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Citric Acid production from orange peel wastes by solid-state fermentation
Ana María Torrado1, Sandra Cortés, José Manuel Salgado
1Departamento de Ingeniería Química. Universidad de Vigo (Campus Ourense), Edificio Politécnico. As Lagoas . 32004 Ourense , Spain.
Summary
Valencia orange peel can be used to produce citric acid (CA) through solid-state fermentation (SSF) using Aspergillus niger. Optimal conditions were identified, demonstrating the viability of this sustainable bioprocess for potential industrial applications.
Area of Science:
- Biotechnology
- Industrial Microbiology
- Biochemical Engineering
Background:
- Citric acid (CA) is a key organic acid with widespread industrial applications.
- Valorization of agricultural waste, such as citrus peels, is crucial for sustainable bioprocessing.
- Solid-state fermentation (SSF) offers an efficient method for microbial metabolite production using solid substrates.
Purpose of the Study:
- To optimize citric acid (CA) production from Valencia orange peel using solid-state fermentation (SSF).
- To investigate the impact of key operating variables on CA yield.
- To evaluate the feasibility of using orange peel as a substrate for industrial CA biosynthesis.
Main Methods:
- Solid-state fermentation (SSF) of Valencia orange peel by Aspergillus niger CECT-2090.
- Optimization of inoculum concentration, bed loading, and moisture content.
- Evaluation of additional water or methanol supplementation.
- Analysis of CA production under optimized conditions.
Main Results:
- Optimal conditions included an inoculum of 0.5·10(6) spores/g dry peel, 1.0 g bed loading, and a specific humidification pattern (70% MWRC initially, with subsequent water additions).
- Methanol addition negatively impacted CA production.
- Achieved a specific CA production of 193 mg CA/g dry orange peel.
- Yields on consumed sugars were high (376-383 mg CA/g).
Conclusions:
- Valencia orange peel is a viable and cost-effective raw material for citric acid production via SSF.
- Optimized SSF parameters significantly enhance CA yield and efficiency.
- The process demonstrates potential for industrial scale-up, contributing to waste valorization and sustainable chemical production.
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