Chemical composition of microalgae Heterochlorella luteoviridis and Dunaliella tertiolecta with emphasis on carotenoids.

BACKGROUND: Microalgae have been used as food supplements owing to their high protein, polyunsaturated fatty acid and carotenoid contents. As different carotenoids have distinct properties and the carotenoid composition of microalgae has been poorly explored in the literature, this study determined the complete carotenoid composition of two microalgae species, Heterochlorella luteoviridis and Dunaliella tertiolecta, using high-performance liquid chromatography coupled with diode array detection and tandem mass spectrometry (HPLC-DAD/MS2 ). Additionally, the proximate composition and major minerals were evaluated. RESULTS: The carotenoid composition of the two microalgae was similar, with 13 carotenoids being found in H. luteoviridis and 12 in D. tertiolecta. The major carotenoids were all-trans-lutein (1.18 mg g-1 in H. luteoviridis and 1.59 mg g-1 in D. tertiolecta), all-trans-violaxanthin (0.52 mg g-1 in H. luteoviridis and 0.45 mg g-1 in D. tertiolecta) and all-trans-ß-carotene (0.50 mg g-1 in H. luteoviridis and 0.62 mg g-1 in D. tertiolecta). All-trans-lutein was the predominant carotenoid in both microalgae, representing around 40% (mass fraction) of the total carotenoids. The lutein content found in these microalgae was significantly higher (2-40 times) than that in other important food sources of lutein (e.g. parsley, carrot, red pepper and broccoli). CONCLUSION: The microalgae H. luteoviridis and D. tertiolecta are excellent sources of lutein that could be commercially exploited by the food and pharmaceutical industries. Moreover, it was confirmed that both microalgae are good sources of protein, lipids and calcium. © 2016 Society of Chemical Industry.

Dynamics of yeast immobilized-cell fluidized-bed bioreactors systems in ethanol fermentation from lactose-hydrolyzed whey and whey permeate.

We studied the dynamics of ethanol production on lactose-hydrolyzed whey (LHW) and lactose-hydrolyzed whey permeate (LHWP) in batch fluidized-bed bioreactors using single and co-cultures of immobilized cells of industrial strains of Saccharomyces cerevisiae and non-industrial strains of Kluyveromyces marxianus. Although the co-culture of S. cerevisiae CAT-1 and K. marxianus CCT 4086 produced two- to fourfold the ethanol productivity of single cultures of S. cerevisiae, the single cultures of the K. marxianus CCT 4086 produced the best results in both media (Y EtOH/S = 0.47-0.49 g g(-1) and Q P = 1.39-1.68 g L(-1) h(-1), in LHW and LHWP, respectively). Ethanol production on concentrated LHWP (180 g L(-1)) reached 79.1 g L(-1), with yields of 0.46 g g(-1) for K. marxianus CCT 4086 cultures. Repeated batches of fluidized-bed bioreactor on concentrated LHWP led to increased ethanol productivity, reaching 2.8 g L(-1) h(-1).

The modeling of ethanol production by Kluyveromyces marxianus using whey as substrate in continuous A-Stat bioreactors.

We investigated the kinetics of whey bioconversion into ethanol by Kluyveromyces marxianus in continuous bioreactors using the "accelerostat technique" (A-stat). Cultivations using free and Ca-alginate immobilized cells were evaluated using two different acceleration rates (a). The kinetic profiles of these systems were modeled using four different unstructured models, differing in the expressions for the specific growth (µ) and substrate consumption rates (r s), taking into account substrate limitation and product inhibition. Experimental data showed that the dilution rate (D) directly affected cell physiology and metabolism. The specific growth rate followed the dilution rate (µ≈D) for the lowest acceleration rate (a = 0.0015 h(-2)), condition in which the highest ethanol yield (0.52 g g(-1)) was obtained. The highest acceleration rate (a = 0.00667 h(-2)) led to a lower ethanol yield (0.40 g g(-1)) in the system where free cells were used, whereas with immobilized cells ethanol yields increased by 23 % (0.49 g g(-1)). Among the evaluated models, Monod and Levenspiel combined with Ghose and Tyagi models were found to be more appropriate for describing the kinetics of whey bioconversion into ethanol. These results may be useful in scaling up the process for ethanol production from whey.

Effect of ultrasound on Pseudoneochloris marina and Chlorella zofingiensis growth.

The present work evaluated the ultrasound (US) effects on the growth of Pseudoneochloris marina and Chlorella zofingiensis. For P. marina, US treatment did not increase cell proliferation and reduced cell density when used for 60 min (exponential phase, for 5 days), indicating a possible occurrence of cell damage. For C. zofingiensis, the application of discontinuous US for 10 min resulted in an increase of 65 % in biomass concentration compared to the control. These distinct behaviors indicate that microalgae species react differently to physical stimuli. After US treatment, a reduction of carotenoid, chlorophyll, lipid and protein concentrations was observed, which may be related to changes in the metabolic pathways to produce these compounds. Overall, the results of the present study show the potential of discontinuous US to enhance microalgae cell proliferation.

Poly(acid lactic) films with carotenoids extracts: Release study and effect on sunflower oil preservation.

Oxidative deterioration is one of the most important factors limiting shelf-life of fatty food products, where the use of active packaging produced with natural antioxidants is a strategy to minimize these reactions. Poly(acid lactic) (PLA) films were produced with carotenoids extracts rich in beta-carotene, lycopene, and bixin. The kinetics of carotenoids' release to a fat simulant was evaluated and successfully explained by a new mathematical release model which considered the degradation of the migrants after their release. In the presence of light, films with lycopene and beta-carotene protected sunflower oil mainly by their light barrier properties, and secondly by their barrier to oxygen and antioxidant gradual releasing. The films produced with bixin presented the best performance as antioxidant active packaging to sunflower oil, where differences found in films barrier properties and in the transfer coefficients among the carotenoids were influenced by their molecular structures.

Ultrasound as an alternative technology to extract carotenoids and lipids from Heterochlorella luteoviridis.

The present work evaluated the use of ultrasound as a pre-treatment to lipid and carotenoid extraction from the microalgae Heterochlorella luteoviridis. The pre-treatment was performed in the presence of ethanol (25%, v/v) with the ultrasound intensity varying from 0 to 100% (435kJkg-1). After the pre-treatment, a diffusive step was performed in order to evaluate different ethanol concentrations (50-75%, v/v). The results regarding carotenoid extraction showed that there is an optimal extraction region: 40-80% of ultrasound intensity and 60-75% of ethanol concentration. The lipid extraction was not influenced by the ultrasound pre-treatment and increased with the increase of ethanol concentration.

Liberation of fermentable sugars from soybean hull biomass using ionic liquid 1-butyl-3-methylimidazolium acetate and their bioconversion to ethanol.

Optimized hydrolysis of lignocellulosic waste biomass is essential to achieve the liberation of sugars to be used in fermentation process. Ionic liquids (ILs), a new class of solvents, have been tested in the pretreatment of cellulosic materials to improve the subsequent enzymatic hydrolysis of the biomass. Optimized application of ILs on biomass is important to advance the use of this technology. In this research, we investigated the effects of using 1-butyl-3-methylimidazolium acetate ([bmim][Ac]) on the decomposition of soybean hull, an abundant cellulosic industrial waste. Reaction aspects of temperature, incubation time, IL concentration, and solid load were optimized before carrying out the enzymatic hydrolysis of this residue to liberate fermentable glucose. Optimal conditions were found to be 75°C, 165 min incubation time, 57% (mass fraction) of [bmim][Ac], and 12.5% solid loading. Pretreated soybean hull lost its crystallinity, which eased enzymatic hydrolysis, confirmed by Fourier Transform Infrared analysis. The enzymatic hydrolysis of the biomass using an enzyme complex from Penicillium echinulatum liberated 92% of glucose from the cellulose matrix. The hydrolysate was free of any toxic compounds, such as hydroxymethylfurfural and furfural. The obtained hydrolysate was tested for fermentation using Candida shehatae HM 52.2, which was able to convert glucose to ethanol at yields of 0.31. These results suggest the possible use of ILs for the pretreatment of some lignocellulosic waste materials, avoiding the formation of toxic compounds, to be used in second-generation ethanol production and other fermentation processes. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 32:312-320, 2016.

Effect of temperature and nitrogen concentration on biomass composition of Heterochlorella luteoviridis

Abstract The interest in microalga as a food supplement has grown due their high contents of carotenoids, polyunsaturated fatty acids and proteins. This study evaluated the effect of different temperatures (22, 27 or 32 °C) and sodium nitrate concentrations (12, 24, 36, 48 or 60 mg L-1 of N-NO3) in culture medium on Heterochlorella luteoviridis biomass production and composition. The highest biomass concentration (3.35 g L-1) was observed at the highest N-NO3 concentration. The N-NO3 concentration positively affected protein, carbohydrate and carotenoids contents of biomass. On the other hand, cells cultured at the lowest N-NO3 concentration showed a slight increment in lipid content. The major carotenoid was lutein (30.7 ± 1.4% of total carotenoids), and the polyunsaturated fatty acids were 37 ± 2% of total fatty acids. Low temperature improved the biosynthesis of ω3 type fatty acids by lowering the ω6:ω3 ratio. Overall, our results indicate H. luteoviridis can yield high biomass concentration under autotrophic growth, resulting in a biomass rich in carotenoids, mainly lutein, and ω3 polyunsaturated fatty acids.

Avaliação sensorial de pães de fermentação natural a partir de culturas starters inovadoras / Sensory evaluation of natural fermentation breads with innovative starter cultures

A fermentação sourdough para a produção de pães é fortemente motivada por seus efeitos benéficos quanto ao sabor, textura, vida de prateleira e pelas propriedades nutricionais dos produtos obtidos. Nesta pesquisa, estudou-se a aplicação dos micro-organismos Kluyveromyces marxianus, Dekkera bruxellensis e Lactobacillus plantarum como culturas starters alternativas na produção de pães. A partir de sete ensaios resultantes de um delineamento de mistura simplex-centroide, foram realizadas nos pães análises sensorial e instrumental. Observou-se que pães produzidos com L. plantarum apresentaram menor volume específico, enquanto que a mistura entre K. marxianus e L. plantarum exerceu influência positiva, possibilitando obter produtos de maior volume específico. A análise sensorial demonstrou a boa aceitabilidade para os pães produzidos com a mistura entre D. bruxellensis e K. marxianus e para a mistura entre os três micro-organismos. Os resultados deste trabalho demonstram a possibilidade do uso de culturas starters definidas para a fermentação sourdough, que é tradicionalmente obtida sem controle de processo.

The sourdough fermentation in bread making is strongly motivated due to its beneficial aspects on flavor, texture, shelf life, and the nutritional properties of the obtained products. In this research, the yeasts Kluyveromyces marxianus and Dekkera bruxellensis, and the bacterium Lactobacillus plantarum were used as alternative starter cultures in bread making. Experimental designs generated from simplex-centroid mixture were used in the sensorial analyses of breads. Results have shown that bread obtained with pure cultures of L. plantarum presented the smallest specific volume, while the mixture of K. marxianus and L. plantarum positively influenced the formation of good specific volume of products. Sensorial analysis showed good acceptability for breads obtained with D. bruxellensis and K. marxianus mixture, as well as for the mixture of the three microorganisms. The results obtained in this research suggest the possibility of using defined starter cultures for sourdough fermentation, which is traditionally carried out without any process controls.

A growth kinetic model of Kluyveromyces marxianus cultures on cheese whey as substrate.

This work presents a multi-route, non-structured kinetic model for determination of microbial growth and substrate consumption in an experimental batch bioreactor in which beta-galactosidase is produced by Kluyveromyces marxianus growing on cheese whey. The main metabolic routes for lactose, and oxygen consumption, cell growth, and ethanol production are derived based on experimental data. When these individual rates are combined into a single growth rate, by rewriting the model equations, the model re-interpretation has a complexity similar to that of the usual variations of the Monod kinetic model, available in the literature. Furthermore, the proposed model is in good agreement with the experimental data for different growth temperatures, being acceptable for dynamic simulations, processes optimization, and implementations of model-based control technologies.