A leitura como um processo cognitivo
Figueiredo, Olívia Maria
1999-01-01
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7 records were found.
In order to develop a fermented product with young stems of salicornia/pickleweed, an experiment was worked out and the fermentative process was studied. Initial data on the bacterial fauna of the plants revealed the existence of no lactic acid bacteria. Therefore, we chose to use of starting cultures. Sterile “heart cabbage”
juice was the base for different fermentative bacteria: Lactobacillus plantarum, Leuconostoc mesenteroides,
Pediococcus acidilactici, and pH, titrated acidity and salinity were evaluated. The same experiment was undertaken with and without the glasswort or salicornia. Significant differences were observed only with L. plantarum: pH variation and percentage of lactic acid suffered a significant increase during the fermentative
process, specially when salicornia was introduced in the juice. Results obtained for t...
The main objective of this study was to evaluate the stability of astaxanthin after drying and storage at different conditions during a 9-week period. Recovery of astaxanthin was evaluated by extracting pigments from the dried powders and analysing extracts by HPLC. The powders obtained were stored under different conditions of temperature and oxygen level and the effects on the degradation of astaxanthin were examined. Under the experimental conditions conducted in this study, the drying temperature that yielded the highest content of astaxanthin was 220°C, as the inlet, and 120°C, as the outlet temperature of the drying chamber. The best results were obtained for biomass dried at 180/110°C and stored at −21°C under nitrogen, with astaxanthin degradation lower than 10% after 9 weeks of storage. A reasonable preservation of astaxanthin...
Anthocyanins have gathered the attention of the scientific community mostly due to their vast
range of possible applications. They have been the center point of the research in many different
fields, among which is food development, where their innate coloring, antioxidant capacity and
biological potential open interesting venues to the development of new food additives and
functional foodstuffs. As the range of application grows, so does the necessity to obtain these
compounds and since they are naturally occurring, the most common way to obtain anthocyanins
is to extract them from different plant sources, such as fruits and flowers. Several efforts have
been made to develop methods that allow for better extraction yields and higher purification rates
therefore this review aims to compile the information regarding extraction a...
info:eu-repo/semantics/publishedVersion
Apple cubes were osmotically dehydrated at 25, 40 and 60C, using sucrose or sorbitol,
and the mass ratio of sample to solution of 1:4 and 1:10, at atmospheric
pressure or vacuum pressure of 150 mbar. Six mathematical models were tested to
describe the mass transfer kinetics of water loss (WL) and sugar gain (SG).
Crank’s, Azuara’s, Peleg’s, Page’s and Weibull’s models could fit well the experimental
data, but the Penetration model resulted in a poor fit. The mass ratio of
sample to solution did not have an influence on the mass transfer kinetics at the
atmospheric pressure. The increase of temperature and the use of sorbitol as the
osmotic agent resulted in an increase of the osmotic process rate at both pressures
used. Therefore, sorbitol is a good alternative to sucrose. The vacuum presented a
tendency to increase the initi...
Este trabalho teve como objetivo estudar a utilização potencial do sorbitol como agente no
processo de desidratação osmótica (DO). Além de apresentar baixas calorias e ser menos doce
e menos cariogénico que a sacarose, o sorbitol é um prebiótico com propriedades de saúde
comprovados.
Cubos de maçã foram desidratados osmoticamente a temperaturas entre 25 e 60 ºC, utilizando
solução de sacarose ou sorbitol a 60 ºBrix e razão mássica de fruto/solução de 1:4 ou 1:10,
sob pressão atmosférica ou vácuo de 150 mbar. A DO de fisális foi realizada nas condições
otimizadas da DO de cubos de maçã (60 ºC, 1:4), relativamente às cinéticas de perda de água
(PA).
A utilização do sorbitol como agente osmótico resultou num aumento das cinéticas, a ambas
as pressões, pelo que é uma boa alternativa para substituir a sacarose. A razão de 1:4 é
t...
The aim of the present work was to study the effect of the osmotic dehydration (OD) pre-treatment on the mass transfer kinetics and water activity (aw) of apple cubes during hot air drying. The adequacy of different mathematical models to describe the moisture content of the product during this process was also evaluated. Apple cubes were osmotically dehydrated with sucrose or sorbitol solutions at 60 °C, and then dried by air at 25-80 °C. Overall, the OD and rise of the air temperature resulted in an increased water loss rate and a reduction of the aw. The osmotic agent used in the OD was not relevant to the air drying kinetics, but the pre-treatment with sorbitol solutions produced dried samples with lower aw. Newton's, Page's, modified Page's, Henderson and Pabis', Two-term, Two-term exponential, Logarithmic, Midilli et al.'s models...
