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Onyeaka, H.;  Mansa, R.F.;  Wong, C.M.V.L.;  Miri, T. Bioconversion of Starch Base Food Waste into Bioethanol. Encyclopedia. Available online: https://encyclopedia.pub/entry/27152 (accessed on 18 April 2024).
Onyeaka H,  Mansa RF,  Wong CMVL,  Miri T. Bioconversion of Starch Base Food Waste into Bioethanol. Encyclopedia. Available at: https://encyclopedia.pub/entry/27152. Accessed April 18, 2024.
Onyeaka, Helen, Rachel Fran Mansa, Clemente Michael Vui Ling Wong, Taghi Miri. "Bioconversion of Starch Base Food Waste into Bioethanol" Encyclopedia, https://encyclopedia.pub/entry/27152 (accessed April 18, 2024).
Onyeaka, H.,  Mansa, R.F.,  Wong, C.M.V.L., & Miri, T. (2022, September 14). Bioconversion of Starch Base Food Waste into Bioethanol. In Encyclopedia. https://encyclopedia.pub/entry/27152
Onyeaka, Helen, et al. "Bioconversion of Starch Base Food Waste into Bioethanol." Encyclopedia. Web. 14 September, 2022.
Bioconversion of Starch Base Food Waste into Bioethanol
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Food wastes are organic wastes or biodegradables. They are generated from various sources such as restaurants and cafeterias, industrial sectors, commercial and domestic kitchens, food processing plants, and other areas where a large number of people consume food. The global demand for fuel keeps increasing daily. The massive depletion of fossil fuels and their influence on the environment as pollution is a severe problem. Meanwhile, food waste disposal is also a complex problem in solid-waste management since one-third of every food consumed is discarded as waste. The standard waste management methods, including food waste incineration and landfilling, are considered hazardous to the environment. Food waste constituents are majorly starch-based and contain various biomolecules, including sugar, lipids, proteins, vitamins, cellulose, etc. These polysaccharides can be hydrolysed into monosaccharides such as glucose, which can then be fermented using microorganisms to produce ethanol through the fermenting of sugars derived from enzymatic hydrolysis treatment of food wastes. The human food system is rich in starch, which can be a potential resource for bioethanol production.

starch food waste bioethanol

1. Bioethanol Production on Starch-Based Food Wastes

Bioethanol is generated through the fermenting of simple sugars found in biomass as well as sugars derived from earlier enzymatic hydrolysis treatment of food wastes [1]. Fermentation is then carried out by microorganisms, generally yeasts. However, bacteria such as Zymomonas mobilis [2] have also been utilised. Co-culture of S. cerevisiae and P. stipitis leads to higher ethanol yield of 0.13 ± 0.01 g/g of food waste [3]. Following fermentation, the ethanol produced is recovered from the fermentation medium using either traditional rectification and distillation or more efficient separation techniques such as membrane filtration, pervaporation, or molecular sieves. Figure 1 depicts a schematic of starch-based bioethanol manufacturing.
Figure 1. Bioethanol production on starch-based food waste.

2. Pretreatment

Food waste comes in a variety of forms. It can either be in raw or in cooked form. Because it is regarded as waste, it necessitates some preprocessing before it can be processed for the production of ethanol [4]. Physical, chemical, and physio-chemical pretreatments have been used in this manner. Pretreatment can be used depending on the nature of the food waste. In most circumstances, extensive pretreatment prior to enzymatic hydrolysis is not required. Various modified hydrolysis and enzymatic hydrolysis are conducted to boost ethanol output. Instead, autoclaving food wastes before fermentation is frequently required to increase the purity and yield of the product, albeit at the expense of increased energy and water usage. It should be mentioned that heat treatment might cause a partial breakdown of sugars and different biological function components and side reactions (e.g., the Maillard reaction) in which the quantity of beneficial amino acid and sugars square measure could be reduced [5].
Furthermore, recent and wet food waste appears to be far more efficient than rewetted dried food waste [6]. This is due mainly to the surface area of the dried substrate, which manifests in the substrate–enzyme reaction efficiency. Consequently, drying food waste is beneficial for high-yielding ethanol with controlled contamination by microorganisms. Contamination by microorganisms can be avoided in acidic conditions without thermal treatment. As a result, acid-tolerant alcohol microbes such as Zymomonas mobilis were used for fermentation [6].

3. Starch Hydrolysis

Starch hydrolysis is an essential stage in starch-based food waste processing for bioethanol generation. The primary function of this process is to convert two key starch polymer constituents, branched amylopectin, a α-D-(1-4)-glucan with α-D-(1-6) linkages at the branching, and amylose, a mainly linear α-D-(1-4)-glucan, to simple sugars that can then be turned to alcohol by microorganisms (bacteria and yeast). Acids can be used to perform hydrolysis, an older method that has mostly been abandoned in favour of a more effective enzymatic method. Recently, some researchers have also used bacterial consortia for this purpose [7][8][9][10]. Starch-based bioethanol production has been widely popular for around 30 years; during that time, enormous advances in process cost, enzyme efficiency, time reduction, and increased hydrolysis and bioethanol production have been accomplished [11]. Current discoveries in the development of thermostable α-amylases, which are starch hydrolysing enzymes that catalyse the hydrolysis of internal α-D-(1-4)-glucosidal linkages in starch in a random fashion, and efficient glucoamylases, that are saccharifying starch enzymes that catalyse the hydrolysis of α-D-(1-6)- and α-D-(1-4)-glycosidic bonds in starch to glucose have brought about the commercial establishment of the popular two-step enzymatic cold process. The main benefits of this technique are the consumption of lesser energy and a reduced proportion of non-glucosidal contaminants, making it considerably more suitable for ethanol synthesis. Enzymatic starch hydrolysis is carried out under relatively mild operative conditions: lower temperatures (up to 100 degrees Celsius), normal pressure, and a pH of between 6–8 [12]. The quantity of endogenous enzymes used in starch hydrolysis, and the hydrolysis parameters, including temperature, process time, concentration, pH, etc., are influenced by the type of food waste, its chemical composition, the source and activity of endogenous enzymes, and the presence of native autoamylolytic potential. Additionally, primarily physical treatments, such as cooking and steaming, micronisation, grinding, ultrasound, microwave, and so on, enhance the gelatinisation process and the susceptibility of the food waste substrate to enzymes, and can strongly impact and enhance the influence of hydrolysis and subsequent fermentation of ethanol [11].

4. Fermentation

Efficient bioethanol production necessitates an accelerated fermentation that results in high ethanol concentrations; consequently, the microbial strain used should possess a good specific growth rate and specific ethanol production rate at high ethanol concentration and high osmotic pressure [13]. A critical problem for efficient ethanol production is optimising the fermentation phase in terms of the following key parameters: pH, temperature, the composition of the medium, aeration, mixing, elimination of infection, etc. [14].The fermentation phase is carried out under temperature range of 28–32 °C, and pH range of 4.8–5.0 [15]. Additionally, anaerobic digestion produces an acidic substrate, which could interfere with the fermentation process [15][16]. It is critical to select and develop an efficient production microorganism. As a result, much research is currently being conducted to develop a microorganism resistant to high concentrations of substrate and ethanol. A yeast strain’s ability to produce a high level of alcohol is significantly dependent on the nutritional conditions and protective activities that specific nutrients can supply [17].
At 14% (v/v), the threshold for ethanol production from starch fermentation is reached [18]. Over this threshold, the growth of the microbes responsible for fermentation is inhibited, and creative approaches are applied to overcome this limitation. The immobilisation of yeast or the fermentation microorganism for bioethanol production has been extensively researched to overcome substrate and product inhibition and enhance ethanol tolerance. Among these approaches, the most studied are yeast immobilisation in/on appropriate matrices like poly-acrylamide-alumina calcium, k-carrageenan gel, alginate, orange peel, PVA gel, wooden chips, etc. [11]. Bai et al. [19] prioritised self-flocculation and simple adsorptive immobilisation techniques because these allow slow developing cells to be removed from the system. The most challenging research on the subject is obtaining a fermentation microorganism with a metabolism that would enable the utilisation of a broader sugar spectrum and thus facilitate complete substrate utilisation [11]. These are the most common applications of technologies of genetic engineering.

5. Methodologies for Enhanced Bioethanol Production

Optimising the substrate medium is one of the most common ways to boost ethanol production. This process can be accomplished utilising various strategies from one-factor-at-a-time to multifactor-at-a-time [20][21] as well as advanced mathematical and statistical techniques such as artificial neural networks, genetic algorithms, etc. [20][21][22][23]. The optimisation of substrate medium entails the formulation of a fermentation medium through screening different carbon and nitrogen sources and their combinations to improve the viability and growth of the ethanologenic microorganisms and, as a result, the production yield of ethanol. Adding cauliflower and/or cabbage waste to molasses increased ethanol production yield by 40.8–52.6% compared to using only molasses [24]. The optimisation of the substrate can be improved by employing the metagenomic method, whereby it offers insights into the metagenome-based bioinformatic roles of unstudied microorganisms [9].
In complimenting the efforts of medium optimisation, strain enhancement via genetic engineering approaches has been used to boost the yield of bioethanol. It should be highlighted that, during the optimisation of a fermentation medium, genetic manipulation or the search for novel ethanologens must constantly be considered. This requirement stems from each microorganism’s inability to synthesise certain metabolites at the gene level [23]. The development of ethanologenic bacteria can be accomplished in three ways: (i) by replacing or introducing heterogeneous genes from a potent ethanol-producing strain; (ii) by overexpressing the native genes which are responsible for ethanol synthesis; and (iii) by eliminating native metabolic pathways, they could compete with ethanol production (e.g., hydrogen and organic acids) [25].
‘Separate hydrolysis and fermentation’ and ‘Simultaneous saccharification and fermentation’ techniques have been used in enhancing bioethanol yield from food wastes (Table 1). Traditional fermentation can also be combined with innovative technologies to boost bioethanol production. Electrochemistry is one of the innovative technologies which allows for regulating the metabolism of microbial fermentation [26]. Incorporating this selective technique may improve sugar assimilation efficiency, improve cell growth, and product recovery while reducing the need for pH control chemicals [26]. The use of electrodes that can operate as an electron source or act as an electron sink has been implicated with the unbalanced growth of microbial cells. These electrochemical changes have the potential to have a large selective effect on the population of microbial cells, interactions of interspecies, metabolism, and cellular regulation [26]. Joshi et al. [26] employed Wickerhanomyces anomalous in a cathodic chamber and Saccharomyces cerevisiae in an anodic chamber. When the electrochemical cell was fed externally with 4 V, the cultures yielded 19.8 and 23.7% more ethanol when compared to the controls (12.6 and 10.1 g/L, respectively). Culturing Saccharomyces cerevisiae in a platinum nanoparticle-coated anodic chamber and Wickerhamomyces anomalous in a neutral red-coated graphite cathode considerably increased the production yield of bioethanol (61.5%) from lignocellulosic biomass hydrolysate with a 3.3% reducing sugar concentration [26].

References

  1. Robak, K.; Balcerek, M. Review of second generation bioethanol production from residual biomass. Food Technol. Biotechnol. 2018, 56, 174.
  2. Xia, J.; Yang, Y.; Liu, C.-G.; Yang, S.; Bai, F.-W. Engineering Zymomonas mobilis for robust cellulosic ethanol production. Trends Biotechnol. 2019, 37, 960–972.
  3. Ntaikou, I.; Menis, N.; Alexandropoulou, M.; Antonopoulou, G.; Lyberatos, G. Valorization of kitchen biowaste for ethanol production via simultaneous saccharification and fermentation using co-cultures of the yeasts Saccharomyces cerevisiae and Pichia stipitis. Bioresour. Technol. 2018, 263, 75–83.
  4. Cao, L.; Tang, X.; Zhang, X.; Zhang, J.; Tian, X.; Wang, J.; Xiong, M.; Xiao, W. Two-stage transcriptional reprogramming in Saccharomyces cerevisiae for optimizing ethanol production from xylose. Metab. Eng. 2014, 24, 150–159.
  5. Barbhuiya, R.I.; Singha, P.; Singh, S.K. A comprehensive review on impact of non-thermal processing on the structural changes of food components. Food Res. Int. 2021, 149, 110647.
  6. Abinaya, S.; Mounika, D.S.; Suganya, A. Bioconversion of food waste into ethanol using enzymatic Hydrolyzation—Mini review. J. Emerg. Technol. Innov. Res. 2020, 7, 819–823.
  7. Xie, M.; An, F.; Zhao, Y.; Wu, R.; Wu, J. Metagenomic analysis of bacterial community structure and functions during the fermentation of da-jiang, a Chinese traditional fermented food. Lwt 2020, 129, 109450.
  8. Lima, C.O.d.C.; Vaz, A.B.; De Castro, G.M.; Lobo, F.; Solar, R.; Rodrigues, C.; Pinto, L.R.M.; Vandenberghe, L.; Pereira, G.; da Costa, A.M. Integrating microbial metagenomics and physicochemical parameters and a new perspective on starter culture for fine cocoa fermentation. Food Microbiol. 2021, 93, 103608.
  9. Song, Q.; Zhao, F.; Wang, B.; Han, Y.; Zhou, Z. Metagenomic insights into Chinese northeast suancai: Predominance and diversity of genes associated with nitrogen metabolism in traditional household suancai fermentation. Food Res. Int. 2021, 139, 109924.
  10. Soyuçok, A.; Yurt, M.N.Z.; Altunbas, O.; Ozalp, V.C.; Sudagidan, M. Metagenomic and chemical analysis of Tarhana during traditional fermentation process. Food Biosci. 2021, 39, 100824.
  11. Mojović, L.; Pejin, D.; Grujić, O.; Markov, S.; Pejin, J.; Rakin, M.; Vukašinović, M.; Nikolić, S.; Savić, D. Progress in the production of bioethanol on starch-based feedstocks. Chem. Ind. Chem. Eng. Q./CICEQ 2009, 15, 211–226.
  12. Kolusheva, T.; Marinova, A. A study of the optimal conditions for starch hydrolysis through thermostable α-amylase. J. Univ. Chem. Technol. Metall. 2007, 42, 93–96.
  13. Sasmal, S.; Mohanty, K. Advance in Bioethanol Technology: Production and Characterization. In Liquid Biofuels: Fundamentals, Characterization, and Applications; Wiley: Hoboken, NJ, USA, 2021; pp. 215–230.
  14. Kumar, V.; Ahluwalia, V.; Saran, S.; Kumar, J.; Patel, A.K.; Singhania, R.R. Recent developments on solid-state fermentation for production of microbial secondary metabolites: Challenges and solutions. Bioresour. Technol. 2021, 323, 124566.
  15. Kawai, M.; Nagao, N.; Tajima, N.; Niwa, C.; Matsuyama, T.; Toda, T. The effect of the labile organic fraction in food waste and the substrate/inoculum ratio on anaerobic digestion for a reliable methane yield. Bioresour. Technol. 2014, 157, 174–180.
  16. Wu, C.; Wang, Q.; Yu, M.; Zhang, X.; Song, N.; Chang, Q.; Gao, M.; Sonomoto, K. Effect of ethanol pre-fermentation and inoculum-to-substrate ratio on methane yield from food waste and distillers’ grains. Appl. Energy 2015, 155, 846–853.
  17. Gomes, D.; Cruz, M.; de Resende, M.; Ribeiro, E.; Teixeira, J.; Domingues, L. Very high gravity bioethanol revisited: Main challenges and advances. Fermentation 2021, 7, 38.
  18. Anwar Saeed, M.; Ma, H.; Yue, S.; Wang, Q.; Tu, M. Concise review on ethanol production from food waste: Development and sustainability. Environ. Sci. Pollut. Res. 2018, 25, 28851–28863.
  19. Bai, F.; Anderson, W.; Moo-Young, M. Ethanol fermentation technologies from sugar and starch feedstocks. Biotechnol. Adv. 2008, 26, 89–105.
  20. Mohammadipanah, F.; Kazemi Shariat Panahi, H.; Imanparast, F.; Hamedi, J. Development of a reversed-phase liquid chromatographic assay for the quantification of total persipeptides in fermentation broth. Chromatographia 2016, 79, 1325–1332.
  21. Panahi, H.K.S.; Mohammadipanah, F.; Dehhaghi, M. Optimization of Extraction Conditions for Liquidliquid Extraction of Persipeptides from Streptomyces Zagrosensis Fermentation Broth. Eur. Chem. Bull. 2016, 5, 408–415.
  22. Sajedi, H.; Mohammadipanah, F.; Shariat Panahi, H.K. An image analysis-aided method for redundancy reduction in differentiation of identical Actinobacterial strains. Future Microbiol. 2018, 13, 313–329.
  23. Singh, V.; Haque, S.; Niwas, R.; Srivastava, A.; Pasupuleti, M.; Tripathi, C. Strategies for fermentation medium optimization: An in-depth review. Front. Microbiol. 2017, 7, 2087.
  24. Thenmozhi, R.; Victoria, J. Optimization and improvement of ethanol production by the incorporation of organic wastes. Pelagia Res. Libr. 2013, 4, 119–123.
  25. Panahi, H.K.S.; Dehhaghi, M.; Dehhaghi, S.; Guillemin, G.J.; Lam, S.S.; Aghbashlo, M.; Tabatabaei, M. Engineered bacteria for valorizing lignocellulosic biomass into bioethanol. Bioresour. Technol. 2022, 344, 126212.
  26. Joshi, J.; Dhungana, P.; Prajapati, B.; Maharjan, R.; Poudyal, P.; Yadav, M.; Mainali, M.; Yadav, A.P.; Bhattarai, T.; Sreerama, L. Enhancement of ethanol production in electrochemical cell by Saccharomyces cerevisiae (CDBT2) and Wickerhamomyces anomalus (CDBT7). Front. Energy Res. 2019, 7, 70.
  27. Prasoulas, G.; Gentikis, A.; Konti, A.; Kalantzi, S.; Kekos, D.; Mamma, D. Bioethanol production from food waste applying the multienzyme system produced on-site by Fusarium oxysporum F3 and mixed microbial cultures. Fermentation 2020, 6, 39.
  28. Ma, K.; Ruan, Z.; Shui, Z.; Wang, Y.; Hu, G.; He, M. Open fermentative production of fuel ethanol from food waste by an acid-tolerant mutant strain of Zymomonas mobilis. Bioresour. Technol. 2016, 203, 295–302.
  29. Matsakas, L.; Christakopoulos, P. Ethanol production from enzymatically treated dried food waste using enzymes produced on-site. Sustainability 2015, 7, 1446–1458.
  30. Kiran, E.U.; Liu, Y. Bioethanol production from mixed food waste by an effective enzymatic pretreatment. Fuel 2015, 159, 463–469.
  31. Cekmecelioglu, D.; Uncu, O.N. Kinetic modeling of enzymatic hydrolysis of pretreated kitchen wastes for enhancing bioethanol production. Waste Manag. 2013, 33, 735–739.
  32. Walker, K.; Vadlani, P.; Madl, R.; Ugorowski, P.; Hohn, K.L. Ethanol fermentation from food processing waste. Environ. Prog. Sustain. Energy 2013, 32, 1280–1283.
  33. Kim, J.H.; Lee, J.C.; Pak, D. Feasibility of producing ethanol from food waste. Waste Manag. 2011, 31, 2121–2125.
  34. Wang, Q.; Ma, H.; Xu, W.; Gong, L.; Zhang, W.; Zou, D. Ethanol production from kitchen garbage using response surface methodology. Biochem. Eng. J. 2008, 39, 604–610.
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