Determination of Phenolic Compounds, Procyanidins, and Antioxidant Activity in Processed Coffea arabica L. Leaves.

Samuchaya Ngamsuk,Tzou-Chi Huang,Jue-Liang Hsu

doi:10.3390/foods8090389

Samuchaya Ngamsuk, Tzou-Chi Huang + Show 1 more

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https://doi.org/10.3390/foods8090389

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Abstract

The effects of dry processing and maturity on antioxidant activity, total phenolic content, total procyanidins, and identity of phenolic compounds in coffee leaves were evaluated. Fresh coffee leaves were tray-dried at 40 °C for 8 h before total phenolic content, total procyanidins, and antioxidant activity were analyzed. The drying process significantly (p < 0.05) improved the release of total phenolic content and total procyanidins compared with the fresh leaves. The results showed that the young leaves exposed to drying processes had the highest total phenolic content, total procyanidins, and DPPH radical scavenging activity. Therefore, the effect of different drying temperatures (30, 40, and 50 °C) in the young leaves were further analyzed. The results indicated that DPPH radical scavenging activity, total phenolic content, and total procyanidins were increasingly generated when exposed to an increase in drying temperatures, whereby the highest bioactivity was evident at 50 °C. The DPPH radical scavenging activity of the coffee leaf teas was significantly correlated with total phenolic content and total procyanidins. Identification of Coffea arabica L. bioactive compounds by LC-MS showed the presence of catechin or epicatechin, mangiferin or isomangiferin, procyanidin B, caffeoylquinic acids (CQA), caffeine, quercetin-3-O-glucoside, procyanidin C, rutin, and 3,4-diCQA. Coffea arabica L. leaf tea was confirmed to be a potential functional food rich in phenolic compounds with strong antioxidant activity.

Highlights

Coffee leaves have been largely neglected and considered to have little or no value to farmers due to the high value placed on coffee beans
The DPPH radical scavenging activity of the coffee leaf teas was significantly correlated with total phenolic content and total procyanidins
The influence of maturity and drying on the antioxidant activity of coffee leaf extracts was measured by DPPH radical scavenging activity (Table 1)

Summary

Introduction

Coffee leaves have been largely neglected and considered to have little or no value to farmers due to the high value placed on coffee beans. Coffee leaves have been used as traditional medicine to treat or mitigate various diseases or disorders. Increased focus has been paid to coffee leaves as an alternative to traditional tea consumption due to the fact or their high levels of polyphenolic compounds and great potential as a healthy beverage [1]. In countries like Indonesia, Jamaica, India, Java, Sumatra, Ethiopia, and South Sudan, sun-dried coffee leaves have been used as a traditional tea substitute [2]. Coffee leaf tea has higher antioxidant potential and lower caffeine than traditional tea. The polyphenol content of coffee leaf depends on the maturity, the harvest times (month of harvest), and the coffee species of its leaf and are phytochemically composed of caffeine, trigonelline, adenine-7-glucosyl, theobromine, theophylline, ent-kaurane diterpenpids, 7-methylxanthine, anthocyanins, mangiferin, isomangiferin, catechin, epicatechin, procyanidin B1, chlorogenic acid (5-CQA), glucoside, rutin, isorhamnetin, quercetin, isoquercitrin, kaempferol, histidine, Foods 2019, 8, 389; doi:10.3390/foods8090389 www.mdpi.com/journal/foods

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