Resumo O presente estudo teve como objetivo verificar a influência do catalisador (metóxido de sódio e lipase de Rhizopus oryzae imobilizada em suporte híbrido - sílica-álcool polivinílico) nos atributos físicos e no aroma dos produtos obtidos a partir da interesterificação da gordura do leite com óleos vegetais (soja e canola). A avaliação foi feita usando nariz eletrônico e texturômetro. As reações de interesterificação foram realizadas com misturas binárias (65% de gordura do leite e 35% de óleo vegetal), usando metóxido de sódio 0,75% (60 °C por 60 min) e lipase de Rhizopus oryzae imobilizada na proporção de 500 unidades de atividade por grama de mistura (45°C durante 6 h). Os resultados mostraram que os sensores do nariz eletrônico discriminaram de forma satisfatória os aromas das matérias-primas e dos produtos e foram capazes de distingui-los de acordo com o catalisador utilizado. Em relação à textura, ambos os catalisadores geraram produtos com consistências adequadas, revelando plasticidade satisfatória e espalhabilidade sob temperatura de geladeira.

Abstract The present study aimed to verify the influence of the catalyst (sodium methoxide and the lipase from Rhizopus oryzae immobilized on a hybrid support - silica-polyvinyl alcohol) on the physical and aroma attributes of the products obtained from the interesterification of milk fat with vegetable oils (soybean and canola). The evaluation was carried out using an electronic nose (e-nose) and a texture analyzer. Interesterification reactions were carried out with binary blends (65% of milk fat and 35% of vegetable oil) using 0.75% sodium methoxide (60 °C for 60 min) and immobilized Rhizopus oryzae lipase at a fixed proportion of 500 units of activity per gram of blend (45 °C for 6 h). The results showed that the e-nose sensors discriminated satisfactorily the aromas of both raw materials and products and were able to distinguish them according to the catalyst used. In relation to the texture, both catalysts generated products with appropriate consistencies with satisfactory plasticity and spreadability at refrigerator temperatures.

A biocompatible and biodegradable hybrid chitosan/glycerol phosphate hydrogel (CS-GP) was prepared and evaluated as support for enzyme immobilization. In this work a lipase sn-1,3 specific from Rhizopus oryzae was physically immobilized in CS-GP by adsorption (PA) and in CS-GP modified chemically with glutaraldehyde (CS-GP-GA) by covalent attachment (CA). The matrices (pure and chemically modified) and immobilized lipases were characterized by scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetric (TG) analysis. Moreover, a comparative study between free and immobilized lipase was provided in terms of pH, temperature, kinetic parameters and thermal stability. The catalytic properties of biocatalysts were assayed in olive oil hydrolysis. The maximum activities were found at 60◦C/pH 8.5 and 50◦C/pH 7.5 for lipase immobilized by PA and CA, respectively. Both immobilization process turned biocatalysts highly active, since they were stable for 120 days at low (-10◦C) temperatures and around 2-fold more stable than free lipase at 60◦C (high temperature). Thus, results revealed the potential application of chitosan/glycerol phosphate hydrogel (CS-GP) as matrix for lipase immobilization. Nevertheless, better performance was achieved when the lipase was immobilized by covalent attachment.

Resumo Lipase de grau alimentício de Rhizopus oryzae, imobilizada em uma matriz híbrida de polissiloxano-polivinilálcool (SiO2-PVA), foi usada como biocatalisador para mediar reações de interesterificação de uma mistura contendo 65% de gordura de leite e 35% de óleo de soja. Todas as reações ocorreram sob atmosfera inerte de nitrogênio, em reatores de vidro cilíndricos (80 mL) com 40 g da mistura. Avaliou-se a influência das seguintes variáveis: carregamento de biocatalisador (250-1.500 unidades de atividade por grama de mistura), umidade do biocatalisador (5-20%), temperatura (45-60 °C) e tempo de incubação (2-48 h). O progresso das reações foi monitorado pela determinação do conteúdo de ácidos graxos livres, da composição em triacilgliceróis (TAGs) em espécies de carbono e da consistência de produtos interesterificados (IE). As condições reacionais foram estabelecidas com base nos parâmetros que proporcionaram alto grau de interesterificação e consistência do produto final dentro da faixa ideal (200 a 800 gf cm-2). Neste contexto, os melhores resultados foram obtidos utilizando-se 500 U de biocatalisador por grama de mistura, com 10% de umidade, a 45 °C, durante 4 h. Sob essas condições, o valor de consistência do produto interesterificado foi 539,7 ± 38 gf cm-2. Os resultados demonstraram o potencial da lipase imobilizada para alterar o perfil de TAGs da mistura gordura de leite e óleo de soja, permitindo a síntese de lipídios estruturados.

Summary A food grade lipase from Rhizopus oryzae immobilized on a hybrid polysiloxane-polyvinyl alcohol matrix (SiO2-PVA) was used as the biocatalyst to mediate the interesterification reactions of a blend containing 65% milkfat and 35% soybean oil. All the reactions occurred in an inert nitrogen atmosphere in cylindrical glass reactors (80 mL) with 40 g of the milkfat-soybean oil blend. The influence of the following variables was evaluated: biocatalyst loading (250-1500 activity units per gram of blend), biocatalyst moisture content (5-20%), temperature (45-60 °C) and incubation time (2-48 h). The reactions were monitored by determining the free fatty acid content, triacylglycerol (TAGs) composition in carbon species, and the consistency of the interesterified (IE) products. The reaction conditions were set based on the parameters that provided a high interesterification yield and good consistency of the final product within the ideal range (200 to 800 gf cm-2). Hence the best results were obtained using a biocatalyst loading of 500 U g-1 of blend with 10% moisture content at 45 °C for 4 h. Under these conditions the consistency of the interesterified product was 539.7 ± 38 gf cm-2. The results demonstrated the potential of the immobilized lipase to alter the TAGs profile of the milkfat-soybean oil blend, allowing for the production of structured lipids.

O presente trabalho teve como objetivo o pré-tratamento de efluente da indústria de laticínios na hidrólise de lipídeos, empregando lipase de fonte de células animais de baixo custo disponível comercialmente (pâncreas de porco) na formação de gás metano por biodegradabilidade anaeróbia empregando diferentes concentrações de lipase (0,05 e 0,5 % w.v-1). A utilização de lipase no pré-tratamento do efluente acelerou a hidrólise de lipídeos e, conseqüentemente, auxiliou o tratamento biológico resultando na redução da matéria orgânica em termos de Demanda Química de Oxigênio (DQO), cor e sólidos em suspensão como lipídeos. Os melhores resultados em termos de remoção de DQO e cor foram obtidos quando a hidrólise e biodigestão foram realizadas simultaneamente, independente da concentração de lipase empregada. Estes resultados mostram que a hidrólise e biodigestão podem ser realizadas simultaneamente empregando baixa concentração de lipase (0,05% w.v-1), contribuindo para a redução de custo e tempo no processo de biodegradação aneróbia.

Lipids-rich wastewater was partial hydrolyzed with porcine pancreas lipase and the efficiency of the enzymatic pretreatment was verified by the comparative biodegradability tests (crude and treated wastewater). Alternatively, simultaneous run was carried out in which hydrolysis and digestion was performed in the same reactor. Wastewater from dairy industries and low cost lipase preparation at two concentrations (0.05 and 0.5% w.v-1) were used. All the samples pretreated with enzyme showed a positive effect on organic matter removal (Chemical Oxygen Demand-COD) and formation of methane. The best results were obtained when hydrolysis and biodegradation were performed simultaneously, attaining high COD and color removal independent of the lipase concentration. The enzymatic treatment considerably improved the anaerobic operational conditions and the effluent quality (lower content of suspended solids and less turbidity). Thus, the use of enzymes such as lipase seemed to be a very promising alternative for treating the wastewaters having high fat and grease contents, such as those from the dairy industry.

Recent advances for improving physicochemical and nutritional properties of lipids are reviewed, with emphasis on products attaining by biochemical processing of natural fats and oils. Enzymatic interesterification provides an important route to modify physical and nutritional properties of milkfat without generating trans isomers. This process makes use of lipases, a versatile class of enzyme that is able to perform efficiently the target modification in both solvent and solvent free systems. The present review covers important features of lipases, lipase-catalyzed interesterification reactions and their effects on the composition and texture of the resulting product.

Lipases microbianas de Mucor miehei e Candida rugosa foram imobilizadas por ligação covalente em partículas magnetizadas de polisiloxano-álcool polivinílico (POS-PVA). Os derivados imobilizados resultantes foram avaliados em solução aquosa (hidrólise de azeite de oliva) e em solvente orgânico (síntese de butirato de butila). As maiores atividades catalíticas foram encontradas quando o procedimento de ligação foi realizado com lipase de M. miehei. O derivado imobilizado de lipase de M. miehei também apresentou melhores resultados de estabilidade operacional e tempo de meia-vida do que o de lipase de C. rugosa, após sucessivas bateladas de esterificação. O desempenho do derivado imobilizado de C. rugosa foi restringido pelo baixo carregamento de lipase usado na etapa de imobilização. Informações adicionais a respeito de ambos derivados imobilizados também foram obtidas através da composição química (FTIR).

Microbial lipase from Mucor miehei and Candida rugosa were immobilized by covalent binding onto magnetized polysiloxane polyvinyl alcohol particles (POS-PVA). The resulting immobilized derivatives were evaluated in aqueous solution (olive oil hydrolysis) and organic solvent (butyl butyrate synthesis). Higher catalytic activities were found when the coupling procedure was made with M. miehei lipase. Immobilized M. miehei lipase also showed a better operational stability and a higher half-life than C. rugosa lipase after the successive batches of esterification. The performance of C. rugosa immobilized derivative was constrained by the low lipase loading used in the immobilizing step. Further information regarding the both immobilized derivatives was also obtained through chemical composition (FTIR).

O objetivo deste trabalho foi verificar o efeito do cloreto de sódio em substituição à goma arábica, na redução do teor de lipídeos presentes em efluentes de laticínios empregando duas preparações de lipases pancreáticas adquiridas no mercado nacional (Kin Master - LKM e Nuclear- LNU). A preparação enzimática LNU foi mais eficiente na redução de proteínas e lipídeos, mostrando ser uma alternativa promissora para uso no pré-tratamento de águas residuárias com elevado teor desses compostos.

The objective of this work was to evaluate the replacement of Gum Arabic for sodium chloride to reduce fat and organic contents in dairy wastewater using two low cost commercially available lipase preparations from animal source (Kin Master - LKM and Nuclear- LNU). The best performance was achieved when lipase Nuclear (LNU) was used as catalyst. In addition, this lipase preparation has also lower cost, which makes its use a quite promising technique for reduction of suspended solids as proteins and lipids contents found in wastewater generated by dairy industries.

The process of anaerobic digestion has been greatly developed during the last decades for the treatment of wastewater from food industries as for example, wastewaters from sugar and starch manufacturing and from breweries. However, for wastewaters which contain high amounts of fats and proteins, such as those from slaughterhouses and dairies, anaerobic digestion was found to be troublesome, due to the potential of sludge flotation, the formation of scum layers of lipids at the surface of the reactor, which are not digested and the toxicity of the intermediate compounds (long chain fatty acids) generated during the anaerobic digestion of the wastewater. The addition of hydrolytic enzymes, such as lipases prior to the anaerobic digestion can minimize these problems. In this work, this strategy is reviewed and the technical issues that must be considered in determining its feasibility are discussed.

Lipase de Candida rugosa na forma livre foi usada na síntese de butirato de butila pela esterificação direta de n-butanolcom ácido butírico. Um planejamento fatorial completo 2(4) foi empregado para determinar a influência da razão molar do álcool para ácido (1: 0,5-2,5), concentração de agente dessecante (0-20%), concentração de enzima (40-80 mg) e temperatura de incubação (30-60 °C) no rendimento de esterificação. A concentração de agente dessecante foi o fator mais significativo na esterificação, sendo sua influência negativa. O progresso da esterificação foi favorecido para substratos contendo ácido em excesso, mesmo em baixa concentrações de enzima (40 mg), sendo a conversão de 50%. Na região avaliada, a formação do butirato de butila (26,67 g/L) foi maximizada para razão molar (1:2,5), ausência de agente dessecante, concentração de enzima (80 mg) e temperatura de incubação de 30 °C.

Free lipase from Candida rugosa was used for the synthesis of butyl butyrate by direct esterification of butyric acid and butyl alcohol. A full factorial experimental design (2(4)) was employed to determine the effect of alcohol to acid ratio (1: 0.5-2.5), water adsorbent concentration (0-20%), enzyme concentration (40-80 mg) and incubation temperature (30-60 °C) on the esterification yield. Water adsorbent concentration has been found to be the most significant factor on the esterification reaction and its influence was negative. The extent of esterification was higher for substrates containing acid in excess even with a low enzyme concentration of 40 mg and 50% conversion was observed. The maximum predicted values for butyl butyrate yield (92.67%) can be attained with substrate containing acid in excess (molar ratio alcohol to acid 1:2.5), 80 mg enzyme concentration in the absence of water adsorbent at temperature incubation of 30 °C.

This work investigates the reaction parameters of an immobilized lipase in the esterification reaction of n-butanol and butyric acid. Microbial lipase from Candida rugosa was immobilized onto styrene-divinylbenzene copolymer (STY-DVB) and subsequently introduced in an organic medium containing substrates in appropriate concentrations. Heptane was selected as solvent on the basis of its compatibility with the resin and the enzyme. The influence of molar ratio of acid to alcohol, amount of immobilized lipase and temperature on the butyl butyrate formation was determined. The results were compared with those achieved with free lipase and Lipozyme (commercially immobilized lipase) under the same operational conditions.