innovations.

The research team approached this question from two angles: the nutritional and chemical composition of roselle seeds after roasting, and the sensory qualities of the resulting brew. They tested seeds roasted at 10, 20, and 30 minutes and compared these to unroasted seeds. Their goal was straightforward: determine how roasting affects antioxidants, flavor compounds, and overall drinkability.

One of the key takeaways is that roasting consistently boosted the concentration of bioactive compounds, especially flavonoids and phenols. These compounds are widely known for their antioxidant properties, which play a role in supporting general health by neutralizing harmful free radicals. The study also measured tannins and saponins — compounds that can contribute bitterness or foam — and found that all remained within acceptable nutritional limits.

What truly sets the 30-minute roast apart is not just its chemical profile but its sensory performance. During taste testing, participants evaluated flavor, body, aroma, balance, and overall acceptability. Among all samples, the beverage brewed from seeds roasted for 30 minutes scored the highest across every category. While dedicated coffee lovers might still prefer the real thing, the researchers report that the longer-roasted roselle drink came surprisingly close to traditional coffee in terms of overall impression. Many existing caffeine-free substitutes, such as grain-based blends or certain herbal mixes, often lack depth or body, but the roselle brew demonstrated a richer and more convincing profile.

Beyond taste and antioxidants, the implications of this discovery extend to sustainability. Roselle plants are primarily cultivated for their tart, bright red calyces, which are used globally to make teas, jams, syrups, and even traditional medicinal preparations. Because the calyces are the main commercial product, the seeds have historically been discarded or used only in small-scale traditional applications. Yet these seeds contain high levels of protein and beneficial fats, and roasting appears to unlock even more desirable characteristics. Turning an agricultural leftover into a valuable product adds economic and ecological benefits, especially in tropical regions where roselle is already well established.

The researchers point out that roasting initiates chemical reactions that transform otherwise mild or bland seeds into something aromatic and flavorful — similar to the transformation coffee beans undergo. While roselle seeds do not contain caffeine, they develop a deepened flavor, darker color, and stronger aroma as the roast time increases. This means the 30-minute roast not only tasted better but also visually resembled coffee more closely.

Even though the study found promising similarities, the authors acknowledge that roselle seed brews are not expected to dethrone commercial coffee anytime soon. Coffee’s complex profile is difficult to replicate, and its cultural significance is enormous. However, this new substitute offers something valuable in its own right: a natural, caffeine-free drink with a fuller, richer body than many alternatives currently on the market. For people who avoid caffeine for health reasons, personal preference, or religious practices, a satisfying replacement can be difficult to find, and roselle seeds may help fill that gap.

The idea of caffeine-free “coffee” alternatives isn’t new. For decades, consumers have experimented with roasted barley, chicory root, dandelion root, and more recently, rooibos-based blends. What makes roselle seeds interesting is that they are already part of a major agricultural crop, widely grown in Africa, Asia, and tropical regions of the Americas. This means that integrating a new use for the seeds requires minimal change to existing farming practices and could provide farmers with an additional source of income.

On the nutritional side, roselle seeds have long been recognized as protein-rich, and earlier studies have explored their use in flours, snacks, and complementary foods. Their high antioxidative content aligns with the known medicinal uses of other roselle parts, especially the calyces, which are commonly used for blood pressure management, liver support, and digestive health in traditional medicine. While the new study does not make clinical claims, the elevated antioxidant levels in roasted seeds add to roselle’s appeal as a functional plant.

As with any emerging food product, more research will be needed. Future studies may look at long-term health effects, consumer preferences across different regions, optimal roasting methods, and commercial scalability. There is also room to explore whether blending roselle seed “coffee” with other herbs or grains could enhance flavor further, much like existing caffeine-free blends.

Still, the findings provide a strong foundation. A plant part that used to be discarded now shows clear potential for added value, reduced waste, and consumer benefit. Given the rising interest in functional beverages, sustainable ingredients, and low-caffeine lifestyles, roselle seed brews could find a place in cafés, wellness shops, or even homemade kitchen experiments.

Below is a bit more information for readers who want to better understand the plant behind this research.

What Exactly Is Roselle?

Roselle (Hibiscus sabdariffa) is a flowering plant widely known for its deep red calyces, which are used to make beverages like hibiscus tea (often called karkade, agua de Jamaica, or sorrel drink depending on the region). These calyces have a pleasantly tart flavor and are rich in anthocyanins, the same pigments responsible for berries’ antioxidant properties.

However, roselle is more than just its flowers. The plant provides edible leaves, stems suitable for fiber production, and, importantly for this research, nutritious seeds. These seeds contain oils, proteins, minerals, and plant compounds that contribute to both flavor and health potential when processed properly.

Why Antioxidants Matter

Antioxidants help protect the body from oxidative stress, which has been linked to aging and various chronic diseases. The increase in antioxidants found in the longer-roasted seeds suggests that the roasting process enhances their health potential. Compounds like flavonoids and phenols not only support overall wellness but also influence flavor, contributing to the pleasant bitterness and aroma associated with coffee-like beverages.

Could Roselle Coffee Become Popular?

It’s too early to say, but the idea is promising. With the global demand for caffeine-free, plant-based, and sustainable beverages growing every year, roselle seeds offer a fresh option. They check many boxes: low waste, nutrient-rich, flavorful, affordable, and caffeine-free. If commercial producers pick up on this research, we might see roselle “coffee” appearing on store shelves or in cafés within a few years.

For now, the key message is simple: a previously overlooked plant part may soon offer coffee lovers and non-coffee drinkers alike a new kind of brew worth paying attention to.

Research Paper:
Development and evaluation of coffee substitute from roselle (Hibiscus sabdariffa) seeds
https://doi.org/10.1504/ijfsnph.2025.149675