Marisa Aparecida Bismara Regitano-d'Arce

Antioxidant activity of rosemary and oregano ethanol extracts in soybean oil under thermal oxidation

Four experiments were conducted to measure the antioxidant activity of ethanol extracts of rosemary and oregano compared with synthetic antioxidants such as TBHQ and BHA/BHT. The antioxidant activity was determined and results differed from those of the Oven test at 63o C. Peroxide values and absorptivities at 232 nm of soybean oil under Oven test were lower in treatments with 25, 50, 75, 100 and 200 mg.Kg-1 TBHQ than in treatments with 1000 mg.Kg-1 oregano extract (O), 500 mg.Kg-1 rosemary extract (R) and their mixture R+O. All the treatments were effective in controlling the thermal oxidation of oils; the natural extracts were as effective as BHA+BHT and less effective than TBHQ. The natural extracts were mixed with 25, 50, 75 and 100 mg.Kg-1 TBHQ and then added to the oil. No improvement in antioxidative properties was observed. The best antioxidant concentration could be determined from polynomial regression and quadratic equation from the experimental data.

Concentrado e isolado protéico de torta de castanha do pará: obtenção e caracterização química e funcional

The best conditions for producing Brazil nut protein concentrate and isolate from defatted cake were determined. Protein precipitation pH was 3.5-4.0 and protein extraction pH was 9.0. Protein concentrate and isolate yields were 70% and 35%, respectively. They were evaluated according to their properties of solubility, oil and water absorption (%WAC and %OAC), and foaming capacity. They presented high protein solubility in pH 12. Concentrate %WAC and %OAC were twice higher than the isolate. Brazil nut protein concentrate and isolate presented both good functionality, except for a good foaming capacity that was presented only by the isolate.

Comportamento do óleo de soja refinado utilizado em fritura por imersão com alimentos de origem vegetal

A fritura e uma operacao que confere aos alimentos caracteristicas de odor, sabor, cor e textura de grande aceitabilidade sensorial. O oleo ou gordura pode, entretanto, se tornar um ingrediente capaz de introduzir alteracoes quimicas provocadas pelo aquecimento prolongado. Neste trabalho, estudou-se o comportamento do oleo de soja refinado em fritura de imersao intermitente, em restaurante universitario, sob temperatura controlada entre 170oC e 180oC, por um periodo de 30 horas. Foram utilizados 101 litros de oleo de soja para processar 373kg de vegetais, como batata, couve-flor, abobrinha e mandioca. Analisou-se o oleo mediante determinacoes fisicas de absortividade no u.v. (A232nm e A270nm) e cor (Lovibond), e quimicas (indice de acidez (IA) e compostos polares (CP)). Analise sensorial de aceitabilidade foi realizada nos produtos. Os parâmetros-limite que determinaram o descarte do oleo foram: 25% de compostos polares, 1% de acidos graxos livres e media de 7,0 para o teste de aceitabilidade. Os resultados ao final do periodo foram: IA, 0,282; CP, 18,8%; cor Lovibond 14Y/2R; A232nm de 9,213; A270nm de 2,409 e 7,96 para o teste de aceitabilidade. Com base nos resultados obtidos, concluiu-se que, apesar do aquecimento do oleo ter levado a alteracoes hidroliticas e oxidativas, os parâmetros nao atingiram o nivel de descarte, indicando que o oleo de soja submetido a essas condicoes de fritura pode ser usado por 30 horas.

Phenolic acids and flavonoids of peanut by-products: Antioxidant capacity and antimicrobial effects

Peanut skin (PS) and meal from dry-blanched peanuts (MDBP) were evaluated as sources of phenolic compounds. PS rendered the highest total phenolic content, antioxidant capacity towards ABTS radical cation, DPPH and hydroxyl radicals as well as reducing power. Phenolic acids were present in PS and MDBP whereas proanthocyanidins and monomeric flavonoids were found only in PS as identified by HPLC-DAD-ESI-MSn. Procyanidin-rich extracts prevented oxidation in non-irradiated and gamma-irradiated fish model system. Both extracts inhibited the growth of gram-positive (Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Geobacillus stearothermophilus) and gram-negative bacteria (Pseudomonas aeruginosa, Pseudomonas fluorescens, Salmonella Enteritidis, Salmonella Typhimurium, Escherichia coli). Regardless of the strain, phenolic acid-rich extracts showed the lowest minimum inhibitory capacity (MIC); therefore presenting higher antibacterial effect. The MIC of phenolic acid-rich extracts (24-49μgphenolics/mL) was higher but comparable to Ampicillin (10μg/mL). Thus, phenolics in PS and MDBP may serve as antioxidants and antimicrobial compounds.

Oxidação lipídica do óleo de vísceras de aves para redução de seu conteúdo de energia metabolizável para frangos de corte na fase de crescimento

In order to determine the apparent metabolizable energy (AME) and N-corrected apparent metabolizable energy (AMEn) of fresh and oxidized poultry fat a metabolism assay with 48 AgRoss male broilers from 31 to 34 days of age was conducted. The birds were fed a basal diet or this diet replaced by 10% of fresh or oxidized fat and the total excreta collection method was applied. The birds were housed in metabolic cages and each diet was supplied for four replicates of four birds. Fresh poultry fat was supplied by a local rendering and then stored frozen (-18oC). The oxidized poultry fat was obtained by heating (80 - 90oC) and specific absorbances were measured frequently to control fat quality. Specific absorbances at 232 and 270 nm were, respectively, 4.64 and 0.47 for fresh fat and 18.54 and 3.76 for oxidized fat, which suggest higher levels of conjugated dienes in the oxidized poultry fat. The results of AME and AMEn were 9,240 and 9,150 kcal/kg (as fed-basis) for the fresh poultry fat and 7,770 and 7,595 kcal/kg (as fed-basis) for the oxidized poultry fat. AME and AMEn values were statistically different, indicating a decrease in the energy from the fresh poultry fat to the oxidized fat due to oxidation.

Determining economical TBHQ doses for corn oil stability

Oleo de milho obtido de uma industria brasileira isento de antioxidantes e de acido citrico foi adicionado de diferentes concentracoes de TBHQ e submetido a testes acelerados de oxidacao em estufa a 630C por 120 horas e em câmara de fotoxidacao por 168 horas. Foram analisados o indice de peroxido e as absortividades em 232nm e 270nm deste oleo. A partir dos resultados do teste em estufa, calculou-se a melhor dose e a dose economica do antioxidante TBHQ. Em seguida foi conduzido, entao ensaio ao ambiente, que confirmou a concentracao de 115mg.kg-1 TBHQ como a dosagem economica e melhor dose para o oleo sob estudo.