Changes in the physico-chemical properties during storage of lettuce varieties, three green and one red

Lettuce, a popularly consumed leafy vegetable, is well known for its health and nutritional value. Thus, the current study focused on the qualitative changes of four lettuce varieties, namely Alpha, Parris Island, Graziella and Lollo Rossa, stored at 5.5 ?C and 90 % RH for 12 days. The analyzed parameters were water content, total soluble solids (TSS), titrable acidity (TA), vitamin C, total phenols, polyphenoloxidase (PPO), color and texture. Under storage conditions, the studied varieties exhibited different rates of water loss. TSS was found to increase until day 8 of storage, which is also when TA differences were observed. The Graziella variety showed the highest vitamin C levels. Total phenol content decreased significantly during the 12 days of storage.No significant PPO activity changes were found,except for those of the Lollo Rossa variety. Biplotanalysis allowed observing not only positive and negative correlations between coordinates L*, a* and b*, but also the separation of the green lettuce varieties from the red one, together with color variations depending on leaf position. Although textural changes were recorded at the end of the study, foliage quality was not altered. In short, the studied parameters, which contribute to lettuce direct consumption properties, can be said to be variety-dependent and better preserved under refrigeration. ConclusionsThe differences expressed by the studied lettuce varieties can be attributed to different phenotypic expressions of their characteristic genetic diversity.Lettuce water content was found to depend on the way the leaves are distributed around the main stem, the butterhead variety Alpha standing out for its elevated scores. Total soluble solids content was found to be higher in the green foliage varieties than in the red one; this particular feature contributed?to good taste preservation in the former varieties (Graziella, Parris Island and Alpha). Significant titratable acidity differences were found between lettuce types. This parameter was observed to increase toward the end of the study. Although?the recorded levels of vitamin C confirm lettuce as a very discrete source of this nutrient, the way the product is usually consumed makes it potentially?beneficial for the consumer. Total phenol contents were higher in variety Lollo Rossa, which confers it relatively better antioxidant properties. The low PPO activity recorded for the varieties Graziella, Parris Island and Alpha favors the maintenance of fresh-cut lettuce physicochemical quality when it is used for the preparation of ready-to-eat foods. Biplot analysis of CIELAB chromaticity parameters was sensitive enough to discriminate the varieties by their color, as well as the tone differences of?the leaves according to their position on the plant.Textural changes observed during storage did not alter the quality of the studied genotypes. SourcesChanges in the physico-chemical properties of four lettuce (Lactuca sativa L.) varieties during storageCambios en las propiedades fisicoqu?micas de cuatro variedades de lechuga (Lactuca sativa L.) durante el almacenamientoMar?a Vargas-Arcila,1 Jos? R?gulo Cartagena-Valenzuela,2 Germ?n Franco,3 Guillermo A. Correa-Londo?o,? Luz Mary Quintero-V?squez,? Carlos A. Gaviria-Montoya? 1 Agr?noma, Universidad Cat?lica de Oriente. Profesional de apoyo, CI La Selva, Corpoica, Rionegro, Colombia. mvargasa@corpoica.org.co2 PhD, Mississippi State University. Profesor titular, Universidad Nacional de Colombia, Colombia. Medell?n. jrcartag@unal.edu.co3 PhD, Universidad Nacional de Colombia. Investigador PhD, CI La Selva, Corpoica, Rionegro, Colombia. gfranco@corpoica.org.co? PhD, Universidad de Salamanca. Profesor asociado, Universidad Nacional de Colombia, Medell?n, Colombia. gcorrea@unal.edu.co? Ingeniera de alimentos, Universidad Nacional Abierta y a Distancia. Profesional de investigaci?n, CI La Selva, Corpoica, Rionegro, Colombia. lquintero@corpoica.org.co? Ingeniero qu?mico, Universidad Nacional de Colombia. Investigador independiente, Medell?n, Colombia. carloandres.gaviria@gmail.coCorpoica Cienc Tecnol Agropecuaria 2017 18(2):257-273DOI: http://dx.doi.org/10.21930/rcta.vol18_num2_art:632Pictures1 -?El Corte Ingl?s2 -?Minolta colorimeter CR-400 by?AQ Instruments?