The improvement of guava (Psidium guajava) juice quality using crude multi-enzymatic extracts obtained from yeasts.

Guava juice is cloudy and viscous, which hinders filtration, decreases yield, and causes the loss of quality after its processing and during storage. This study aimed to evaluate enzymatic treatment effects using crude multi-enzymatic extracts (CME) obtained from Rhodotorula mucilaginosa, Rhodotorula orizycola, and Pseudozyma sp. produced by submerse fermentation in the extraction of juice guava. Mixtures of 100 ml of guava pulp and multi-enzymatic extracts proposed by Doehlert planning were incubated under constant agitation at 150 rpm and 50°C, and a Doehlert design was applied as a multivariate optimization strategy. The optimal conditions using the multi-enzymatic extract were: 0.4% (v/v) of CME for 131 min for the multi-enzymatic treatment using Pseudozyma sp.; 3.0% (v/v) of CME for 154 min using the R. mucilaginosa CME; and 5.0% (v/v) of CME for 90 min using R. oryzicola. The maximum viscosity reduction values for the juices treated with the CME of yeasts were 10.33%, 86.38%, and 13.33% for the juices treated with the CME of Pseudozyma sp., R. mucilaginosa, and R. orizycola, respectively. The physical-chemical properties were improved after treatment with CMEs, yielding a reduction of clarity, increase of total soluble solids and reducing sugars, and decreasing the acidity (pH) for all treatments with enzymatic extracts of all strains. The yeasts studied showed a potential for CME production to be applied to juice, improving the quality of the juice, and R. mucilaginosa was the most prominent yeast due to most significant reduction of viscosity in guava juice.

Clarification of tangerine juice using cellulases from Pseudoyma sp.

Tangerine juice was treated with crude extract containing cellulase from Pseudozyma sp. obtained by liquid fermentation. The thermal stability of cellulase was investigated by incubating crude extract at different temperatures and times. The pulp, obtained from tangerine, was pasteurized at 85 °C for 5 min and then used in a clarification process with a Doehlert experimental design. The results showed that the cellulase obtained from Pseudozyma sp. is thermostable at temperatures of 60, 70 and 90 °C and retained 98%, 88% and 80% of activity, respectively, after a 1-h incubation time. The optimum conditions for clarification were verified by varying the enzyme extract concentration (%, v v-1) and the time (minutes) in a shaker at 150 rpm, at 50 °C. The optimum condition for clarification was obtained in the 80th min with a 1.25% enzymatic extract concentration (v v-1), resulting in a reduction of tangerine juice viscosity by 65%. The analysis of physical and chemical parameters of tangerine juice after clarification showed that the enzyme extract improved the process responsible for the clarification of tangerine juice. The results are promising since this is a methodology that can be used in the citrus juice industry.

Production and partial characterization of ß-1,3-glucanase obtained from Rhodotorula oryzicola.

The current study aims to assess the kinetics of population growth of Rhodotorula oryzicola and the production of ß-1,3-glucanase (EC 3.2.1.39) enzyme by this yeast. It also aims to obtain the optimum conditions of ß-1,3-glucanase enzymatic activity by varying the pH as well as to study the enzyme thermostability. R. oryzicola population doubled within 12 hr. During this period, 9.26 generations were obtained, with 1 hr and 29 min of interval from one generation to the other, with specific growth rate (µ) of 0.15 (hr-1). The entire microorganism growth process was monitored during ß-1,3-glucanases production, and the maximum value was obtained in the stationary phase in the 48-hr fermentation period. pH and temperature optimum values were 4.7 and 96°C, respectively. The enzyme maintained 88% of its activity when submitted to the temperature of 90°C for an incubation period of 1 hr. The results show that the enzyme can be used in industrial processes that require high temperatures and acidic pH.

Kinetic and thermodynamic parameters, and partial characterization of the crude extract of tannase produced by Saccharomyces cerevisiae CCMB 520.

Tannase can be used in different industrial sectors such as in food (juices and wine) and pharmaceutical production (trimethoprim) because it catalyses the hydrolysis of hydrolysable tannins. The aim of the current study is to assess the tannase found in the crude extract of Saccharomyces cerevisiae CCMB 520, and to set its catalytic and thermodynamic properties. The enzyme was optimally active at pH 6.0 and temperature 30 °C. Tannase was activated by Na+, Ca2+, K+ at 5 × 10-3 mol/L. The half-life at 30 °C was 3465.7 min. The activation energy was 40.32 kJ/mol. The Gibbs free energy, enthalpy and entropy at 30 °C were 85.40, 48.10 and -0.12 kJ/mol K, respectively. Our results suggest that the tannase found in the crude extract of S. cerevisiae is an attractive enzyme for industrial applications, such as for beverage manufacturing and gallic acid production, due its catalytic and thermodynamic properties (heat-stable and resistant to metal ions).

Application of aqueous biphasic systems as strategy to purify tannase from Aspergillus tamarii URM 7115.

The aims of the current study are to assess the influence of polyethylene glycol (PEG) concentration, molar mass, pH, and citrate concentrations on aqueous biphasic systems based on 24 factorial designs, as well as to check their capacity to purify tannase secreted by Aspergillus tamarii URM 7115. Tannase was produced through submerged fermentation at 26°C for 67 h in Czapeck-Dox modified broth and added with yeast extract and tannic acid. The factorial design was followed to assess the influence of PEG molar mass (MPEG 600; 4,000 and 8,000 g/ mol), and PEG (CPEG 20.0; 22.0 and 24.0% w/w) and citrate concentrations (CCIT 15.0, 17.5, and 20.0%, w/w), as well as of pH (6.0, 7.0, and 8.0) on the response variables; moreover, partition coefficient (K), yield (Y), and purification factor (PF) were analyzed. The most suitable parameters to purify tannase secreted by A. tamarii URM 7115 through a biphasic system were 600 (g/mol) MPEG, 24% (w/w) CPEG, 15% (w/w) CCIT at pH 6.0 and they resulted in 6.33 enzyme partition, 131.25% yield, 19.80 purification factor and 195.08 selectivity. Tannase secreted by A. tamarii URM 7115 purified through aqueous biphasic systems composed of PEG/citrate can be used for industrial purposes, since it presents suitable purification factor and yield.

Antimicrobial activity of Marcetia DC species (Melastomataceae) and analysis of its flavonoids by reverse phase-high performance liquid chromatography coupled-diode array detector.

BACKGROUND: Marcetia genera currently comprises 29 species, with approximately 90% inhabiting Bahia (Brazil), and most are endemic to the highlands of the Chapada Diamantina (Bahia). Among the species, only M. taxifolia (A.St.-Hil.) DC. populates Brazil (state of Roraima to Paraná) and also Venezuela, Colombia, and Guyana. OBJECTIVE: This work evaluated the antimicrobial activity of hexane, ethyl acetate, and methanol extracts of three species of Marcetia (Marcetia canescens Naud., M. macrophylla Wurdack, and M. taxifolia A.StHil) against several microorganism. In addition, the flavonoids were analyzed in extracts by HPLC-DAD. MATERIALS AND METHODS: The tests were made using Gram-positive (three strains of Staphylococcus aureus) and Gram-negative (two strains of Escherichia coli, a strain of Pseudomonas aeruginosa and another of Salmonella choleraesius) bacteria resistant and nonresistant to antibiotics and yeasts (two strains of Candida albicans and one of C. parapsilosis) by the disk diffusion method. Solid-phase extraction (SPE) was performed on the above extracts to isolate flavonoids, which were subsequently analyzed by high performance liquid chromatography coupled diode array detector (HPLC-DAD). RESULTS: Results showed that extracts inhibited the Gram-positive bacteria and yeast. The hexane extracts possessed the lowest activity, while the ethyl acetate and methanolic extracts were more active. CONCLUSION: Marcetia taxifolia was more effective (active against 10 microorganisms studied), and only its methanol extract inhibited Gram-negative bacteria (P. aeruginosa and S. choleraesius). SPE and HPLC-DAD analysis showed that M. canescens and M. macrophylla contain glycosylated flavonoids, while the majority of extracts from M. taxifolia were aglycone flavonoids.