Towards sustainable yeast-based isoamyl acetate production: Biotechnological strategies, biomass valorisation, and downstream process intensification

Isoamyl acetate is one of the most widely used aroma compounds in the food industry, known for its characteristic banana or pear-like aroma. It is produced through three main methods: chemical synthesis, enzymatic synthesis, and by microbial fermentation or bioconversion. Among these, the biotechnological pathway by fermentation is not yet used industrially despite being classified as a natural method. However, growing demand for biobased chemicals and strict industrial regulations on synthetic additives in human-related applications (food, cosmetics, pharmaceuticals, personal care products, etc. ) are renewing interest in microbial production pathways for high-value aroma compounds. This review compiles existing reports on fermentation-based isoamyl acetate production using yeasts as well as genetic engineering of yeasts to enhance higher titre and yield of the molecule of interest. It is aimed at identifying the key challenges hindering a large-scale adoption of this production pathway and highlighting future research directions for overcoming these limitations. It also explores the valorisation of agro-industrial residues as sustainable feedstock and highlights them as alternative sources of L-leucine, a key but very costly precursor for isoamyl acetate biosynthesis via the Ehrlich pathway. Finally, membrane-based in-situ /in-stream product recovery (ISPR) and intensification techniques are discussed as promising solutions for overcoming product loss and toxicity and enable its recovery, which are major bottlenecks in microbial fermentation process. • Non-conventional yeasts show higher Isoamyl acetate titre than S. cerevisiae • Yarrowia lipolytica identified as a promising chassis for high IAA titres • Biomass valorisation limited by heterogeneity, inhibitors and precursor specificity • In-situ product recovery is a key lever for overcoming toxicity and low titres