Linear and non-linear regression analysis for the biosorption kinetics of methylene blue

The nonviable biomass of Rhizopus sp. R-18, Penicillium candidum and Penicillium chrysogenum was studied for biosorption of methylene blue (MB). The sorption of MB was studied be performing batch kinetic experiments. Kinetic measurements showed that sorption of MB reached equilibrium in 4 hours. The batch sorption models, based on a pseudo-first, pseudo-second and pseudo-nth order were applied to predict the rate constant of sorption and the equilibrium capacity. The linear and nonlinear least-square methods were used to obtain the kinetic parameters. The best-fit model was identified using statistic analysis. The results showed that both linear and nonlinear form of pseudo- second order expression could be used to fit the experimental data but nonlinear method may be a better way to obtain the desired parameters. As well the pseudo n-th order kinetic model was successfully applied to the kinetic data. The order (n) of adsorption reaction was found for all employed biosorbents: for Rhizopus sp. R-18 it had value 3.1, P. candidum 3.0 and P. chrysogenum 3.8.

Development of the Technology of Soft Camembert-type Cheese with Flowery rind in Morocco

Camembert is a French cheese characterized by a soft paste and a flowery rind. Morocco imports camembert cheese paste as a raw material. Today, Moroccan cheese manufacturers are looking to uncover the secrets associated with making Camembert cheese including the ones facilitating the smooth running of the stages of its manufacture. In Morocco, this type of cheese is scarce, not fully enumerated and no studies have been conducted on it as of yet. This is why we tried to manufacture this type of cheese in the laboratory to valorize it in Morocco due to its growing importance in the international market. The objective of this work is the optimization of the production of soft cheese with a flowery rind such as Camembert, while determining the quantity of microorganisms used for the fermentation of milk. Four types of industrial ferments with pre-established doses were used in addition to rennet. Fifteen cheese samples were made. The physico-chemical parameters checked during the manufacturing tests were fat content, pH and titratable acidity. The results show that the production of cheese requires the use of milk of good microbiological quality as well as the selection of specific ferments depending on the type of cheese to make. The best amount of the ferments used to make Camembert-type cheese during this work is: from 0.6% to 0.8% mesophilic if the viability rate is more than 3.73 x102, 0.3 % to 0.4% thermophilic if the viability rate is more than 3.95 x 103, 1% to 5% yeast if the viability rate is more than 2.60 x 103 , and 2% to 10% mesophilic if the viability rate is more than 3.30 x 103. The most effective dose formula is two doses of Mesophiles for one dose of Thermophile. Or two doses of Penicillium Candidum mold for one dose of Geotrichum Candidum yeast. The microbiological quality of the milk used in this work and the cheese produced during this work is generally acceptable and conforms to Moroccan standards. During each Camembert production, whey quantity was measured. Cheese yield was determined by measuring cheese portions before and after ripening from a known quantity of milk. The sensory properties of dairy products are defined by their appearance, texture and flavor and are ultimately evaluated by tasting panels from the Agronomic and Veterinary Institute of Rabat.

Efeito do tratamento térmico e adição do Lactobacillus acidophilus no processamento do queijo tipo brie

O queijo tipo brie é um produto com boa aceitação no Brasil, a estimativa é que esta classe de queijo represente cerca de 3% da produção mundial de queijos. O presente trabalho teve como objetivo desenvolver queijos tipo brie com leite cru e pasteurizado adicionados de cultura probiótica, constituída de Lactobacillus acidophilus, cultura inicial Lactococcus lactis, cultura secundária Penicillium candidum, bem como avaliar o efeito do tratamento térmico e da adição da cultura probiótica nas características físico-químicas e perfil eletroforético após trinta dias de maturação, a 10 ºC. Os queijos tipo brie foram processados em batelada, sendo processados cinco formulações. Foram realizadas caracterizações físico-químicas e perfil eletroforético bem como a viabilidade da cultura probiótica do L. acidophilus após a maturação. As amostras com tratamento térmico apresentaram características diferentes das obtidas com leite cru, refletindo na composição físico-química dos queijos. A mobilidade eletroforética relativa, posição das bandas protéicas, e seus respectivos pesos moleculares em maior abundância nos queijos foram identificadas como: α S1-caseína (23,61 kDa), α S2-caseína (25,23 kDa), β-caseína (23,98 kDa), к-caseína (19,02 kDa) e α- lactoalbumina (14,2 kDa). Em todos os queijos obtidos o microrganismo Lactobacillus acidophilus apresentaram viabilidade do microrganismo acima do mínimo recomendado, na ordem de 107 UFC/g. O que mostra que o queijo tipo brie é uma boa matriz para o probiótico analisado.

The technology of soft Camembert cheese with the usage of different bacterial preparations

The aim of the work was to develop a technology of soft Camembert cheese from pasteurized cow's milk using various bacterial preparations and to investigate its basic physicochemical and organoleptic properties. Two experimental samples of cheese were made: sample 1 – culture of direct application of mesothermophilic type RSF-742 + culture of white mold (Penicillium candidum + Geotrichum candidum) + rennet enzyme + calcium chloride; sample 2 – culture of direct application of mesophilic type CHN-19 + culture of white mold (Penicillium candidum + Geotrichum candidum) + rennet enzyme + calcium chloride. The finished product analyzed by the organoleptic and physicochemical parameters. Syneretic properties of rennet clots were studied after the process of fermentation and coagulation at a temperature of 32 ºC. The sample with the use of CNH-19 was characterized by the best consistency and pronounced mushroom and creamy aroma. Sample № 1, made with the bacterial preparation RSF-742, was characterized by a less pronounced aroma and structure, typical of Camembert cheese. It was found that the sample №1 (RSF-742) was characterized by higher syneretic properties. According to syneretic properties, lower moisture content characterized sample 1 (62 %) versus sample 2 (64 %). The volume of serum released in 1 hour was 65 % for sample 1 and 62 % for sample 2. The highest values for the fat content was sample 1 – 43 %, and sample 2 – 42 %. The content of salt did not differ, in sample № 1 – 1.8 % and in sample № 2 – 1.75 %. There were changes in the active acidity of the finished product when using different bacterial preparation. Lower pH values in sample 1 – 6.2, and slightly higher in sample 2 – 6.5 were observed. The highest number of points according to the results of the score was given to sample № 2 – 86 points, sample № 1 – 77 points out of possible 100.

Biochemical characteristics of reduced-fat cheese made from high-heat treated goat’s milk supplemented with Penicillium candidum

Novel reduced-fat goat-cheese (R) was produced from high-pasteurized milk using Penicillium candidum as an adjunct. A full-fat goat-cheese (F) from pasteurized milk without mold addition was produced for comparison reasons. Physicochemical analyses of the two cheeses were performed through the 14-d period of ripening. The effect of P.candidum on proteolysis of goat-cheese caseins and the production of hydrophilic and hydrophobic peptides during cheese ripening were investigated. To our knowledge, similar results for reduced-fat, mold-ripened, goat-milk cheeses have not been previously reported before. R-cheese exhibited a higher organoleptic score and developed properties similar to Kopanisti, which is a Protected Designation of Origin Greek soft cheese with specific intense flavour manufactured from raw milk without the use of starters. Moreover, R-cheese had significantly higher moisture, protein in dry matter and water soluble nitrogen contents than F-cheese and was less adhesive. The high-pasteurization improved the texture and cheese yield, while the use of P. candidum as an adjunct improved the flavour, increased and accelerated proteolysis in R-cheese. According to the results, the technology for R-cheese employed in the present study can be easily adopted and could be used to produce a reduced-fat goat-cheese.

Biocorrosion of AISI 4340 Steel

ABSTRACTThe objective of the present work is to evaluate the Penicillium candidum filamentous fungi biocorrosion effects on AISI 4340 steel. Small AISI 4340 steel blocks are exposed to a biocorrosion process inside glass tubes containing culture media (Sabouraud Dextrose HIMEDIA broth) inoculated with Penicillium candidum spores for 14 days, at 25ºC constant temperature. The surface microstructures are evaluated by scanning electron microscopy, atomic force microscopy, and the chemical composition by energy dispersive X-ray spectroscopy. Comparison of micrographies before and after biocorrosion shows that surface structures present morphological alterations, suggesting corrosion wear. Grain contours can no longer be visualized and oxygen content on the steel surface increases to 32% after biocorrosion. Besides, topographic parameters like root mean square roughness (Rms), arithmetic mean roughness (Ra) and mean roughness (Rz) increase 57%, 132%, and 71%, respectively, from their initial values. It is concluded that AISI 4340 steel is reasonably susceptible to corrosion.