Helen Hackbart - Academia.edu (original) (raw)
Papers by Helen Hackbart
Onions are rich in bioactive and volatile compounds with antioxidant activity. When concentrated ... more Onions are rich in bioactive and volatile compounds with antioxidant activity. When concentrated in plant extracts and applied directly into food matrices or packaging, they are sensitive to external factors and may have undesirable sensory attributes, such as odors. Therefore, this study sought to encapsulate red onion extract (ROE) in different concentrations (10, 20, 30, and 40%, v/v) into zein fibers by electrospinning. The major volatile compound in ROE was 3(2H)-furanone, 2-hexyl-5-methyl. Adding ROE into the polymeric solutions increased their electrical conductivity and decreased the apparent viscosity, thus decreasing the average diameter of the fibers. The loading capacity of ROE on fibers ranged from 77.3 to 91.5%. The fibers’ random and continuous morphology showed beads at the highest ROE concentration (40%). Fibers membranes showed lower values for contact angles as ROE was added. The antioxidant activity of the fibers ranged from 32.5 to 57.3%.
Revista do Instituto Adolfo Lutz (Impresso), 2012
International Journal of Food Microbiology, 2020
Synthetic preservatives can have harmful effects on the body, so plant essential oils appear to b... more Synthetic preservatives can have harmful effects on the body, so plant essential oils appear to be an attractive natural alternative. However, the use of essential oils is limited due to the low stability and possible negative effects on the sensory properties of food. Oil encapsulation was suggested as a way to overcome these drawbacks. The objective of this study was to encapsulate thyme essential oil and to evaluate its antioxidant and antimicrobial potential in vitro and in situ in of hamburger-like meat products. The casein-maltodextrin capsules produced by spray-drying were assessed for encapsulation efficiency, thermal stability, chemical compounds and morphology. Antioxidant activity was evaluated by DPPH, hydroxyl and nitric oxide methods, while antimicrobial activity was evaluated in vitro against four bacteria and in situ in hamburger-like products. The capsule showed high encapsulation efficiency and thermal stability, and spherical and irregular morphology. The casein-maltodextrin encapsulated essential oil showed antioxidant and antimicrobial activity against Staphylococcus aureus, Escherichia coli, Listeria monocytogenes and Salmonella Typhimurium tested in vitro and against thermotolerants coliforms and Escherichia coli in situ, showing potential for application as a natural preservative in food.
Journal of Food Science and Technology, 2021
The combination of oats such as water-soluble oat extract (SOE) and probiotic microorganisms can ... more The combination of oats such as water-soluble oat extract (SOE) and probiotic microorganisms can add nutritional value to the food and benefits to the consumer's health. The SOE contains soluble fiber, whose major soluble fraction is composed of b-glucan contains soluble antioxidants such as ferulic acid, avenanthramides and other phenolic acids. The purpose of this study was to develop a fermented dairy beverage containing SOE, evaluating the viability of the probiotic culture, the fatty acid profile, phenolic compounds content and sensory characteristics during the storage. It was verified that Lactobacillus casei remained viable during the 21 days of storage (count above 7 Log CFU.mL-1) and that the addition of SOE does not affect the viability of probiotic bacteria. The levels of bioactive compounds soluble in aqueous medium, increased between the beginning of the experiment and the end, being influenced by the addition of SOE. Seven fatty acids were found in all formulations with a prevalence of C16:0 followed by C18:1. The addition of SOE in the formulation contributes to a significant increase in linoleic acid (C18:2n6). The sensory evaluation of the fermented oat dairy beverage with L. casei (BAC) was positive: the product was highly appreciated by consumers, with acceptance rate of 84.4%. The combination of SOE, with L. casei in the production of novel probiotic fermented dairy beverage, was technologically feasible, improving the functional properties of the product and offering health benefits to the consumer. More studies should be made to evaluate the composition and functional properties of SOE.
Journal of the Science of Food and Agriculture, 2020
BACKGROUND: Thyme essential oil (TEO) is a great natural substitute for synthetic compounds in or... more BACKGROUND: Thyme essential oil (TEO) is a great natural substitute for synthetic compounds in order to maintain the quality and safety of food products acting as an antioxidant agent. We aimed at the nanoencapsulation of TEO at concentrations of 1, 3, and 5% (v/w, dry basis) in electrospun nanofibers made of starch (50% w/v) and formic acid (75% v/v). Rheological parameters of the fiber-forming solutions were measured, and various physical and chemical properties of the nanofibers were analyzed. RESULTS: The starch/TEO nanofibers presented homogeneous morphology. The starch nanofibers showed high encapsulation efficiency (EE, 99.1 to 99.8%), that along with FT-IR spectrum and TGA analysis, indicate great protection of the phenolic compounds of TEO. The nanofibers with 5% TEO retained up to 50% of the phenolic compounds after exposure to thermal treatment. The antioxidant activity against DPPH radical of the starch/TEO nanofibers varied from 11.1 to 14.2% and the values of inhibition (29.8%, p ≤ 0.05) against hydroxyl radical were same for free TEO and the nanofibers. CONCLUSION: Owing to these properties, electrospun starch/TEO nanofibers can be applied in food products or food packaging.
Journal of Food Science and Technology, 2020
Considering the low availability of gluten-free products that are offered an affordable price and... more Considering the low availability of gluten-free products that are offered an affordable price and good sensory characteristics, the main objective of the study was developed a gluten-free muffin based on green banana flour and evaluate their physical-chemical and sensorial aspects. The quality of the muffin was analyzed through such moisture content, ashes, proteins, lipids, fiber, carbohydrates, total caloric content, yield mass, weight loss in the supply, antioxidant activity, protein digestibility, and hedonic scale. The results showed that the gluten-free muffin had a moisture content of 26.7%, ash of 2.39%, lipids of 15.4%, proteins of 10.3%, fibers of 1.2%, carbohydrates of 44.0%, the total caloric value of 261.2 kcal, high protein digestibility and moderate antioxidant activity. The acceptability index was 84.5%. It has been concluded that gluten-free muffin with green banana flour is a viable alternative for the reason that they have higher protein content than other alternative flours.
Colloids and Surfaces B: Biointerfaces, 2020
Gliomas, intracranial malignant tumors, are aggressive, asymptomatic and difficult to treat due t... more Gliomas, intracranial malignant tumors, are aggressive, asymptomatic and difficult to treat due to their degree of infiltration, alternatives are needed to treat the disease. In this sense, natural compounds from the specialized metabolism of plants can act to control the disease. Glucosinolates and phenolic compounds, present in broccoli, have a potential to promote tumor cell death, however due to the low stability of these compounds, encapsulation becomes an alternative for their preservation. The objective was to encapsulate the broccoli extract by electrospraying and to evaluate its cytotoxicity in the primary cell culture of astrocytes and gliomas. The capsules were produced and characterized by encapsulation efficiency, functional groups, thermal stability and morphology, the capsule that presented the best parameters was used for the evaluation of cell cytotoxicity and antitumor activity. Capsules with equal or less than 50 % extract showed high encapsulation efficiency, high thermal stability and uniform morphology due to non-saturation of the active zein sites, which allowed a complete encapsulation of the added extract, as well as a greater protection of the compounds. The capsule with 50 % of the extract showed good results of the efficiency, morphology and thermal stability and was used to evaluate the antitumor activity, since the addition of extract in proportions greater than 60 % promoted saturation of the active sites and lower encapsulation efficiency, and directly affects the morphology and thermal stability. The encapsulated and unencapsulated extracts showed strong selective antitumor effect against glial tumor cells without toxicity to non-tumor cells.
Revista Ibero-Americana de Ciências Ambientais, 2019
Os hidrocarbonetos são listados como alguns dos principais contaminantes ambientais nos dias de... more Os hidrocarbonetos são listados como alguns dos principais contaminantes ambientais nos dias de hoje e são considerados indicadores geoquímicos em relação aos níveis e fontes de contaminação em ambientes hídricos. Por este motivo existem metodologias padronizadas para a determinação destes contaminantes em sedimentos, entre as mais utilizadas, podemos listar o método de extração por soxhlet e o método de extração sob ultrassom, porém os dois métodos de extração apresentam desvantagens em sua utilização. Neste estudo, foi desenvolvida uma metodologia para a extração, pré concentração e clean up de hidrocarbonetos presentes em sedimento, combinando etapas de extração por solvente sob ultrassom e em soxhlet, seguidas por fracionamento em coluna líquida preparativa e os extratos analisados por cromatografia gasosa acoplada a espectrometria de massas. Para otimização utilizou-se um planejamento experimental 2² com ponto central avaliando os tempos de pré sonificação e extração soxhlet....
Food Biophysics, 2019
In this study, ultrafine fibers were produced from black bean protein concentrates (BPCs) and pol... more In this study, ultrafine fibers were produced from black bean protein concentrates (BPCs) and polyvinyl alcohol (PVA) by electrospinning. The BPC was denatured under acidic (pH 2) or basic (pH 11) conditions. Polymer solutions containing different PVA concentrations (11% or 21%, w/v) and different BPC: PVA ratios (50:50 or 75:25, v/v) were used for fiber production. The electrical conductivity and rheological properties of the fiber-forming solutions were evaluated, as well as the morphology, size distribution, infrared spectrum, and thermal properties of the electrospun fibers. The fibers showed a homogeneous morphology and diameters ranging from 115 to 541 nm. Fibers from the solution containing BPC denatured at pH 11, 11% PVA, and 75:25 (v/ v) BPC: PVA presented the lowest diameter, and those from BPC denatured at pH 2 had less beads than the fibers obtained from BPC denatured at pH 11. The solution formulation affected the thermal properties of the fibers, with weight loss increases ranging from 39.0% to 60.9%. The polymeric solutions containing PVA and BPC (whether denatured under basic or acidic conditions) resulted in ultrafine electrospun fibers with highly favorable characteristics that could potentially be used for the encapsulation of bioactive compounds and food applications.
Journal of Food Processing and Preservation, 2019
Dairy products are widely consumed in developed countries and the incorporation of ingredients th... more Dairy products are widely consumed in developed countries and the incorporation of ingredients that promote the health of the consumer in this market can cause an increase in consumption (de
Visão Acadêmica, 2018
Atualmente a população tem buscado uma alimentação mais saudável devido ao aumento das doenças cr... more Atualmente a população tem buscado uma alimentação mais saudável devido ao aumento das doenças crônicas não transmissíveis, entre os alimentos com atividades biológicas protetores se encontram o amido resistente e outros oligossacarídeos. O objetivo do presente trabalho foi realizar uma breve revisão sistemática utilizando bases de dados indexadas acerca dos benefícios do amido resistente e de outros oligossacarídeos não digeríveis sobre a saúde humana. Como resultado da breve revisão evidenciou-se que os oligossacarídeos não-digeríveis e o amido resistente apresentam diversos benefícios para a saúde, atuando principalmente sobre o funcionamento do trato gastrointestinal, sistema nervoso central, sistema imunológico, biodisponibilidade de nutrientes, prevenção do câncer colorretal e na redução dos níveis bioquímicos de glicose, triglicerídeos e colesterol.
International Journal of Biological Macromolecules, 2019
The objective of this study was to immobilize α-amylase in ultrafine polyvinyl alcohol (PVA) fibe... more The objective of this study was to immobilize α-amylase in ultrafine polyvinyl alcohol (PVA) fibers by electrolysis and to evaluate its stability at different temperatures and pHs using various starch substrates such as corn starch and germinated and ungerminated wheat starches. The α-amylase-loaded ultrafine fibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and loadability and enzymatic activity evaluations. Incorporation of the enzyme resulted in a slight change in fiber morphology; the fibers became flatter and thicker with increasing enzyme concentration. The mean diameters ranged from 187 to 282 nm. FT-IR spectra indicated that the enzyme was incorporated into the fibers. PVA showed a high loading capacity for α-amylase at all concentrations tested (1.0, 1.5, and 2.0% w/v), indicating that PVA is an excellent support. The enzymatic activity of α-amylase was tested on the different starch substrates; the activity was higher in the immobilized form than in the free form. Enzymatic immobilization improved the stability of α-amylase over a wide range of temperatures and pHs. Enzymatic activity was highest when germinated wheat starch was used as the substrate at different temperatures and pHs, indicating great potential for its application in hydrolysis with α-amylase.
![Research paper thumbnail of Inorganic and organic structures as interleavers among [bis(1-methyl-3-(p-carboxylatephenyl)triazenide 1-oxide)Ni(II)] complexes to form supramolecular arrangements](https://attachments.academia-assets.com/94362449/thumbnails/1.jpg)
](Journal of Molecular Structure, 2016
Inorganic and organic structures as interleavers among [bis(1-methyl-3-(pcarboxylatephenyl)triaze... more Inorganic and organic structures as interleavers among [bis(1-methyl-3-(pcarboxylatephenyl)triazenide 1-oxide)Ni(II)] complexes to form supramolecular arrangements
The simultaneous determination of aflatoxins (AFLA) B1, B2, G1 and G2 was investigated in onions ... more The simultaneous determination of aflatoxins (AFLA) B1, B2, G1 and G2 was investigated in onions by means of matrix solid-phase dispersion (MSPD) extraction methodology, and using rice husk as adsorbent element. The AFLA identification and quantification were carried out by using high efficiency thin layer chromatography (HPTLC) and high efficiency liquid chromatography coupled to a fluorescence detector (HPLC-FD). The best adsorbent was the compound constituted by the rice husk:celite mixture (1:1) in a 1:1 ratio with the mass of the sample, and employing the mixture chloroform:methanol (5:25) as eluent. The methodology showed the limit of detection ranging from 0.05 to 1 μg.kg-1, and of the accuracy from 78 to 93%; and variation coefficients ranged from 11 to 14%. After being validated, the methodology was tested on its applicability in determining the aflatoxins occurrence in onion samples, which were classified according to the standard MAPA. Aflatoxin contamination was found in...
![Research paper thumbnail of Corrigendum to “Antioxidant activity and enzyme inhibition of phenolic acids from fermented rice bran with fungus Rizhopus oryzae” [Food Chem. 146 (2014) 371–377]](https://attachments.academia-assets.com/94361762/thumbnails/1.jpg)
](Food Chemistry, 2016
Corrigendum to ''Antioxidant activity and enzyme inhibition of phenolic acids from fermented rice... more Corrigendum to ''Antioxidant activity and enzyme inhibition of phenolic acids from fermented rice bran with fungus Rizhopus oryzae'' [Food Chem. 146 (2014) 371-377]
Mycotoxin Research, 2014
This study evaluated the ability of the microorganisms Rhizopus oryzae (CCT7560) and Trichoderma ... more This study evaluated the ability of the microorganisms Rhizopus oryzae (CCT7560) and Trichoderma reesei (QM9414), producers of generally recognized as safe (GRAS) enzymes, to reduce the level of aflatoxins B 1 , B 2 , G 1 , G 2 , and M 1. The variables considered to the screening were the initial number of spores in the inoculum and the culture time. The culture was conducted in contaminated 4 % potato dextrose agar (PDA) medium, and the residual mycotoxins were determined every 24 h by HPLC-FL. The fungus R. oryzae has reduced aflatoxins B 1 , B 2 , and G 1 in the 96 h and aflatoxins M 1 and G 2 in the range of 120 h of culture by approximately 100 %. The fungus T. reesei has reduced aflatoxins B 1 , B 2 , and M 1 in the 96 h and aflatoxin G 1 in the range of 120 h of culture by approximately 100 %. The highest reduction occurred in the middle of R. oryzae culture.
Aflatoxins - Biochemistry and Molecular Biology, 2011
Química Nova, 2012
The QuEChERS extraction method followed by quantification using HPLC/ UV-FL was evaluated for deo... more The QuEChERS extraction method followed by quantification using HPLC/ UV-FL was evaluated for deoxynivalenol (DON) and zearalenone (ZEA) determination in natural and parboiled rice and their fractions (bran and husk). The comparison between QuEChERS and partition with acetonitrile extraction showed that the first one was better. It presented higher recovery (91% for DON, 105% for ZEA) wih precision ranging from 1.5 to 18.6%. The limits of quantification were 22.2 µg kg-1 for DON and 4.3 µg kg-1 for ZEA. DON and ZEA showed higher levels in endosperm of parboiled rice (8 e 111.7 µg kg-1 , respectively) when compared to natural rice.
Química Nova, 2012
THE QuEChERS METHOD FOR DETERMINATION OF OCHRATOXIN A AND CITRININ IN RICE AND RICE BRAN. The pre... more THE QuEChERS METHOD FOR DETERMINATION OF OCHRATOXIN A AND CITRININ IN RICE AND RICE BRAN. The present study was carried out to establish the optimal conditions for performing ochratoxin A (OTA) and citrinin (CIT) extraction using the QuEChERS method in rice. Employing the factorial experimental design, variables that significantly influenced the extraction stages were determined. The following variables were analyzed: addition of water, acidification of acetonitrile with glacial acetic acid, as well as amounts of magnesium sulfate, sodium acetate, sodium citrate and diatomaceous earth. The best combining procedure resulted in a predictive model using more water and less diatomaceous earth. Recoveries of CIT and OTA were 78-105%.
Onions are rich in bioactive and volatile compounds with antioxidant activity. When concentrated ... more Onions are rich in bioactive and volatile compounds with antioxidant activity. When concentrated in plant extracts and applied directly into food matrices or packaging, they are sensitive to external factors and may have undesirable sensory attributes, such as odors. Therefore, this study sought to encapsulate red onion extract (ROE) in different concentrations (10, 20, 30, and 40%, v/v) into zein fibers by electrospinning. The major volatile compound in ROE was 3(2H)-furanone, 2-hexyl-5-methyl. Adding ROE into the polymeric solutions increased their electrical conductivity and decreased the apparent viscosity, thus decreasing the average diameter of the fibers. The loading capacity of ROE on fibers ranged from 77.3 to 91.5%. The fibers’ random and continuous morphology showed beads at the highest ROE concentration (40%). Fibers membranes showed lower values for contact angles as ROE was added. The antioxidant activity of the fibers ranged from 32.5 to 57.3%.
Revista do Instituto Adolfo Lutz (Impresso), 2012
International Journal of Food Microbiology, 2020
Synthetic preservatives can have harmful effects on the body, so plant essential oils appear to b... more Synthetic preservatives can have harmful effects on the body, so plant essential oils appear to be an attractive natural alternative. However, the use of essential oils is limited due to the low stability and possible negative effects on the sensory properties of food. Oil encapsulation was suggested as a way to overcome these drawbacks. The objective of this study was to encapsulate thyme essential oil and to evaluate its antioxidant and antimicrobial potential in vitro and in situ in of hamburger-like meat products. The casein-maltodextrin capsules produced by spray-drying were assessed for encapsulation efficiency, thermal stability, chemical compounds and morphology. Antioxidant activity was evaluated by DPPH, hydroxyl and nitric oxide methods, while antimicrobial activity was evaluated in vitro against four bacteria and in situ in hamburger-like products. The capsule showed high encapsulation efficiency and thermal stability, and spherical and irregular morphology. The casein-maltodextrin encapsulated essential oil showed antioxidant and antimicrobial activity against Staphylococcus aureus, Escherichia coli, Listeria monocytogenes and Salmonella Typhimurium tested in vitro and against thermotolerants coliforms and Escherichia coli in situ, showing potential for application as a natural preservative in food.
Journal of Food Science and Technology, 2021
The combination of oats such as water-soluble oat extract (SOE) and probiotic microorganisms can ... more The combination of oats such as water-soluble oat extract (SOE) and probiotic microorganisms can add nutritional value to the food and benefits to the consumer's health. The SOE contains soluble fiber, whose major soluble fraction is composed of b-glucan contains soluble antioxidants such as ferulic acid, avenanthramides and other phenolic acids. The purpose of this study was to develop a fermented dairy beverage containing SOE, evaluating the viability of the probiotic culture, the fatty acid profile, phenolic compounds content and sensory characteristics during the storage. It was verified that Lactobacillus casei remained viable during the 21 days of storage (count above 7 Log CFU.mL-1) and that the addition of SOE does not affect the viability of probiotic bacteria. The levels of bioactive compounds soluble in aqueous medium, increased between the beginning of the experiment and the end, being influenced by the addition of SOE. Seven fatty acids were found in all formulations with a prevalence of C16:0 followed by C18:1. The addition of SOE in the formulation contributes to a significant increase in linoleic acid (C18:2n6). The sensory evaluation of the fermented oat dairy beverage with L. casei (BAC) was positive: the product was highly appreciated by consumers, with acceptance rate of 84.4%. The combination of SOE, with L. casei in the production of novel probiotic fermented dairy beverage, was technologically feasible, improving the functional properties of the product and offering health benefits to the consumer. More studies should be made to evaluate the composition and functional properties of SOE.
Journal of the Science of Food and Agriculture, 2020
BACKGROUND: Thyme essential oil (TEO) is a great natural substitute for synthetic compounds in or... more BACKGROUND: Thyme essential oil (TEO) is a great natural substitute for synthetic compounds in order to maintain the quality and safety of food products acting as an antioxidant agent. We aimed at the nanoencapsulation of TEO at concentrations of 1, 3, and 5% (v/w, dry basis) in electrospun nanofibers made of starch (50% w/v) and formic acid (75% v/v). Rheological parameters of the fiber-forming solutions were measured, and various physical and chemical properties of the nanofibers were analyzed. RESULTS: The starch/TEO nanofibers presented homogeneous morphology. The starch nanofibers showed high encapsulation efficiency (EE, 99.1 to 99.8%), that along with FT-IR spectrum and TGA analysis, indicate great protection of the phenolic compounds of TEO. The nanofibers with 5% TEO retained up to 50% of the phenolic compounds after exposure to thermal treatment. The antioxidant activity against DPPH radical of the starch/TEO nanofibers varied from 11.1 to 14.2% and the values of inhibition (29.8%, p ≤ 0.05) against hydroxyl radical were same for free TEO and the nanofibers. CONCLUSION: Owing to these properties, electrospun starch/TEO nanofibers can be applied in food products or food packaging.
Journal of Food Science and Technology, 2020
Considering the low availability of gluten-free products that are offered an affordable price and... more Considering the low availability of gluten-free products that are offered an affordable price and good sensory characteristics, the main objective of the study was developed a gluten-free muffin based on green banana flour and evaluate their physical-chemical and sensorial aspects. The quality of the muffin was analyzed through such moisture content, ashes, proteins, lipids, fiber, carbohydrates, total caloric content, yield mass, weight loss in the supply, antioxidant activity, protein digestibility, and hedonic scale. The results showed that the gluten-free muffin had a moisture content of 26.7%, ash of 2.39%, lipids of 15.4%, proteins of 10.3%, fibers of 1.2%, carbohydrates of 44.0%, the total caloric value of 261.2 kcal, high protein digestibility and moderate antioxidant activity. The acceptability index was 84.5%. It has been concluded that gluten-free muffin with green banana flour is a viable alternative for the reason that they have higher protein content than other alternative flours.
Colloids and Surfaces B: Biointerfaces, 2020
Gliomas, intracranial malignant tumors, are aggressive, asymptomatic and difficult to treat due t... more Gliomas, intracranial malignant tumors, are aggressive, asymptomatic and difficult to treat due to their degree of infiltration, alternatives are needed to treat the disease. In this sense, natural compounds from the specialized metabolism of plants can act to control the disease. Glucosinolates and phenolic compounds, present in broccoli, have a potential to promote tumor cell death, however due to the low stability of these compounds, encapsulation becomes an alternative for their preservation. The objective was to encapsulate the broccoli extract by electrospraying and to evaluate its cytotoxicity in the primary cell culture of astrocytes and gliomas. The capsules were produced and characterized by encapsulation efficiency, functional groups, thermal stability and morphology, the capsule that presented the best parameters was used for the evaluation of cell cytotoxicity and antitumor activity. Capsules with equal or less than 50 % extract showed high encapsulation efficiency, high thermal stability and uniform morphology due to non-saturation of the active zein sites, which allowed a complete encapsulation of the added extract, as well as a greater protection of the compounds. The capsule with 50 % of the extract showed good results of the efficiency, morphology and thermal stability and was used to evaluate the antitumor activity, since the addition of extract in proportions greater than 60 % promoted saturation of the active sites and lower encapsulation efficiency, and directly affects the morphology and thermal stability. The encapsulated and unencapsulated extracts showed strong selective antitumor effect against glial tumor cells without toxicity to non-tumor cells.
Revista Ibero-Americana de Ciências Ambientais, 2019
Os hidrocarbonetos são listados como alguns dos principais contaminantes ambientais nos dias de... more Os hidrocarbonetos são listados como alguns dos principais contaminantes ambientais nos dias de hoje e são considerados indicadores geoquímicos em relação aos níveis e fontes de contaminação em ambientes hídricos. Por este motivo existem metodologias padronizadas para a determinação destes contaminantes em sedimentos, entre as mais utilizadas, podemos listar o método de extração por soxhlet e o método de extração sob ultrassom, porém os dois métodos de extração apresentam desvantagens em sua utilização. Neste estudo, foi desenvolvida uma metodologia para a extração, pré concentração e clean up de hidrocarbonetos presentes em sedimento, combinando etapas de extração por solvente sob ultrassom e em soxhlet, seguidas por fracionamento em coluna líquida preparativa e os extratos analisados por cromatografia gasosa acoplada a espectrometria de massas. Para otimização utilizou-se um planejamento experimental 2² com ponto central avaliando os tempos de pré sonificação e extração soxhlet....
Food Biophysics, 2019
In this study, ultrafine fibers were produced from black bean protein concentrates (BPCs) and pol... more In this study, ultrafine fibers were produced from black bean protein concentrates (BPCs) and polyvinyl alcohol (PVA) by electrospinning. The BPC was denatured under acidic (pH 2) or basic (pH 11) conditions. Polymer solutions containing different PVA concentrations (11% or 21%, w/v) and different BPC: PVA ratios (50:50 or 75:25, v/v) were used for fiber production. The electrical conductivity and rheological properties of the fiber-forming solutions were evaluated, as well as the morphology, size distribution, infrared spectrum, and thermal properties of the electrospun fibers. The fibers showed a homogeneous morphology and diameters ranging from 115 to 541 nm. Fibers from the solution containing BPC denatured at pH 11, 11% PVA, and 75:25 (v/ v) BPC: PVA presented the lowest diameter, and those from BPC denatured at pH 2 had less beads than the fibers obtained from BPC denatured at pH 11. The solution formulation affected the thermal properties of the fibers, with weight loss increases ranging from 39.0% to 60.9%. The polymeric solutions containing PVA and BPC (whether denatured under basic or acidic conditions) resulted in ultrafine electrospun fibers with highly favorable characteristics that could potentially be used for the encapsulation of bioactive compounds and food applications.
Journal of Food Processing and Preservation, 2019
Dairy products are widely consumed in developed countries and the incorporation of ingredients th... more Dairy products are widely consumed in developed countries and the incorporation of ingredients that promote the health of the consumer in this market can cause an increase in consumption (de
Visão Acadêmica, 2018
Atualmente a população tem buscado uma alimentação mais saudável devido ao aumento das doenças cr... more Atualmente a população tem buscado uma alimentação mais saudável devido ao aumento das doenças crônicas não transmissíveis, entre os alimentos com atividades biológicas protetores se encontram o amido resistente e outros oligossacarídeos. O objetivo do presente trabalho foi realizar uma breve revisão sistemática utilizando bases de dados indexadas acerca dos benefícios do amido resistente e de outros oligossacarídeos não digeríveis sobre a saúde humana. Como resultado da breve revisão evidenciou-se que os oligossacarídeos não-digeríveis e o amido resistente apresentam diversos benefícios para a saúde, atuando principalmente sobre o funcionamento do trato gastrointestinal, sistema nervoso central, sistema imunológico, biodisponibilidade de nutrientes, prevenção do câncer colorretal e na redução dos níveis bioquímicos de glicose, triglicerídeos e colesterol.
International Journal of Biological Macromolecules, 2019
The objective of this study was to immobilize α-amylase in ultrafine polyvinyl alcohol (PVA) fibe... more The objective of this study was to immobilize α-amylase in ultrafine polyvinyl alcohol (PVA) fibers by electrolysis and to evaluate its stability at different temperatures and pHs using various starch substrates such as corn starch and germinated and ungerminated wheat starches. The α-amylase-loaded ultrafine fibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and loadability and enzymatic activity evaluations. Incorporation of the enzyme resulted in a slight change in fiber morphology; the fibers became flatter and thicker with increasing enzyme concentration. The mean diameters ranged from 187 to 282 nm. FT-IR spectra indicated that the enzyme was incorporated into the fibers. PVA showed a high loading capacity for α-amylase at all concentrations tested (1.0, 1.5, and 2.0% w/v), indicating that PVA is an excellent support. The enzymatic activity of α-amylase was tested on the different starch substrates; the activity was higher in the immobilized form than in the free form. Enzymatic immobilization improved the stability of α-amylase over a wide range of temperatures and pHs. Enzymatic activity was highest when germinated wheat starch was used as the substrate at different temperatures and pHs, indicating great potential for its application in hydrolysis with α-amylase.
Journal of Molecular Structure, 2016
Inorganic and organic structures as interleavers among [bis(1-methyl-3-(pcarboxylatephenyl)triaze... more Inorganic and organic structures as interleavers among [bis(1-methyl-3-(pcarboxylatephenyl)triazenide 1-oxide)Ni(II)] complexes to form supramolecular arrangements
The simultaneous determination of aflatoxins (AFLA) B1, B2, G1 and G2 was investigated in onions ... more The simultaneous determination of aflatoxins (AFLA) B1, B2, G1 and G2 was investigated in onions by means of matrix solid-phase dispersion (MSPD) extraction methodology, and using rice husk as adsorbent element. The AFLA identification and quantification were carried out by using high efficiency thin layer chromatography (HPTLC) and high efficiency liquid chromatography coupled to a fluorescence detector (HPLC-FD). The best adsorbent was the compound constituted by the rice husk:celite mixture (1:1) in a 1:1 ratio with the mass of the sample, and employing the mixture chloroform:methanol (5:25) as eluent. The methodology showed the limit of detection ranging from 0.05 to 1 μg.kg-1, and of the accuracy from 78 to 93%; and variation coefficients ranged from 11 to 14%. After being validated, the methodology was tested on its applicability in determining the aflatoxins occurrence in onion samples, which were classified according to the standard MAPA. Aflatoxin contamination was found in...
Food Chemistry, 2016
Corrigendum to ''Antioxidant activity and enzyme inhibition of phenolic acids from fermented rice... more Corrigendum to ''Antioxidant activity and enzyme inhibition of phenolic acids from fermented rice bran with fungus Rizhopus oryzae'' [Food Chem. 146 (2014) 371-377]
Mycotoxin Research, 2014
This study evaluated the ability of the microorganisms Rhizopus oryzae (CCT7560) and Trichoderma ... more This study evaluated the ability of the microorganisms Rhizopus oryzae (CCT7560) and Trichoderma reesei (QM9414), producers of generally recognized as safe (GRAS) enzymes, to reduce the level of aflatoxins B 1 , B 2 , G 1 , G 2 , and M 1. The variables considered to the screening were the initial number of spores in the inoculum and the culture time. The culture was conducted in contaminated 4 % potato dextrose agar (PDA) medium, and the residual mycotoxins were determined every 24 h by HPLC-FL. The fungus R. oryzae has reduced aflatoxins B 1 , B 2 , and G 1 in the 96 h and aflatoxins M 1 and G 2 in the range of 120 h of culture by approximately 100 %. The fungus T. reesei has reduced aflatoxins B 1 , B 2 , and M 1 in the 96 h and aflatoxin G 1 in the range of 120 h of culture by approximately 100 %. The highest reduction occurred in the middle of R. oryzae culture.
Aflatoxins - Biochemistry and Molecular Biology, 2011
Química Nova, 2012
The QuEChERS extraction method followed by quantification using HPLC/ UV-FL was evaluated for deo... more The QuEChERS extraction method followed by quantification using HPLC/ UV-FL was evaluated for deoxynivalenol (DON) and zearalenone (ZEA) determination in natural and parboiled rice and their fractions (bran and husk). The comparison between QuEChERS and partition with acetonitrile extraction showed that the first one was better. It presented higher recovery (91% for DON, 105% for ZEA) wih precision ranging from 1.5 to 18.6%. The limits of quantification were 22.2 µg kg-1 for DON and 4.3 µg kg-1 for ZEA. DON and ZEA showed higher levels in endosperm of parboiled rice (8 e 111.7 µg kg-1 , respectively) when compared to natural rice.
Química Nova, 2012
THE QuEChERS METHOD FOR DETERMINATION OF OCHRATOXIN A AND CITRININ IN RICE AND RICE BRAN. The pre... more THE QuEChERS METHOD FOR DETERMINATION OF OCHRATOXIN A AND CITRININ IN RICE AND RICE BRAN. The present study was carried out to establish the optimal conditions for performing ochratoxin A (OTA) and citrinin (CIT) extraction using the QuEChERS method in rice. Employing the factorial experimental design, variables that significantly influenced the extraction stages were determined. The following variables were analyzed: addition of water, acidification of acetonitrile with glacial acetic acid, as well as amounts of magnesium sulfate, sodium acetate, sodium citrate and diatomaceous earth. The best combining procedure resulted in a predictive model using more water and less diatomaceous earth. Recoveries of CIT and OTA were 78-105%.