Wort disinfection treatment with electron beam for bioethanol production

Calegari, Rubens Perez; Silva, Eric Alberto da; Silva, Ana Paula Maria da; Gomes, Marcelo Pego; Mota, Layna Amorim; Arthur, Valter; Baptista, Antonio Sampaio

doi:10.1590/1678-992X-2021-0260

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Agricultural Engineering, Research Article • Sci. agric. (Piracicaba, Braz.) 80 • 2023 • https://doi.org/10.1590/1678-992X-2021-0260 copy

Wort disinfection treatment with electron beam for bioethanol production

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

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.

alcoholic fermentation; biofuel; electron accelerator; microbial contamination; reduction of contamination

Treatment	Flavonoids	Phenolics	Furfural	5-HMF
		------------- µg mL^–1 -------------
T0 - Control	26.74 ± 1.57^a	925.27 ± 13.72^c	0.61 ± 0.00^a	0.44 ± 0.00^a
T1 - 10 kGy	23.47 ± 5.22^a	980.68 ± 11.74^b	0.64 ± 0.02^a	0.44 ± 0.02ª
T2 - 20 kGy	25.18 ± 7.92^a	1012.64 ± 16.20^b	0.63 ± 0.02^a	0.43 ± 0.02ª
T3 - 40 kGy	25.44 ± 1.11^a	1089.38 ± 9.94^a	0.62 ± 0.01^a	0.43 ± 0.01ª
CV	19.19	1.31	2.30	3.95

Treatment	Total bacteria	pH	Glycerol	Mannitol	Sucrose	Glucose	Produced during the fermentation					Yeast viability
Treatment	Total bacteria	pH	Glycerol	Mannitol	Sucrose	Glucose	Frutose	Alcohol Content	Yeast biomass	Productivity	Yield	Yeast viability
	Log CFU mL^–1				------ g L^–1 ------			----- w w^–1 ------	------ g mL^–1 -------	------g L^–1 h^–1------	-----------------%-----------------
T0 - Control	5.55 ± 0.37^a	4.38 ± 0.06^bc	15.51 ± 0.67^a	0.41 ± 0.02^a	<LoQ	0.25 ± 0.02^bc	0.10 ± 0.02^b	6.82 ± 0.19^b	0.14 ± 0.01^a	0.85 ± 0.02^b	88 ± 2^b	81 ± 2^a
T1- 10 kGy	2.68 ± 0.40^b	4.44 ± 0.11^b	15.56 ± 0.25^a	0.39 ± 0.01^ab	<LoQ	0.23 ± 0.07^c	0.13 ± 0.02^ab	7.09 ± 0.13^a	0.15 ± 0.00^a	0.89 ± 0.02^a	92 ± 2^a	80 ± 2^a
T2 - 20 kGy	2.25 ± 0.05^b	4.27 ± 0.02^c	15.81 ± 0.52^a	0.38 ± 0.02^b	<LoQ	0.37 ± 0.28^a	0.14 ± 0.04^a	7.09 ± 0.04^a	0.15 ± 0.00^a	0.88 ± 0.01^a	93 ± 1^a	79 ± 2^a
T3 - 40 kGy	2.60 ± 0.49^b	4.58 ± 0.05^a	15.97 ± 0.31^a	0.32 ± 0.03^c	<LoQ	0.31 ± 0.44^ab	0.12 ± 0.01^ab	6.97 ± 0.13^ab	0.16 ± 0.02^a	0.87 ± 0.02^ab	94 ± 2^a	81 ± 2^a
CV	11.17	1.51	2.72	3.51	0	13.59	16.43	1.94	5.85	1.72	1.99	2.79

Treatment	Sucrose	Fructose	Glucose	Glycerol	Mannitol	TRS
	------------------------------------- g L^–1 -------------------------------------
T0 - Control	102.03 ± 0.09^a	22.47 ± 0.31^a	22.55 ± 0.14^a	<LoQ	0.28 ± 0.01^a	152.15 ± 0.52ª
T1 - 10 kGy	102.77 ± 0.47^a	21.04 ± 0.89^ab	22.24 ± 1.43^a	<LoQ	0.28 ± 0.01^a	151.19 ± 2.44ª
T2 - 20 kGy	103.30 ± 3.79^a	20.04 ± 1.00^b	20.88 ± 1.55^a	<LoQ	0.30 ± 0.06^a	149.38 ± 4.33ª
T3 - 40 kGy	99.65 ± 0.09^a	20.35 ± 0.54^b	21.00 ± 0.65^a	<LoQ	0.27 ± 0.01^a	145.99 ± 1.19ª
CV	1.96	3.19	4.6	0	9.88	1.72

Treatment	Radiation dose	Δt	Cost
	kGy	s	US$
T0	0	0	0
T1	10	11.6	0.0644
T2	20	23.2	0.128
T3	40	46.4	0.258

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[1] *Corresponding author <rubenscalegari@live.com>