Stevia, Ka'a He'e, wild sweet herb from South America - An overview

Abstract

The use of Stevia rebaudiana Bertoni, perennial indigenous native plant from the tropical region of South America is presented, with a brief outlook on the history and uses of the wild plant by Guarani Indians, the crop domestication, and the authorization of its use as a natural sweetener in food and beverages. Other aspects considered are natural glycosides and physicochemical properties for food processing, nutritional information, medicinal properties, Stevia market and household uses. The future of this plant is promising but more research is needed to ensure use of leaves and steviosides, and also to study cultivation practices in various regions of the world.

Full text

Emir. J. Food Agric. 2013. 25 (10): 746-750
doi: 10.9755/ejfa.v25i10.16405
http://www.ejfa.info/
REVIEW ARTICLE
Stevia, ka'a he'e, wild sweet herb from South America - An overview
L. Giuffré*, R. Romaniuk and E. Ciarlo
Edafología, Facultad de Agronomía. UBA, Av. San Martín4453.1417 Buenos Aires, Argentina
Abstract
The use of Stevia rebaudiana Bertoni, perennial indigenous native plant from the tropical region of South
America is presented, with a brief outlook on the history and uses of the wild plant by Guarani Indians, the crop
domestication, and the authorization of its use as a natural sweetener in food and beverages. Other aspects
considered are natural glycosides and physicochemical properties for food processing, nutritional information,
medicinal properties, Stevia market and household uses. The future of this plant is promising but more research
is needed to ensure use of leaves and steviosides, and also to study cultivation practices in various regions of the
world.
Key words: Stevia, Steviosides, Uses, Properties
Introduction
Stevia Rebaudiana Bertoni (more commonly
known as Stevia) is a wild herb, from the
Asteraceae Family, a perennial indigenous native
plant from the tropical region of South America,
still in wild state in Paraguay, especially in the
Department of Amambay, and Argentina's
Misiones province. The name in Guarani language
is ka'a he'e, which means sweet herb, and in
Spanish is transcribed as "caaje'é".
The Guarani Indians had known for centuries
about the unique advantages of ka'a he'e long
before the arrival of the invaders from the Old
World. These native people knew the leaves of the
wild stevia shrub to have a sweetening power
unlike anything else, they commonly used the
leaves to enhance the taste of the typical beverage:
“mate” a bitter infusion (a tea-like beverage), and
medicinal potions, or simply chewed them for their
sweet taste. The widespread native use of stevia
was chronicled by the Spaniards in historical
documents preserved in the Paraguayan National
Archives in Asuncion. Historians noted that
indigenous peoples had been sweetening herbal teas
with stevia leaves since ancient times. In due
course, it was introduced to settlers. By the 1800s,
daily stevia consumption had become well
entrenched throughout the region - not just in
Paraguay, but also in neighboring Brazil and
Argentina (Stevia net, 2012).
Stevia Rebaudiana Bertoni is one of the 154
genuses of Stevia, with elongate, lanceolate, or
spatulate leaves shape, serrate margins from the
middle to the tip and entire below (Figure 1).
Maximum active principle for sweetening is found
just prior to flowering. In wild conditions grows in
sandy soils, acid infertile sand or muck soils
(Madan et al., 2010).
Figure 1. Stevia in natural habitats of Argentina.
(Original photography from the author).
Stevia is named after the Spanish botanist
Pedro Jaime Esteve (1500-1556) who found it in
northeastern territory of modern Paraguay, later the
Swiss naturalist Moises Bertoni described the
Received 11 March 2013; Revised 02 June 2013; Accepted
04
June 2013; Published Online 24 June 2013
*Corresponding Author
L. Giuffré
Edafología. Facultad de Agronomía. Av. San Martín4453.1417
Buenos Aires, Argentina
Emails: giuffre@agro.uba.ar

L. Giuffré et al.
747
species in the Upper Paraná, and then the
Paraguayan chemist Ovid Rebaudi published in
1900 the first chemical analysis, and he found a
glycoside able to sweeten 200 times more than
refined sugar.
The Stevia plants use as a sweetener was first
observed in 1889 and since then Stevia has become
more widely produced for its natural sweetness as a
no calorie, no carbohydrate alternative to sugar.
These subtropical plants can be grown easily like
most other vegetables, so they have been cultivated
for decades due to their interesting properties, and it
is important also that can be grown in small
gardens, kitchen gardens or pots. Crop
domestication began in the 1960´s, then it was
introduced in Japan, Argentina, France, Spain,
Colombia, Bolivia, Peru, Korea, Chile,
Brazil, Mexico, United States, Canada and China.
In December 2008, the FDA of USA authorized
its use as a natural sweetener in food and
beverages. An ADI (average daily intake) of 0–4
mg/kg body weight/day was established (expressed
as steviol). FDA notes that the equivalent ADI for
rebaudioside A is 0-12 mg/kg bw/d, due to the
relative molecular weights of rebaudioside A of 967
g/mol and steviol of 318 g/mol (FDA, 2009) . From
December 2011 steviol glycosides extracted from
high purity Stevia are permitted by regulation of the
EU as a food additive sweetener with the number
E-960 (EU 1131, 2011).
Natural glycosides and physicochemical
properties for food processing
The leaves of wild Stevia plants contain several
different natural glycoside compounds including
dulcoside A & B, rebaudiosides A-E, steviolbioside
and stevioside – these are the compounds
responsible for producing the sweet taste sensation.
The sweet Stevia extract is similar to other non-
nutritive sweeteners, such as sucralose, in that it has
zero calories, is 200-300 times sweeter than table
sugar, is non-fermentable, and does not contribute
to dental caries or plaque. Stevia is incredibly sweet
in its raw form (Forsythe-Pribanic, 2012).
Stevia presents a mix of eight diterpene
glycosides, which are mainly stevioside and
rebaudioside. Stevioside could be described as a
glycoside composed by steviol, which is adhered to
sophorose through a carbon hydroxyl group.Its
empirical formula is C38H60O18, and its molecular
weight is 804.98 (WHO, 1999).
The pattern of glicosilation heavily influences
the taste perception of these intensely sweet
compounds. The reactions generally start with
steviol and end with rebaudioside A. In addition to
the eight Stevia glycosides, the triterpens amyrin
acetate and 3 esters of lupeol, and the sterols like
stigmasterol, sitosterol and campesterol were also
isolated from leaves (Madan et al., 2010).
Desirable physicochemical properties for food
processing can include:
Heat resistance
Its structure is not altered by exposure to high
temperatures and therefore does not lose its
sweetness. It is suitable for hot or baked. Stable at
normal temperatures used in food processing:
pasteurization, sterilization, cooking. High
solubility in water and hydroalcoholic solutions.
pH resistance
It is stable in a wide pH range, 3 to 9, even at
100°C. Above pH 9 there is a rapid loss of
sweetness, food however show few values of pH>
9. In carbonated beverages that include in their
composition citric and phosphoric acid, are detected
loss of sweetness of 36% and 17%, respectively,
when stored at 37°C.
Do not add calories
There are a large number and variety of patents
of extraction and purification processes of
stevioside, which may be summarized in the
following steps: extraction of the leaves of Stevia
rebaudiana with organic solvents, filtration,
coagulation and precipitation of impurities by
change of pH; clean-up on ion exchange resins,
crystallization, drying. Importantly, if the process is
not a product with acceptable taste (stevioside high
concentrations exhibits somewhat bitter aftertaste),
other treatments such as chemical or enzymatic
modifications could be applied, but the resulting
product could not be called natural (Fundació n
Tierra, 2008).
Besides the known extraction methods, new
methods from glycoside-based extraction from
Stevia were developed, and it was found that water
can be very effective for extracting glycosides at
selected pH and temperature (Madan et al.,2010).
Nutritional information
According to results presented by Encuentro
Bariátrico (2009), dried stevia leaves contain about
42% of water-soluble substances (hence sweetens
more mixed with liquids). The main active
ingredient is the stevioside, buy it also contains
protein, fiber, iron, phosphorus, calcium,
potassium, zinc, rutin, vitamin A and C. Several
laboratory tests have shown that Stevia has the
following properties: rich in iron, manganese and
cobalt, has no caffeine, pure crystal melting is at
238°C, presents no ferments.

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Medicinal properties
Sweetener
Studies revealed that Stevia has been used
throughout the world since ancient times for
various purposes, for example, as a sweetener and a
medicine. Stevia is likely to become a major source
of high-potency sweetener for the growing natural
food market in the future, and its use is
recommended by various researchers. A Stevia leaf
powder with no processing is highly safe to use,
calorie free, and around 20-30 times sweeter than
sugarcane. Although Stevia can be helpful to
anyone, there are certain groups who are more
likely to benefit from its remarkable sweetening
potential. These include diabetic patients, those
interested in decreasing caloric intake, and children
(Geuns, 2004; Goyal et al., 2010).
Sugar blood
Stevia and natural sweetener steviosides have
been used for many years in the treatment of
diabetes among Indians in Paraguay and Brazil.
Quality of life of diabetics (estimated over 135
million worldwide) could benefit from the
regulatory properties of blood sugar level by tender
leaves of stevia. The active principle of the plant
induces pancreatic beta cells by themselves to
produce large quantities of insulin, which helps to
reduce blood glucose, which is the cause of
diabetes mellitus 2 (Jeppesen et al., 2000;
Gregersen et al., 2004).
Anti-cancer activity
Isosteviol (hydrolisis product of stevioside)
were assayed for their inhibitory activity toward
DNA metabolic enzymes and human cancer cell
growth. It potently inhibited mammalian DNA
polymerases and human topoisomerases II. It
prevented the growth of human cancer cells(Madan
et al., 2010).
Cardiovascular Action
A good deal of experimental work has been
done on the effects of Stevia and stevioside on
cardiovascular functioning in man and animals.
Some of this work was simply looking for possible
toxicity, while some was investigating possible
therapeutic action, with no significant properties
found by Humbolt (1978), only a slight lowering of
arterial blood pressure at low and normal doses,
changing to a slight rise in arterial pressure at very
high doses.The most curious finding is a dose
dependent action on heartbeat, with a slight
increase appearing at lower doses, changing to a
mild decrease at higher doses. The long-term use of
Stevia would probably have a cardiotonic action,
that is, would produce a mild strengthening of the
heart and vascular system (Agricultural
information, 2004). Chan et al. (2000) found that it
acts as a cardiotonic agent (it regulates blood
pressure and heart rate), and resulted in decreased
systolic and diastolic blood pressure. Regulation of
blood pressure and heartbeat could be associated
with Stevia high richness of potassium (3.45%) and
very low sodium (0.03%) level. In relation to effect
on cardiovascular system, Sharma et al. (2009)
reported that extract of Stevia has been found to
reduce heart rate and mean arterial blood pressure,
and that stevioside also lowers mean arterial blood
pressure, an effect that is blocked by Indomethacin.
This suggests that cardiovascular action of
stevioside is mediated via a prostaglandin-
dependent mechanism.
Anti-hypertensive
A 1-year, double-blind, placebo-controlled
study of 106 individuals with high blood pressure
evaluated the potential benefits of Stevia for
reducing blood pressure. In the treated group, the
average blood pressure at the beginning of the
study was about 166/102. By the end of the study,
this had fallen to 153/90, a substantial if not quite
adequate improvement. In contrast, no significant
reductions were seen in the placebo group (Chan et
al., 2000).
Antiviral activity
Stevia rebaudiana extracts are potent anti-
rotavirus inhibitors in vivo and in vitro. Activity of
hot water extract showed inhibition of replication of
all four serotypes of HRV (Anti-Human rotavirus)
in vitro (Madan et al., 2010).
Antibacterial qualities
Stevia extracts have shown strong bactericidal
activity against a wide range of pathogenic bacteria,
including certain Escherichia coli strains. They
also are very effective against bacteria in the oral
mucosa and also the type Candida albicans, which
causes recurrent vaginitis. Research clearly shows
that Streptococcus mutans, Pseudomonas
aeruginosa, Proteus vulgaris and other microbes do
not thrive in the presence of the non-nutritive
Stevia constituents. Also, it has shown to lower the
incidence of dental caries, this fact, combined with
the naturally sweet flavor of the herb, makes it a
suitable ingredient for mouthwashes and for
toothpastes (Pinheiro et al., 1987; Tomita et al.,
1997; Agricultural information 2004; Matsukubo
and Takazoe, 2006). Abou-Arab and Abu-Salem
(2010) reported the importance of Stevia leaves and
callus extracts for pharmaceutical uses and food

L. Giuffré et al.
749
preservation due to their antioxidant and
antimicrobial activities.
Toxicity and uses in non-traditional medicine
Acute and subacute toxicity studies revealed a
very low toxicity of Stevia and steviosides. Stevia
uses in folk medicine include against hypertension,
diabetes, and as a contraceptive, and for obese
persons intending to lose weight by avoiding sugar
(Madan et al., 2010).
Digestive Tonic Action
In the literature of Brazil, Stevia ranks high
among the list of plants used for centuries by the
"gauchos" of the southern plains to flavor the bitter
medicinal preparations used by that nomadic
culture, and their "mate". Stevia made a significant
contribution to improved digestion, and improved
overall gastrointestinal function. Likewise, since its
introduction in China, Stevia tea, made from either
hot or cold water, is used as a low calorie, sweet
tasting tea, as an appetite stimulant, as a digestive
aid, as an aid to weight management, and even for
staying young (Agricultural information, 2004).
Effects on the Skin
The Guarani and other people who have
become familiar with Stevia report that it is
effective when applied to acne, seborrhea,
dermatitis, eczema. Placed directly in cuts and
wounds, more rapid healing, without scarring, is
observed. Smoother skin, softer to the touch is
claimed to result from the frequent application of
Stevia poultices and extracts. Stevia is also known
for skin shining and tightening properties, and has
found its way in several commercial skin tightening
products or anti-wrinkle products (Agricultural
information, 2004).
Precautions must be taken into consideration,
as adverse cardiovascular and kidney/genitory-
urinary effects have been documented with Stevia.
Stevia extracts were found to decrease the fertility
of male rats, while steviosides induced diuresis and
natriuresis and a fall in renal tubular reabsorption of
glucose (Madan et al., 2010).
Stevia market
Data from Leatherhead Food Research valued
the world Stevia market (defined as including both
crude extracts and high purity products such as reb
A) at US$100m in 2010, up by nearly 27% from
$79m the previous year. During this time, volume
sales rose from less than 2,300 tonnes to 2,400
tonnes, with crude extracts accounting for up to
80% of this figure. At present, the US is thought to
account for more than 80% of worldwide sales of
reb A, with the market expected to reach up to
$700m within the next five years. Furthermore,
annual retail sales of US food and drinks promoted
as containing stevia have grown from practically
zero to over $1bn since regulatory approval was
granted. Reb A could have the potential to penetrate
up to 25% of the world sugar market, as sugar
consumption has fallen in many parts of the world
(Thomas, 2012).
Artificial sweeteners such as aspartame and
Splenda have dominated the non-nutritive
sweetener market, but according to the August
2011 report by the market research firm Mintel, the
trend is turning toward natural sweeteners. Mintel
estimated the global market for stevia sweeteners
reached $500 million by mid-2011, and food
consultant Zenith International expects the global
market for stevia-derived products to reach $825
million by 2014. Coca-Cola, and PepsiCo have
taken notice and have invested years of research
and millions of dollars to find new ways to lower
the calorie content in their brands without affecting
the taste (Kawabe, 2012).
Household uses
Stevia is a new promising renewable raw stuff
for the food market, with a high potential of
development. This natural sweetener is used is used
in products like biscuits, jams, chocolates, ice-
creams, baked foods, soft drinks, soda, candies ,
and beverages like dip tea, coffee and herbal tea, in
particular for diabetics and health conscious
consumers. The leaves of Stevia impart a pleasant
flavour apart from increasing the sweetness. The
Stevia leaves or their powder are used in typical
Indian dishes, and ground Stevia is excellent when
sprinkled over cooking vegetable and meat, cereals
and salads (Barathi, 2003).
Stevia is an ideal plant for autocultivation, in
order to take advantage of each day leaves that have
proven very beneficial effects on health. Stevioside
obtained from leaves is a "white crystalline powder,
odorless, non-hygroscopic, non-fermentable,
sweeter flavor in very dilute solutions, very soluble
in water". However, its main obstacle for marketing
what is called an aftertaste, that to be removed
requires expensive laboratory processes. The intake
of fresh leaves is much more economical and
equally healthy. The dose most commonly used is 4
tender leaves, eaten directly before or during lunch
and 4 leaves, before or while dining, or a tea of
dried leaf (an infusion in the morning and another
in the evening). The infusion dose is one teaspoon
of chopped dried leaf dessert per cup of infusion
(Fundació n Tierra, 2012).

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Conclusions
More scientific research is needed to ensure use
of Stevia leaves and steviosides, related to toxicity
and health effects, and its application in food
industry.
Furthermore, as it can be grown in different
conditions, it is necessary to study cultivation
practices in various regions of the world, in natural
conditions or in greenhouse production, regarding
propagation, planting density, adequate soil types,
fertilization, irrigation, and net profit for small
producers.
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