Use of monosodium glutamate in foods: the good, the bad, and the controversial side / Uso de glutamato monossódico em alimentos: o bom, o mau e o lado controverso

Introduction: Monosodium glutamate (MSG) is known as a flavor-enhancing compound and also the fifth basic taste (umami). About the safety of using MSG as a food additive, some studies show indications that there is no threat and others showthe opposite. There is no consensus about the advantages and disadvantages of using MSG. Objective: To systematically review studies in the international literature on the knowledge of the pros and cons of using glutamate in food. Methods: Systematic review of studies published in journals indexed in ScienceDirect and PubMed databases. Articles published until 2020 were included. The aspects involving the advantages and disadvantages were discussed, as well as the health risks related to the MSG intake from diet. Results: The revised studies showed that MSG can reduce the amount of sodium in foods without modifying flavor. Although authorities indicate that MSG is safe for human consumption, some studies highlight that health risk is real. The use of MSG is still controversial because there are some misunderstandings in the applied amounts of MSG absorption and metabolism. Conclusion: MSG is widely applied in industrial and homemade food. The need for further studies is crucial, and aspects such as metabolism and amounts of MSG effectively consumed must be better evaluated.

Produção de biossurfactantes: manoproteínas intracelulares e soforolipídios extracelulares por Saccharomyces cerevisiae / Biosurfactant production: intracellular manoproteins and extracellular sophorolipids by Saccharomyces cerevisiae

RESUMO Os biossurfactantes apresentam inúmeras aplicações ambientais e são produzidos por diversos microrganismos. Os provenientes da levedura Saccharomyces cerevisiae são pouco estudados para fins ambientais, sendo atóxicos. Objetivou-se o estudo da produção de biossurfactantes intra e extracelular por essa levedura, desenvolvida em meio de cultivo contendo 0,5% de extrato de levedura e 1% de peptona, além de concentrações variadas de sacarose e indutores oleosos - glicerol e óleos de soja e diesel. Os experimentos foram realizados durante 96 horas, e a produção de biossurfactantes foi avaliada diariamente, por meio da redução da tensão superficial e de estabilização de emulsões. O biossurfactante extracelular foi extraído da biomassa obtida, com posterior precipitação e caracterização química por intermédio de espectrometria de massa. As maiores produtividades de emulsificantes extracelulares foram obtidas com glicerol (0,20 UE.h-1) e óleo de soja (0,21 UE.h-1), em 48 horas de cultivo. Em ensaios posteriores, realizados com aumento da concentração de indutor, foi verificado um aumento das produtividades extracelulares para 0,45 UE.h-1 para o glicerol e 0,30 UE.h-1 para o óleo de soja. A maior redução da tensão superficial foi de 9,89%, em 72 horas, para o indutor óleo diesel. A diminuição dessa tensão, aliada ao aumento das atividades emulsificantes, é um importante indicativo da utilização do substrato hidrofóbico pelo microrganismo. O estudo comprova aumento na produção de biossurfactantes extracelulares quando realizada otimização de cultivo. Para a produção dos intracelulares, a necessidade de processo de rompimento celular aumenta os custos do bioprocesso.

ABSTRACT Biosurfactants implicate many environmental applications, being produced by a wide range of microorganisms. Those from the Saccharomyces cerevisiae yeast are still poorly studied for environmental purposes and are non-toxic. The aim of the study was the production of intra- and extracellular biosurfactants by the Saccharomyces cerevisiae yeast. The yeast was grown in cultured medium containing 0.5% yeast extract, 1% peptone and variable concentrations of sucrose and oily inducers. Inducers used were glycerol, soybean oil and diesel oil. Experiments were conducted for 96 h, and the daily production of biosurfactants was evaluated by reducing surface tension and stabilizing emulsions. Extracellular biosurfactant was extracted from the obtained biomass, with subsequent precipitation and chemical characterization by mass spectrometry. The highest extracellular emulsifier yields were achieved with glycerol inductor (0.20 UE h-1) and soybean oil (0.21 UE h-1) in 48h of cultivation. In later tests performed with increasing concentration of inducer, an increase in extracellular yields was noticed in these experiments (0.45 UE h-1 for glycerol and 0.30 UE h-1 for the soybean oil). The greatest reduction in surface tension was 9.89% in 72 h for diesel oil inducer. The reduction of surface tension combines with the increase of emulsifying activities in an important indicator of the use of hydrophobic substrate by the microorganism. The study confirms an increase in the production of extracellular biosurfactants when optimizing cultivation. The production of intracellular biosurfactants has also been verified, however the process of cellular disruption increases the cost of the bioprocess.

Surface response methodology for the optimization of lipase production under submerged fermentation by filamentous fungi

Abstract A Plackett–Burman Factorial Design of 16 experiments was conducted to assess the influence of nine factors on the production of lipases by filamentous fungi. The factors investigated were bran type (used as the main carbon source), nitrogen source, nitrogen source concentration, inducer, inducer concentration, fungal strain (Aspergillus niger or Aspergillus flavus were selected as good lipase producers via submerged fermentation), pH and agitation. The concentration of the yeast extract and soybean oil and the pH had a significant effect (p < 0.05) on lipase production and were consecutively studied through a Full Factorial Design 23, with the concentration of yeast extract and pH being significant (p < 0.05). These variables were optimized using a central composite design, obtaining maximum lipolytic activities with the use of 45 g/L of yeast extract and pH 7.15. The statistical model showed a 94.12% correlation with the experimental data.

Characterization of the spoilage lactic acid bacteria in “sliced vacuum-packed cooked ham”

The lactic acid bacteria are involved with food fermentation and in such cases with food spoilage. Considering the need to reduce the lactic acid bacteria growth in meat products, the aim of this work was to enumerated and investigated the lactic acid bacteria present on sliced vacuum-packed cooked ham stored at 4 °C and 8 °C for 45 days by phenotypic and molecular techniques. The quantification showed that the lactic acid bacteria were present from the first day with mean count of 1.98 log cfu/g for the four batches analyzed. The lactic acid bacteria grew rapidly on the samples, and plate counts around 7.59 log cfu/g and 8.25 log cfu/g were detected after 45 days of storage at 4 °C and 8 °C, respectively; storage temperatures studied showed significant influence on the microorganism in study growth. The predominant lactic acid bacteria associated with the spoilage samples at one day of storage includes Lactobacillus sp., the phenotypic overlap Leuconostoc/Weissella sp. and Enterococcus sp. At 45 days of storage at 4 and 8 °C the mainly specie was Lactobacillus curvatus, following by Lactobacillus sakei and Leuconostoc mesentereoides; the Enterococcus sp. was not present in the samples.

Antioxidant effect of phycocyanin on oxidative stress induced with monosodium glutamate in rats

The objective of this work was to study the antioxidant effect of phycocyanin on the oxidative stress induced by monosodium glutamate in the rats. The tests were performed with 32 rats of Wistar breed, divided into four groups, which were administered saline solution of phycocyanin, monosodium glutamate and monosodium glutamate plus phycocyanin. Sulfhydryl groups and the secondary substances derived from lipid oxidation were determined through the level of TBA. The evaluation of these values and the level of sulfhydryl showed that the administration of phycocyanin presented significant antioxidant effect (p < 0.05) reducing the oxidative stress induced by the monosodium glutamate in vivo.

Efeito antioxidante da ficocianina em pescado salgado-seco / Antioxidant effect of phycocianin on dried-salted fish

A conservação e o armazenamento de alimentos com elevados teores lipídicos podem conduzir ao desencadeamento do processo oxidativo, causando modificações nas características sensoriais e redução da vida útil dos mesmos. A ficocianina é um pigmento extraído da microalga Spirulina platensis que apresenta propriedades antioxidantes, por isso, objetivou-se verificar o efeito antioxidante da ficocianina durante o armazenamento do pescado salgado. O pescado salgado foi produzido com o peixe Pacu (Piaractus mesopotamicus, Holmberg, 1887), o qual foi submetido a 5 tratamentos (T1: sem adição de antioxidante, T2: com adição de antioxidante sintético BHT na concentração de 0,01 por cento, T3, T4 e T5: com a adição de ficocianina nas concentrações de 0,5 por cento, 1 por cento e 1,5 por cento, respectivamente). As amostras foram analisadas nos tempos: zero, 30 d e 60 d de armazenamento através do índice de TBA. Pelos resultados observou-se que a presença do antioxidante natural ficocianina ocasionou uma inibição no processo de oxidação lipídica, com índices de TBA, estatisticamente iguais (p>0,05) ao tratamento com uso de antioxidante sintético.

Conservation and storage of food with a lipidic content may unchain oxidative processes, causing modifications of sensorial characteristics and reduction of useful life. Phycocianin is a pigment of Spirulina platensis, which presents antioxidant proprieties. The objective of this work was to verify the antioxidant effect of phycocyanin during the storage of salted fish. The salted fish was produced with the pacu species (Piaractus mesopotamicus Holmberg, 1887), which was submitted to 5 treatments (T1: without addition of antioxidant; T2: with addition of synthetic antioxidant BHT in the concentration of 0.01 percent, T3, T4 and T5: with addition of phycocianin at concentrations of 0.5 percent, 1 percent and 1.5 percent respectively). Samples were analyzed at zero (0), 30 and 60 days of storage determining the physics-chemical quality through the index of TBA. The results showed that the addition of the natural antioxidant phycocianin caused the inhibition of the process of oxidation, with TBA index statistically equal (p>0.05) of that obtained with the use of synthetic antioxidant.

Effect of microalga Spirulina platensis (Arthrospira platensis) on hippocampus lipoperoxidation and lipid profile in rats with induced hypercholesterolemia

Studies have been conducted on microalga Spirulina platensis (Arthrospira platensis) due to its therapeutic potential in several areas, including the capacity for preventing and decreasing the damages caused by hyperlipidemia and the antioxidant activity. The aim of the study was to evaluate the effect of microalga Spirulina platensis on hippocampus lipoperoxidation and lipid profile in rats with induced hypercholesterolemia during 60 days. The measurement of hippocampus lipoperoxidation did not demonstrate significant difference (p>0.05) when Spirulina platensis was added to hypercholesterolemic diet. The evaluation of lipid profile showed that the administration of the microalga in therapeutic and preventive ways led to a significant protective effect (p<0.05) from hypercholesterolemia.

A microalga Spirulina platensis (Arthrospira platensis) vem sendo fonte de pesquisas devido a evidências de seu potencial terapêutico em diversas áreas, dentre elas a capacidade de prevenção e diminuição dos danos causados por dislipidemias e sua atividade antioxidante. Objetivou-se avaliar o efeito da microalga Spirulina platensis sobre a lipoperoxidação no hipocampo e perfil lipídico sérico em ratos com hipercolesterolemia induzida durante 60 dias. A dosagem da lipoperoxidação no hipocampo não demonstrou diferença significativa (p>0,05) quando Spirulina platensis foi adicionada na dieta hipercolêsterolemica. A avaliação do perfil lipídico demonstrou que a administração da microlaga de forma terapêutica e preventiva demonstrou efeito significativo (p<0,05) na proteção do desenvolvimento de hipercolesterolemia.

Potencial amilolítico do grão de milho maltado no processo de sacarificação do mesmo cereal / Amylolytic potential of maize malt in the process of sacarification of the same cereal

Objetivou-se avaliar o potencial de sacarificação do malte de milho para produção de álcool deste cereal. Para tal, foi realizada germinação do grão de milho a 20 ºC por 5 dias. O potencial amilolítico do malte de milho foi otimizado por meio de um PlanejamentoFatorial Completo 22 com 3 pontos centrais, sendo as variáveis de estudo a temperatura de incubação e concentração de substrato [S]. A sacarificação foi realizada por meio de um Planejamento de Mistura com três pontos centrais, sendo as variáveis de estudo a concentração de malte e concentração de substrato, durante 6 horas. A fermentação foi conduzida com a melhor condição de sacarificação, em reator de 5 L e volume útil de 2 L. O pH foi fixado em 4,5-5. O Brix foi acertado para o valor de 14º. O mosto hidrolisado foi esterilizado e inoculado com 5,0 g.L-1 de Saccharomyces cerevisiae proveniente de fermento comercial liofilizado. O sistema foi submetido a 2 horas de aeração inicial (170 LO2.h -1) e mantido na temperatura de 30 °C. Durante o processo de fermentação, foram realizadas determinações da concentração de células (g.L-1), açúcares redutores (mg.mL-1) e álcool (g.L-1). As variáveis temperatura de incubação e concentração de substrato foram significativos (p< 0,05) na condição de estudo de 20 % de substrato e incubação a 70 °C. Os experimentos centrais com 50 % de malte apresentaram os melhores parâmetros cinéticos com taxa volumétrica de formação de produto em etanol de 2,81 getanol.L-1.h-1 que corresponde a 8,0 ºGL e conversão de substrato em células 0,127 gcélula.gglicose-1.

The aim of this research was the production of maize malt and the evaluation of its use for alcohol production. The maize grain was allowed to germinate at 20°C for five days. The amylolitic potential of malt was optimized through a Complete Factorial Planning 22 with three central points, where the study variables were the temperature of incubation and the substrate concentration [S]. The sacarification was performed through a Planning of Mixture with three central points, where the study variables were the malt concentration and [S] during six 6 hours. The fermentation was carried out using the best sacarification condition, in a five-liter reactor and a two-liter working volume. The pH was maintained at 4.5 – 5.0. The Brix was corrected to 14º. The sterile hydrolyzedproduct was inoculated with 5.0 g.L-1 Saccharomyces cerevisiae. The system was submitted to two hours of initial aeration (170 LO2.h-1) and kept at 30°C. During the fermentation process, analyses were made to determine the cell concentrations (g.L-1), reducingsugars (mg.mL-1), alcohol (g.L-1) and °Brix. The temperature of incubation and substrate concentration were significant factors (p<0.05) in the determination of the amylolytic potential under the conditions of study utilizing 20% of substrate and incubation at 70°C. The central experiments with 50% malt presented the best kinetic parameters with a volumetric rate of ethanol formation of 2.81 gethanol.L-1.h-1, which correspond to 8.0 ºGL, and a substrate conversion in cells of 0.127gcells.gglucose -1.

Isolamento e seleção de fungos para biorremediação a partir de solo contaminado com herbicidas triazínicos / Isolation and screening of fungi to bioremediation from triazine herbicide contaminated soil

A biorremediação é uma tecnologia que utiliza o metabolismo de microrganismos para eliminação ou redução, a níveis aceitáveis, de poluentes presentes no ambiente. Os herbicidas triazínicos são usados intensivamente no controle de ervas daninhas, principalmente na cultura de milho. Objetivou-se, neste trabalho, isolar fungos filamentosos de solos contaminados com herbicidas triazínicos (atrazine e simazine) e selecionar os microrganismos isolados quanto à capacidade de crescimento em meio adicionado de atrazine. Os microrganismos foram isolados, cultivados em meio Ágar-Batata-Dextrose (BDA) acidificado com ácido tartárico 10 por cento, adicionado de 50 mg.Kg-1 de atrazine e incubados por 5 dias a 25ºC. Foi realizada a medida diária do crescimento fúngico e calculada a velocidade de crescimento radial através de regressão linear dos raios das colônias utilizando-se a equação r(t) = a + VCR .t (r:raio; t: tempo; VCR: velocidade de crescimento radial). Os resultados de VCR foram analisados através de Anova simples e do teste de Tukey, para comparação de médias. Foram isolados 15 fungos, pertencentes aos gêneros Aspergillus, Penicillium e Trichoderma. As maiores VCRs foram obtidas com fungos Aspergillus (A1) e Penicillium (AS1), isolados de solo contaminado com atrazine e atrazine adicionado de simazine, respectivamente, que apresentaram VCRs de 1,57 mm.d-1 e 1,28 mm.d-1. O crescimento dos fungos em meio contaminado com a atrazine indica a possibilidade de utilização desses fungos em estudos de biorremediação de solos contaminados com herbicidas triazínicos.

Bioremediation is a technology that uses microrganism metabolism to quickly eliminate or reduce pollutants to acceptable levels into the environment. The triazine herbicides are intensively used to control harmful grass in the culture of maize. The aim of this work was to isolate filamentous fungi from soil contaminated with triazine herbicides and screening these fungi due to their ability of growth in a medium added by atrazine. The fungi were isolated, cultivated in potato-dextrose-agar plus 50 mg.Kg-1 of atrazine and incubated for 5 days at 25ºC. The measure of the rays of the colonies was carried out daily and the radial growth rate (RGR) through linear regression of colonies rays using the equation: r(t) = a + RGR .t (r:ray; t: time; RGR: radial growth rate). The RGR results were analyzed through analysis of variance and Tukey test for comparison of averages. Fifteen filamentous fungi from genus Aspergillus, Penicillium and Trichoderma were isolated. The highest RGRs were obtained with the fungi Aspergillus and Penicillium, when isolated from contaminated soil with atrazine and atrazine + simazine, respectively, showing RGR of 1.57 mm.d-1 and 1.28 mm.d-1. The growth of these fungi in atrazine contaminated meas indicates a possible of use of them in bioremediation experiments with contaminated soil containing triazine herbicides.

Spirulina platensis effects on the levels of total cholesterol, HDL and triacylglycerols in rabbits fed with a hypercholesterolemic diet

In this work, hypercholesterolemia was induced in rabbits by feeding them a high cholesterol diet (CD, 350 mg/d) and the effects of supplementing this diet with 0.5 g/d Spirulina platensis was evaluated by measuring the levels of serum total-cholesterol (TC), triacylglycerols (TAG) and high-density lipoprotein (HDL-cholesterol) at the start of the experiment and after 30 d and 60 d. It was found that the levels of serum cholesterol decreased from 1,054±101 mg.dL-1 in the rabbits fed a CD without S. platensis to 516±163 mg.dL-1 to those fed with a high cholesterol diet supplemented with S. platensis (significant at p <0.0001). The addition of Spirulina to the cholesterolemic diet did not cause significative decrease on the levels of triacylglycerols in the animals. The levels of serum high-density lipoprotein (HDL-cholesterol) was 73±31 mg.dL-1 for rabbits fed a CD without S. platensis as compared to 91.0±15.7 mg.dL-1 in those fed a CD supplemented with S. platensis (significant at p=0.1533).

A microalga Spirulina é cultivada e comercializada no mundo devido a suas características nutricionais (elevada concentração de proteínas, em torno de 65 por cento, vitaminas e sais minerais) e ao seu potencial terapêutico no tratamento de inúmeras doenças, inclusive a hipercolesterolemia. Neste trabalho foi avaliada a inibição da hipercolesterolemia induzida em coelhos por uma dieta adicionada de colesterol (350 mg.d-1), pela suplementação de 0,5 g.dia-1 de biomassa de Spirulina platensis, sendo avaliados os níveis de colesterol total, triglicerídeos e HDL nos tempos de 0 d, 30 d e 60 d de tratamento. Os resultados indicaram que a adição de Spirulina platensis na dieta ocasionou decréscimo nos níveis de colesterol total de 1054±101 mg.dL-1 para 516±163 mg.dL-1 (p<0,0001), para os coelhos alimentados com a dieta colesterolêmica em comparação com os que receberam a dieta adicionada de Spirulina platensis. A adição de Spirulina a dieta colesterolêmica não ocasionou decréscimo significativo nos níveis de triglicerídios dos coelhos. Os valores de HDL aumentaram de 73±31 mg.dL-1 para 91,0±15,7 mg.dL-1, comparando-se os coelhos alimentados com a dieta colesterolêmica e os alimentados com a dieta adicionada de Spirulina, estatisticamente diferentes a um nível de significância maior que 0,1533.

Antioxidant properties of Spirulina (Arthospira) platensis cultivated under different temperatures and nitrogen regimes

The main aim of this work was to investigate the effects of temperature and nitrogen concentration on the antioxidant potential of extracts from Spirulina (Arthospira) platensis biomass. S. platensis biomass obtained at 35°C and with 1.875 g.L-1 or 2.5 g.L-1 of sodium nitrate in the culture medium presented higher concentrations of phenolic compounds. The antioxidant potential of methanol extracts of biomass on the enzymatic browning caused by peroxidase were 29 and 35 percent, respectively, being the reduction related to the amount of phenolic compounds present in this extract.

A cianobactéria Spirulina tem sido comercializada e estudada devido as suas propriedades nutricionais e terapêuticas no tratamento de doenças como o câncer, a hipercolesterolemia e a aterosclerose. Determinados compostos presentes na Spirulina, como os compostos fenólicos, a ficocianina e o tocoferol, podem apresentar atividade antioxidante. O principal objetivo deste trabalho foi avaliar o efeito da temperatura de cultivo e da concentração de nitrogênio no meio de cultivo, sobre o potencial antioxidante da microalga Spirulina (Arthospira) platensis. Quando a microalga foi cultivada a 35°C e concentrações de nitrato de sódio de 1,875 g.L-1 ou 2,5 g.L-1, o potencial antioxidante dos extratos obtidos a partir da biomassa, sobre o escurecimento enzimático causado pela peroxidase, foi de 29 por cento e 35 por cento, respectivamente, sendo a redução no escurecimento relacionada com as quantidades de compostos fenólicos presentes nos extratos.