ABSTRACT For optimization of biochemical processes in food and pharmaceutical industries, the evaluation of enzyme inactivation kinetic models is necessary to allow their adequate use. Kinetic studies of thermal inactivation of β-galactosidase from Aspergillus oryzae were conducted in order to critically evaluate mathematical equations presented in the literature. Statistical analysis showed that Weibull model presented the best adequacy to residual enzymatic activity data through the processing time and its kinetic parameters as a function of the temperature, in the range of 58-66 ºC. The investigation suggests the existence of a non-sensitive heat fraction on the enzyme structure, which is relatively stable up to temperatures close to 59 ºC. Thermodynamic parameters were evaluated and showed that such β-galactosidase presents activation energy of 277 kJ mol-1 and that the enzyme inactivation is due to molecular structural changes. Results shown that the enzyme is quite stable for biotechnological applications.

O estudo e o uso de pigmentos naturais nas indústrias de alimentos têm aumentado nos últimos anos devido à toxicidade apresentada pelos pigmentos de origem artificial. Monascus ruber é um fungo filamentoso conhecido por produzir pigmento vermelho, laranja e amarelo sob diferentes condições de cultivo. Paralelo ao crescimento do mercado de alimentos naturais cresce o de biocombustíveis, como é o caso do biodiesel, que gera concomitantemente um aumento na produção de glicerina, podendo esta ser utilizada em bioprocessos. O objetivo deste estudo foi utilizar glicerina e glicose como substratos para produção de pigmentos naturais em biorreator. O cultivo foi realizado em biorreator Bioflo III, com volume útil de 4 L, equipado com controle de temperatura, pH, vazão de aeração e frequência de agitação. A maior produção de pigmentos foi observada em 60 horas de cultivo com 8,28 UDO510 de pigmento vermelho. O pH permaneceu na faixa de 5,45 a 6,23, favorecendo a liberação de pigmentos vermelhos. O estudo realizado mostra a viabilidade da produção de pigmentos naturais por Monascus ruber, em biorreator, utilizando resíduos da produção de biodiesel, sem tratamento prévio.

The study and use of natural pigments in food industries have increased in recent years due to the toxicity presented by artificial pigments. Monascus ruber is a filamentous fungus that produces red, orange, and yellow pigments under different growing conditions. The growth of health food market has increased in parallel with the growth in biofuels production, such as biodiesel, which generates a concomitant increase in the production of glycerin that can be used in bioprocesses. The objective of this study was to use glycerin and glucose as substrates in the production of natural pigments in a bioreactor. The culture of Monascus ruber was carried out in a Bioflo III reactor with 4 L of working volume and pH, temperature, aeration, and agitation control. The highest pigment production was observed after 60 hours of fungal culture with 8.28 UA510 of red pigment. The pH range remained from 5.45 to 6.23 favoring the release of red pigment in the medium. This study shows the feasibility of the production of natural pigments by Monascus ruber in a bioreactor using a co-product of biodiesel without previous treatment as a substrate.

Omega-3 enriched partial acylglycerols are beneficial for human health. The aim of this study was to obtain monoacylglycerols (MAG) and diacylglycerols (DAG) by means of glycerolysis of fish oil catalyzed by a lipase from Rhizomucor miehei in the presence of food grade surfactants (Tween 65, 80 or 85). Glycerolysis was successful in the reaction media for all the tested surfactants, showing their potential for use as additives in such a system. The best results, however, were obtained for the reaction medium in the absence of surfactant whose peroxide value was the lowest after glycerolysis.

Pleurotus ostreatus, conhecido mundialmente como cogumelo ostra, foi cultivado em palha de folha de bananeira, utilizando-se inóculos produzidos por dois processos diferentes: inóculo líquido e inóculo sólido usado tradicionalmente. Diferentes taxas de inoculação (5, 10, 15 e 20%) foram testadas. Eficiência biológica, rendimento, produtividade, perda de matéria orgânica e umidade dos corpos frutíferos, como também as características físico-químicas da palha de folha de bananeira, foram estudadas. Diferenças significativas foram observadas para os teores de celulose, lignina e hemicelulose entre a primeira e segunda colheita, tanto para inóculo sólido quanto líquido. Foi observado que o cultivo de P. ostreatus proporcionou maior degradação de lignina (80,36%), seguido de hemicelulose (78,64%) e celulose (60,37%). Diferenças significativas entre uma e duas colheitas também foram observadas para os parâmetros de produção (eficiência biológica e rendimento) para os dois tipos de inóculos, líquido e sólido. No entanto, diferenças significativas para produtividade entre uma e duas colheitas foram observadas somente para o inóculo sólido.

Pleurotus ostreatus, worldwide known as oyster mushroom, was cultivated in banana straw using inocula produced by two different processes - liquid inoculum and the traditionally used solid inoculum. Different ratios (5, 10, 15, and 20%) were tested. Biological efficiency, yield, productivity, organic matter loss, and moisture of fruiting bodies as well as physical-chemical characteristics of banana straw were studied. Significant differences were observed for cellulose, lignin, and hemicellulose content between one and two harvests for both solid and liquid inocula. It was observed that P. ostreatus growth promoted higher degradation of lignin (80.36%), followed by hemicellulose (78.64%) and cellulose (60.37%). Significant differences between one and two harvests were also observed for the production parameters (biological efficiency and yield) for both kinds of inocula, liquid and solid. However, significant differences in productivity between harvests were observed only for solid inoculum.