Assessing Ionizing Radiation and Chlorine Dioxide (ClO<sub>2</sub>) as Potential Aseptization Treatments for Yeast Recycling on Mixed Wort of Corn and Sugarcane in Brazil
Rafael Douradinho,
Pietro Sica,
Matheus Oliveira,
Alana Uchoa Pinto,
Layna Mota,
Eduardo Mattos,
Danilo Perecin,
Vanessa Garcilasso,
João Monnerat Araujo Ribeiro de Almeida,
Sonia Piedade,
Lucílio Alves,
Valter Arthur,
Suani Coelho,
Antonio Baptista
Affiliations
Rafael Douradinho
Department of Agri-Food Industry, Food and Nutrition, College of Agriculture “Luiz de Queiroz”, University of São Paulo, Padua Dias Avenue, 11, Piracicaba 13148-900, SP, Brazil
Pietro Sica
Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsenvej, 40, 1821 Frederiksberg, Denmark
Matheus Oliveira
Department of Agri-Food Industry, Food and Nutrition, College of Agriculture “Luiz de Queiroz”, University of São Paulo, Padua Dias Avenue, 11, Piracicaba 13148-900, SP, Brazil
Alana Uchoa Pinto
Department of Agri-Food Industry, Food and Nutrition, College of Agriculture “Luiz de Queiroz”, University of São Paulo, Padua Dias Avenue, 11, Piracicaba 13148-900, SP, Brazil
Layna Mota
Center for Nuclear Energy in Agriculture, University of São Paulo, Centenário Avenue, 303, Piracicaba 13416-000, SP, Brazil
Eduardo Mattos
Department of Agri-Food Industry, Food and Nutrition, College of Agriculture “Luiz de Queiroz”, University of São Paulo, Padua Dias Avenue, 11, Piracicaba 13148-900, SP, Brazil
Danilo Perecin
Institute of Energy and Environment, University of São Paulo, Prof. Luciano Gualberto Avenue, 1289, São Paulo 05508-900, SP, Brazil
Vanessa Garcilasso
Institute of Energy and Environment, University of São Paulo, Prof. Luciano Gualberto Avenue, 1289, São Paulo 05508-900, SP, Brazil
João Monnerat Araujo Ribeiro de Almeida
Chemistry Institute, Federal University of Rio de Janeiro, Athos da Silveira Ramos Avenue, 149, Rio de Janeiro 21941-909, RJ, Brazil
Sonia Piedade
Department of Math, Chemistry and Statistics, College of Agriculture “Luiz de Queiroz”, University of São Paulo, Padua Dias Avenue, 11, Piracicaba 13148-900, SP, Brazil
Lucílio Alves
Department of Economics, Administration and Sociology, College of Agriculture “Luiz de Queiroz”, University of São Paulo, Padua Dias Avenue, 11, Piracicaba 13148-900, SP, Brazil
Valter Arthur
Center for Nuclear Energy in Agriculture, University of São Paulo, Centenário Avenue, 303, Piracicaba 13416-000, SP, Brazil
Suani Coelho
Institute of Energy and Environment, University of São Paulo, Prof. Luciano Gualberto Avenue, 1289, São Paulo 05508-900, SP, Brazil
Antonio Baptista
Department of Agri-Food Industry, Food and Nutrition, College of Agriculture “Luiz de Queiroz”, University of São Paulo, Padua Dias Avenue, 11, Piracicaba 13148-900, SP, Brazil
Yeast recycling, which is a common practice in sugarcane ethanol plants, could be expanded if it could be successfully implemented in corn-based ethanol production. However, the process of recycling the yeast remaining after fermentation is hampered by contaminating microorganisms that reduce the fermentation efficiency and compete with the yeast for the fermentable sugars. Currently, antibiotics are used to control microbial contamination. This study proposes chlorine dioxide and electron beam irradiation as alternative control methods for completely inactivating contaminants and minimizing their effect on recycled yeast. For that, wort sterilization using electron radiation (20 kGy) and treatment with a chemical biocide, namely chlorine dioxide (125 mg kg−1), were compared with non-treated wort. Five fermentation cycles were performed using fed-batch systems with 300 g L−1 of fermentable sugars. The results obtained in this study showed the inactivation of contaminants under the effect of electron beam irradiation, which led to an increase in the productivity, yield, and efficiency of fermentation by 0.21 g L−1h−1, 2.6%, and 4.7%, respectively. However, ClO2 did not show promising results in reducing contamination or improving fermentative parameters. Thus, electron beam irradiation of contaminated wort may be a suitable alternative to chemical biocides and would allow the use of recycled yeast in corn-based ethanol plants.
