From Waste to Resource: Exploring Circular Solutions for Cocoa Pod Husk

HeTa Food Research Centre for Excellence

Introduction

The global cocoa products market size reached USD 24.5 billion in 2019 and is expected to grow at a CAGR of 3.1% to reach USD 30.2 billion by 2026 (1). However, cocoa processing produces a large number of by-products. Only 10% of the cocoa production process can be processed into a saleable product, and the remaining 90% is discarded in landfills because it cannot be used (2). Cocoa bean shells account for about 10%-17% of the total weight of cocoa beans and are one of the most important by-products of cocoa production (3). This mass disposal in landfills poses serious economic and environmental problems for cocoa producers. Because cocoa bean shells contain a large amount of theobromine and a variety of polyphenols with phytotoxic activity. 

In recent years, due to the scarcity of natural resources and serious environmental problems, the value of agricultural by-products such as cocoa bean shells have attracted more and more attention. Cocoa husks contain similar nutrients to cocoa beans, although cocoa husks are often considered a by-product or waste (4). According to research, cocoa bean shells are rich in nutritional value, especially high content of dietary fiber and bioactive compounds such as tea polyphenols (5). Cocoa bean shells also contain protein and oil nutrients. Bioactive compounds have the function of regulating human advanced life activities. Many phenolic compounds have antioxidant properties and can effectively prevent the formation of blood clots (6). It also has a good anti-inflammatory effect, which can block the growth of tumors and inhibit cancer (7). 

Nutrients in cocoa shells 

Fiber 

Dietary fiber is generally divided into soluble fiber and insoluble fiber. The ideal ratio of soluble fiber to insoluble fiber is 3:7, and the ratio of soluble fiber to insoluble fiber in the cocoa shell is close to ideal (8). Dietary fiber can effectively reduce the risk of certain diseases, such as Chronic Bowel Disease, Obesity, Diabetes, Cardiovascular disease, and Cancer, by regulating human metabolism. Cocoa shells can be an alternative inexpensive source of dietary fiber, with the added benefit of being incorporated into high-fiber diets as a low-calorie, bulk ingredient to reduce calorie and cholesterol levels and control blood sugar levels.(9)

Protein

The protein content of cocoa bean shells is very similar to that of cocoa beans, but only about 1% of the protein is present in the free state (10). All the important components of the body require the participation of protein. The development of the human body and the repairing and renewing damaged cells are inseparable from protein. Protein breakdown can also provide energy for the body’s activities (11).

Fatty Acids

The fatty acids in cocoa bean shell fat are mainly palmitic and oleic acids. The linoleic acid content of cocoa bean shell fat is approximately twice that of cocoa butter (12). Palmitic acid, one of the most common saturated fatty acids, makes up 20-30% of the body’s total fatty acids and can be obtained in the diet. The structure of palmitic acid is relatively close to that of breast milk fat, it can be used as a substitute for breast milk fat (13). Palmitic acid can lower serum cholesterol levels. Studies have suggested that replacing other fatty acids in the diet with palmitic acid may be beneficial in the treatment of blood clots (14).

Polyphenols

A particular group of polyphenols in the cocoa shell is flavonoids. Flavonoids have biological activities, including antiallergic, antiviral, anti-inflammatory, and vasodilatory effects. Flavonoids have anti-inflammatory properties and can inhibit transcription factor regulation and cell populations involved in inflammation.(15)  Other polyphenols such as catechin, quercetin, and caffeic acid are also found in cocoa bean shells. Catechins have many health benefits. Catechin is an effective scavenger of reactive oxygen species in vitro, which can effectively improve the antioxidant capacity of plasma by scavenging free radicals and promoting metabolism (16). Caffeine in cocoa shells affects the central nervous system and increases the brain’s dopamine neurotransmitter. Therefore, the right amount of caffeine can excite people and create a pleasant mood. Moderate amounts of caffeine can increase alertness and make you more awake (17).

Cocoa shell waste applications – How and where can cocoa shell waste be used?

Processing Industry

Cocoa shells are a source of pectin, containing about 9%. (18) The non-degradability of plastic products causes great harm to the environment, but at the same time, people’s demand for and dependence on plastic products is extremely high. Therefore, the pectin in cocoa shells can be processed into pectin-based products to replace plastic-based products. Pectin can serve as a promising biomaterial for the manufacture of bio-based sustainable packaging films and coatings.

Medical industry

Flavonoids are powerful antioxidants that scavenge free radicals, reduce their formation, and delay the apoptosis of normal tissue cells. Therefore, flavonoids are often used in the field of medicine (19). Flavonoids act as powerful antioxidants and anti-allergic nutrients and significantly affect asthma (20).

Catechin can also inhibit cell growth, especially the growth of vascular cells involved in the formation of arteriosclerosis, thereby inhibiting the proliferation of vascular smooth muscle cells. Therefore, catechins can be used to treat arteriosclerosis. Catechins inhibit platelet adhesion, thereby inhibiting thrombus formation. Catechin can be used to treat various diseases such as obesity and cardiovascular disease (21).

Animal Breeding Industry

The bioactive substances in cocoa shells have good anti-inflammatory properties and can be used in animal breeding. The use of cocoa shells in animal feed may have a positive impact on the balance of the intestinal microbial ecosystem. Various bioactive compounds in cocoa shells positively impact the growth and differentiation of animal intestinal cells and exert anti-inflammatory effects, thereby reducing the incidence of various intestinal inflammatory diseases. Adding cocoa shells to animal feed helps reduce the risk of over-fattening.

During the processing of cocoa raw materials, cocoa shell waste generates a large number of by-products. These by-products have extremely high utilization value and can be used to develop new products or serve as higher-value raw materials. Cocoa shells are rich in dietary fiber, protein, and various valuable bioactive compounds (flavonoids, catechins, caffeine, etc.). These nutrients can be used in pharmaceutical, animal breeding, or manufacturing industries. In addition, the recycling of cocoa shells can greatly reduce the environmental burden. The reuse of cocoa shells can bring higher economic benefits, a good interpretation of the circular economy, and the true achievement of sustainable development.

References

1. Beg, M. S., Ahmad, S., Jan, K. And Bashir, K. 2017. Status, Supply Chain And Processing Of Cocoa – A Review. Trends In Food Science And Technology, 66, 108-116.Https://Doi.Org/10.1016/j.Tifs.2017.06.007 
2. Soares, T. F. And Oliveira, M. 2022. Cocoa By-Products: Characterization Of Bioactive Compounds And Beneficial Health Effects. Molecules, 27.Https://Doi.Org/10.3390/Molecules27051625 
3. Rojo-Poveda, O., Barbosa-Pereira, L., Zeppa, G. And Stevigny, C. 2020. Cocoa Bean Shell-A By-Product With Nutritional Properties And Biofunctional Potential. Nutrients, 12.Https://Doi.Org/10.3390/Nu12041123 
4. Nsor-Atindana, J., Zhong, F. And Mothibe, K. J. 2012. In Vitro Hypoglycemic And Cholesterol Lowering Effects Of Dietary Fiber Prepared From Cocoa (Theobroma Cacao L.) Shells. Food And Function, 3, 1044-1050.Https://Doi.Org/10.1039/c2fo30091e 
5. Balentic, J. P., Ackar, D., Jokic, S., Jozinovic, A., Babic, J., Milicevic, B., Subaric, D. And Pavlovic, N. 2018. Cocoa Shell: A By-Product With Great Potential For Wide Application. Molecules, 23.Https://Doi.Org/10.3390/Molecules23061404 
6. Rice-Evans, C., Miller, N. And Paganga, G. 1997. Antioxidant Properties Of Phenolic Compounds. Trends In Plant Science, 2, 152-159.Https://Doi.Org/10.1016/S1360-1385(97)01018-2 
7. Anantharaju, P. G., Gowda, P. C., Vimalambike, M. G. And Madhunapantula, S. V. 2016. An Overview On The Role Of Dietary Phenolics For The Treatment Of Cancers. Nutrition Journal, 15.Https://Doi.Org/10.1186/s12937-016-0217-2 
8. Barisic, V., Jozinovic, A., Flanjak, I., Subaric, D., Babic, J., Milicevic, B., Doko, K. And Ackar, D. 2020. Difficulties With Use Of Cocoa Bean Shell In Food Production And High Voltage Electrical Discharge As a Possible Solution. Sustainability, 12.Https://Doi.Org/10.3390/Su12103981 
9. Handojo, L., Triharyogi, H. & Indarto, A. Cocoa bean shell waste as potential raw material for dietary fiber powder. Int J Recycl Org Waste Agricult 8 (Suppl 1), 485–491 (2019). Https://Doi.Org/10.1007/S40093-019-0271-9
10. Martincabrejas, M. A., Valiente, C., Esteban, R. M., Molla, E. And Waldron, K. 1994. Cocoa Hull – A Potential Source Of Dietary Fiber. Journal Of The Science Of Food And Agriculture, 66, 307-311.Https://Doi.Org/10.1002/Jsfa.2740660307 
11. Szklarczyk, D. And Jensen, L. J. 2015. Protein-Protein Interaction Databases. In: Meyerkord, C. L. And Fu, H. (Eds.) Protein-Protein Interactions: Methods And Applications, 2nd Edition
12. Elsaied, H. M., Morsi, M. K. And Amer, M. M. A. 1981. Composition Of Cocoa Shell Fat As Related To Cocoa Butter. Zeitschrift Fur Ernahrungswissenschaft, 20, 145-151.Https://Doi.Org/10.1007/Bf02021260 
13. Innis, S. M. 2016. Palmitic Acid In Early Human Development. Critical Reviews In Food Science And Nutrition, 56, 1952-1959.Https://Doi.Org/10.1080/10408398.2015.1018045 
14. Sundram, K., Hayes, K. C. And Siru, O. H. 1994. Dietary Palmitic Acid Results In Lower Serum-Cholesterol Than Does a Lauric-Myristic Acid Combination In Normolipemic Humans. American Journal Of Clinical Nutrition, 59, 841-846.Https://Doi.Org/10.1093/Ajcn/59.4.841 
15. Spagnuolo, C., Moccia, S. And Russo, G. L. 2018. Anti-Inflammatory Effects Of Flavonoids In Neurodegenerative Disorders. European Journal Of Medicinal Chemistry, 153, 105-115.Https://Doi.Org/10.1016/j.Ejmech.2017.09.001 
16. Higdon, J. V. And Frei, B. 2003. Tea Catechins And Polyphenols: Health Effects, Metabolism, And Antioxidant Functions. Critical Reviews In Food Science And Nutrition, 43, 89-143.Https://Doi.Org/10.1080/10408690390826464 
17. Smith, A. 2002. Effects Of Caffeine On Human Behavior. Food And Chemical Toxicology, 40, 1243-1255.Https://Doi.Org/10.1016/s0278-6915(02)00096-0 
18. Mollea C, Chiampo F, Conti R. Extraction and characterization of pectins from cocoa husks: A preliminary study[J]. Food Chemistry, 2008, 107(3): 1353-1356.
19. Abotaleb, M., Samuel, S. M., Varghese, E., Varghese, S., Kubatka, P., Liskova, A. And Busselberg, D. 2019. Flavonoids In Cancer And Apoptosis. Cancers, 11.Https://Doi.Org/10.3390/Cancers11010028 
20. Tanaka, T. And Takahashi, R. 2013. Flavonoids And Asthma. Nutrients, 5, 2128-2143.Https://Doi.Org/10.3390/Nu5062128  
21. Velayutham, P., Babu, A. And Liu, D. M. 2008. Green Tea Catechins And Cardiovascular Health: An Update. Current Medicinal Chemistry, 15, 1840-1850.

Further Reading

• How to Exploit Watermelon Rinds
• Food Waste – A Valuable Resource in the Circular Economy
• The benefits behind fruit and vegetable peels
• Value-added products from by-products generated from fruits and vegetables