Recently, in Brazil, corn ethanol industries are being installed and the integration with sugar/energy-cane has been proposed, using bagasse for cogeneration and the juice to dilute the corn. However, this integration may have some limitations, such as the quality of the cane juice and potential contamination by microorganisms brought with the cane from the field. In this article, we first tested the effects of mixing energy cane juice with corn on fermentative parameters. We also assessed the effects of Lactobacilli. contamination on organic acids produced during the fermentation and fermentation parameters and proposed the use of ionizing radiation to replace antibiotics as a disinfection control method. Our results showed that mixing energy cane juice with corn does not have any negative effect on fermentation parameters, including ethanol production. The contamination with Lactobacilli. considerably increased the production of acetic, lactic, and succinic acid, reducing the pH and ethanol content from 89.2 g L−1 in the sterilized treatment to 72.9 g L−1 in the contaminated treatment. Therefore, for the integration between corn and cane to be applied on an industrial scale, it is essential to have effective disinfection before fermentation. Ionizing radiation (20 kGy) virtually disinfected the wort, showing itself to be a promising technology; however, an economic viability study for adopting it in the industry should be carried out.

Microbial contamination of the wort during the fermentation process causes significant losses in ethanol production worldwide and creates a dependence of the industry on chemicals and antibiotics to control contamination. Therefore, this study used electron beam (e-beam) to disinfect wort from sugarcane (Saccharum officinarum L.) molasses and investigate the bioethanol fermentation. Four treatments (T0 -T3) were carried out using ionizing doses of radiation through the electron accelerator: 0 (control), 10, 20, and 40 kGy. Total mesophiles, total bacteria, sucrose, glucose, fructose, phenolics, flavonoids, hydroxymethylfurfural (5-HMF), and Furfural were measured. An alcoholic fermentation assay was performed after the irradiation process. The irradiated treatments showed no inversion of sugars and formation of the inhibitory by-products flavonoids, furfural and 5-HMF, except for the phenolic compounds. The lower dose tested (10 kGy) reduced more than 99.9 % of the total mesophiles and more than 99.99 % of the total bacteria in the substrate. In the fermentation, the irradiated worts presented similar (p > 0.05) yields (92, 93, and 94 %) and ethanol productivity levels (0.89, 0.88, and 0.87 g L -1 h -1 , for T1, T2, and T3 respectively). However, all treatments presented higher yields and productivity (p < 0.05) when compared to the control (88 % and 0.85 g L -1 h -1 ), highlighting the possible use of e-beam in wort fermentation at a lower dose (10 kGy). This allows reduction in losses caused by microbial contamination, besides increasing fermentation yield and productivity with lower energy consumption.

The alcoholic fermentation industry generates a large surplus of yeasts, which, in turn, have the ability to bioaccumulate minerals and enable their bioavailability after cell autolysis. Among these minerals, selenium (Se) stands out, which participates in the formation of antioxidant enzymes. The objectives of the work were to define the minimum and maximum concentration of Se that yeasts (Saccharomyces cerevisiae – Y904) support and the concentrations that they tolerate once adapted. To this end, a test of tolerance to Se was carried out, using treatments with different concentrations of Se. The adaptive process started at the maximum concentration obtained in the tolerance test of 60 mg mL-1, with increasing addition of 6 mg mL-1, reaching up to 246 mg mL-1 of Se. The macromorphological characteristics and number of colony forming units (CFU) were evaluated. It was identified that yeasts without adaptation grew on substrate containing up to 60 mg mL-1 of Se and those adapted, up to 246 mg mL-1 of Se. In addition to the reduction in yeast growth speed, from the concentration of 84 mg mL-1 of Se in the medium, morphological changes in colony color were observed. It is concluded that non-adapted yeasts support up to 60 mg mL-1 of Se and, after the adaptive process, they support 246 mg mL-1 of Se in the medium after the adaptive process, which adds value to the final product, and makes yeasts suitable for human nutrition as a supplement or even in the formulation of probiotics.

The presence of microbial contamination in the wort during the fermentation process results in damages of billions of dollars per year all around the world and promotes the industry dependence of chemicals and antibiotics to control the contamination. For these reasons, this study aimed to use the electron beam to sterilise wort from sugarcane molasses and investigate its bioethanol fermentation. Five treatments (T0 – T4) were carried out using ionizing doses of radiation through the electron accelerator: (0, 10, 20, 40, and 80 kGy) and a positive control (T5-steam by autoclave) were performed. It was evaluated total mesophiles, total bacteria, sugars, phenolics, flavonoids, 5-hidroximetylfurfural, and Furfural. After the irradiation process, it was conducted an alcoholic fermentation assay using baker’s yeast Saccharomyces cerevisiae. It was not observed inversion of sugars and formation of the inhibitory by-products flavonoids, furfural, and 5-hidroximetylfurfural, with exception of the phenolic compounds. Only T4 and T5 were able to sterilise the wort. However, T3 was able to eliminate > 99.99% of the microorganisms. In the fermentation T2 promoted the best ethanol yield and productivity among the irradiated treatments, evidencing the possibility of electron beam use in the wort treatment prior to fermentation which may allow a reduction in losses caused by microbial contamination, besides the possibility of promoting fermentation yield and productivity increase. The operation cost for applying the e-beam with a dose of 20 kGy in a standard ethanol plant was estimated at US$ 0.014 per m3 of wort.