Quality of Minimally Processed Lettuce as Influenced by Packaging and Chemical Treatment

Abstract

Shredded lettuce was packaged in sealed bags of monoorientedpolypropylene (OPP) film and also in polyethylene (PE) trays overwrapped with a rnultilayer polyolejn (RD1 06) or plasticizedpolyvirryl chloride (P VC) film; and stored at 4C in a refiigerated case during 8 days. Chemical treatment by dipping in a 0.3% ascorbic acid /0.3% citric acid solution did not significantly affect changes in microbial populations or visual sensory attributes. Type of package was not a signrfcant factor for microorganism populations, but was signijkant @<O. 001) for changes in gas composition andvisual sensoty attributes. The modiJied atmosphere within the packages changedfrom normal air composition to about 1.5% 0, /12% C 0 2 for OPP bags and to about 17-18% 0, /I-2% CO, for PVC-PE trays and RD106-PE trays after 8 &ys of storage. The visual sensory quality of the product was retained better in OPP bags than in the other ones.

Aceptabilidad de lechuga de hoja fresca troceada, tratada con ácido ascórbico mediante hidroenfriamiento

“…Por otro lado, Pirovani et al (1997) reportaron que la inmersión de lechuga Iceberg en una solución de 0.3% ácido ascórbico + 0.3% ácido cítrico no causo cambios en los atributos visuales del producto después de 8 días. Además, Bolin y Huxsoll (1991) explican que la inmersión de lechuga Iceberg en una solución de ácido ascórbico al 0.5% aumentó 10% la vida de anaquel de esta variedad de lechuga, pero Roura et al (2003) indican que la calidad visual de lechuga Romaine tratada por inmersión en una solución de ácido ascórbico al 0.5% no mostró mejoría.…”

“…Esparza et al (2006) found no differences in the instrumental color values of leaf lettuce hydrocooled with a solution of 1% ascorbic acid by immersion or spraying, reporting that the lettuce cooled by spraying maintained its instrumental color values (L* (intensity of color), a* (red-green scale), and b* (yellow-blue scale)) during 21 days of cold storage, but the lettuces treated by immersion showed an increase in their a* values (considered as an indicator of the development of browning) after 14 days of storage at 5 °C. Pirovani et al (1997) reported that immersing Iceberg lettuces in a solution of 0.3% ascorbic acid + 0.3% citric acid did not cause changes in the visual attributes of the product after 8 days. Furthermore, Bolin and Huxsoll (1991) explain that immersing Iceberg lettuce in a solution of 0.5% ascorbic acid increased by 10% the shelf life of this variety of lettuce, but Roura et al (2003) indicate that the visual quality of Romaine lettuce treated by immersion in a solution of 0.5% ascorbic acid showed no improvement.…”

Hygienic-sanitary quality of vegetables and evaluation of treatments for the elimination of indigenous E. coli and E. coli O157:H7 from the surface of leaves of lettuce (Lactuca sativa L.)

“…The cell suspensions were transferred to sterile eppendorf tubes, (LIN et al, 2000). Other sanitizers studied for their effectiveness in removing pathogens from fresh fruit and vegetables include trisodium phosphate (ZHUANG; BEUCHAT, 1996, WEBER;OBRIEN;BENDER, 2004;MOLINOS et al, 2005), organic acids (PIROVANI et al, 1998;RHEE et al, 2003;BJORNSDOTTIR;BREIDT;McFEETERS, 2006), hydrogen peroxide (BRENNAN; PORT; GORMLEY, 2000), and ozone (KOSEKI et al, 2001;ACHEN;YOUSEF, 2001;BELTRAN et al, 2005). Although various sanitizers have been examined for their effectiveness, most treatments have been shown to have minimal effects, resulting in less than a 2 log cfu.g -1 (cm 2 ) reduction in bacterial numbers, and most would not be suitable products for use at the household level (BEUCHAT et al, 1998).…”

Effect of modified atmosphere applied to minimally processed radicchio (Cichorium intybus L.) submitted to different sanitizing treatments

“…change is associated with senescence and can be considered a key attribute along with the texture to determine the edible quality of the leaves (Streit et al, 2005). In situations where modified atmosphere is associated with cooling, which is used to reduce microbial growth, undesirable chemical and physiological changes modify the appearance of the product (Pirovani, 1998). The food market provides new and interesting opportunities for producers of radicchio and other vegetables to apply technologies that can modify food products in order to provide benefits to the consumer health.…”