Summary
Development of alternative energy sources, that is, renewable, environmental co‐friendly, and cost effective, is highly imperative to mitigate the harmful effects associated with the use of fossil fuels. Thus, Abrus precatorius seeds are commercially unexploited in the production of bioethanol in Nigeria. The seed was found to contain an appreciable amount of carbohydrates (ca 61%), which are the main source of ethanol. Its lignin content (1.23%) was very low compared to its hydrolyzable components of lignocellulose‐cellulose (13.67%) and hemicellulose (12.53%), making the seed a potential source of bioethanol. The Abrus hydrolysate produced by liquefaction and saccharification, using partially purified α‐amylase and glucoamylase, respectively, had a reducing sugar content of 10.90 mg/mL. Studies on the liquefaction of Abrus seed slurry showed that a maximum reducing sugar of 5.32 mg/mL was released at optimal conditions of substrate concentration (5 g/100 mL), pH 5.0, temperature 60°C, α‐amylase concentration 50 U/mL, and incubation period of 80 minutes, while the saccharification of liquefied slurry released a maximum reducing sugar of 10.90 mg/mL at optimal conditions of pH 5.5, temperature 60°C, glucoamylase concentration 40 U/mL, and incubation period of 90 minutes. The optimization of bioethanol production from Abrus hydrolysate showed that a maximum bioethanol yield of 90.57 ± 0.24% was obtained at an optimal incubation period of 5 days, inoculum size of 5% w/v, and pH of 5.5. The fuel properties of the Abrus bioethanol compared favorably well with standard ethanol, especially in the aspect of heat content (28 580.77 ± 0.05 KJ/Kg), kinematic viscosity at 40°C (1.30 ± 0.02 mm2/s), refractive index (1.36 ± 0.27), and pour point (−18.00 ± 0.07°C). Ash and sulfur were not detected in the produced bioethanol. This study showed that, under normal bioethanol production conditions, inedible Abrus seed flour can serve as cheap and effective feedstock for industrial production of bioethanol.
Novelty Statement
The depletion of the global reserves of fossil fuels and the increasing environmental concerns due to fossil fuel usage had spurred global interests in renewable alternative energy sources. Most of the carbon‐neutral alternative sources are edible crops, raising concern about food security in the ever‐increasing global population. Here, a good quality bioenergy is developed from a nonfood plant source, Abrus precatorius seed, to mitigate the negative effects of fossil fuel consumption on the environment without interfering with the global food chain.
