Modified atmosphere in post-harvest mangaba fruit conservation in three maturity degrees / Atmosfera modificada passiva na conservação pós-colheita de mangaba em três graus de maturação

Mangaba fruits are highly perishable, presenting short shelf life, rapid maturation and delicate and fragile bark, making it difficult to commercialize over long distances. The objective of this study was to evaluate the best harvest maturity degree as well as the most suitable modified atmosphere for post-harvest quality preservation. Mangaba fruits maturity degrees were: green, middle-mature and mature; and packed in three types of modified atmosphere: polyethylene terephthalate PET; expanded polystyrene tray with polyvinyl chloride film (PVC) and low density polyethylene (LDPE) packaging with lid. In each evaluation were analysed: loss of fresh mass, firmness, ascorbic acid, soluble solids, titratable acidity, pH and reducing sugars. Falling mangaba limit the storage period in 6 days, regardless modified atmosphere used, presenting greater loss of mass, reducing sugar content and less firmness. These fruits must be destined to processing, in order to add value to the product. Mangabas harvested in middle-mature stage conditioned in polyethylene tray with PVC stored at a temperature 3 C ± 1 and 80% ± 1 RU maintains ascorbic acid contents during the storage period.

Os frutos da mangabeira são altamente perecíveis, apresentando vida de prateleira curta, maturação rápida e casca delicada e frágil, dificultando sua comercialização a longas distâncias.Objetivou-se avaliar o melhor grau de maturação para colheita assim como a atmosfera modificada mais adequada para a conservação da qualidade pós-colheita da mangaba.Foram utilizados frutos de mangaba nos estádios verde, de vez e maduro; e acondicionadas em três tipos de atmosfera modificada: polietileno tereftalato – PET, bandeja de poliestireno expandido, com filme de cloreto de polivinila (PVC) e embalagem de polietileno de baixa densidade (PEBD) com fechamento.A cada retirada foram analisadas:perda de massa fresca, firmeza, ácido ascórbico, sólidos solúveis, acidez titulável, pH e açúcares redutores.Mangabas de caída ou maduras limitam até 6 dias o período de armazenamento, independente da atmosfera modificada utilizada, apresentando maior perda de massa (2,39 a 2,91%),teor de açúcar redutor (4,05 a 4,58%) e menor firmeza (0,98 a 1,47 N).Esses frutos devem ser destinados ao processamento, de modo a agregar valor ao produto.Mangabas colhidas no estádio de vez acondicionadas em bandeja de polietileno com PVC armazenadas em temperatura de 3°C ± 1 e 80% ± 1 UR mantém teores de ácido ascórbico no período de armazenamento.

Modified atmosphere in post-harvest mangaba fruit conservation in three maturity degrees / Atmosfera modificada passiva na conservação pós-colheita de mangaba em três graus de maturação

Mangaba fruits are highly perishable, presenting short shelf life, rapid maturation and delicate and fragile bark, making it difficult to commercialize over long distances. The objective of this study was to evaluate the best harvest maturity degree as well as the most suitable modified atmosphere for post-harvest quality preservation. Mangaba fruits maturity degrees were: green, middle-mature and mature; and packed in three types of modified atmosphere: polyethylene terephthalate PET; expanded polystyrene tray with polyvinyl chloride film (PVC) and low density polyethylene (LDPE) packaging with lid. In each evaluation were analysed: loss of fresh mass, firmness, ascorbic acid, soluble solids, titratable acidity, pH and reducing sugars. Falling mangaba limit the storage period in 6 days, regardless modified atmosphere used, presenting greater loss of mass, reducing sugar content and less firmness. These fruits must be destined to processing, in order to add value to the product. Mangabas harvested in middle-mature stage conditioned in polyethylene tray with PVC stored at a temperature 3 C ± 1 and 80% ± 1 RU maintains ascorbic acid contents during the storage period.(AU)

Os frutos da mangabeira são altamente perecíveis, apresentando vida de prateleira curta, maturação rápida e casca delicada e frágil, dificultando sua comercialização a longas distâncias.Objetivou-se avaliar o melhor grau de maturação para colheita assim como a atmosfera modificada mais adequada para a conservação da qualidade pós-colheita da mangaba.Foram utilizados frutos de mangaba nos estádios verde, de vez e maduro; e acondicionadas em três tipos de atmosfera modificada: polietileno tereftalato PET, bandeja de poliestireno expandido, com filme de cloreto de polivinila (PVC) e embalagem de polietileno de baixa densidade (PEBD) com fechamento.A cada retirada foram analisadas:perda de massa fresca, firmeza, ácido ascórbico, sólidos solúveis, acidez titulável, pH e açúcares redutores.Mangabas de caída ou maduras limitam até 6 dias o período de armazenamento, independente da atmosfera modificada utilizada, apresentando maior perda de massa (2,39 a 2,91%),teor de açúcar redutor (4,05 a 4,58%) e menor firmeza (0,98 a 1,47 N).Esses frutos devem ser destinados ao processamento, de modo a agregar valor ao produto.Mangabas colhidas no estádio de vez acondicionadas em bandeja de polietileno com PVC armazenadas em temperatura de 3°C ± 1 e 80% ± 1 UR mantém teores de ácido ascórbico no período de armazenamento.(AU)

Production and Catalytic Properties of Amylases from Lichtheimia ramosa and Thermoascus aurantiacus by Solid-State Fermentation.

The present study compared the production and the catalytic properties of amylolytic enzymes obtained from the fungi Lichtheimia ramosa (mesophilic) and Thermoascus aurantiacus (thermophilic). The highest amylase production in both fungi was observed in wheat bran supplemented with nutrient solution (pH 4.0) after 96 hours of cultivation, reaching 417.2 U/g of dry substrate (or 41.72 U/mL) and 144.5 U/g of dry substrate (or 14.45 U/mL) for L. ramosa and T. aurantiacus, respectively. The enzymes showed higher catalytic activity at pH 6.0 at 60°C. The amylases produced by L. ramosa and T. aurantiacus were stable between pH 3.5-10.5 and pH 4.5-9.5, respectively. The amylase of L. ramosa was stable at 55°C after 1 hour of incubation, whereas that of T. aurantiacus maintained 60% of its original activity under the same conditions. Both enzymes were active in the presence of ethanol. The enzymes hydrolyzed starch from different sources, with the best results obtained with corn starch. The enzymatic complex produced by L. ramosa showed dextrinizing and saccharifying potential. The enzymatic extract produced by the fungus T. aurantiacus presented only saccharifying potential, releasing glucose monomers as the main hydrolysis product.

Influence of different substrates on the production of a mutant thermostable glucoamylase in submerged fermentation.

Three mutations, Ser54→Pro, Thr314→Ala, and His415→Tyr, were identified in Aspergillus awamori glucoamylase gene expressed by Saccharomyces cerevisiae. The mutant glucoamylase (GA) was substantially more thermostable than a wild-type GA at 70 °C, with a 3.0 KJ mol(-1) increase in the free energy of thermo-inactivation. The effect of starch from different botanical sources on the production of this GA was measured in liquid fermentation using commercial soluble starch, cassava, potato, and corn as the carbon source. The best substrate for GA production was the potato starch showing an enzymatic activity of 6.6 U/mL. The commercial soluble starch was also a good substrate for the enzyme production with 6.3 U/mL, followed by cassava starch and corn starch with 5.9 and 3.0 U/mL, respectively. These results showed a significant difference on GA production related to the carbon source employed. The mutant GA was purified by acarbose-Sepharose affinity chromatography; the estimated molecular mass was 100 kDa. The mutant GA exhibited optimum activity at pH 4.5 and an optimum temperature of 65 °C.

Screening and production study of microbial xylanase producers from Brazilian Cerrado.

Hemicelluloses are polysaccharides of low molecular weight containing 100 to 200 glycosidic residues. In plants, the xylans or the hemicelluloses are situated between the lignin and the collection of cellulose fibers underneath. The xylan is the most common hemicellulosic polysaccharide in cell walls of land plants, comprising a backbone of xylose residues linked by beta-1,4-glycosidic bonds. So, xylanolytic enzymes from microorganism have attracted a great deal of attention in the last decade, particularly because of their biotechnological characteristics in various industrial processes, related to food, feed, ethanol, pulp, and paper industries. A microbial screening of xylanase producer was carried out in Brazilian Cerrado area in Selviria city, Mato Grosso do Sul State, Brazil. About 50 bacterial strains and 15 fungal strains were isolated from soil sample at 35 degrees C. Between these isolated microorganisms, a bacterium Lysinibacillus sp. and a fungus Neosartorya spinosa as good xylanase producers were identified. Based on identification processes, Lysinibacillus sp. is a new species and the xylanase production by this bacterial genus was not reported yet. Similarly, it has not reported about xylanase production from N. spinosa. The bacterial strain P5B1 identified as Lysinibacillus sp. was cultivated on submerged fermentation using as substrate xylan, wheat bran, corn straw, corncob, and sugar cane bagasse. Corn straw and wheat bran show a good xylanase activity after 72 h of fermentation. A fungus identified as N. spinosa (strain P2D16) was cultivated on solid-state fermentation using as substrate source wheat bran, wheat bran plus sawdust, corn straw, corncob, cassava bran, and sugar cane bagasse. Wheat bran and corncobs show the better xylanase production after 72 h of fermentation. Both crude xylanases were characterized and a bacterial xylanase shows optimum pH for enzyme activity at 6.0, whereas a fungal xylanase has optimum pH at 5.0-5.5. They were stable in the pH range 5.0-10.0 and 5.5-8.5 for bacterial and fungal xylanase, respectively. The optimum temperatures were 55 and 60 degrees C for bacterial and fungal xylanase, respectively, and they were thermally stable up to 50 degrees C.

Optimization of cyclodextrin glucanotransferase production from Bacillus clausii E16 in submerged fermentation using response surface methodology.

Cyclodextrin glucanotransferase production from Bacillus clausii E16, a new bacteria isolated from Brazilian soil samples was optimized in shake-flask cultures. A 2(4) full-factorial central composite design was performed to optimize the culture conditions, using a response surface methodology. The combined effect among the soluble starch concentration, the peptone concentration, the yeast extract concentration, and the initial pH value of the culture medium was investigated. The optimum concentrations of the components, determined by a 2(4) full-factorial central composite design, were 13.4 g/L soluble starch, 4.9 g/L peptone, 5.9 g/L yeast extract, and initial pH 10.1. Under these optimized conditions, the maximum cyclodextrin glucanotransferase activity was 5.9 U/mL after a 48-h fermentation. This yield was 68% higher than that obtained when the microorganism was cultivated in basal culture medium.

Purification and characterization of a cyclomaltodextrin glucanotransferase from Paenibacillus campinasensis strain H69-3.

A cyclomaltodextrin glucanotransferase (E.C. 2.4.1.19) from a newly isolated alkalophilic and moderately thermophilic Paenibacillus campinasensis strain H69-3 was purified as a homogeneous protein from culture supernatant. Cyclomaltodextrin glucanotransferase was produced during submerged fermentation at 45 degrees C and purified by gel filtration on Sephadex G50 ion exchange using a Q-Sepharose column and ion exchange using a Mono-Q column. The molecular weight of the purified enzyme was 70 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the pI was 5.3. The optimum pH for enzyme activity was 6.5, and it was stable in the pH range 6.0-11.5. The optimum temperature was 65 degrees C at pH 6.5, and it was thermally stable up to 60 degrees C without substrate during 1 h in the presence of 10 mM CaCl(2). The enzyme activity increased in the presence of Co(2+), Ba(2+), and Mn(2+). Using maltodextrin as substrate, the K(m) and K(cat) were 1.65 mg/mL and 347.9 micromol/mg x min, respectively.

Evaluation of solid and submerged fermentations for the production of cyclodextrin glycosyltransferase by Paenibacillus campinasensis H69-3 and characterization of crude enzyme.

Cyclodextrin glycosyltransferase (CGTase) is an enzyme that produces cyclodextrins from starch by an intramolecular transglycosylation reaction. Cyclodextrins have been shown to have a number of applications in the food, cosmetic, pharmaceutical, and chemical industries. In the current study, the production of CGTase by Paenibacillus campinasensis strain H69-3 was examined in submerged and solid-state fermentations. P. campinasensis strain H69-3 was isolated from the soil, which grows at 45 degrees C, and is a Gram-variable bacterium. Different substrate sources such as wheat bran, soybean bran, soybean extract, cassava solid residue, cassava starch, corn starch, and other combinations were used in the enzyme production. CGTase activity was highest in submerged fermentations with the greatest production observed at 48-72 h. The physical and chemical properties of CGTase were determined from the crude enzyme produced from submerged fermentations. The optimum temperature was found to be 70-75 degrees C, and the activity was stable at 55 degrees C for 1 h. The enzyme displayed two optimum pH values, 5.5 and 9.0 and was found to be stable between a pH of 4.5 and 11.0.

Purification and characterization of two xylanases from alkalophilic and thermophilic Bacillus licheniformis 77-2.

The alkalophilic bacteria Bacillus licheniformis 77-2 produces significant quantities of thermostable cellulase-free xylanases. The crude xylanase was purified to apparent homogeneity by gel filtration (G-75) and ionic exchange chromatography (carboxymethyl sephadex, Q sepharose, and Mono Q), resulting in the isolation of two xylanases. The molecular masses of the enzymes were estimated to be 17 kDa (X-I) and 40 kDa (X-II), as determined by SDS-PAGE. The Km and V(max) values were 1.8 mg/mL and 7.05 U/mg protein (X-I), and 1.05 mg/mL and 9.1 U/mg protein (X-II). The xylanases demonstrated optimum activity at pH 7.0 and 8.0-10.0 for xylanase X-I and X-II, respectively, and, retained more than 75% of hydrolytic activity up to pH 11.0. The purified enzymes were most active at 70 and 75 degrees C for X-I and X-II, respectively, and, retained more than 90% of hydrolytic activity after 1 h of heating at 50 degrees C and 60 degrees C for X-I and X-II, respectively. The predominant products of xylan hydrolysates indicated that these enzymes were endoxylanases.