Urban food waste presents a significant environmental challenge, but it also offers a promising opportunity for sustainable protein production. In Addis Ababa, it's estimated that around 70%–74% of municipal solid waste is biodegradable, with a large portion made up of fruit and vegetable residues; bananas, mangoes, avocados, and citrus fruits dominate these organic streams. These high‐moisture, nutrient‐rich materials are particularly well‐suited for single‐cell protein (SCP) production through microbial fermentation, positioning them as a climate‐resilient alternative to conventional animal or plant‐based proteins. Current research explores various aspects: substrate composition, effective pretreatment strategies, selecting optimal microbial strains, different fermentation approaches, and crucial safety issues such as nucleic acid content, allergenicity, and potential mycotoxin contamination. Globally, SCP yields range from 20 to 50 g/L, but translating these results to Addis Ababa is complicated by local variability in feedstock quality and seasonal availability. This means solutions must be tailored to the specific context. Scaling up SCP production isn't without hurdles. Major challenges include the heterogeneous nature of the feedstock, its high moisture content, limited cold‐chain infrastructure, and noticeable gaps in technical expertise. Despite these challenges, there are tangible avenues for progress: establishing pilot‐scale fermentation facilities, developing decentralized preprocessing and collection systems, and embedding these efforts within broader circular bio‐economy frameworks. Together, these strategies could enhance local protein availability, reduce landfill contributions, and help curb greenhouse gas emissions. Still, several knowledge gaps remain particularly regarding Ethiopia‐specific techno‐economic analyses, process optimization for mixed fruit waste, and capacity‐building in fermentation biotechnology. Addressing these gaps is essential for moving SCP production from the laboratory to a viable, city‐wide solution. By integrating technological, regulatory, and industrial strategies, Addis Ababa can leverage fruit‐waste valorization to address urban organic waste, strengthen nutritional security, and further Ethiopia's goals in advancing a circular bio‐economy.

Escalating global protein insecurity, combined with the environmental and economic limitations of conventional plant and animal protein systems, underscores the need for sustainable alternatives. Fruit processing residues, generated at >500 million tons annually worldwide, represent underutilized, carbon-rich bio-resources with potential for microbial protein production. In this PRISMA-compliant meta-analysis, peer-reviewed studies on fruit-derived single-cell protein (SCP) were systematically evaluated across substrate types and microbial platforms. Meta-analysis revealed mean biomass yields of 0.24-37.40 g/L substrate and protein contents ranging from 20.58 to 54.74% (dry weight). Evidence from engineered strains suggests possible improvements in essential amino acid composition, particularly lysine and methionine, although direct validation on fruit-waste substrates remains limited. Synthetic biology interventions may enhance nutrient enrichment and digestibility, yet human clinical or in vivo data are currently lacking. Life-cycle analyses indicate potential reductions in greenhouse gas emissions and land use relative to animal proteins, although energy-intensive pretreatment and substrate heterogeneity may influence these outcomes. Overall, fruit-waste-derived SCP presents a promising avenue for circular bio-economy strategies, offering a framework for programmable nutrition systems that integrate synthetic biology, precision fermentation, and regional waste valorization, while acknowledging the current experimental and translational limitations.

The alginate, a naturally occurring polymer, is mainly obtained from brown algae such as Laminaria, Macrocystis and Aspirin. This review shall examine the sources, processes and uses of alginate, with a focus on modern, high-tech extraction techniques. Although conventional alkaline extraction is still widely used, newer techniques such as supercritical CO2 extraction, microwave assisted extraction (MAE) and ex-traction by ultrasound are viable alternatives because of their higher efficiency, low environmental impact and scalability. Alginate is useful for applications in the food industry such as texture modification, food coating and encapsulation of bio-active substances because of its functions such as glazing, film-forming and stabilization. Vigorifyingly, vitamins, polyphenols, probiotics and essential oils can be encapsulated for increased stability, bioavailability and controlled dispersion. Alginate is also considered an environmentally friendly substitute for food packaging because of its potential as a sustainable and biodegradable material. The review focuses on recent studies on the bio-activities of alginate and its potential for use in the formulation of pharmaceuticals and functional foods. Despite these developments, more studies are needed to optimise the extraction of alginate, to improve knowledge of its biological activity and to explore new applications in food and other areas. This in-depth review highlights the growing importance of alginate in the food industry and its potential for future innovation in sustainable food technologies.

The valorization of agro‐industrial by‐products as functional food ingredients represents a promising strategy for developing sustainable prebiotic sources. This study aimed to formulate and optimize composite flour derived from green banana peel, carrot bagasse, and orange peel, and to evaluate its physicochemical characteristics, inulin recovery, and probiotic growth‐promoting as potential prebiotic composite flour. Sixteen formulations were generated using a D‐optimal mixture design to assess proximate composition, inulin yield, resistance to simulated gastrointestinal conditions, and stimulation of probiotic bacteria. The composite flours exhibited low moisture (6.70–7.05%), high dietary fiber (12.5–13.25%), moderate protein (7.0–7.6%), and low fat (2.4–2.85%), indicating suitability for functional food applications. Inulin extraction ranged from 12.2% to 19.8%, with the highest yield obtained from a banana‐dominant blend. The extracted inulin showed a molecular weight of ~6.0 kDa and a degree of polymerization (DP) of 21, consistent with a strong prebiotic profile. Mixture‐design optimization predicted that a formulation containing 51.6% banana peel, 20.1% carrot bagasse, and 28.3% orange peel maximizes both inulin yield and probiotic growth. Cultivation with this formulation supported the proliferation of Lactobacillus rhamnosus GR‐1 and Bifidobacterium longum BB536, reaching 9.8 × 10 ⁸ CFU mL ⁻¹ . Simulated gastrointestinal assays further demonstrated enhanced survival of these probiotic strains in the presence of the composite flour. The results highlight the synergistic contribution of banana‐derived fructans and citrus pectic oligosaccharides (POS) in promoting probiotic growth. Overall, this study demonstrates the potential of fruit and vegetable processing residues as sustainable substrates for the development of value‐added prebiotic ingredients suitable for functional food formulations.