Qualidade de alface crespa minimamente processada armazenada sob refrigeração em dois sistemas de embalagem

Abstract

Quality of fresh-cut crisphead lettuce stored under refrigeration and two packaging systemsMinimal processing usually causes quality loss, reduces shelflife, and promotes sensory attributes alterations. The occurrence of browning in the midrib of fresh-cut lettuce is commonly observed and is associated with cell tissue disrupture, putting in contact enzymes and their respective substrates. Chemical, physical, and biochemical quality of fresh-cut crisphead lettuce stored under refrigeration and two different packaging systems were evaluated in the present work. Lettuce cv. Verônica was harvested in commercial fields in Brasilia, Brazil, and was minimally processed as whole leaves and 5 mm strips. Fresh-cut lettuce was then packed into polypropylene and low density polyethylene plastic films and was stored at 5 o C during 14 days. Every two days processed material was evaluated for titratable acidity, color (L*a*b*) and polyphenoloxidase and peroxidase enzymes activity. Lettuce processed as whole leaves showed higher brightness (L*) when compared to the material sliced at 5 mm, for both the packaging systems studied. Both polyphenoloxidase and peroxidase activities were higher for fresh-cut lettuce sliced at 5 mm when compared to whole leaves. Lettuce processed as 5 mm strips had the highest enzymatic browning, lowest brightness and organic acid content for both the packaging systems studied.

Biodegradable films of starch/PVOH/alginate in packaging systems for minimally processed lettuce (Lactuca sativa L.)

“…Such a decrease in acidity is related to the enzymatic reactions that occur in minimally processed food. Mattos et al (2007) found the same behavior in minimally processed lettuce. The values of the ASC were determined for the lettuce packed in different treatments (Figure 3,.…”

“…It was observed that there was an increase in the values of L* for the treatments with biodegradable films and a decrease for the PVC treatment at 4 days of storage; at this stage, the values of C* had already increased in the lettuce packaged in films with PVC, remained the same in EOLM films, and declined in EOCP and WEO films. Mattos et al (2007) found that minimally processed lettuce presented a lower lightness value than lettuce in whole leaves. These authors concluded that the higher activity of peroxidase and polyphenol oxidase in cut leaves was responsible for the results.…”

“…The occurrence of enzymatic browning can diminish lightness (L*), and it can be increase the gray tones, consequently increase the values of C⃰ (Mattos et al, 2007). It was observed that there was an increase in the values of L* for the treatments with biodegradable films and a decrease for the PVC treatment at 4 days of storage; at this stage, the values of C* had already increased in the lettuce packaged in films with PVC, remained the same in EOLM films, and declined in EOCP and WEO films.…”

Efeito da refrigeração na conservação de hortaliças orgânicas minimamente processadas

“…Em repolho, na colheita, os valores de AT (0,2) estão abaixo dos reportados por outros autores (0,36-0,91), enquanto que para o mix de folhas (0,2) são semelhantes aos apresentados na alface crespa armazenada sob refrigeração, podendo ser reportadas como hortaliças de baixa acidez, assim como o kit yakissoba (0,3). 26,23 A manutenção dos valores de AT pode estar relacionada à redução da atividade respiratória em decorrência da redução dos níveis de O 2 e concentração de CO 2 no interior das embalagens, promovendo manutenção dos ácidos orgânicos.…”

Insights in agricultural practices and management systems linked to microbiological contamination of lettuce in conventional production systems in Southern Brazil

“…In Brazil, as in many other countries, lettuce (Lactuca sativa L.) is one of the most consumed leafy vegetables, attributable to year round availability, low cost and nutritional factors (Abreu et al, 2010;Mocelin and Figueiredo, 2009;WHO et al 2008;Mattos et al, 2007). The Brazilian lettuce cultivation system is predominantly done in open fields, which are located for the most part at urban surroundings.…”