Leila Queiroz Zepka

Thermal Degradation Kinetics of Carotenoids in a Cashew Apple Juice Model and Its Impact on the System Color

The thermal degradation kinetics of the main carotenoids of cashew apple in a juice model system was studied by HPLC and related to the changes of its CIELAB color parameters. Similar isomerization equilibrium constants and activation energies were observed for both all-trans-beta-carotene and all-trans-beta-cryptoxanthin. The curves for the decay of the main carotenoids and color changes showed a biphasic behavior that was best fitted by a biexponential equation. For the same heating conditions (60 or 90 degrees C), similar rate constants for the fast (gamma(1)) and slow (gamma(2)) decays were obtained for both the chemical (carotenoids) and physical (color) parameters monitored in the present research. This fact indicates that color parameters, such as DeltaE*, are good predictors of both all-trans-beta-cryptoxanthin and all-trans-beta-carotene thermal degradation. A mechanism for thermal carotenoid degradation was proposed, involving parallel irreversible and reversible coupled reactions of both the initial all-trans-beta-cryptoxanthin and all-trans-beta-carotene to yield, respectively, degradation compounds and mono-cis isomers.

Nutritional evaluation of single-cell protein produced by Aphanothece microscopica Nägeli

The aim of this research was to evaluate the nutritional characteristics of Aphanothece microscopica Nägeli microalgae developed in the effluent of parboiled rice. The biomass was biologically evaluated by rat growth, during 10 days for nitrogen balance studies and 28 days for blood analysis. The feeding of Aphanothece biomass diets resulted in a nitrogen balance of 1.42 g/rat/day, an apparent biological value of 73.33%, an apparent digestibility of 82.12%, an apparent net protein utilization of 60.21% and a net protein retention of 2.40. Significant differences between the glycemic indices of rats fed with the Aphanothece and those fed with the control diet were not observed. However, the total cholesterol levels in the plasma of rats fed the test diet proved to be significantly lower. These results suggest the use of A. microscopica Nägeli developed in parboiled rice effluent as a potential source of single-cell protein.

Perfil sensorial de iogurte light, sabor pêssego

SuMMarY SENSORY PROFILE OF PEACH FLAVORED LIGHT YOGURT. The descriptive terminology and sensory profile of three samples of peach flavored light yogurt were determined using methodology based on the Quantitative Descriptive Analysis (QDA). A sensory panel consensually defined sensory descriptors, their respective reference materials and the descriptive evaluation ballot. Ten individuals were selected as judges and trained. They used the following as criteria: discriminant power, reproducibility and individual consensus. Twelve descriptors were devised showing similarities and differences among the light yogurt samples. Each descriptor was evaluated using a nine-centimeter non-structured scale with the intensity terms anchored at its ends. The data were analysed by ANOVA, the Tukey test and the Principal Component Analysis (PCA). The results showed a great difference in the sensory profile of light yogurts, where sample C showed more variation. The PCA showed sample A to be more distinguished by the sweetness, flavor of peach and firmness of fruit pieces. Sample B was characterized by the brightness, peach color and creamy aspect. Sample C had a higher intensity of sourness and astringency, a more farinaceous texture and more artificial aroma of peach. According to the acceptability test, all the products were accepted positively for all evaluated attributes. Sample C which contains soy protein in its formulation showed that

The role of photoperiods on photobioreactors - A potential strategy to reduce costs.

The aim of this work was evaluate the role of photoperiods (long-term, frequencies and short) on the growth and lipid content of microalgae Scenedesmus obliquus CPCC05. The results showed that Scenedesmus obliquus can store sufficient energy to sustain cell growth for continuous periods of up to 2h in the dark, without affecting the photosynthetic rate. The values for maximum biomass (9.58mg/Lh) and lipid productivities (2.56mg/Lh) were obtained at photoperiod of 0.91:0.09s (light:dark) and 48 t/d, respectively. Moreover, the best trade-offs between biomass productivity and light energy economy occurred in photoperiods of 0.5:0.5s and 0.91:0.09s (light:dark), and those between lipid productivity and light energy economy occurred in the frequency photoperiod of 24 and 48 t/d. Thus, the use of the photoperiods are an effective strategy for reducing costs of microalgal biomass production.

Microencapsulação de probióticos: avanços e perspectivas

Because of their health benefits, probiotics have been incorporated into a range of dairy products, including yogurts, soft-, semi-hard and hard cheeses, ice cream, milk powders and frozen dairy desserts. However, there are still several problems with respect to the low viability of probiotic bacteria in dairy foods. This review focuses mainly on current knowledge and techniques used in the microencapsulation of probiotic microorganisms to enhance their viability during fermentation, processing and utilization in commercial products. Microencapsulation of probiotic bacteria can be used to enhance the viability during processing, and also for the targeted delivery in gastrointestinal tract.

Treatment of cattle-slaughterhouse wastewater and the reuse of sludge for biodiesel production by microalgal heterotrophic bioreactors

Microalgal heterotrophic bioreactors are a potential technological development that can convert organic matter, nitrogen and phosphorus of wastewaters into a biomass suitable for energy production. The aim of this work was to evaluate the performance of microalgal heterotrophic bioreactors in the secondary treatment of cattle-slaughterhouse wastewater and the reuse of microalgal sludge for biodiesel production. The experiments were performed in a bubble column bioreactor using the microalgae Phormidium sp. Heterotrophic microalgal bioreactors removed 90 % of the chemical oxygen demand, 57 % of total nitrogen and 52 % of total phosphorus. Substantial microalgal sludge is produced in the process (substrate yield coefficient of 0.43 mgsludge mgchemical oxygen demand−1), resulting in a biomass with high potential for producing biodiesel (ester content of more than 99 %, cetane number of 55, iodine value of 73.5 giodine 100 g−1, unsaturation degree of ~75 % and a cold filter plugging point of 5 oC).

Heterotrophic Cultivation of Cyanobacteria: Study of Effect of Exogenous Sources of Organic Carbon, Absolute Amount of Nutrients, and Stirring Speed on Biomass and Lipid Productivity

The production of bioproducts from cyanobacteria with techno-economic feasibility is a challenge to these biotechnological processes. The choice of low-cost raw materials is of great importance for the overall economy of bioprocesses, as they represent a significant percentage in the final cost of the product. The objective of this work was to study the operational parameters of cultivation (exogenous sources of organic carbon and absolute amount of nutrients) to optimize productivity in bioproducts by Aphanothece microscopica Nägeli, for further evaluation of stirring speed. The experiments were performed in a bubble column bioreactor, operating at 30°C, pH of 7.6, C/N ratio of 20, 100 mg/L of inoculum, continuous aeration of 1 volume of air per volume of culture per minute (VVM), and absence of light. The results indicate that absolute amounts of 5,000/250 using cassava starch resulted in improved system performance, reaching biomass productivity of 36.66 mg/L/h in parallel with lipid productivity of 6.65 mg/L/h. Finally, experiments with variation in stirring speed indicate that 200 rpm resulted in better average rate of substrate consumption (44.01 mg/L/h), in parallel to biomass productivity of 39.27 mg/L/h. However, the increase of stirring speed had a negative effect on lipid productivity of the process. The technological route developed indicates potential to production of biomass and bulk oil, as a result of the capacity of cyanobacteria to adapt their metabolism in varying culture conditions, which provides opportunities to modify, control, and thereby maximize the formation of targeted compounds.

Treatment of rice parboiling wastewater by cyanobacterium Aphanothece microscopica Nägeli with potential for biomass products

AbstractCyanobacterium Aphanothece microscopica Nageli has been used in research for the removal of nitrogen and organic matter in order to associate single-cell protein production with wastewater treatment. These micro-organisms use photosynthesis as the main metabolic way, although some strains are able to grow in absence of light in heterotrophic cultures. Therefore, the main purpose of the work was to evaluate the growth kinetics of unicellular cyanobacterium A. microscopica in rice parboilization effluent without light source. Experimental conditions were 100 and 300 mg L−1 inoculum concentration at 25 and 35°C. Results showed that biomass production with maximum nitrogen and organic matter removal at 12 h of batch time was 300 mg L−1 inoculum at 35°C. Our results demonstrate that A. microscopica shows high yield of nitrogen and organic matter removal from rice parboilization effluent, promising of potential for biomass products and wastewater treatment.

Carotenoid profile of three microalgae/cyanobacteria species with peroxyl radical scavenger capacity

Carotenoids from cyanobacteria Aphanothece microscopica Nageli and green microalgae Chlorella vulgaris and Scenedesmus obliquus were identified. The total carotenoid content, based on dry weight of biomass, of A. microscopica Nägeli, C. vulgaris and S. obliquus were 1398.88μg/g, 1977.02μg/g and 2650.70μg/g, respectively. A total of 23 different carotenoids were separated in all the extracts, the major ones being all-trans-β-carotene (29.3%) and all-trans-lutein (28.1%) in Scenedesmus; all-trans-echinenone (22.8%) and all-trans-β-carotene (17.7%) in Chlorella; all-trans-echinenone (28.3%) and all-trans-β-carotene (26.2%) in Aphanothece. The carotenoid extracts were shown to be a potent scavenger of peroxyl radical, with values of 31.1 (Chlorella), 14.0 (Scenedesmus) and 7.3 (Aphanothece) times more potent than α-tocopherol.

Why does the Photobioreactors Fail

Luis G Ramírez-Mérida1,2, Leila Queiroz Zepka2 and Eduardo Jacob-Lopes2* 1Applied Biotechnology Center, Department of Biology, University of Carabobo, Universidad Avenue, 2002, Valencia, Edo. Carabobo, Venezuela 2Food Science and Technology Department, Federal University of Santa Maria, UFSM, Roraima Avenue 1000, 97105-900, Santa Maria, RS, Brazil *Corresponding author: Eduardo Jacob-Lopes, Food Science and Technology Department, Federal University of Santa Maria, UFSM, Roraima Avenue 1000, 97105-900, Santa Maria, RS, Brazil, Tel: +55-553-220-8822; E-mail: jacoblopes@pq.cnpq.br