tion. This approach holds promise as it aligns with the principles of the circular economy, providing a dual benefit of waste valorization and the generation of valuable chemical building blocks [1]. In particular, targeted acidogenic fermentation--a refined process of acidogenic fermentation in which operational parameters and microbial consortia are optimized to selectively produce specific VFAs from organic waste streams--has emerged as a powerful tool to fine-tune the production of VFAs, enabling the generation of tailored chemical intermediates for diverse industries [2]. Unlike conventional acidogenic fermentation, where a mixture of VFAs is often generated, targeted fermentation is designed to steer the metabolic pathways of microorganisms toward the production of desired VFAs, depending on the end-use application. This approach enhances process efficiency, reduces downstream processing, and ensures that the VFA profile is tailored to meet industrial needs [3]. The circular economy concept seeks to create a closed-loop system where resources are reused, recycled, or repurposed, minimizing environmental impact. Within this framework, VFAs act as critical intermediates in the production of high-value products such as bioplastics, biofuels, and other chemicals, providing a renewable alternative to fossil fuel-based processes [4; 5]. As the demand for sustainable solutions grows, biologically derived VFAs, including acetic, propionic, butyric, and valeric acids, offer significant potential due to their versatility and broad industrial applications. Table 1 highlights their chemical properties and current market data, underscoring their economic relevance. The market for VFAs is projected to experience significant growth between 2024 and 2032. This growth is driven by several key factors, including increasing demand for sustainable solutions, the adoption of circular economy practices, and the expansion of industrial applications such as biogas production, bioplastics, and food additives. Particularly, the increasing interest in bioplastics is positioning VFAs at the center of discussions around green alternatives to petrochemical-based plastics. Estimates suggest that the global VFA market, valued at approximately USD 29.5 billion in 2023, is expected to grow at a compound annual growth rate of 6.4%, reaching approximately USD 46.9 billion by 2032 [10]. The primary drivers behind this growth include rising demand in the energy sector, particularly for biogas production from organic waste, advancements in fermentation technology to improve VFA production efficiency, and the increasing use of VFAs in emerging industries like pharmaceuticals, where their therapeutic properties are being explored [11]. This anticipated growth underscores the critical role that targeted fermentation can play in ad \begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**Acid** & **Chemical Formula** & **Molecular Mass (g/mol)** & **Density (g/L) at 20 \({}^{\circ}\)C** & **Boiling Point (\({}^{\circ}\)C)** & **pKa** & **Average Price (USD/kg, 2024)** & **Market Size 2023** \\ \hline Acetic (HAc) & CH\({}_{3}\)COOH & 60 & 1050 & 118 & 4.76 & 0.80–1.25 & 12.1 US\$ Billion \\ \hline Propionic (HPr) & CH\({}_{3}\)CH\({}_{2}\)COOH & 74 & 990 & 141 & 4.88 & 2.00–2.45 & 1.11 US\$ Billion \\ \hline Butyric (HBu) & CH\({}_{3}\)CH\({}_{2}\)CH\({}_{2}\)COOH & 88 & 960 & 164 & 4.82 & 2.20–2.75 & 389.2 US\$ Billion \\ \hline Isobutyric (iHBu) & (CH\({}_{3}\))\({}_{2}\)CHCOOH & 88 & 950 & 154 & 4.84 & 2.50–3.00 & 182.4 US\$ Billion \\ \hline Valeric (HVA) & CH\({}_{3}\)(CH\({}_{2}\))\({}_{3}\)COOH & 102 & 940 & 186 & 4.84 & 4.20–4.65 & 13 US\$ Billion \\ \hline Isovaleric (iHVA) & (CH\({}_{3}\))\({}_{2}\)CHCH\({}_{2}\)COOH & 102 & 930 & 177 & 4.77 & 3.50–4.00 & 1.6 US\$ Billion \\ \hline \hline \end{tabular}
\end{table} 
Table 1: VFA properties and market price [6; 7; 8; 9].