Background and methodology
The purpose of this project was to study the quality of Swiss chard produced by conventional and organic methods and to establish the differences in microbial populations, biochemical degradative processes and in the sensory attributes. Raw material was obtained from a local conventional producer and an organic producer located near Mar del Plata in the southeast region of the Buenos Aires province of Argentina. Both producers planted and harvested at optimal maturity. Samples of winter Swiss chard (Beta vulgaris of the Bressanne variety, characterized by heavily crimpled, dark green leaves) were sorted for integrity, uniformity of color and size, and lack of defects to reduce the natural variability among leaves of chard. Chard leaves were soaked in tap water at 18–20° C for 4 minutes. Surface moisture was removed with a manual salad centrifuge. Leaves were piled in 120-gram stacks and placed in polyethylene bags and stored at 4±2°C. Samples were evaluated periodically for up to 25 days.
Findings
No significant differences were found in the initial populations of yeast, molds and psychrotrophic mesophilic and lactic acid bacteria. The evolutions of the population of those microorganisms during storage also were similar for both chards. First-order kinetics after an induction period were found for the degradation of ascorbic acid. Although the rate constant was similar for both chards, the induction period for organic chard (equal to 10 days) was longer than for conventional chard (equal to 3 days). No significant differences were found between the water and chlorophyll content and in pH and titratable acidity of both chards. Sensorial analysis showed that organically produced chard retained turgidity, color and brightness longer than the conventionally produced chard.
Reference
Moreira, M. D. R., Roura, S. I. & Carlos E. del Valle. C. E. D. (2005). Quality of Swiss chard produced by conventional and organic methods. LWT - Food Science and Technology, 36(1), 135-141.