Acorn-based espresso boosts antioxidants with minimal well being danger

Researchers reveal how oak acorns became coffee-like drinks, pack potent antioxidants whereas staying safely under toxin limits, making them a shocking new superfood for health-conscious espresso drinkers.

Examine: Oak Acorns as Useful Meals: Antioxidant Potential and Security Evaluation. Picture credit score: New Africa/Shutterstock.com

Thermally processed oak acorns (Quercus robur) of their native flour kind are wealthy in antioxidants and are protected for consumption. A latest examine in Meals investigated whether or not totally different processing strategies impression bioactive compounds in acorn-based merchandise.

Why are oak acorns a wealthy supply of meals and beverage?

Acorns are the nuts of the oak tree (Quercus spp.), which have been historically utilized in many cultures for hundreds of years. The oak tree belongs to the Fagaceae household and is extensively distributed throughout Asia, Europe, and North America. Quite a few research have demonstrated that Quercus species are wealthy in bioactive compounds, together with phenolic acids, flavonoids, and tannins, which possess antioxidant, anticancer, and antimicrobial properties.

Over time, the consumption of oak acorns has declined on account of their excessive tannin content material, which makes them bitter and impairs nutrient absorption by binding to proteins and minerals. Nevertheless, a latest surge in acorn consumption has been famous on account of its sustainability and health-promoting properties. For instance, acorn flour has been used as a gluten-free and fiber-rich various to wheat flour, enhancing the dietary and sensory properties of many baked merchandise, corresponding to bread, muffins, and cookies.

Just lately, many health-conscious people with dietary restrictions have substituted typical espresso with alternate options corresponding to chicory, barley, spelt, dandelion, and acorns. These alternate options are typically wealthy in nutritional vitamins, fiber, minerals, and phenolic acids (e.g., gallic, caffeic, and chlorogenic acid). Phytochemical evaluation has revealed that acorns include a excessive focus of carbohydrates, lipids, dietary fiber, proteins, and unsaturated fatty acids.

There’s a lack of analysis relating to the antioxidant exercise of Q. robur fruits, notably in coffee-like drinks constituted of roasted acorns. Acorn roasting is a typical pre-treatment course of carried out to boost taste, which alters the chemical profile of the seeds. A earlier examine has indicated that when mixed with ginseng, acorn-based drinks have a superior antioxidant potential in comparison with business espresso alternate options.

Thermal processing at excessive temperature, sometimes above 200°C, results in the formation of polycyclic fragrant hydrocarbons (PAHs) that possess potential mutagenic and carcinogenic properties. Though espresso and low substitutes are exempt from European Union PAH limits, some research have recognized these dangerous chemical substances, notably benzo[a]anthracene and anthracene. Due to this fact, analyzing the benefit-to-risk profile of roasted acorns used as espresso substitutes is essential. Nevertheless, the examine confirmed that benzo[a]pyrene, essentially the most regarding PAH carcinogen, was not detected in any acorn product, additional supporting their security

In regards to the examine

The present examine investigated the PAH content material and the antioxidant potential of coffee-like drinks ready from roasted Q. robur acorns. Oak acorns had been processed utilizing totally different strategies, and every pattern was individually assessed.

Oak acorns had been collected from the Kosmaj mountain, air-dried at room temperature, and powdered to supply “acorn flour”. As well as, 100 grams of dry acorns had been roasted at 200°C for half-hour, and had been powdered as “espresso”. For one more pattern sort, 100 grams of dry-shelled acorns had been coarsely chopped and soaked in water (60 to 70 °C) for half-hour. After repeating this soaking course of a few occasions, the oak acorns had been dried at 40°C for round three hours. Subsequently, these acorns had been roasted at 200 °C for half-hour and powdered to make “tremendous espresso”. Methanol, acetone, and hexane extracts of acorn espresso and flour had been ready.

Examine findings

Extremely polar solvents, corresponding to methanol and aqueous acetone, readily extracted phenols and flavonoids from Quercus robur acorns. Complete phenol content material (TPC) in methanol extracts was estimated to be 66.53 mg gallic acid equal (GAE) per gram dry weight (dw), whereas acetone extracts yielded 24.21 mg GAE/g dw. This distinction in phenolic content material is as a result of acetone is much less polar than methanol.

Each thermally processed espresso and tremendous espresso indicated a 15% and 9% enhance in TPC in methanol and acetone extracts, respectively, relative to uncooked flour. This enhance in phenolic focus could possibly be attributed to the formation of low-molecular-weight phenolics throughout roasting.

Equally, the best whole flavonoid content material (TFC) was discovered within the methanolic extracts of the acorn flour pattern, adopted by “espresso” and “tremendous espresso”. Flavonoid ranges declined from about 181.5 mg RE/g dw in flour to 161.7 mg RE/g dw in “espresso” and 150.7 mg RE/g dw in “tremendous espresso”, confirming thermal degradation of those compounds. No matter solvent polarity, the native acorn flour persistently exhibited the best flavonoid ranges in comparison with its roasted counterparts. The lower in TFC post-roasting confirms the susceptibility of flavonoids to thermal degradation.

The antioxidant exercise of acorn extracts was evaluated utilizing ABTS, DPPH, CUPRAC radical scavenging assays, and FRAP and TRP electron switch assays, which indicated excessive antioxidant properties. In comparison with the hexane extract, methanol extracts of all samples exhibited the best antioxidant exercise, reflecting the minimal extraction of hydrophilic phenolics, as indicated by trolox equivalents (TE)/g dw estimates. Nevertheless, acetone extracts exhibited a touch increased DPPH scavenging exercise, implying that sure mid-polarity antioxidants are higher extracted by acetone.

Methanol CUPRAC values reached as much as 584 mg TE/g dw, ABTS values had been about 127 mg TE/g dw, and FRAP values approached 200 mg Fe/g dw, all of which examine favorably to typical roasted espresso beans.

The FRAP assay revealed that thermal processing elevated antioxidant energy in nonpolar extracts. FRAP values rose dramatically post-roasting, by roughly 100% in methanol, 124% in acetone, and 375% in hexane extracts. This highlights how Maillard response merchandise fashioned throughout roasting considerably improve antioxidant capability, notably in lipophilic fractions.

The bioactive estimates of “tremendous espresso” decreased with rising lipophilicity of the solvent. The sums of TPC for acorn flour, “espresso”, and “tremendous espresso” had been 89.2, 92.9, and 87 mg GAE/g dw, respectively, whereas the sums of whole discount potential (TRP) had been 6.86, 7.0, and 6.99 mg AAE/g dw, respectively. The studied samples’ antioxidant exercise was related to the whole content material of phenols and flavonoids.

Within the present examine, “espresso” and “tremendous espresso” samples contained PAHs that had been 2 to three occasions increased than these in native acorn flour. “Tremendous espresso” was discovered to include each low-molecular-weight (LMW) and high-molecular-weight (HMW) PAHs. Since not one of the PAHs had been current in native acorn flour (except for indeno[1,2,3-cd] pyrene at ~8.8 ng/g dw, possible from environmental contamination), it signifies that roasting was the supply. The researchers be aware that solely about 30% of PAHs switch into brewed acorn infusions, decreasing precise dietary publicity.

The full PAH degree reached 222 ng/g dw in “espresso” and 290 ng/g dw in “tremendous espresso”, akin to the ranges reported for different espresso substitutes. The first PAH4 marker was benzo[a]anthracene (34 – 39.8 ng/g) whereas chrysene, benzo[b]fluoranthene, and benzo[a]pyrene weren’t detected.

Conclusions

The present examine demonstrated that native and heat-treated acorns include a excessive quantity of phenol and flavonoid compounds. Methanol extracts exhibited the best antioxidant exercise. The absence of carcinogenic PAH4 marker within the native flour indicated that unprocessed acorn powder is protected for dietary use. 

Regardless of measurable PAHs in roasted samples, all ranges remained nicely under EU regulatory limits for cocoa-based merchandise, suggesting minimal well being danger when consumed as espresso substitutes.

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