Whilst in the Wageningen University, he developed an Apoptotic Model in Zinnia Plant Cell Culture System which is today considered the best model for apoptotic and programmed cell death studies worldwide in animals and plants alike. Other important areas of his research works include molecular characterization of human cleft palate and pica practice in humans, development of plant-based heavy metallic detoxification drugs, and assessment of heavy metals in urban-grown vegetables, tissue culture for varietal development in cassava, groundnuts and Hibiscus.

Prof. Twumasi has contributed greatly to Biotechnology Education in Ghana especially in the area of GM Foods where he gives talks to schools, farmers and other stakeholders under various projects sponsored by the Government of Ghana and the Embassy of the United States of America.