Isolamento, seleção e aplicação de leveduras não convencionais para produção de bioetanol a partir de coprodutos gerados pelos laticínios

• Ano de defesa: 2017
• Autor(a) principal: Murari, Cleidiane Samara [UNESP]
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Coprodutos; Laticínios; Levedura; Bioetanol; Meio ambiente
• Link de acesso: http://hdl.handle.net/11449/150322

The development of the technology of fermentation processes associated to the environmental concern, due to industrial activities, has motivated the advancement of new alternative energy generation strategies. The cheese whey and permeate whey are co-products generated from dairy industrial and represent nutrient rich substrates, with carbon source for ethanol production. The aim of this study was isolate and select yeasts from cheese whey for the development of a ethanol production process, in comparison with a standard yeast, Kluyveromyces marxianus, CCT 4086. For the isolation, it was used cheese whey obtained from the production of gorgonzola cheese, fresh cheese and curd. After isolation, the yeasts that presented higher growth, were submitted to fermentation in cheese whey and whey permeate, in aerobic (100 rpm), microaerobic (50 rpm) and anaerobic conditions, at 30ºC for 24 hours. After this stage, the yeast, the cultive condition and the substrate that presented better results, were submitted to fermentation in different supplementation conditions (with salts and yeast extract). Subsequently, it was carried out the improvement of the cultive conditions, varying pH, lactose concentration, and temperature, followed by the increase of fermentation scale (1 L, 6 L, 21 L, and 36 L). Analysis of ethanol, biomass, lactose, protein, and chemical oxygen demand (COD), were carried out. Then, it was isolated and selected two yeasts able to grow and consume the substrate of cheese whey. One yeast was isolated from the gorgonzola cheese whey (LSQG), and the another, from the curd (LCOA). Among the yeasts studied, the LSQG yeast, identified as K. marxianus (URM 7404) presented better results for ethanol production and cellular growth in cheese whey, in anaerobic and aerobic conditions. This yeast produced initially (Pmax) 8.08 g.L.h-1 of ethanol and a productivity of (QX) 0.81 g. L-1 .h-1 in 10 hours, with ethanolic yield () of 76%. The LCOA yeast obtained (Pmax) of 1.56 g. L-1 , (QX) of 0.09 g. L-1 .h-1 and () of 9.82%, in 14 hours. Finally, the K. marxianus CCT 4086 presented (Pmax) of 7.54 g. L-1 in 12 hours, (QX) of 0.63 g. L-1 .h-1 and () of 57.71%, all in cheese whey. The production of biomass was also higher by K. marxianus URM 7404, even in aerobic condition, producing 8.88 g. L-1 in 12 hours, with productivity 0.94 g. L-1 .h-1 , while the LCOA yeast had maximum production of 6.40 g. L-1 and maximum productivity of 0.62 g. L-1 .h-1 . The standard yeast obtained maximum biomass production of 8.24 g. L-1 in 10 hours, with productivity 0.82 g. L-1 .h-1 . After adaptation of the yeast K. marxianus URM 7404 in the substrate, it was tested anaerobic condition and cheese whey supplemented with yeast extract. In this cultive condition, there was an increase in ethanol of 60,77%, reaching (Pmax) of 12 20.60 g. L-1 ethanol, (QX) of 2.58 g. L-1 .h-1 e () of 95.70%, in 8 hours. After the improvement of the conditions, the (Pmax) of ethanol reached 27.61 g. L-1 with () of 98.23% in 12 hours, using lactose concentration of 60 g.L -1 , at 33ºC and pH 5. In the increase of the fermentation scale up, using the cultive conditions obtained after improvement, the results of ethanol production were close between them in 1, 6, 21, and 36 L with (Pmax) of 28 g. L-1 , 27.51 g. L-1 and 26.90 g. L-1 (in 12 hours) and 25.81 g. L-1 (in 16 hours) and () of 97.84%, 96.70%, 96.30%, and 95.80%, and lactose consumption of 95%, 94.7%, 94.5%, and 93.3%, respectively. Finally, according to the efficiency in reducing COD it was 85.18% for 1L, 86.54% for 6L, 80.90% for 21L for 78.94% for 36L, at the end of 18 hours of fermentation. Representing a promising alternative for valorization of coproducts generated by dairy and an effective alternative to obtain a renewable source of biofuel.