FLAVANONES
Hesperidin, Naringenin
Flavanones
 The most abundant citrus flavanoid; 98% in grapefruit,
96% in limes and 90% in lemons
 A type of flavanoid with several chemical variations.
 These include Hesperidin, Naringenin, Eriodictyol,
Sterubin, Butin, and many others
 Primary focus today is HESPERIDIN
 Highest content is in lemons
 Genus of flowering
CITRUS
plants in the Rue
family, Rutaceae
 Lemons are further
classified as citrus limon
 Fruit is hesperidium
“Lemons, …. commonly known as the fruit that
evokes images of sunshine and the sweet smiles
of children standing roadside at their homemade
lemonade stands”
G. Mateljan, www.whfoods.com
The History of
Lemons
 Lemons originally developed
as a cross of lime & citron and
thought to have originated in
China and India 2500 years
ago

Brought to the Americas by
Christopher Columbus in 1493
 Prized by California Gold Rush
miners to prevent scurvy;1849

United States, Italy, Spain,
Greece, Israel, &Turkey are
the main producers in the
marketplace today
Availability in the marketplace
California/Arizona Citrus produce 95% of the lemons in the US
Availability in the marketplace
Florida Citrus
Availability in the marketplace
Texas Citrus
Imported Citrus
Listing of lemon cultivars of commercial importance worldwide
Lemon Cultivars
Other Names
Bears
Berna
Location(s)
Florida
Verna, Bernia, Vernia
Eureka
Spain, Algeria, Morocco
S. Africa, Argentina, Australia,
California, Greece, Israel, Mexico,
Pakistan, China, Arizona, Florida
Femminello ovale or Feminello
comune
Commune, Ruvittaru
Sicily
Interdonato
Speciale
Sicily
Kusner
Russia
Lisbon
California, Algeria, China, Greece,
Mexico, Morocco, Argentina,
Portugal
Mesero
Fino, Primifiori
Italy, Spain
Monachello
Moscatello
Italy
Monroe
California
Sicilian lemon
Brazil
Villafranca
Sicily, California
Health Benefits
 Contain important natural chemical components:
 Phenolic compounds - mainly flavonoids
 Vitamins - especially vitamin C
 Minerals – especially potassium

Fiber
 Carotenoids
 Essential oils
 Health promoting properties associated with vitamin C and
flavanoid content due to natural antioxidant characteristics
 Important part of a balanced diet for role in prevention of disease
Health Benefits
 Experimental data from in vitro, in vivo and clinical trials in
support of the health-promoting activity of lemon and its
bioactive compounds:
 Cancer - esophagus, mouth, stomach and colon
 Cardiovascular, coronary heart disease and oxidative damage
 Lipid metabolism and obesity
 Gastrointestinal diseases
 Diabetes
 Antimicrobial activity
 Urinary diseases
 Psychiatric diseases
 Bone protection
Health Benefits
 Citrus fruits may be among the fruits with the greatest cancer
fighting potential.
 This is especially true in the cancers of the esophagus, mouth,
stomach and colon
 Anti cancer benefits are mainly due to significant quantities of
monoterpenes and flavanones which are believed to cut the
risks of cancers of the digestive track in half.
 These compounds reduce cancer risks in two significant ways:
1. Interfere with some of the processes necessary for cancer cell
growth, making it difficult for tumors to develop.
2. Inhibit inflammation, a stimulus for cancer cell growth.
Health Benefits
 Citrus flavonoids act as modulators of tyrosine kinases – important
implications in treatment of cancer
 Eriocitrin (from lemon juices and its metabolites) was tested in
different Citrus juices by Ogata et al. and showed that it induced
apoptosis in HL-60 cells
 Hesperidin in different citrus juices showed antiproliferative activity
 Lemons showed relatively potent antiproliferative activities on HepG2
human liver cancer cell growth
 Other studies showed eriocitrin as an inhibitory compound acting against
both rat platelet 5- and 12-lipoxygenases, and its aglycone, eriodictyol,
was a much more potent inhibitor of these lipoxygenases involved in
biosynthesis of various bioregulators closely related to the pathogenesis
of several diseases such as allergies, atherosclerosis and cancer
Health Benefits
Digestion
 Lemon added to warm water helps the digestive tract. Natural acidity
helps to stimulate the liver increasing bile secretions. This causes the
digestive tract to move more efficiently, resulting in better digestion.
Lemon water can also help to eliminate constipation and nausea and
may also treat worm infestations of the digestive tract.
Flush Toxins
 Lemon also has antibacterial properties. Good for throat infections
and tonsillitis because of its antibacterial content and diuretic
properties. When consumed with water, has the ability to flush toxins
and bacteria out of the system, making it an especially effective
treatment for ailments of the blood and organic systems of the body.
Health Risks
 Gastroesophageal Reflux
 Acidic citrus fruits may increase esophageal irritation and exacerbate
GERD symptoms. Acidity can also lead to gastric ulcer irritation.
 Dental Erosion
 The acids in lemon juice eat away at the enamel, the shiny surface
component of teeth that protects from decay. Erosion can lead to
surface staining, cavities and sensitivity if prolonged exposure
continues.
 Medicine Interactions
 The FDA has clearly defined a link between altered drug metabolism
and citrus fruit juices. As little as 120mL of lemon juice contains 5.9g of
citric acid, which is shown to decrease the blood levels of chloroquine,
which is used by those entering an area with a high risk of malarial
infection.
Health Risks
 Lemon and Lime Peels and Oxalates
 The peels of lemons are among a small number of foods that contain
measurable amounts of oxalates. When oxalates become too
concentrated in body fluids, they can crystallize and cause health
problems. So, individuals with already existing and untreated kidney
or gallbladder problems may want to avoid eating lemon or lime peels.
 Lemons and Limes and Wax Coatings
 Conventionally grown lemons may be waxed to protect from bruising
during shipping. Plant, insect, animal or petroleum-based waxes may
be used. Carnauba palm is the most common plant-source wax. Other
compounds, such as ethyl alcohol or ethanol, are added to the waxes
for consistency, milk casein for "film formers" and soaps for flowing
agents. Since you may not be able to determine the source of waxes,
another good reason to choose organically grown lemons.
Flavonone content in
lemons and pure lemon juice
http://www.phenol-explorer.eu/
Varieties of Lemons

Eureka –
o texturized skin, a short neck at one end and a few seeds
o Sour flavor
o Originated in California
o Forms an open, spreading tree, with relatively few
branches and twigs which are virtually thornless
o Production occurs mostly in spring and summer
Varieties of Lemons

Lisbon –
o smoother skin, no neck and is generally seedless
o Sour flavor
o Originated in Australia
o Characterized by a rather dense tree having
numerous upright, thorny branches
o Production occurs mostly in summer and
fall
Varieties of Lemons

Meyer
o They are more round a have a smooth unpitted
skin
o As they mature they become deep yellow to
orange takes on a deep yellow to orange color
when mature.
o tangy aroma and less acidic.
o introduced from China in 1908
o The tree is spreading and relatively
small, nearly thornless and more
cold tolerant than true lemons
o Production occurs mostly in winter
Major Lemon Growers Worldwide
González-Molina E., Domínguez-Perles R., Moreno D.A., García-Viguera C. Natural bioactive compounds of Citrus limon for food and
health. Journal of Pharmaceutical and Biomedical Analysis.2010:51:327–345.
Terry, Leon A. Health-promoting Properties of Fruits and Vegetables. Wallingford, Oxfordshire: CABI, 2011.96-105.
Bioavailability of flavonoids in
Lemons
 Citrus flavonoids can exist as free aglycones but most
of them commonly occur as C- or O-glycosides
 In lemons the sugars, rutinosides are tasteless
Distribution throughout the fruit:
 Juice: hesperidin and eriocitrin
 Peel: hesperidin, eriocitrin, neoeriocitrin,
neohesperidin and naringin and minor amt of narirutin
 Seeds: hesperidin and eriocitrin, low amts of naringin
Guihua X., Donghong L., Jianchu C., XingqianY., Yaqin M., John S. Juice components and antioxidant capacity of citrus varieties
cultivated in China. Food Chemistry.2008:106:545–551.
Growing Conditions
CLIMATE:
o Not cold tolerant
o Mediterranean climate
Soil Type:
o Well adapted to virtually any soil type
o Require full sunlight for optimum growth
and production
o Good drainage
Growing Conditions and
Bioactivity
The concentration of bioactives is influenced by
the following factors:
o Cultivar (rootstock & scion)
o Climate
o Cultural practices during production
o Position of the fruit tree
o Fruit maturation
o Post harvest treatments
 Handling, storage and transportation of
fruit
Absorption of flavonoids
 O-glucosides undergo intestinal hydrolysis to release
aglycones
 Hesperidin and hesperetin may be metabolized into
hesperetin after oral administration
 Eriocitrin is metabolized to eriodictyol (aglycone) in
intestional flora
 Post ingestion hesperetin and erodictyol were detected
in human urine and plasma as the glucuro-and/or sulfoconjugates - suggesting these undergo extensive phase
II metabolism
 Most absorbed Citrus flavanones undergo
glucuronidation before urinary excretion
Storing Lemons: nutrient content
 Fruit: maintains its levels of juice, vitamins, minerals,
fibers and carbohydrates for several months
 Fruit and juice: suffer degradation of vitamin C during
storage or industrial process (pasteurization)
 Oxygen, heat light, storage temperature, and storage
time affect ascorbic acid retention in juices.
 To prevent loss of ascorbic acid:
o Keep at 0-5o C and protected from water loss
 Pasteurization does not modify hesperidin content
Storage and Processing
•Stay fresh at room temperature, away from exposure
to sunlight, for about one week.
•Can be stored in the refrigerator crisper and will keep
for about four weeks.
•Fresh juice storage; squeeze into ice trays and freeze
stored in plastic freezer bags
•Zest storage; dry and store in a cool dry place in an
airtight glass container.
Choosing the best Lemon
• Look for thin skinned lemons since they have more
flesh and juice; choose lemons that are heavy for their
size, with peels that have a grainy surface
• Bright yellow fruit indicates that the lemon is at the
peak of ripeness.
Cooking with Citrus Peel
•Xu et al. reported in 2008 on the efficiency of heat infusion to extract both
minerals and phenolic compounds, including flavanone glycosides from
citrus varieties.
•Peels of 2 varieties ( Satsuma & Ponkan mandarin) were selected & boiled in
hot water to extract minerals & phenolics.
•The result showed that this was an efficient means of extracting many
phenolics and minerals, however, hesperidin was the most difficult to
extract, suggesting that it is more tightly bound within its food matrix there.
•The study also showed that the antioxidant capacity of the citrus peels
boiled in hot water was almost the same as that extracted with methanol.
•Lengthening time or raising temperature extracted more in 2 studies
Cooking with Lemons
•The bioactives in citrus partly determine the unique flavor.
Neohesperidosides in grapefruits are intensively bitter, but rutinosides, in
lemons, are tasteless.
•Peels are the main fiber content in lemons & pectin is the major component
of fiber in the lemon.
•Recently, research has been focused on the lemon in comparison to major
carotenoid components of orange species varieties, showing that lemon
contains reasonable quantities of carotenoids for a daily nutritional source of
these bioactives.
•Lemons sprayed with pesticides may be toxic for humans or animals, but
also prompt changes in essential oil composition as an effect on plant
metabolism.
Cooking with Lemons
• The juice can be used to prevent browning
• The acidic lemon juice can be exchanged for vinegar in dressings
•Limoncello liquor is made by macerating lemon peels free of pesticide
residues in ethanol, water &sugar.
• Preserved lemons are a popular condiment in Indian, North African, and
Moroccan cuisines
•Candied Lemon Peel can make great holiday gifts and can be dipped in dark
chocolate for an added bioactive bonus!
•Lemon juice in water stimulates bile flow in the mornings or before meals.
• The acidity of lemon juice
brings everything into
balance as you finish
preparing a dish.
Cooking with
Lemons; Juicing
•
To get the most juice out,
press down on it while
rolling it back and forth on
the counter, then juice it.
•
A good juicy lemon,
contains ¼ cup of fresh
lemon juice.
Natural beauty tips!
• Natural facial-boil orange and grapefruit peels with 2 cups of
non-carbonated mineral water. Strain liquid into a bottle and
apply to face twice daily. Keep refrigerated
• Skin bracer-blend juice of half a grapefruit with warm water
and splash on face immediately after washing to tighten pores.
• To soften rough red elbows, dip and rub into grapefruit halves
for two or three days.
• To soften cuticles and whiten nails, mix 3 cups warm water
with the juice of half a grapefruit. Soak fingers for 5 minutes.
Recipe
Ingredients
Zest from 1 organic lemon, finely diced
1 cup water
1/2 cup turbinado
1/2 cup fresh lemon juice
1/2 cup carbonated mineral water
6 strips of lemon zest, for garnish
Directions
In a saucepan, stir together the lemon zest, 1 cup of water and turbinado. Bring to a
boil, reduce heat to medium and simmer for 5 minutes. Remove from heat, and allow
to cool.
In a bowl, stir together the lemon syrup, lemon juice and mineral water. Pour into an
ice cream maker, and freeze according to the manufacturer's instructions. Garnish
each serving with a twist of lemon peel.
If you do not have an ice cream maker, you may freeze it in a tall canister. Freeze for 1 1/2 hours. Remove and stir
with a whisk. Return to the freezer and stir about once every hour for about 4 hours. The more times you stir, the
more air will be incorporated, resulting in a lighter finished product.
Discussion Topic
References
http://www.whfoods.com/genpage.php?tname=foodspice&dbid=27
http://www.phenol-explorer.eu/
http://www.sunkist.com/kids/facts/lemons.asp
The End