Abstract
Leafy green production in high tunnels (HTs) results in increased yields, improved visual quality, and extended production with polyethylene (poly) film and/or shade cloth coverings. However, altering visible and ultra-violet light with HT coverings may reduce phytochemicals, thus influencing plant pigmentation and taste. The objective of this study was to examine various HT coverings on the sensory perceptions, soil temperature, color, and anthocyanin accumulation of red leaf lettuce. The coverings included standard poly, standard poly with removal two weeks prior to harvest (movable), diffuse poly, clear poly, UV-A/B blocking poly (block), standard poly with 55% shade cloth, and the open field. A highly trained descriptive panel evaluated the samples using a scale from 0 (none) to 15 (extremely high) and determined a list of 20 sensory attributes. The color intensity attribute had the most differentiation between coverings, and the open field was higher (i.e., darker) than the others at 7.5 (p < 0.0001), followed by clear and movable coverings at 6.8, and the shade covering scored a 2. Strong relationships existed between both colorimetric (hue°) and anthocyanin analysis to panelist-based scores (R2 = 0.847 and 0.640, respectively). The initial crispness was similar for movable, standard, diffuse, and block coverings at 5.3 on average, which was higher than the open field at 4 (p < 0.01). The open field lettuce grew under cooler soil temperatures, which may have slowed down maturation and resulted in softer tissue. Based on this study, HT growers can implement specific coverings to cater to markets that value visual quality.
Highlights
Fruit and vegetable consumption may lead to the reduction of certain diseases, due to their antioxidant properties [1,2]
Significant differences were found in eight attributes (Table 3)
This study clearly shows that light variations during growth have significant effects on the color intensity of red lettuce, explaining most of the differentiation between coverings
Summary
Fruit and vegetable consumption may lead to the reduction of certain diseases, due to their antioxidant properties [1,2]. Phenolic acids (such as caffeic acid) and flavonoids (such as anthocyanin and quercetin) act as antioxidants pre- and post-consumption in both plant tissues and consumers. In humans, they have been shown to reduce arteriosclerotic plaques and inflammation [5], and habitual consumption is associated with decreased mortality due to cardiovascular and cancer [6]. The red pigment in lettuce leaves is due to phenolic compound accumulation, especially anthocyanin, and is an important appearance attribute responsible for the commercial value of red leaf lettuce [20]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call