RESUMO
The effect of different high-pressure processing (HPP) treatments on casein micelles was analyzed through scanning electron microscopy (SEM) and a particle size distribution analysis. Raw whole and skim milk samples were subjected to HPP treatments at 400, 500 and 600 MPa for Come-Up Times (CUT) up to 15 min at ambient temperature. Three different phenomena were observed in the casein micelles: fragmentation, alterations to shape and agglomeration. The particle size distribution analysis determined that, as pressure and time treatment increased, the three phenomena intensified. First, the size of the casein micelles began to decrease as their fragmentation occurred. Subsequently, the casein micelles lost roundness, and their shape deformed. Finally, in the most intense treatments (higher pressures and/or longer times), the micelles fragments began to agglomerate, which resulted in an increase in their average diameter. Homogenization and defatting had no significant effect on the casein micelles; however, the presence of fat in whole milk samples was bioprotective, as the effects of the three phenomena appeared faster in treated skim milk samples. Through this study, it was concluded that the size and structure of casein micelles are greatly altered during high-pressure treatment. These results provide information that broadens the understanding of the changes induced on casein micelles by high-pressure treatments at room temperature.
Assuntos
Caseínas , Micelas , Animais , Caseínas/química , Leite/química , Proteínas do Leite/químicaRESUMO
High-pressure processing (HPP) is a nonthermal technology used for food preservation capable of generating pasteurized milk products. There is much information regarding the inactivation of microorganisms in milk by HPP, and it has been suggested that 600 MPa for 5 min is adequate to reduce the number of log cycles by 5-7, resulting in safe products comparable to traditionally pasteurized ones. However, there are many implications regarding physicochemical and functional properties. This review explores the potential of HPP to preserve milk, focusing on the changes in milk components such as lipids, casein, whey proteins, and minerals, and the impact on their functional and physicochemical properties, including pH, color, turbidity, emulsion stability, rheological behavior, and sensory properties. Additionally, the effects of these changes on the elaboration of dairy products such as cheese, cream, and buttermilk are explored.
RESUMO
In this study, the supercritical CO2-based extraction approach was used from the green technologies to extract Oregano oil (Origanum vulgare L.). A Taguchi experimental design was applied to evaluate the effect of pressure, temperature and ethanol as co-solvent. High yield of oregano oil (13.40%) was obtained at 40 °C, 100 bar and 8 g min-1 of co-solvent flow. Fatty acids profile include α-linolenic, palmitic, oleic and linoleic that contribute to 70.9-76.8% of total fatty acids. Volatile compounds including carvacrol (29.99%), heneicosane (8.21%), nonacosane (11.78%), docosane (7.18%), borneol (4.35%) and thymol (4.51%) were the main compounds identified. Antimicrobial activity assays showed that extracts obtained at 40 °C were highly efficient against S. aureus, E. coli, and C. albicans. Highest antioxidant activities on DPPH and FRAP assays were reached under 8 g min-1 of co-solvent flow (6.08 and 6.89 µmol TE g-1 extract, respectively). On the other hand, antioxidant activity (35.76 µmol TE g-1) on ABTS assay was improved at 40 °C, 100 bar, and 4 g min-1 of co-solvent flow.
Assuntos
Origanum , Antioxidantes , Dióxido de Carbono , Escherichia coli , Extratos Vegetais , Staphylococcus aureusRESUMO
Arthrospira platensis was used to obtain functional extracts through supercritical carbon dioxide extraction (SFE-CO2). Pressure (P), temperature (T), co-solvent (CX), static extraction (SX), dispersant (Di) and dynamic extraction (DX) were evaluated as process parameters through a Plackett-Burman design. The maximum extract yield obtained was 7.48 ± 0.15% w/w. The maximum contents of bioactive metabolites in extracts were 0.69 ± 0.09 µg/g of riboflavin, 5.49 ± 0.10 µg/g of α-tocopherol, 524.46 ± 0.10 µg/g of ß-carotene, 1.44 ± 0.10 µg/g of lutein and 32.11 ± 0.12 mg/g of fatty acids with 39.38% of palmitic acid, 20.63% of linoleic acid and 30.27% of γ-linolenic acid. A. platensis extracts had an antioxidant activity of 76.47 ± 0.71 µg GAE/g by Folin-Ciocalteu assay, 0.52 ± 0.02, 0.40 ± 0.01 and 1.47 ± 0.02 µmol TE/g by DPPH, FRAP and TEAC assays, respectively. These extracts showed antimicrobial activity against Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922 and Candida albicans ATCC 10231. Overall, co-solvent was the most significant factor for all measured effects (p < 0.05). Arthrospira platensis represents a sustainable source of bioactive compounds through SFE using the following extraction parameters P: 450 bar, CX: 11 g/min, SX: 15 min, DX: 25 min, T: 60 °C and Di: 35 g.
Assuntos
Fatores Biológicos/química , Dióxido de Carbono/química , Spirulina/química , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Antioxidantes/química , Antioxidantes/farmacologia , Bactérias/efeitos dos fármacos , Fatores Biológicos/farmacologia , Candida albicans/efeitos dos fármacos , Ácidos Graxos/química , Ácidos Graxos/farmacologia , Ácido Linoleico/química , Ácido Linoleico/farmacologia , Luteína/química , Luteína/farmacologia , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Pressão , Riboflavina/química , Riboflavina/farmacologia , Solventes/química , Temperatura , alfa-Tocoferol/química , alfa-Tocoferol/farmacologia , beta Caroteno/química , beta Caroteno/farmacologiaRESUMO
Traditional medicine has led to the discovery of important active substances used in several health-related areas. Phytochemicals in Rhoeo discolor extracts have proven to have important antimicrobial activity. In the present study, our group determined the antimicrobial effects of extracts of Rhoeo discolor, a plant commonly used in Mexico for both medicinal and ornamental purposes. We evaluated the in vitro activity of phenolic rich extracts against specifically chosen microorganisms of human health importance by measuring their susceptibility via agar-disc diffusion assay and flow cytometry: Gram-positive Listeria innocua and Streptococcus mutans, Gram-negative Escherichia coli and Pseudomonas aeruginosa, and lastly a fungal pathogen Candida albicans. Ten different extracts were tested in eight different doses on all the microorganisms. Analytical data revealed a high content of phenolic compounds. Both agar-disc diffusion assay and flow cytometry results demonstrated that Pseudomonas aeruginosa was the least affected by extract exposure. However, low doses of these extracts (predominantly polar), in a range from 1 to 4 µg/mL, did produce a statistically significant bacteriostatic and bactericidal effect on the rest of the microorganisms. These results suggest the addition of certain natural extracts from Rhoeo discolor could act as antibacterial and antimycotic drugs or additives for foods and cosmetics.
Assuntos
Antibacterianos/farmacologia , Antifúngicos/farmacologia , Fenóis/farmacologia , Folhas de Planta/química , Tradescantia/química , Antibacterianos/isolamento & purificação , Antifúngicos/isolamento & purificação , Candida albicans/efeitos dos fármacos , Candida albicans/crescimento & desenvolvimento , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Listeria/efeitos dos fármacos , Listeria/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Fenóis/isolamento & purificação , Extratos Vegetais/química , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Solventes/química , Streptococcus mutans/efeitos dos fármacos , Streptococcus mutans/crescimento & desenvolvimentoRESUMO
The bactericidal effect of 3 natural agents (carvacrol, thymol, and eugenol) was evaluated as well as their binary and ternary mixtures on Listeria innocua inactivation in liquid model systems. Minimal bactericidal concentrations (MBC) of these agents were determined, and then binary and ternary mixtures were evaluated. Culture media were inoculated with L. innocua and incubated for 72 h at 35 °C. Turbidity of studied systems were determined every 24 h. The most effective individual antimicrobial agent was carvacrol, followed by thymol and then eugenol with MBCs of 150, 250, and 450 mg kg(-1), respectively. It was observed that the most effective binary mixture was 75 mg kg(-1) carvacrol and 62.5 mg kg(-1) thymol. Furthermore, the ternary mixture carvacrol-thymol-eugenol in concentrations of 75, 31.25, and 56.25 mg kg(-1), correspondingly, was the most effective for L. innocua inactivation. Several binary and ternary mixtures of these 3 natural antimicrobial agents worked adequately to inactivate L. innocua.