Reusable nanobiocatalysts for the efficient extraction of pigments from orange peel

Nagpur mandarin orange (Citrus reticulata) peels were subjected to treatment with nanobiocatalysts in the form of cellulase and pectinase immobilized magnetic nanoparticles (MNPs). MNPs (Fe3O4) with average diameter in range of 40–90 nm were immobilized with cellulase and pectinase through APTES and glutaraldehyde. Treatment followed by extraction into organic solvents resulted in 8-9 fold increase in extraction of carotenoidic pigments compared to use of free enzymes. Optimum pH and temperature for the process were determined to be 5.0 and 50 °C, respectively. The nanobiocatalysts could be reused across three cycles with only 15 % drop in yield per cycle. Dinitrosalicylic acid assays showed that superior peel hydrolysis also led to greatest extent of pigment extraction.by Sanjay Kumar, Pramila Sharma, Poonam Ratrey and Bhaskar Datt

Relation between citric acid production by solid-state fermentation from cassava bagasse and respiration of Aspergillus niger LPB 21 in semi-pilot scale

The aim of this work was to study the relation between citric acid production and respiration of Aspergillus niger LPB 21 in solid-state fermentation of cassava bagasse. The experiments were carried out in horizontal drum bioreactor coupled with a gas chromatography system. Fermentation was conduced for 144 h with initial substrate moisture of 60% using heat-treated cassava bagasse as sole carbon source. The exhausted air from the bioreactor was analyzed for the monitoring of CO2 produced and O2 consumed in order to estimate the biomass biosynthesis by the fungal culture. The metabolic activity of A. niger growth was associated to citric acid production. The system using FERSOL software determined 4.372 g of biomass/g of consumed O2. Estimated and analytically determined biomass values followed the same pattern showing that the applied mathematical model was adapted.<br>Este estudo permitiu verificar a relação ente a produção de ácido cítrico e a respiração do Aspergillus niger LPB 21 na fermentação no estado sólido do bagaço de mandioca. Os experimentos foram realizados em biorreator tipo tambor horizontal acoplado com um sistema de cromatografia gasosa. A fermentação foi conduzida durante 144 h com 60% de umidade inicial do substrato usando bagaço de mandioca termicamente tratado como única fonte de carbono. O ar de saída do biorreator foi analisado para monitorar a produção de CO2 e o consumo de O2 com o objetivo de estimar a biomassa sintetizada pelo fungo. A atividade metabólica do crescimento do Aspergillus niger está associada à produção de ácido cítrico. Usando o software FERSOL, o sistema determinou uma biomassa de 4.372 g de biomassa/g de O2 consumido. Os valores da biomassa estimada e da determinada analiticamente seguiram a mesma tendência mostrando que o modelo matemático aplicado foi adaptado