Green Coffee: Processing and Health Benefits

Drinking coffee can do much more than providing a boost to our energy. Roasted coffee is familiar to everyone but green coffee is not much. If you have noticed, you can see various brands of green coffee available at super markets and online platforms, in both beans and powder form.

After seeing green coffee, many questions come to our mind. Green coffee is claimed to provide various health benefits to individuals but is it true? Is there any scientific data to prove this? How’s it different from roasted coffee beans?

There are two different methods for the processing of coffee beans: dry processing and wet processing. The dry processing of making green coffee starts with the harvesting of the right coffee cherries (properly ripe with red color) from the plants by a hand-picking method. The harvested cherries are dried under the sun (till moisture content of 13% w/w or less) followed by dehusking to separate the green coffee beans from the fruit. However, the mechanical drying process is also followed in many areas but it lacks various flavor compounds which form during the sun-drying process due to the fermentation. The color of the beans prepared by this process ranges from green to brown.

The wet processing of coffee gives a better quality product which commands for the high price. Harvesting of properly ripe cherries is done carefully for a good quality coffee. The sorted cherries are pulped in a pulping machine where beans and the flesh are separated. The separated beans are waster washed and sent for the fermentation process. The fermentation cause removal of the adhering pulp, adhesive mucilage, and any other compound around the cherries, leaving the thin parchment layer (parchment is the thin covering around the beans). During the fermentation process, various pectin-degrading and hydrolyzing enzymes act on the pulp and mucilage, causing liquefaction of these compounds and release the free beans. This process causes a drop in pH from 6.7-6.8 to 4.2-4.5, due to the production of various organic acids and leads to the formation of various flavor compounds. Post-fermentation, beans are washed to remove any adhered material and sent for drying, either sun-drying or mechanical drying depending on the availability of technology and batch size. The parchment is then removed by the hulling process.

The difference in the processing of green coffee and brown coffee is the roasting process. After the above-mentioned processing, if the coffee is sent for the roasting process, it causes the development of various flavor compounds and brown color, making the coffee which is generally known to everyone.

Now the question is, why should we consume unroasted coffee? What is the benefit of consuming green coffee against roasted coffee?

The major compound which is present in green coffee and absent in roasted coffee is Chlorogenic Acids. It is a phenolic acid (cinnamic acid derivative) and is known for its antioxidant and anti-inflammatory activities. It exists in the form of Caffeoylquinic acids and dicaffeoylquinic acids and their derivatives. Studies suggested that the major chlorogenic acids present in green coffee had high bioavailability i.e. can be absorbed and metabolized by the human body. These chlorogenic acids are known to cause a reduction in the risk of cardiovascular disease, type-2 diabetes, and Alzheimer’s disease. Moreover, their lactones are found to show a positive effect on the enhancement of insulin action in rats which may be effective for humans also.

The roasting of coffee causes the degradation of the chlorogenic acids. Mild roasting causes up to 60% degradation while severe roasting causes 100% degradation of the chlorogenic acids. The severe heat treatment causes the breakage of the carbon-carbon bonds in the chlorogenic acids, resulting in isomerization and degradation, leading to loss of their activity. Henceforth, green coffee offers an added advantage to the consumer compared to roasted coffee.

The taste of green coffee is very different from roasted coffee. Due to the lack of roasting process, it has a milder color and flavor. It looks light-green in color and tastes like herbal tea, opposite to bitter taste and brown color. Some people have associated the flavor of green coffee similar to green tea while others claimed it little grassy and acidic. Different people have different perceptions of the product.

So why don’t you try a cup of green coffee and describe its flavor in your own words?

References:

1. Clarke, R. (1985). Green Coffee Processing. Coffee, 230-250. doi: 10.1007/978-1-4615-6657-1_10

2. Clifford, M. (1985). Chemical and Physical Aspects of Green Coffee and Coffee Products. Coffee, 305-374. doi: 10.1007/978-1-4615-6657-1_13

3. Farah, A., Monteiro, M., Donangelo, C., & Lafay, S. (2008). Chlorogenic Acids from Green Coffee Extract are Highly Bioavailable in Humans. The Journal Of Nutrition, 138(12), 2309-2315. doi: 10.3945/jn.108.095554

4. Farah, A., de Paulis, T., Trugo, L., & Martin, P. (2005). Effect of Roasting on the Formation of Chlorogenic Acid Lactones in Coffee. Journal Of Agricultural And Food Chemistry, 53(5), 1505-1513. doi: 10.1021/jf048701t