Valorization of Fruit and Vegetable Wastes for CA Production: A Comprehensive Review with Emphasis on Aspergillus niger Bioprocessing and Future Prospects

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Year : 2026 | Volume : 14 | 01 | Page :
    By

    Kothapalli Nirmitha,

  • V. Sridevi,

  1. PhD Scholar, Department of Biological and Chemical Sciences, School of Liberal Arts and Science, Mohan Babu University, Tirupati, Andhra Pradesh, India
  2. Assistant Professor, Department of Biological and Chemical Sciences, School of Liberal Arts and Science, Mohan Babu University, Tirupati, Andhra Pradesh, India

Abstract

Citric Acid (CA) is a multifunctional organic acid with diverse industrial applications, recently gaining prominence in polymer and composite science as a green crosslinker, compatibilizer, and functional additive. Conventionally produced through submerged fermentation of refined sugars by Aspergillus niger, industrial CA production faces sustainability challenges due to reliance on food-grade substrates. This review highlights emerging strategies for CA biosynthesis from vegetable and fruit processing residues—including cucumber peels, broccoli stalks, spinach stems, bottle gourd peels, onion skins, pumpkin waste, and mango peels—through optimized pre-treatment and fermentation processes. Case studies illustrate the role of acid hydrolysis, steam or alkali treatment, ethanol washing, and methanol supplementation in enhancing fermentable sugar release and yield. Furthermore, we explore the integration of waste-derived CA in polymer and composite manufacturing, where it acts as an eco-friendly crosslinker for cellulose, starch, chitosan, and synthetic polymer blends, improving mechanical, thermal, and barrier performance. The review also discusses the potential of genetically engineered A. niger strains to further enhance CA yields, alongside future prospects for scaling waste-to-CA processes for sustainable material fabrication. By coupling agro-waste valorization with green composite engineering, this approach aligns with circular economy principles and advances sustainable materials development.

Keywords: CA, agro-waste valorization, Aspergillus niger, polymer composites, green crosslinker, circular economy, fermentation, sustainable materials.

How to cite this article:
Kothapalli Nirmitha, V. Sridevi. Valorization of Fruit and Vegetable Wastes for CA Production: A Comprehensive Review with Emphasis on Aspergillus niger Bioprocessing and Future Prospects. Journal of Polymer & Composites. 2026; 14(01):-.
How to cite this URL:
Kothapalli Nirmitha, V. Sridevi. Valorization of Fruit and Vegetable Wastes for CA Production: A Comprehensive Review with Emphasis on Aspergillus niger Bioprocessing and Future Prospects. Journal of Polymer & Composites. 2026; 14(01):-. Available from: https://journals.stmjournals.com/jopc/article=2026/view=236429


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Ahead of Print Subscription Review Article
Volume 14
01
Received 03/09/2025
Accepted 08/10/2025
Published 25/01/2026
Publication Time 144 Days
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