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Start Over Author "Gil, Maria M." Topic kinetics
2 results on '"Gil, Maria M."'

1. Stability, kinetics, and application study of phycobiliprotein pigments extracted from red algae Gracilaria gracilis.

Author

Pereira, Tatiana, Barroso, Sónia, Mendes, Susana, and Gil, Maria M.

Subjects
ANALYTICAL mechanics, PHYCOBILIPROTEINS, RED algae, PHOSPHATES, DIALYSIS (Chemistry)
Abstract

Phycobiliprotein (PBP) pigments were extracted from red algae Gracilaria gracilis through maceration in phosphate buffer using previously optimized conditions. The stability of PBPs in the extracts was assessed by monitoring the extracts at different pHs and temperatures for 10 days. Since phycoerythrin (PE) is the main PBP present in G. gracilis, PE content was spectroscopically determined and used as a response factor. Kinetic modeling was used to describe PE degradation under different ranges of T and pH. The pigment extracts presented higher stability at pH 6.9 and −20 °C. PE was semipurified by precipitation with ammonium sulphate 65% followed by dialysis against water until a purity index of 0.7. The pigment was successfully applied as colorant in pancakes and yogurts with a pigment concentration of 0.15%. This study highlights the potential of PE pigments extracted from G. gracilis for applications in food products. Practical Application: Phycobiliprotein pigments were extracted from red algae Gracilaria gracilis through maceration in phosphate buffer. The stability of the pigment was evaluated at different pHs and temperatures, presenting higher stability at neutral pH and low temperatures. The pigment was successfully applied as colorant in pancakes and yogurts with a low pigment concentration. This study highlights the potential of phycobiliprotein pigments extracted from G. gracilis for applications in food products. [ABSTRACT FROM AUTHOR]

Published
2020
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2. Influence of pH, type of acid and recovery media on the thermal inactivation of Listeria innocua

Author

Miller, Fátima A., Ramos, Bárbara, Gil, Maria M., Brandão, Teresa R. S., Teixeira, Paula, Silva, Cristina L.M., and Veritati - Repositório Institucional da Universidade Católica Portuguesa

Subjects
Hot Temperature, food.ingredient, Listeria, Food Contamination, Hydrochloric acid, Sodium Chloride, Models, Biological, Microbiology, Thermal inactivation, 03 medical and health sciences, chemistry.chemical_compound, Acetic acid, 0404 agricultural biotechnology, food, Yeasts, Humans, Agar, Food science, Listeria innocua, 2. Zero hunger, 0303 health sciences, Microbial Viability, biology, pH, 030306 microbiology, Recovery media, Type of acid, 04 agricultural and veterinary sciences, General Medicine, Hydrogen-Ion Concentration, biology.organism_classification, 040401 food science, Yeast, Culture Media, Lactic acid, Kinetics, chemistry, Biochemistry, Food Microbiology, Fermentation, Soybeans, Acids, Bacteria, Food Science
Abstract

Acidification of foods with organic acids, either by fermentation or by intentional addition, is an important and common mechanism for controlling foodborne pathogens in a diversity of food products. The objective of this work was to study thermal inactivation of Listeria innocua, an acid tolerant microorganism, at 52.5, 60.0 and 65.0 °C, at different pH values (4.5, 6.0 and 7.5), using three types of acid (lactic, acetic and hydrochloric) and three different plating media (Tryptic Soy Agar with 0.6% yeast extract-TSAYE; TSAYE plus 5% NaCl-TSAYE + 5%NaCl; and Palcam Agar with selective supplement-Palcam Agar), according to a 34 factorial experimental design. Survival data experimentally obtained were fitted with a Gompertz-inspired model and kinetic parameters (shoulder, maximum inactivation rate-kmax, and tail) were estimated for all conditions considered. The influence of temperature, pH, type of acid and enumeration media on kinetic parameters was assessed. Results showed that, with the exception of the type of acid, all the remaining factors and their combinations significantly affected the shoulder period and kmax. In relation to tail, temperature and recovery media were the affectable factors. It was concluded that the survival of this bacteria is higher when combining low temperature with neutral pH, and when TSAYE is the enumeration medium. Bigelow-inspired models were successfully developed and describe accurately the temperature and pH effects on the kinetic parameters.

Published
2009

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