Determining aroma differences among basil, parsley, and dill grown under varied supplemental light wavelengths using consumer sensory and flash gas chromatograph-electronic nose analyses

Abstract

Greenhouse herb producers may use artificial lighting to supplement the natural light available to their crops. High-pressure sodium (HPS) lights are the most common supplemental lighting systems employed in such operations, but light-emitting diode (LED) lighting is increasing in popularity because of its energy efficiency, customizability, and environmental friendliness. LED lights can be customized to emit specific proportions of light wavelengths, but many herb producers do not know how these "light recipes" affect their crops, specifically their crops' aroma. This research utilized consumer sensory difference panels and flash gas chromatograph-electronic nose (GC-EN) analysis to evaluate the aroma of fresh basil, parsley, and dill herbs after cultivation under one of three supplemental light treatments: HPS, LED with a high proportion of blue to red diodes (high blue LED), or LED with a low proportion of blue to red diodes (low blue LED). Consumer sensory panels using triangle difference tests found that consumers could not determine the difference between herbs grown under HPS and high blue LED. Preliminary work suggests a similar result for HPS and low blue LED, but further research is required to confirm this. GC-EN analysis revealed no significant chemical differences between lighting treatments among basil or parsley. Subtle chemical differences were uncovered in dill GC-EN data, especially when nonpolar and mid-polar column data were examined separately to prevent false correlation from multiple detections of a single compound. Consistent with literature findings, linear discriminant analysis of these data subsets revealed that multiple volatile compounds in dill are affected by the supplemental lighting wavelengths available to the herb. viii In the scope of this study, there appears to be no overall aroma difference between herbs grown under HPS light and those grown under LED light, but more research must be conducted to confirm and expand upon these findings. Future research including sensory preference tests, descriptive analyses, GC-olfactometry, and GC-MS studies will make research like this more practical for herb farmers. CHAPTER 2: LITERATURE REVIEW Conventional Herb Cultivation Herb cultivation is extremely varied; small farms and large-scale producers alike operate in the U.S. (Rogers, 2012). Herbs and other essential oil crops like lavender and lemongrass are widely grown outdoors in warm climates (Adam, 2005). For example, much of the country's fresh basil comes from California, Hawaii, Florida, or abroad (U.S. Department of Agriculture, 2016). Because of wide global commerce, herbs grown in greenhouses abroad could supply the entire U.S. herb market (Adam, 2005). But should it? Promoting the local production of herbs would supplement local farming economies and provide fresher, higher quality herbs to consumers. In the U.S., herbs are often grown as "a way to stabilize small farm ventures" (Miller, 1985). The same is true in greenhouse systems: growing herbs is an easy way to supplement ...

Leveraging Controlled-Environment Agriculture to Increase Key Basil Terpenoid and Phenylpropanoid Concentrations: The Effects of Radiation Intensity and CO2 Concentration on Consumer Preference

“…Although researchers have investigated the influence of DLI on secondary metabolite accumulation, there are limited data on how these aroma and flavor profile changes affect consumer preference. Sensory analysis panels have been conducted to determine perceived differences in basil aroma due to radiation source, radiation quality, and temperature during production ( Chang et al, 2007 ; Seely, 2017 ); to determine perceived differences in drying methods ( Díaz-Maroto et al, 2004 ; Calín-Sánchez et al, 2012 ); and to characterize basil cultivars ( D’Antuono et al, 2007 ; de Costa et al, 2014 ; Bernhardt et al, 2015 ; Tangpao et al, 2018 ). Although some of these studies connect production practices with consumer preference, recommendations based on radiation intensity are needed.…”