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Candida maltosa was cultivated in the liquid phase of residual brewing yeast, a major brewery residue, to produce biomass and biofilm. Using response surface methodology, the effect of two variables at two different levels was investigated. The independent variables were agitation speed (at 100 and 200 rpm), and aeration (at 1 and 3 L min−1). Aeration was identified to be important for the production of both biomass and biofilm, while agitation was the only factor significantly affecting biofilm production. The maximal production of biofilm (2.33 g L−1) was achieved for agitation of 200 rpm and aeration of 1 L min−1, while the maximum for biomass (16.97 g L−1) was reached for 100 rpm agitation and 3 L min−1 air flow. A logistic model applied to predict the growth of C. maltosa in the exponential phase and the biofilm production, showed a high degree of agreement between the prediction and the actual biomass measured experimentally. The produced biofilms were further characterized using Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA). FTIR allowed the identification of methyl, carbonyl ester and sulfate groups, and revealed the presence of uronic acid moieties and glycosidic bonds. Water-retention ability up to relatively high temperatures was revealed by TGA, and that makes the produced biofilm suitable for production of hydrogels. SEM also gave indications on the hydrogel-forming potential of the biofilm. This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products 2.0

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2020-09-16T15:19:11Z No. of bitstreams: 1 2010 - Marcia de Souza Vieira.pdf: 902316 bytes, checksum: 9331594420db37d7e98c1141c5033891 (MD5) Made available in DSpace on 2020-09-16T15:19:11Z (GMT). No. of bitstreams: 1 2010 - Marcia de Souza Vieira.pdf: 902316 bytes, checksum: 9331594420db37d7e98c1141c5033891 (MD5) Previous issue date: 2010-03-08 Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior, CAPES, Brasil. This study was carried out to evaluate the chemical composition, the gross energy and the apparent digestibility of the nutrients of the barley bagasse (BB). For the chemical composition, three samples of the BB originated from the same beer industry were evaluated. Each sample of BB was submitted to the proximal analyses to determinate the dry matter (DM), gross energy (GE), crude protein (CP), ether extract (EE), ash, crude fiber (CF), neutral detergent fiber (NDF), acid detergent fiber (ADF), macro and micro minerals and the total carbohydrates (TCH) and macro and micro minerals levels. The average of 21,59; 5215,29 kcal/kg, 24,89; 10,82; 8,01; 15,99; 66,32; 24,24 e 56,28%, respectively, for the DM, GE, CP, FE, MM, CF, NDF, ADF, TCH, that were determinate had their values similar to that met in the literature, characterizing the BB as an ingredient of great potential for swine feeding. For the digestibility assay, it was used five barrows with 35,0 kg of bodyweight, housed individually in metabolic cages. The treatments consisted of one ration based on corn and soybean meal, formulated to growing pigs, and one ration test where the BB replace 40% of the control ration. The barrows were raised on metabolism cages during 12 days, with seven days for the adaptation to the cages and five days of feces and urine collection. It was used the iron oxide as fecal marker. The barrows were fed based on metabolic weight (kg0,75). It was used the method of total collect and the feces were collected twice daily at the morning and at afternoon, identified, weighted and kept in freezer. The urine was collected daily and kept in refrigerator. At the end of the experimental period it was made the analyzes of chemical composition of the rations, the feces and urine to determinate the digestibility of these nutrients and the balance of N and P. The DE of the BB was to 2983 kcal/kg. The replacement of 40% control ration to BB caused change in the nitrogen metabolism. Occurred reduction in the urinary excretion in the barrows fed with ration containing 40% of BB improving the utilization of N. Although, occurred reduction of retention of and in the digestibility of the DM, and the nutrients, CP, EE, MM, NDF, ADF, N and P. It concluded that the BB worsted the digestibility of the nutrients. O presente trabalho foi realizado com o objetivo de avaliar a composi??o qu?mica, a energia digest?vel e a digestibilidade aparente dos nutrientes do baga?o de cevada. Para a an?lise da composi??o qu?mica foram avaliadas tr?s partidas do BCV de mesma origem. As amostras foram submetidas ? an?lise proximal para determina??o da mat?ria seca (MS), energia bruta (EB), prote?na bruta (PB), extrato et?reo (EE), mat?ria mineral (MM), fibra bruta (FB), fibra em detergente neutro (FDN), fibra em detergente ?cido (FDA), macro e microminerais. As m?dias de 21,59; 5215,29 kcal/kg, 24,89; 10,82; 8,01; 15,99; 66,32; 24,24 e 56,28%, respectivamente, para MS, EB, PB, EE, MM, FB, FDN, FDA e carboidrato total encontradas nas tr?s partidas tiveram valores semelhantes aqueles encontrados na literatura, caracterizando o BCV como um ingrediente de grande potencial para ser utilizado na alimenta??o de su?nos. Para o ensaio de digestibilidade foram utilizados cinco su?nos machos castrados com peso m?dio de 35,0 kg. Os tratamentos consistiram de uma ra??o controle, formulada para atender as exig?ncias dos su?nos na fase de crescimento e uma ra??o teste, onde o BCV substituiu, na base na mat?ria seca, 40% da ra??o controle. Os animais foram alojados em gaiolas de metabolismo por um per?odo de 12 dias, sendo sete dias para adapta??o ?s gaiolas e as dietas e cinco dias para coleta de fezes e urina. Foi utilizado ?xido f?rrico como marcador fecal. Os animais foram pesados no in?cio do experimento e antes de iniciar as coletas para se determinar o consumo de ra??o que seria ofertado nesta fase. Cada su?no recebeu uma quantidade di?ria de ra??o restrita por unidade de peso metab?lico (kg0,75). As fezes foram coletadas diariamente no per?odo da manh? e da tarde, identificadas, pesadas e congeladas em freezer. A urina foi coletada uma vez ao dia, identificada, pesada e armazenada em refrigerador. Ao fim do experimento foi feita an?lise proximal das dietas, BCV, fezes e urina para determina??o da digestibilidade dos nutrientes e do balan?o do nitrog?nio e do f?sforo. A energia digest?vel do BCV foi de 2983 kcal/kg. A substitui??o de 40% da ra??o controle por baga?o de cevada alterou o metabolismo de nitrog?nio. Houve uma redu??o na excre??o urin?ria dos animais que receberam o BCV, aumentando a efici?ncia na utiliza??o do N deste tratamento. Contudo houve redu??o na reten??o do N e na digestibilidade da MS, PB, EE, MM, FDN, FDA, N e P. Concluiu-se que a caracter?stica fibrosa do BCV pode ter interferido de forma negativa na digestibilidade dos nutrientes.