Ethanol production from carob extract by using Saccharomyces cerevisiae

Area of Science:

• Biotechnology
• Renewable Energy
• Agricultural Science

Background:

• Carob, a long-cultivated Mediterranean fruit, has been historically undervalued for its economic potential.
• Growing concerns over petroleum depletion have spurred global interest in renewable energy sources.
• Underutilized agricultural products like carob are being explored for sustainable bioethanol production.

Purpose of the Study:

• To optimize extraction conditions for carob fruit using response surface methodology.
• To investigate the fermentation of carob extract for ethanol production using Saccharomyces cerevisiae.
• To evaluate key fermentation parameters (pH, media content, inoculum size) and nitrogen sources for efficient ethanol yield.

Main Methods:

• Response surface design was employed to determine optimal carob fruit extraction parameters (temperature, time, dilution rate).
• Ethanol fermentation was conducted using suspended Saccharomyces cerevisiae with carob extract as the substrate.
• Fermentation variables including pH, media composition, inoculum size, and nitrogen sources (e.g., meat-bone meal) were systematically evaluated.

Main Results:

• Optimal extraction conditions yielded 115.3 g/L of carob extract at 80°C, 2h, and a 1:4 fruit:water ratio.
• Fermentation at pH 5.5 resulted in higher final ethanol concentration (42.6 g/L) and production rates (3.37 g/L/h) compared to uncontrolled pH.
• An inoculum size of 3% and meat-bone meal as a nitrogen source led to the highest ethanol production (44.51% and 3.48 g/L/h).

Conclusions:

• Carob extract is a viable substrate for bioethanol production, contributing to renewable energy strategies.
• Optimized extraction and fermentation parameters significantly enhance ethanol yield and production efficiency.
• The study highlights the potential of carob as a sustainable resource for meeting renewable energy demands.