Variation in Macronutrient Content, Phytochemical Constitution and In Vitro Antioxidant Capacity of Green and Red Butterhead Lettuce Dictated by Different Developmental Stages of Harvest Maturity

Abstract

Rising life expectancy and the demanding modern lifestyle drive the growing appeal of healthy and balanced diets centered on vegetable and fruit consumption. Functional, phytonutrient-packed and principally raw food is in high demand. Microgreens constitute such a novel functional food that combines a high sensory and bioactive value, which invites comparison to their mature-leaf counterparts. For this purpose, a controlled environment chamber experiment was carried out to compare the mineral, phytochemical and antioxidant capacity attributes of two-pigmented Lactuca sativa L. var. capitata cultivars (green and red Salanova®) harvested at the microgreens and the mature-leaf stage. Macronutrients were assessed through ion chromatography, while carotenoids and polyphenols were assessed and quantified through HPLC-DAD and UHPLC-Q-Orbitrap HRMS, respectively. Calcium and magnesium were higher in microgreens irrespective of the cultivar; conversely, phosphorous, potassium and nitrate where higher in mature leaves. All pigments including chlorophyll, lutein and β-carotene augmented at advanced maturity stage and were more concentrated in the red pigmented cultivar at both stages. Total polyphenols accumulated more densely in red Salanova, particularly in the microgreens stage; whereas, in green Salanova, the accumulation was significant but less pronounced in the mcirogreens stage. Chlorogenic acid, quercetin malonyl glucoside, rutin and coumaroyl quinic acid were the most concentrated phenolic acids in microgreens, while feruloyl tartaric acid was predominant in mature leaves. Finally, when a high carotenoids content is sought, mature lettuce leaves should be the prime culinary choice, whereas high polyphenolic content is dictated by both the cultivar and the harvest stage, with red Salanova microgreens being the most nutrient-packed choice.

Nutrient Supplementation Configures the Bioactive Profile and Production Characteristics of Three Brassica L. Microgreens Species Grown in Peat-Based Media

“…The highest TAA content was 390.6 mg 100 g −1 fw, registered for rocket × C, while the lowest content was 219.5 mg 100 g −1 fw, registered for cabbage × NS. Ascorbic acid is a powerful water-soluble antioxidant [18]; it is a typical example of an imperative secondary metabolite that acts as enzymes 'cofactor, regulates the photosynthesis and cell division, other than being involved in the transduction of signals in plants [10], and inhibits the N-nitroso compounds deriving from nitrite [44]. The TAA values obtained for Brussels sprouts were consistent with those obtained by Xiao et al [45], where they were higher than those registered for cabbage.…”

“…Several biological processes related to the growth and development of plants are based on the presence of minerals (17 key minerals), which are also conveyed to human nutrition [18]. The present results on microgreens macronutrient content were in the range obtained by Weber [11] on cabbage, by Kamal et al [13] on Brussels sprouts and green cabbage and by Kyriacou et al [12,27], who assessed several Brassica microgreens on peat-based substrate.…”

“…Microgreens constitute a fresh popping crop with antioxidant punch, naturally dense in nutrients without the interference of biofortification or genetic engineering [11]. Their consumption is rising due to their high nutrient content [1,12,13], vivid colors and intense flavors [14][15][16]; they are highly packed in secondary metabolites compared to their mature counterparts [15,17,18]. Notably, Brassica microgreens are a prominent choice due to their simple germination, short growing cycle and the potential health benefits attributed to their content of vitamins, polyphenols, glucosinolates, etc.…”

Sensory Attributes and Consumer Acceptability of 12 Microgreens Species

“…Microgreens are also regarded as fresh "super foods" [4,9,10] due to their innate fortification with plant secondary metabolites [9,[11][12][13]. Additionally to carotenoids, ascorbic acid, phylloquinone, γ-tocopherols, and phenolic compounds, microgreens are also a source of macro and micro-minerals.…”

“…Such nutritive and functional values enhance human diet and prevent a range of common diseases [4,9,10,12,14]. Indeed, microgreens enclose a greater load of essential phytonutrients compared to their mature counterparts [3,4,6,10,13]. Suchlike dense phytochemical composition has garnered the attention of nutrition researchers [6,15] and gained them prevalence among food technologists, urban farmers, and consumers [15].…”