Bioethanol production from concentration fruit wastes juice using bakery yeast

Materials for Renewable and Sustainable Energy https://doi.org/10.1007/s40243-024-00283-6 (2025) 14:6 ORIGINAL PAPER Bioethanol production from concentration fruit wastes juice using bakery yeast Lewis Atugonza Mtashobya2 · Shedrack Thomas Mgeni1,2 · Jovine Kamuhabwa Emmanuel2 Received: 4 September 2024 / Accepted: 28 November 2024 © The Author(s) 2024 Abstract Appropriate and effective management of fruit wastes is fundamental for promoting sustainability, minimizing environmental impacts, and safeguarding human health. This underscores the necessity for sustainable waste management practices including transforming them into valuable products to mitigate their adverse effects. This study focuses on the production of bioethanol from pineapple, mango, watermelon, and pawpaw fruit wastes juice through yeast fermentation and controlled distillation. The juice from a mixture of fruit wastes was enriched with 200 g of bakery yeast to facilitate the fermentation process. Results show that bioethanol from fruit waste juice mixture with bakery yeast produced bioethanol with alcohol content of 30%, while the fruit waste juice mixture without yeast had 20%. The bioethanol from the initial distillation was combined and re-distilled to improve the quality of bioethanol from 12 to 30% to an impressive alcohol content of 88%. The bioethanol production from fruit wastes, achieved through bakery yeast fermentation and distillation, demonstrated promising outcomes and potential use as bioenergy and its contribution to environmental conservation. Future research may focus on enhancing yeast-fruit waste juice ratio and utilizing enzymes to expedite carbohydrate breakdown. Keywords Alcohol contents · Fermentation · Distillation · °Brix · Specific gravity · Blending Introduction The growing demands for sustainable and renewable energy sources has promoted interest in bioethanol production as an alternative to fossil fuels (FFs) energy sources [1]. Bioethanol, a biofuel produced by fermenting biomass sugars, has the potential to decrease greenhouse gases (GHGs) emissions and decrease reliance on petroleum-based fuels [2]. This renewable energy source can be produced from various types of biomass, including agricultural residues, forest residues, and food waste [3]. Globally, bioethanol production has formed notable substantial growth over the past few decades [4]. The current global ethanol production capacity totals 6.84 billion litres which is produced from molasses Lewis Atugonza Mtashobya ; 1 Department of Biological Science, Mkwawa University College of Education, P.O. Box 2513, Iringa, Tanzania 2 Department of Chemistry, Mkwawa University College of Education, P.O. Box 2513, Iringa, Tanzania and grain-based sources [5]. This production is primarily driven by the United States and Brazil, which altogether account for nearly 80% of global bioethanol output [6]. The 2005 Renewable Fuel Standard (RFS) policy mandates the use of renewable fuels in gasoline, leading to an increase in bioethanol production [7]. In 2021, the United States produced approximately 57 billion litres of bioethanol [8]. The country’s Proálcool program initiated in the 1970s, has been instrumental in promoting bioethanol production, resulting in the production of approximately 30 billion litres of bioethanol in 2021 [9]. The growing global consumption of fruits leads to significant fruit waste, posing environmental and disposal challenges [10]. About 1.3 billion tons of food produced for human consumption is wasted annually, accounting for nearly one-third of all food produced [11]. Fruit and vegetable waste, a significant portion of the total food production, has the potential to be converted into valuable biofuels [12]. Fruit wastes (FWs) represents an abundant and underutilized resource for bioethanol production [13]. The process of converting FWs into bioethanol not only offers a sustainable waste management solution but also contributes 13 6 Page 2 of 7 to the circular economy by generating value product such as biofuel [14]. The process reduces environmental impacts of FWs disposal, including methane emissions from landfills, and provide an eco-friendly alternative to traditional waste management methods [15]. The FWs juice with high sugar content can be efficiently converted into bioethanol through fermentation processes [16]. Bakery yeast (Saccharomyces cerevisiae) is a widely used microorganism for bioethanol production and is highly favoured due to its high bioethanol yield, rapid fermentation rate, and adaptability to various fermentation conditions [17]. Bioethanol production from FWs juice using bakery yeast offers a promising solution for managing wastes and generating renewable energy. This method, through optimized fermentation processes and resource efficient use, has the potential to significantly contribute to sustainable energy solutions and environmental conservation. This study underscores a significant solution in managing FWs, promoting a more sustainable and environmentally conscious future. The study explores the potential of producing bioethanol from FW juice using bakery yeast. The research focuses on enhancing fermentation conditions and effective distillation to boost bioethanol yield and assessing the effectiveness of bakery yeast in converting FW juice sugars into bioethanol. The study aims to develop sustainable bioethanol production methods using FWs, addressing the ongoing Materials for Renewable and Sustainable Energy (2025) 14:6 on energy crisis and alleviate the negative impacts on the environmental. Materials and methods Substrates preparation and the fermentation process The FWs including pineapple (PIFWs), mango (MAFWs), watermelon (WMFWs), and pawpaw (PAFWs) were sourced from markets, juice processing vendors and hotels within Iringa Municipality. The FWs were washed with clean tape water and then chopped into small pieces using a sharp knife in order to increase the substrate’s surface area as presented in Fig. 1. The juice from FWs was extracted using electronic blender (Kenwood-BLPA-10) as shown in Fig. 1. After physical pre-treatment, the FWs juice was analysed to assess the total soluble solids (TSS), pH, specific gravity and alcohol content. The fermentation setup involved two containers, each with a capacity of ten litres. The first container was fed with eight litres of FWs juice mixture while the second was filled with eight litres of FWs juice mixture and added 200 g of yeast. The containers with fermentation broths were then sealed with boxes for effective natural fermentation process at room temperature. Fig. 1 Fruit wastes and fruit wastes juice ((A) watermelon (B) pawpaw (C) mango and (D) pineapple peels) before and after blending 13 Materials for Renewable and Sustainable Energy (2025) 14:6 Page 3 of 7 6 The experimental setup ensured homogeneity by assessing parameters including alcohol content, pH, TSS, and specific gravity at (...truncated)