Production of 4th range iceberg lettuce enriched with calcium. Evaluation of some quality parameters

Abstract

This project is part of a study on the process of production of 4th range Iceberg lettuce leaves enriched with Ca using the vacuum impregnation (VI) technique. The objectives of this work were (i) to verify if it is possible that a 250g portion of impregnated lettuce leaves provides the same quantity of Ca (300mg) as a 250mL glass of milk, and (ii) to analyze the effects of VI on some quality parameters of the lettuce leaves: water activity, humidity, soluble solids content, real and apparent densities, pH, optical and mechanical properties, and respiration rate. For the study, three zones of the whole lettuce leaf were differentiated (on a longitudinal axis), because of the different distribution of the vascular system: apical (A), medium (M) and basal (B). Iceberg lettuce leaves with a global content of 169mg of Ca in 250g of impregnated product were obtained. A fresher, shinier product is obtained without presenting differences in colour. In average, Ca enrichment doesn’t affect significantly the mechanical behaviour. The respiration rates and the respiratory quotient remain almost unchanged in the A area, whereas in the M area the intake of O2 increases lightly, without change in the production of CO2, and both respiratory rates increase notably in the B area, with an important decrease in the respiratory quotient, indicating that the operation seems to prevent the fermentative anaerobic routes. The study shows it seems possible to obtain a Ca enriched product, being a possible alternative to dairy products. The industrial application of this process should include the control of the hydric state of the vegetable material, to increase impregnation capacity and reduce its variability.