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Nutrient content of cabbage and lettuce microgreens grown on compost and hydroponic growing pads

Authors:
  • Weber Physical Therapy and Wellness, PLLC

Abstract

Current food systems, the collective processes involved in food production, distribution and consumption, create a dichotomous problem of nutritional excess and insufficiency and are not environmentally sustainable. One specific nutritional problem that needs attention is mineral (e.g., Fe, Zn) malnutrition, which impacts over two-thirds of the World’s people living in countries of every economic status. Microgreens, the edible cotelydons of many vegetables, flowers, and herbs, is a newly emerging crop that is potentially a dense source of minerals that can be sustainably produced in almost any locale. In this study, the nutrient contents of lettuce and cabbage microgreens grown hydroponically (HP) and on vermicompost (C) were assessed and compared to each other as well as to the nutrient contents of store-bought cabbage and lettuce (mature vegetables). Of the 10 nutrients examined (P, K, S, Ca, Mg, Mn, Cu, Zn, Fe, Na), C cabbage microgreens had significantly larger quantities of all nutrients than HP cabbage microgreens (p-values <0.00321) with the exception of P; C lettuce microgreens had significantly larger quantities of all nutrients than HP lettuce microgreens (p-values <0.024) except for P, Mg and Cu. Compared to the mature vegetable, C or HP cabbage microgreens had significantly larger quantities of all nutrients examined (p-values <0.001) and C or HP lettuce microgreens had significantly larger quantities of all nutrients except for Ca and Na (p-values <0.0012). Results of this study indicate that microgreens grown on vermicompost have greater nutrient contents than those grown hydroponically. As microgreens can be grown easily in one’s home using the methods used in this study, they may provide a means for consumer access to larger quantities of nutrients per gram plant biomass relative to store-bought mature vegetables, which had lower nutrient contents than microgreens with respect to most nutrients examined.
Research Article Open Access
Volume 3 • Issue 4 • 1000190
J Hortic, an open access journal
ISSN: 2376-0354
OMICS International
Research Article
Weber, J Hortic 2016, 3:4
DOI: 10.4172/2376-0354.1000190
Journal of Horticulture
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*Corresponding author: Carolyn F Weber, Department of Biological Sciences,
Idaho State University, Pocatello, ID 83209, USA, Tel: (505) 412-8384; E-mail:
Carolyn.F.Weber@dmu.edu
Received November 01, 2016; Accepted December 13, 2016; Published
December 16, 2016
Citation: Weber CF (2016) Nutrient Content of Cabbage and Lettuce Microgreens
Grown on Vermicompost and Hydroponic Growing Pads. J Hortic 3: 190. doi:
10.4172/2376-0354.1000190
Copyright: © 2016 Weber CF. This is an open-access article distributed under the
terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and
source are credited.
Nutrient Content of Cabbage and Lettuce Microgreens Grown on
Vermicompost and Hydroponic Growing Pads
Carolyn F Weber*
Department of Biological Sciences, Idaho State University, Pocatello, ID 83209, USA
Keywords: Microgreens; Lettuce; Cabbage; Nutrients;
Vermicompost; Hydroponic
Abbreviations: LV: Lettuce (Mature Vegetable); LC: Lettuce
Microgreens Grown on Vermicompost; LHP: Lettuce Microgreens
Grown Hydroponically; CV: Cabbage (Mature Vegetable); CC: Cabbage
Microgreens Grown on Compost; CHP: Cabbage Microgreens Grown
Hydroponically; MG’s: Microgreens; s.d.: Standard Deviation
Introduction
One-third of the World’s people, living in countries of every
economic status, is overweight and/or undernourished [1-3]. is
dichotomous problem of nutritional excess and insuciency is the
product of processes associated with food production, distribution and
consumption [1]. e reliance of urban populations on long food chains
that begin in distant rural areas limits accessibility to produce that has
short shelf-lives and, therefore, poor transportability [4]. As a result,
many urban populations reside in areas classied as “food deserts”,
where people do not have ready access to a complete compliment of
required nutrients and depend primarily on heavily processed and
packaged foods [4]. Fresh produce that does reach urban centers has
usually lost substantial nutritional value during transport [5,6]. is
transport consumes 10% of the total energy budget in the United
States [6] and contributes to food waste as it spoils or is contaminated
enroute [1]. is waste comprises the largest component of municipal
waste and is responsible for a large fraction of annual methane
emissions in the United States [6]. erefore, in addition to creating
problems of nutritional excess and insuciency, current food systems
are detrimental to the very environment on which the production of
nutritious food depends [1].
One specic nutritional problem that is common in both developed
and developing countries is mineral malnutrition with over 60% and
30% of the World’s seven billion people, being Fe and Zn decient,
respectively [7]. Rates of mineral malnutrition are especially high in
Asia and Africa [8], where soil degradation is especially severe and has
signicantly decreased the nutritional value of crops [9]. However,
mineral malnutrition is considered to be one of the most important
global challenges to human kind that can be prevented [10] and is one
of the Millennium Development Goals [8]. Current eorts to mitigate
mineral malnourishment are focused on developing biofortication
methods [7] and genetically engineering crops for maximal nutrient
uptake from soils [10].
However, a newly emerging crop that may be a dense source of
nutrition in the absence of biofortication and genetic engineering and
has the potential to be produced in just about any locale is microgreens.
Microgreens (MG’s) are edible seedlings of vegetables, herbs and some
owers that are usually harvested 7-14 days aer germination, when
they have two fully developed cotyledon leaves [11]. MG’s are used
to add texture and avor to various dishes [12] and they are earning
a reputation as dense sources of nutrition even though only a few
studies have examined their vitamin, nutrient and carotenoid contents
[11,13,14]. e potential nutritional benets of MG’s combined with
their ease of cultivation in one’s home has piqued consumer interest in
cultivating MG’s, especially given that they are not widely available for
retail sale. e impact of commonly recommended cultivation methods
Abstract
Current food systems, the collective processes involved in food production, distribution and consumption, create
a dichotomous problem of nutritional excess and insufciency and are not environmentally sustainable. One specic
nutritional problem that needs attention is mineral (e.g., Fe, Zn) malnutrition, which impacts over two-thirds of the World’s
people living in countries of every economic status. Microgreens, the edible cotelydons of many vegetables, owers,
and herbs, is a newly emerging crop that is potentially a dense source of minerals that can be sustainably produced
in almost any locale. In this study, the nutrient contents of lettuce and cabbage microgreens grown hydroponically
(HP) and on vermicompost (C) were assessed and compared to each other as well as to the nutrient contents of
store-bought cabbage and lettuce (mature vegetables). Of the 10 nutrients examined (P, K, S, Ca, Mg, Mn, Cu, Zn,
Fe, Na), C cabbage microgreens had signicantly larger quantities of all nutrients than HP cabbage microgreens
(p-values <0.00321) with the exception of P; C lettuce microgreens had signicantly larger quantities of all nutrients
than HP lettuce microgreens (p-values <0.024) except for P, Mg and Cu. Compared to the mature vegetable, C or HP
cabbage microgreens had signicantly larger quantities of all nutrients examined (p-values <0.001) and C or HP lettuce
microgreens had signicantly larger quantities of all nutrients except for Ca and Na (p-values <0.0012). Results of this
study indicate that microgreens grown on vermicompost have greater nutrient contents than those grown hydroponically.
As microgreens can be grown easily in one’s home using the methods used in this study, they may provide a means for
consumer access to larger quantities of nutrients per gram plant biomass relative to store-bought mature vegetables,
which had lower nutrient contents than microgreens with respect to most nutrients examined.
Citation: Weber CF (2016) Nutrient Content of Cabbage and Lettuce Microgreens Grown on Vermicompost and Hydroponic Growing Pads. J Hortic
3: 190. doi: 10.4172/2376-0354.1000190
Page 2 of 5
Volume 3 • Issue 4 • 1000190
J Hortic, an open access journal
ISSN: 2376-0354
on the nutritional value of MG’s remains to be assessed, but could assist
consumers in making educated decisions about how to grow MG’s in
their own homes.
is study compares the nutrient content of lettuce and cabbage
MG’s grown on vermicompost and on hydroponic growing pads, both
of which are easily utilized in one’s own home. e nutrient contents
of store-bought cabbage and lettuce (mature vegetables) were also
completed to determine if it may be nutritionally advantageous for
people to eat home-grown MG’s rather than industrially produced
mature vegetables that are commonly available in supermarkets.
Materials and Methods
Growth conditions and harvest
All growing and insert trays, humidity domes and Micro-Mat
Hydroponic Growing Pads used for growing MG’s were obtained from
Handy Pantry (Salt Lake City, UT, USA). All seeds were obtained from
Mountain Valley Seeds (Salt Lake City, UT, USA). Five grams of cabbage
seed (“C”; Brassica oleracea var capitata, Golden Acre) was sowed into
each of eight 5 inch × 5 inch insert trays containing vermicompost (4
insert trays; “C”) or Micro-Mat Hydroponic Growing Pads (four insert
trays; “HP”). Similarly, 42 g of lettuce seed (“L”; Lactuca sativa, Parris
Island Cos) was sowed into four insert trays containing vermicompost
and four insert trays containing Micro-Mat Hydroponic Growing Pads.
Seeds sowed on C were hydrated with sterile deionized water during
the 7-day growth period (a total of 110 mL per insert tray), using sterile
serological pipets in volumes of 15, 25 or 30 mL. Seeds sowed on HP
were hydrated with a 0.4% solution of General Hydroponics® FloraGro®
Advanced Nutrient System® 2-1-6 (“FloraGro”; GH Inc., Sebastopol,
CA, USA), made in sterile deionized water, during the 7-day growth
period (a total of 110 mL per insert tray); hydration was applied in 15,
25 or 45 mL volumes per insert tray using sterile serological pipets.
All 16-insert trays were placed into 10 inch × 20 inch black plastic
growing trays for the duration of the experiment. HP and C insert trays
were maintained in separate growing trays to avoid contaminating C
trays with FloraGro. Growing trays were covered with clear humidity
domes and incubated under constant light produced by GE® Plant
and Aquarium Ecolux Bulbs positioned approximately six inches
above the surface of the growth substrate; light intensity ranged
from 3,790 to 4,920 LUX across the light eld and insert trays were
randomly shied to dierent positions within the light eld each day
(Figure 1). Vermicompost was generated from 0.5 bricks of Eco Earth®
Compressed Coconut Fiber Expandable Reptile Substrate, vegetable
and fruit waste, coee grounds, coee lters and shredded paper in
two Worm Factories housing Eisenia fetida. e Worm Factories were
purchased from and maintained using instructions from Uncle Jim’s
Worm Farm (Spring Grove, PA, USA). Vegetable and fruit waste and
coee grounds and lters were applied to the Worm Factories at a rate
of approximately 0.14 kg per day. Worm Factories were kept indoors
at room temperature. Compost was manually turned every two days.
MG’s were harvested seven days aer sowing using ethanol-
cleaned scissors by cutting the cotyledon stems as close to the growth
substrate as possible. Harvested biomass from each of the 16-insert
trays was placed into pre-weighed foil cups and weighed. e foil cups
were placed into a drying oven at 80oC for 48 h prior to weighing again
to determine the fraction dry mass. Similarly, fraction dry mass was
determined for four samples of cabbage (mature vegetable; CV) and
four samples of romaine lettuce (mature vegetable; LV) purchased
from a local grocer.
Elemental analysis
Dried MG’s and vegetables (2 g per experimental replicate) were
manually ground into a ne powder using a clean mortar and pestle
and placed into clean scintillation vials. Ground material was sent to
the Penn State Agriculture Analytical Services Program (University
Park, PA) for elemental analysis. Each of the samples was subjected to
standard acid digestion procedures to determine the dry mass content
of the following elements: P, K, Ca, Mg, S, Na, Fe, Mn, Cu, and Zn.
Data analysis
Elemental analysis data was examined by the Shapiro Tests for
normality and Fligner-Kileen Tests for homoscedasticity using R
soware [15]. Based on these results, a nonparametric Welch’s ANOVA
(α=0.05) followed by a Bonferroni Correction for multiple comparisons
was utilized to determine if there were signicant dierences among
the mean nutrient contents of LV, LC and LHP and among the mean
nutrient contents of CV, CC and CHP (α=0.05).
Results and Discussion
Overall, results of this study indicate that vermicompost-grown
MG’s are signicantly more nutrient-rich than hydroponically-grown
MG’s, and that MG’s are relatively dense sources of nutrients relative
to store-bought vegetables (Table 1). Based on nutrient mass per gram
dry plant material, CC MG’s had signicantly larger quantities of all
nutrients than CHP MG’s (all p-values <0.00321) with the exception
of P. LC MG’s had signicantly larger quantities of all nutrients (all
p-values <0.024) than LHP MG’s except for P, Mg and Cu. CC or CHP
MG’s had signicantly larger quantities of all nutrients examined than
CV (all p-values <0.001); LC or LHP MG’s had signicantly greater
quantities of all nutrients than LV (all p-values <0.0012) except for Ca
and Na.
e relative nutritional values of MG’s to mature vegetables on a
nutrient mass per gram fresh plant material are illustrated in Figure 2.
Average ratios across the 10 nutrients (P, K, Ca, Mg, S, Mn, Cu, Zn, Na,
and Fe) indicate that LC, LHP, CC and CHP were 2.8, 2.7, 8.1 and 2.9
times more nutrient-rich than the mature vegetable. Particularly high
nutrient ratios were observed for Fe in cabbage microgreens with CC
having 54.6 times the amount of Fe as the mature vegetable, while CHP
had 5.4 times the amount of Fe as the mature vegetable. For Fe, lettuce
microgreens still contained between 2 and 3 times the amount as the
mature vegetable, but it is clear that cabbage microgreens are able to
acquire far greater amounts of Fe when grown on the same substrates.
For Zn, cabbage microgreens contained between 5 and 7.5 times the
amount of Zn as the mature vegetable. e relatively high levels of Fe
and Zn are of particular interest given the prevalence of deciencies in
these two nutrients across the globe [1,7,9].
Pinto et al. [13] found lettuce MG nutrient contents to be on par
with those previously reported for “baby leaf” lettuce [16], but P, K,
Fe, Cu and Zn contents of lettuce MG’s in this study were between 16
and 98 times higher. is, in combination with the dierences between
the nutrient contents of vermicompost and hydroponically-grown
MG’s found in this study; highlight the signicant eect of cultivation
methods on MG nutrient content.
e average biomass yields (gfw) per experimental replicate (± 1
s.d.; n=4) were as follows: 35.1 g ± 7.6 g (LHP), 26.5 g ± 4.9 g (LC),
38.1 g ± 8.1 g (CC), 21.5 g ± 5.4 g (CHP). As nutritional data for MG’s
is still relatively scarce and MG’s are not widely available products,
established serving sizes do not exist. However, on the basis of serving
Citation: Weber CF (2016) Nutrient Content of Cabbage and Lettuce Microgreens Grown on Vermicompost and Hydroponic Growing Pads. J Hortic
3: 190. doi: 10.4172/2376-0354.1000190
Page 3 of 5
Volume 3 • Issue 4 • 1000190
J Hortic, an open access journal
ISSN: 2376-0354
Figure 1: (a) Microgreen growing set-up. Humidity domes were removed for the purpose of taking the photo. (b) Lettuce microgreens in 5 inch × 5 inch growing trays
just prior to harvest, 7-days after sowing.
10
9
8
7
6
5
4
3
2
1
0P K Ca Mg S Mn Cu Zn Na
Lc
LHP
CC
CHP
microgreen mature vegetable nutrient ratio
Fe
60
50
40
30
20
10
0
Figure 2: Microgreen: mature vegetable nutrient ratio based on mass of nutrient per gfw plant material for P, K, Ca, Mg, S, Mn, Cu, Zn, Na (left) and Fe (right). Note
the different scale on the y-axis for the two graphs. For both graphs, horizontal lines at a microgreen: mature vegetable ratio: 1 indicate where nutrient values of
microgreens and mature vegetables are equivalent. LC: Lettuce microgreens grown on vermicompost; LHP: Lettuce microgreens grown hydroponically; CC: Cabbage
microgreens grown on vermicompost; CHP: Cabbage microgreens grown hydroponically. Symbols plotted are listed on the legend on the graph.
sizes for lettuce and cabbage vegetables and the relative nutrient
contents of MG’s to these mature vegetables, estimates of serving sizes
can be made. e serving sizes for mature lettuce and cabbage are 91
g and 89 g, respectively [17]. On the basis of the average microgreen:
vegetable nutrient ratios for LC, LHP, CC and CHP (2.8, 2.7, 8.1
and 2.9, respectively), microgreen serving sizes that are nutritionally
equivalent to the mature vegetable servings can be calculated as: 32.5 g
(LC), 33.7 g (LHP), 11 g (CC), 30.7 g (CHP). is indicates that a single
5 inch × 5 inch growing tray produces the following number of MG
servings based on fresh mass yields in this study: 1 (LHP), 0.8 (LC), 3.5
(CC), 0.7 (CHP).
MG’s can be grown easily in one’s home via the methods used in
this study. erefore, results presented here indicate that MG’s could
provide a means for consumer-access to larger quantities of nutrients
per gram plant biomass relative to store-bought mature vegetables.
e hydroponic mats utilized are compostable and may be especially
convenient for consumers who wish to grow MG’s in relatively small
urban dwellings and avoid purchasing or working with a soil matrix.
Citation: Weber CF (2016) Nutrient Content of Cabbage and Lettuce Microgreens Grown on Vermicompost and Hydroponic Growing Pads. J Hortic
3: 190. doi: 10.4172/2376-0354.1000190
Page 4 of 5
Volume 3 • Issue 4 • 1000190
J Hortic, an open access journal
ISSN: 2376-0354
However, compostable waste is produced by every household and
includes “unavoidable waste” from fruit and vegetables that is nutrient
rich, but comprises a large amount of fresh mass that goes uneaten.
An example of such unavoidable food waste is banana peels, which
make up about 40% of the fruit’s fresh weight [18], and contain 45,000
and 64,000 mg potassium (Kg dry mass)-1 [19]. Growing MG’s in the
vermicompost generated from such unavoidable food waste provides
a mechanism for recapturing some of these nutrients in plant biomass
for human consumption rather than having it lost to a landll. e
MG ability to acquire micronutrients from vermicompost that had
been made bioavailable via decomposition of nutrient rich-food wastes
is likely responsible for the higher levels of some nutrients in the
compost-grown MG’s than in the hydroponically-grown MG’s. e
hydroponic fertilizer solution used in this study was an N, P, K-based
fertilizer; although it contains trace elements, their availability for
plant uptake was not as great as it was in the vermicompost utilized.
e ability of vermicompost to improve plant growth when added to
growth matrix has been documented previously, but its impact can
vary tremendously depending on the materials being composted (e.g.,
fruits and vegetables, manure, sewage sludge; [20]). Additionally, the
microbial community composition and activity in vermicompost can
also dramatically aect plant growth [20]. Nutrient quantities and
microbial properties of the vermicompost were not assessed in this
study, as the focus was to examine whether or not the two growing
methods yielded MG’s with dierent nutrient contents. However, given
the dierences in the nutrient contents of MG’s grown hydroponically
or on vermicompost, a more detailed study that examines the nutrient
and microbial properties of the vermicompost is warranted. e ability
of microbial communities to enhance MG growth is intriguing because
the HP treatment in this study likely contained far fewer microbes than
the vermicompost treatment [21].
Conclusion
Results of this study indicate that, on average, MG’s grown
on vermicompost had greater nutrient contents than those grown
hydroponically. However, MG’s, irrespective of growing method, had
greater average nutrient contents than store-bought mature vegetables.
As microgreens can be grown easily in one’s home using the two
methods used in this study, they may provide a means for consumer
access to larger quantities of nutrients per gram plant biomass relative
to store-bought mature vegetables. Simultaneously, growing and
consuming MG’s could reduce consumer need to rely on industrialized
food systems, which involve environmentally damaging processes (i.e.,
fertilizer application, high water use, long transport chains [1]).
Acknowledgements
I thank BIOL2207 students at Idaho State University (Spring 2016), Emily
Baergen, Cassie Thibeault and the Department of Biological Sciences for making
this work possible. This project was funded by student laboratory course fees. This
work is dedicated to the memory of Myrtle C. Bart, a horticulturist who was ahead
of her time. The author declares no conicts of interest.
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Element
Lettuce Cabbage
LV LHP LC CV CHP CC
mg (gdw)-1
P5.58
(0.43)a
13.34
(0.43)b
8.66
(1.24)c
1.28
(0.07)a
14.76
(0.42)b
12.95
(0.27)c
K41.06
(2.63)a
13.92
(1.77)b
60.14
(6.23)c
24.22
(1.04)a
12.34
(0.99)b
42.99
(2.55)c
Ca 8.48
(1.67)a
2.61
(0.19)b
8.50
(0.88)a
2.93
(0.36)a
7.88
(0.11)b
13.22
(0.27)c
Mg 3.49
(0.50)a
6.48
(0.25)b
5.78
(0.08)c
0.90
(0.02)a
4.75
(0.09)b
5.82
(0.05)c
S2.76
(0.23)a
4.48
(0.16)b
5.89
(0.72)c
5.74
(0.19)a
15.77
(0.49)b
19.39
(0.69)c
Na 5.02
(0.47)a
1.80
(0.41)b
2.71
(0.21)c
1.07
(0.02)a
2.61
(0.25)b
3.49
(0.12)c
µg (gdw)-1
Mn 28.99
(3.64)a
48.61
(3.10)a
118.03
(38.59)b
34.34
(1.36)a
41.84
(1.16)b
64.96
(2.77)c
Fe 99.59
(12.57)a
232.75
(46.50)a
2327.45
(916.94)c
21.83
(3.03)a
121.35
(9.02)b
187.19
(32.72)c
Cu 9.44
(1.24)a
21.22
(0.92)b
17.49
(0.74)c
1.42
(0.30)a
3.69
(0.21)b
5.07
(0.10)c
Zn 42.65
(4.69)a
143.49
(7.15)b
200.97
(31.95)c
13.84
(0.71)a
60.78
(2.79)b
160.02
(4.97)c
Table 1: Average nutrient content (n=4, (standard deviation)), for lettuce vegetable (LV), hydroponically grown lettuce microgreens (LHP), vermicompost-grown lettuce
microgreens (LC), cabbage vegetable (CV), hydroponically-grown cabbage microgreens (CHP) and vermicompost-grown cabbage microgreens (CC). The average fraction
dry masses (standard deviation) were as follows: 0.059 (0.009), LHP; 0.060 (0.007), LC; 0.056 (0.002), LV; 0.096 (0.016), CHP; 0.070 (0.006), CC; 0.120 (0.002), CV.
Small letters denote signicance (α=0.05) of statistical comparisons among LV, LC and LHP nutrient contents and comparisons among CV, CC and CHP nutrient contents.
Citation: Weber CF (2016) Nutrient Content of Cabbage and Lettuce Microgreens Grown on Vermicompost and Hydroponic Growing Pads. J Hortic
3: 190. doi: 10.4172/2376-0354.1000190
Page 5 of 5
Volume 3 • Issue 4 • 1000190
J Hortic, an open access journal
ISSN: 2376-0354
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Citation: Weber CF (2016) Nutrient Content of Cabbage and Lettuce
Microgreens Grown on Vermicompost and Hydroponic Growing Pads. J Hortic
3: 190. doi: 10.4172/2376-0354.1000190
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... Weber [104] studied the mineral content of lettuce (Lactuca sativa) and cabbage (Brassica oleracea var. capitata) microgreens and compared them to their mature vegetable stage. ...
... The substrates used for microgreen production significantly impact the nutrient content per gram of fresh weight of plant material. Cabbage microgreens grown on vermicompost had considerably higher concentrations of K, S, Ca, Mg, Mn, Cu, Zn, Fe, and Na than hydroponically grown cabbage [104]. Exceptionally high nutrient ratios for Fe were detected in cabbage microgreens grown on vermicompost (54.6-fold content of mature cabbage), while cabbage microgreens grown hydroponically still exceeded mature cabbage by a factor of 5.4. ...
... Exceptionally high nutrient ratios for Fe were detected in cabbage microgreens grown on vermicompost (54.6-fold content of mature cabbage), while cabbage microgreens grown hydroponically still exceeded mature cabbage by a factor of 5.4. Similarly, lettuce microgreens grown on vermicompost showed significantly larger quantities of K, S, Ca, Mn, Zn, Fe, and Na than hydroponically grown lettuce microgreens [104]. Regarding Zn, cabbage microgreens had a 5 to 7.5 times higher nutrient ratio than mature cabbage. ...
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With the growing interest of society in healthy eating, the interest in fresh, ready-to-eat, functional food, such as microscale vegetables (sprouted seeds and microgreens), has been on the rise in recent years globally. This review briefly describes the crops commonly used for microscale vegetable production, highlights Brassica vegetables because of their health-promoting secondary metabolites (polyphenols, glucosinolates), and looks at consumer acceptance of sprouts and microgreens. Apart from the main crops used for microscale vegetable production, landraces, wild food plants, and crops’ wild relatives often have high phytonutrient density and exciting flavors and tastes, thus providing the scope to widen the range of crops and species used for this purpose. Moreover, the nutritional value and content of phytochemicals often vary with plant growth and development within the same crop. Sprouted seeds and microgreens are often more nutrient-dense than ungerminated seeds or mature vegetables. This review also describes the environmental and priming factors that may impact the nutritional value and content of phytochemicals of microscale vegetables. These factors include the growth environment, growing substrates, imposed environmental stresses, seed priming and biostimulants, biofortification, and the effect of light in controlled environments. This review also touches on microgreen market trends. Due to their short growth cycle, nutrient-dense sprouts and microgreens can be produced with minimal input; without pesticides, they can even be home-grown and harvested as needed, hence having low environmental impacts and a broad acceptance among health-conscious consumers.
... 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]. ...
... 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. Moreover, potassium and calcium were among the most abundant minerals detected in microgreens, which is in line with the results of Waterland et al. [39] for Brassica microgreens. ...
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Brassica microgreens are a fresh microscale vegetable crop of high antioxidant value and naturally dense in nutrients without the intervention of biofortification or genetic engineering. A climate chamber experiment on peat-based substrate was set up to test microgreens growth and accumulation of secondary metabolites in response to nutrient supplementation. Microgreens mineral content was analyzed through ion chromatography and total ascorbic acid through UV-Vis spectrophotometry, while carotenoids and phenolic acids were quantified by HPLC-DAD and UHPLC-HRMS, respectively. Brussels sprouts and cabbage yield was only reduced by 10%, while nitrate was reduced by 99% in the absence of nutrient supplementation. Rocket yield was prominently reduced by 47%, with a corresponding nitrate reduction of 118%. Brussels sprouts secondary metabolites were not improved by the absence of nutrient supplementation, whereas cabbage microgreens demonstrated a 30% increase in total ascorbic acid and a 12% increase in total anthocyanins. As for rocket, the absence of nutrient supplementation elicited an extensive increase in secondary metabolites, such as lutein (110%), β-carotene (30%), total ascorbic acid (58%) and total anthocyanins (20%), but caused a decrease in total phenolic acids. It is hereby demonstrated that growing microgreens on a commercial peat-based substrate without nutrient supplementation can be feasible for certain species. Moreover, it might elicit a species-dependent spike in bioactive secondary metabolites.
... This inspires comparisons with their mature-leaf counterparts, particularly as very few studies have examined their vitamin, nutrient, and carotenoid contents [9,15] and even fewer have provided comparative evidence of the phytochemical content of microgreens and baby leaves as opposed to their mature-leaf counterparts. The studies of Pinto et al. [9] and Weber [16] solely addressed the comparative mineral profiles of mature leaves and microgreens. El-Nakhe et al. [17] compared some nutraceutical compounds (chlorophylls, vitamin C, carotenes, phenolics), but this study was carried out with only two lettuce varieties at two harvest times (microgreen and adult). ...
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Interest in the cultivation of lettuce landraces is increasing because native varieties, as high-quality products, are particularly attractive to consumers. Lettuce is a popular leafy vegetable worldwide, and interest in the consumption of first leaves (microgreens) and seedlings (baby leaves) has grown due to the general belief that young plants offer higher nutritional value. The content of some bioactive compounds and antioxidants (chlorophylls, carotenoids, anthocyanins, ascorbic acid, phenols, antioxidant activity) was monitored in six lettuce landraces and five commercial varieties, and compared across three development stages: microgreen, baby, and adult. Ascorbic acid and phenolic contents were 42% and 79% higher, respectively, in the early stages than in adult lettuces, and red-leaf varieties (CL4 and L11) stood out. This finding agrees with lettuce’s marked antioxidant capacity and correlates with its pigment contents, especially anthocyanins. The nutritional value of adult lettuce is conditioned by its size, shape, and head structure as phytochemical concentrations are regulated by light. The low content of ascorbic acid, phenolics, and anthocyanins in crisphead lettuce (CL5) is a clear example (49, 67%, and 27% lower, respectively, than the adult mean). Our results indicate the wide variability of lettuces’ nutritional characteristics and emphasize that traditional varieties are a helpful source of agricultural biodiversity.
... However, while there are similarities, some aspects of microgreen production differ from that of sprouts and lettuce. While sprouts are germinated for five days in a warm, mostly enclosed, moist environment [1,2], microgreens are germinated for up to 72 h in either a hydroponic nutrient solution, soil, or a soil substitute [3][4][5]. Germinated microgreens are then allowed to grow for approximately 10 to 20 days-until the opening of the cotyledon or the formation of the first set of true leaves. Lettuce, by contrast, is typically grown in a field, or hydroponically, and reaches the mature rosette stage after 90 days [6]. ...
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Microgreens are an emerging salad crop with properties similar to those of sprouted seeds and lettuce. This study aimed to determine bacterial pathogen persistence during microgreen cultivation and transfer from soil-free cultivation matrix (SFCM) to mature microgreens. Salmonella enterica subsp. enterica ser. Javiana and Listeria monocytogenes were inoculated onto biostrate mats as well as peat SFCM and sampled (day 0). Next, sunflower and pea shoot seeds were planted (day 0) and grown in a controlled environment until the microgreen harvest (day 10). On day 10, SFCM and microgreens were sampled to determine the pathogen levels in the SFCM and the pathogen transfer to microgreens during production. Salmonella Javiana log CFU/g were significantly higher than L. monocytogenes in SFCM on day 10 in both planted and unplanted regions (p < 0.05). Significant differences in pathogen transfer (log CFU/g) were observed between the pea shoot and sunflower microgreens, regardless of the pathogen or SFCM type (p < 0.05). Meanwhile, pathogen transfer to the pea shoot and sunflower microgreens from the biostrate was 1.53 (95% CI: −0.75–3.81) and 5.29 (95% CI: 3.01–7.57) mean log CFU/g, respectively, and transfer from the peat was 0.00 (95% CI: −2.28–2.28) and 2.64 (95% CI: 0.36–4.92) mean log CFU/g, respectively. Results demonstrate that pathogen transfer to microgreens during production is influenced by SFCM and microgreen variety.
... • 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. Pinto et al. (2015) and Weber (2016) obtained similar results by comparing the mature leaves of lettuce with lettuce microgreens and their respective mineral profiles. According to Pinto et al. (2015), microgreens possess higher contents of most minerals (Ca, Mg, Fe, Mn, Zn, Se, and Mo) and a lower NO3content than mature lettuce. ...
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Lettuce microgreens are one of the most popular vegetables due to them being perceived as a “healthy food”, with high concentrations of nutrients, beneficial vitamins, and minerals. With a short vegetation period, they can be cultivated with minimum investment, and they are increasingly accepted by consumers, as they are healthy and easy to prepare. Lettuce has high ecological plasticity, but, despite this, its phenotypic expression, morphology, physiology, and anatomy are significantly influenced by environmental conditions. Lettuce microgreens contain higher quantities of phytonutrients and minerals and lower quantities of nitrates at the early stage of development than at the completely developed stage. The environmental conditions that influence the development of lettuce microgreens (and their quality) in a hydroponic system are as follows (average ideal values): light (400 W), photoperiodicity (12 h), light intensity (400 µmol m−2 s−1), colour spectrum (440-460 nm), temperature (20 ± 2 °C), and humidity (80 ± 5 %). The nutritional solution in a hydroponic system must be carefully monitored, by checking certain essential parameters such as the following (average ideal values): pH (6.3 ± 0.4), electrical conductivity (1.8 ± 0.2 mS), dissolved oxygen (6 mg L−1), and temperature (18 ± 2 °C). The analysis of expert literature reveals that there is a need to establish certain protocols for cultivating microgreens in hydroponic systems, to minimize the factors that can negatively influence the plants, in order to obtain higher concentrations of active substances.
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Various studies have been done on the nutritional aspects of microgreens that is trending now days as fresh green salad in urban population. We have worked on the idea to make these microgreens more popular among soldiers posted at high altitude as self growing potential fresh food supplement. In this study we have explored the nutrition capabilities of fast and easily growing microgreens of five crops at high altitude i.e. Fenugreek, cabbage, garden orche (atriplex), buckwheat, broccoli and their microgreens were selected for the comparative nutrient analysis with their mature part. Nutrient analysis results have shown that protein content and dietary fibre is significantly higher in mature part of these five crops except cabbage (high in cabbage microgreens). Mature cabbage, broccoli and fenugreek possessed significantly higher minerals contents except, Mg, total P, Na, Zn and Fe (significantly higher in fenugreek microgreens). The mean K content (4481.3±1.86 mg/kg) in mature broccoli was highest. The vitamin C and vitamin B3 are found higher in all the three microgreens than counterpart while beta carotene is found higher in cabbage and broccoli microgreens but comparatively less in fenugreek. Vitamin B9 was found significantly higher in cabbage microgreen, almost equal amount in microgreen broccoli and in mature fenugreek. In harsh climatic condition where fresh food availability throughout the year is a major challenge. Microgreens rich with mineral and vitamins can be good option as dietary supplement to the troops and for local residents especially when mature fresh vegetables are not available.
Thesis
Food supply to ever-growing urban areas follows a linear tendency: cities consume a vast amount of imported food while generating waste and environmental impacts in different fronts. Urban agriculture (UA) has stood out as a practice to mitigate the volume of the imported flow, generating benefits in all three dimensions of sustainability and an excellent opportunity for the restoration of flows. The young concept of a circular economy (CE) can contribute to this mitigation by minimizing waste flows and take advantage of strategies to recover resources while exploiting synergies between urban systems, contributing to an improvement of the urban metabolism. However, the application of CE principles in UA systems should be strictly monitored in terms of environmental performance to avoid a clash between CE and sustainability goals. To avoid this, the present thesis aims to evaluate the environmental performance of applying circular strategies in UA systems. We use the Life Cycle Assessment (LCA) combined with other complementary methods and tools: nutrient balances, analysis of climatic variables, geographical information systems or a circularity assessment through the material circularity indicator (MCI). We first analyze the environmental performance of 25 cycles of 7 different crops in a hydroponic rooftop greenhouse to determine which should be the targets to optimize within the inventory and define the best year-round crop combinations. The results show that the fertilizers and their related emissions to water are the item with the biggest room for improvement. To avoid nutrient depletion, we evaluate the application of three possible nutrient recovery strategies: membrane filtration, chemical precipitation and direct leachate recirculation, finding that the latter had the best environmental performance. Considering this, we evaluate with different approaches the performance of two different recirculation strategies: the recirculation of leachates in the same crop and the recirculation of leachates in a parallel crop in what is known as a cascade system. The results of the analysis outline the potentials and limitations of both systems, concluding that the ultimate configuration would include a cascade system in which the receiving crop reuses the nutrients that leaches. Phosphorus (P) is a scarce and valuable resource due to the anthropogenic demand to produce fertilizers. The synergy between urban systems can contribute to enlarge the utility of P resources at the urban level. In this sense, we analyze the recovery of struvite in urban wastewater treatment plants and its application in UA systems with two different approaches: experimentally to test its potential and limitations in hydroponic systems, and with a regional perspective that treats a metropolitan area like a self-sufficient entity. The results show how the use of struvite can produce higher yields than mineral fertilizers while diminishing P losses. The regional perspective showed how the area under study is able to recover enough P to feed all the agriculture of the region, although parameters like the choice of the wastewater treatment plant or the recovery technology are important to avoid additional environmental impacts. Finally, we gather all the recovery strategies and evaluate their environmental performance and degree of circularity to prioritize circular strategies in UA systems. After solving detected limitations of the assessment through indicator development, we find that nutrient recirculation, the use of struvite or recycled materials are the best strategies to improve both the circularity and environmental performance of the system. Considering the findings of the thesis, different future research lines were defined: standardization of circular economy metrics and concepts or integration of different perspectives in the assessment of UA systems.
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The paper explores the germination of seeds, yields and an tioxidant properties of microgreens of different varieties and varieties of Petroselinumcrispum (Mill.) Nym. in controlled microclimatic conditions. The most active germination of seeds was observed in the interval of 7-11 days after sowing. The total increase in microgreens in height almost stops after 14 days of germination in the dark. Thus, growing products by germination in the dark is advisable longer than this period to get microgreens promising leafy varieties of parsley. A significant increase in total antioxidant activity in seed germination has been established – 2.7-5.6 times for different varieties. Parsley Petroselinumcrispum (Mill.) Nym. – a herbaceous plant used in many kitchens of the world as spicy and for the preparation of side dishes. The main flavor compounds of parsley are 1.3.8-n-metatrien, apiol, myristicin, and tetramethoxyallbenzene, of which apiol and mydisticin are “toxic in large doses”. Green, herbaceous and fruit notes in parsley are determined by the hex-3-enil, (Z)-hex-3-enol and (Z)-hex-3-enylacerate. It is proposed to use parsley as a component of functional products in the treatment of cancer. Growing parsley microgreens is advisable due to the high antioxidant and other beneficial properties. Despite the slow and time-stretched germination of seeds, within 2 weeks of cultivation formed a fairly high vegetative mass, which can be used for food and medicinal purposes, for example, as a product of functional nutrition. It is possible to grow products in the dark without the use of artificial light sources. The highest yield is provided by leafy varieties of parsley compared to root varieties.
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Brassica vegetables are known to contain relatively high concentrations of bioactive compounds associated with human health. A comprehensive profiling of polyphenols from five Brassica species microgreens was conducted using ultra high-performance liquid chromatography photo diode array high-resolution multi-stage mass spectrometry (UHPLC-PDA-ESI/HRMS/MSn). A total of 161 polyphenols including 30 anthocyanins, 101 flavonol glycosides, and 30 hydroxycinnamic acid and hydroxybenzoic acid derivatives were putatively identified. The glycosylation patterns of the flavonols were assigned based on direct comparisons of their parent flavonoid glycosides reference compounds. The putative identifications were based on UHPLC-HRMSn analysis using retention times, elution orders, UV/Vis spectra and high resolution mass spectra, as well as an in-house polyphenol database, and literature comparisons. This study showed that these five Brassica species microgreens could be considered as good sources of food polyphenols.
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Microgreens (seedlings of edible vegetables and herbs) have gained popularity as a new culinary trend over the past few years. Although small in size, microgreens can provide surprisingly intense flavors, vivid colors, and crisp textures and can be served as an edible garnish or a new salad ingredient. However, no scientific data are currently available on the nutritional content of microgreens. The present study was conducted to determine the concentrations of ascorbic acid, carotenoids, phylloquinone, and tocopherols in 25 commercially available microgreens. Results showed that different microgreens provided extremely varying amounts of vitamins and carotenoids. Total ascorbic acid contents ranged from 20.4 to 147.0 mg per 100 g fresh weight (FW), while β-carotene, lutein/zeaxanthin, and violaxanthin concentrations ranged from 0.6 to 12.1, 1.3 to 10.1, and 0.9 to 7.7 mg/100 g FW, respectively. Phylloquinone level varied from 0.6 to 4.1 μg/g FW; meanwhile, α-tocopherol and γ-tocopherol ranged from 4.9 to 87.4 and 3.0 to 39.4 mg/100 g FW, respectively. Among the 25 microgreens assayed, red cabbage, cilantro, garnet amaranth, and green daikon radish had the highest concentrations of ascorbic acids, carotenoids, phylloquinone, and tocopherols, respectively. In comparison with nutritional concentrations in mature leaves (USDA National Nutrient Database), the microgreen cotyledon leaves possessed higher nutritional densities. The phytonutrient data may provide a scientific basis for evaluating nutritional values of microgreens and contribute to food composition database. These data also may be used as a reference for health agencies' recommendations and consumers' choices of fresh vegetables.
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Microgreens are young, tender greens that are used to enhance the color, texture, or flavor of salads, or to garnish a wide variety of main dishes. Harvested at the first true leaf stage and sold with the stem, cotyledons (seed leaves), and first true leaves attached, they are among a variety of novel salad greens available on the market that are typically distinguished categorically by their size and age. Sprouts, microgreens, and baby greens are simply those greens harvested and consumed in an immature state. This article offers production advice for greenhouse microgreen production.https://edis.ifas.ufl.edu/hs1164 This is a minor revision of Treadwell, Danielle, Robert Hochmuth, Linda Landrum, and Wanda Laughlin. 2010. “Microgreens: A New Specialty Crop”. EDIS 2010 (3). https://journals.flvc.org/edis/article/view/118552.
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Microgreens are a new class of edible vegetables harvested when seed-leaves have fully expanded and before true leaves have emerged. They are gaining increasing popularity as new culinary ingredients. However, no scientific data comparing the mineral content of microgreens and mature plants are available. Thus, the goal of this work was to perform a comparison between mineral profile and NO3- content of microgreens and mature lettuces. Results showed that microgreens possess a higher content of most minerals (Ca, Mg, Fe, Mn, Zn, Se and Mo) and a lower NO3- content than mature lettuces. Therefore, microgreens can be considered as a good source of minerals in the human diet, and their consumption could be an important strategy to meet children's minerals dietary requirements without exposing them to harmful NO3-.
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The mineral content (phosphorous (P), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn) and copper (Cu)) of eight ready-to-eat baby leaf vegetables was determined. The samples were subjected to microwave-assisted digestion and the minerals were quantified by High-Resolution Continuum Source Atomic Absorption Spectrometry (HR-CS-AAS) with flame and electrothermal atomisation. The methods were optimised and validated producing low LOQs, good repeatability and linearity, and recoveries, ranging from 91% to 110% for the minerals analysed. Phosphorous was determined by a standard colorimetric method. The accuracy of the method was checked by analysing a certified reference material; results were in agreement with the quantified value. The samples had a high content of potassium and calcium, but the principal mineral was iron. The mineral content was stable during storage and baby leaf vegetables could represent a good source of minerals in a balanced diet. A linear discriminant analysis was performed to compare the mineral profile obtained and showed, as expected, that the mineral content was similar between samples from the same family. The Linear Discriminant Analysis was able to discriminate different samples based on their mineral profile.
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The global food system makes a significant contribution to climate changing greenhouse gas emissions with all stages in the supply chain, from agricultural production through processing, distribution, retailing, home food preparation and waste, playing a part. It also gives rise to other major environmental impacts, including biodiversity loss and water extraction and pollution. Policy makers are increasingly aware of the need to address these concerns, but at the same time they are faced with a growing burden of food security and nutrition-related problems, and tasked with ensuring that there is enough food to meet the needs of a growing global population. In short, more people need to be fed better, with less environmental impact. How might this be achieved? Broadly, three main 'takes' or perspectives, on the issues and their interactions, appear to be emerging. Depending on one's view point, the problem can be conceptualised as a production challenge, in which case there is a need to change how food is produced by improving the unit efficiency of food production; a consumption challenge, which requires changes to the dietary drivers that determine food production; or a socio-economic challenge, which requires changes in how the food system is governed. This paper considers these perspectives in turn, their implications for nutrition and climate change, and their strengths and weaknesses. Finally, an argument is made for a reorientation of policy thinking which uses the insights provided by all three perspectives, rather than, as is the situation today, privileging one over the other.
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The first of a two-part review of the recent and classical literature reveals that loss of nutrients in fresh products during storage and cooking may be more substantial than commonly perceived. Depending on the commodity, freezing and canning processes may preserve nutrient value. The initial thermal treatment of processed products can cause loss of water-soluble and oxygen-labile nutrients such as vitamin C and the B vitamins. However, these nutrients are relatively stable during subsequent canned storage owing to the lack of oxygen. Frozen products lose fewer nutrients initially because of the short heating time in blanching, but they lose more nutrients during storage owing to oxidation. Phenolic compounds are also water-soluble and oxygen-labile, but changes during processing, storage and cooking appear to be highly variable by commodity. Further studies would facilitate the understanding of the changes in these phytochemicals. Changes in moisture content during storage, cooking and processing can misrepresent changes in nutrient content. These findings indicate that exclusive recommendations of fresh produce ignore the nutrient benefits of canned and frozen products. Nutritional comparison would be facilitated if future research would express nutrient data on a dry weight basis to account for changes in moisture. Copyright © 2007 Society of Chemical Industry