Nguyen Thuy Vy Tu. Potential study on bioethanol production from low grade and damaged longans. ปริญญาโท(วิศวกรรมศาสตรมหาบัณฑิต วิศวกรรมศาสตรมหาบัณฑิต). มหาวิทยาลัยแม่โจ้. สำนักหอสมุด . : Maejo University, 2021.
Potential study on bioethanol production from low grade and damaged longans
Abstract:
One of the significant fruits in the economy and industry is longan fruits. The longan (Dimocarpus longan Lour.) is a subtropical enduring tree belonging to the family Sapindaceae whose name is a well-known subtropical fruit in many countries, particularly in China, Thailand, Vietnam, India, Australia, and some tropical and subtropical regions in the USA. On the other hand, the status of fruit waste, which becomes stuck prior to landfills, has concerned researchers over the years. Low-grade and waste longan fruits are also no exceptions; they are feedstock material for bioethanol production.
In this study, physical pretreatment has been carried out which includes boiling (30 min) and autoclave (15, 30, 45 minutes and 0 min for control). Afterward, samples were scanned by scanning electron microscope (SEM) to recognize differences between raw materials, boiled samples, and autoclaved samples.
Hydrolysis process has been done with three varied hydrolysis methods which were utilized in samples: 2% commercial cellulase, 20% algal enzyme, and a combination of 1% commercial cellulase and 10% algal enzyme (C+A). Response Surface Methodology (RSM) was utilized to determine and optimize conditions leading to the best pretreated and hydrolyzed outcomes.
For fresh longan, the optimum condition produced a high amount of sugar by using 2% commercial cellulase in hydrolysis and 30 min autoclave, leading to the highest bioethanol production (9.25 ± 0.25 g/L) after 24 hours of fermentation. For dried longan, the optimum condition produced a high amount of sugar by using 2% commercial cellulase in hydrolysis and 15 min autoclave, leading to the highest bioethanol production (16.74 ± 0.62 g/L) after 24 hours of fermentation.
As a result, dried longan has been chosen for large-scale production. Results showed that after pretreatment, the total and reducing sugar were 157.19 and 36.43 g/L, respectively; the total and reducing sugar increased in hydrolysis to 271.07 and 48.21 g/L, respectively.
Fermentation with 1% Saccharomyces cerevisiae for 24 hours resulted in bioethanol production reaching 1.4%; alcohol concentration increased to 9% in distillation. The High Heating Value (HHV) was 4.55 MJ/kg. In this experiment, mass balance, energy, and economic analysis were analyzed to consider investment as a project.