HSW : Cis-Trans isomerism cooking tomatoes and healthy
hearts
ALCH 20Cis-Trans isomerism cooking tomatoes and healthy
hearts
Content
ContentPage
Acknowledgment(i)
Introduction(ii)
Cis-Trans isomerism cooking tomatoes and healthy hearts
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Conclusion6
Reference 7
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Acknowledgement
In performing our assignment, we had to take the help and
guideline of some respected persons, who deserve our greatest
gratitude. The completion of this assignment gives us much
pleasure. We would like to show our gratitude to Miss Rawaida for
giving us a good guideline for assignment throughout numerous
consultations. We would also like to expand our deepest gratitude
to all those who have directly and indirectly guided us in writing
this assignment.
Many people, especially our classmates and team member itself,
have made valuable comment suggestions on this proposal which gave
us an inspiration to improve our assignment. We thank all the
people for their help directly and indirectly to complete our
assignment.
Introduction This present study aims to evaluate the beneficial
effect of tomatoes, a rich source of lycopene, which is a
relatively new carotenoid known to play an important role in human
health and disease.There is a history behind this tomatoes.Tomatoes
are one of the most popular fruits. Although found in the vegetable
section of your supermarket in botanical terms tomatoes are in fact
a fruit grown from a vine.
The Aztecs and Incas first cultivated tomatoes in 700AD; they
were then introduced to Europe by the Mexicans in around 1556. It
actually took some time for the Spanish to accept the tomato for
fear that it was poisonous like other members of the nightshade
family. Later down the line, however, some tomato advocates claimed
the fruit to have aphrodisiac powers that is why the French called
them Pommes damour meaning love apples. Tomatoes are now eaten
freely throughout the world, and are believed to have numerous
health benefits.
There are around 7500 different varieties of tomato, all grown
for different purposes, some more resilient to pests, others more
flavourful. While to the common supermarket shopper red tomatoes
and the odd green unripe tomato are all that is available, there is
also a rainbow of colours grown by some cultivars, ranging from
yellow, orange, pink, black, ivory, white, and purple as well as
different shapes and sizes; cherry, plum, pear and beefsteak.
HSW : Cis-Trans isomerism cooking tomatoes and healthy
hearts
Inorganic chemistry,cis/trans isomerism(also known asgeometric
isomerism) is a form ofstereoisomerismdescribing
therelativeorientation offunctional groupswithin a molecule. Cis
and transisomersoccur both in organic molecules and in inorganic
coordination complexes. The terms cis and trans are from Latin, in
whichcismeans "on this side" andtransmeans "on the other side" or
"across". The term "geometric isomerism" is considered an obsolete
synonym of "cis/trans isomerism" byIUPAC. Example :
Biological system are often very sensitive to different
geometric isomer. Based on research, show that the antioxidant
lycopene is very effective to prevent a variety of problem such as
heart disease, atherosclerosis and cancer on prostate, breast,
lung, bladder, ovaries, colon and pancreas. Lycopene is also used
for treating Human Papilloma Virus (HPV) infection, which is a
major caused of uterine cancer. Some people also used lycopene for
cataracts and asthma. Lycopene works as a powerful antioxidant that
may help protect cells from damaged. This is why, there is a lot of
research interest in lycopenes role in preventing cancer. Lycopene
naturally gives fruits and vegetables a red colour because the
presence of pigment called carotenoids. Lycopene is found in
watermelons, pink grape fruit, apricots and pink guavas. It is
particularly high amounts in tomatoes and tomato product. In North
America, 85% of dietary lycopene comes from tomato products such as
tomato juice or paste. Processing raw tomatoes using heat (in
making of tomato juice, tomato paste, and ketchup) actually changes
the lycopene in the raw product into a form that is easier for the
body to used. Scientists have found that cooked tomatoes seemed to
be more biologically active that the raw tomatoes even-though they
have the similar lycopene levels. Trans-lycopene, a straight chain
molecule is the dominant isomer found in most red tomatoes, but
biologically active form found in the human body is cis-lycopene
(bent molecule).
Scientist are not sure whether the body converts one isomer into
another using an enzyme of whether cis-isomer is absorbed into the
body more easily. Nevertheless, they discovered that cooking
tomatoes can alter the ratio of trans:cis isomers in the fruit from
19:11 to 11:19. If the cis-isomers in the fruit is more, the more
readily the lycopene is absorbed and more benefit to the body.
Therefore, we should cook our tomatoes thoroughly before we eat
them for maximum benefit. Researchers from Cornell University ,
USA, said that cooking the tomatoes increase the level of
phytochemicals they contain, although it also reduces the amount of
vitamin C found in the vegetables. Writing in the latest issue of
the Journal of Agriculture and Food Chemistry Rui Hai Liu, Cornell
assistant professor of food science, said this research
demonstrates that heat processing actually enhance the nutritional
value of tomatoes by increasing the lycopene contain that can be
absorbed by the body as well as the total antioxidant activity.
While the antioxidant activity in tomatoes is enhance during the
cooking process, vitamin C loss occurs when the foods ascorbic acid
is oxidised to dehydroascorbic acid and the other form of
nutritionally inactive components. Lycopene is the most efficient
single oxygen quencher and devours more than 10 times more
oxygenated free radical than Vitamin E, Cornell researchers said.
Therefore, cis-lycopene in cooked tomatoes is better than
trans-lycopene in the raw one. On the other hand, studies show
that, tangerine tomatoes is better than common red tomatoes.
Tangerine tomatoes, named for their attractive orange colour, are
plump, juicy and slightly sweeter than ordinary red tomatoes. The
difference lies in the form of lycopene that the two tomato types
provide. The trans-lycopene form makes up most of the lycopene in
common red tomatoes. In contrast, most of the lycopene in tangerine
tomatoes is tetra-cis-lycopene. For the California study, 21
healthy men and women volunteers were asked not to eat any fresh
tomatoes, tomato products or other food rich in lycopene other than
that provided by other researchers that instruct when into effect
at the start of a 1 week washout period and stay in effect
throghout the rest of the study period. In the week after the
washout, volunteers ate their usual breakfast, dinner and snack
(minus lycopene rich food), but came to the ARS Western Human
Nutrition Research Centre in Davis to have a special lunch which is
tangerine tomato sauce. Blood was analysed weekly for lycopene
level with a standard labaratory instrument known as a high
perfomance liquid chromatograph. The analysis indicate that
lycopene levels increase relative to does measures just before each
one week of special lunch. Total lycopene level increase more after
the tangerine tomato treatment than the red tomato treatment. Thus,
tangerine tomatoes contain tetra-cis-lycopene rich may be able to
improve our health. Another case study from Ohio State University,
USA state that Lycopene, the predominant carotenoid in tomatoes and
tomato products responsible for the red colour, has attracted
considerable attention as epidemiological evidence continues to
suggest that it may provide protection against a number of cancers
and other degenerative diseases. The observation that serum and
tissue lycopene consists of between 50% and 90% cis-lycopene
isomers, whereas tomatoes and tomato-based products contain mainly
all-trans-lycopene, has led to the hypothesis that cis-isomers of
lycopene are produced during food processing, cooking, or digestion
or are more bioavailable. Improved absorption of lycopene
cis-isomers is hypothesised to result from greater solubility in
mixed micelles and a lower tendency to aggregate, a hypothesis
supported by rodent studies. Although most commercially processed
tomato products such as juice, paste, soup and ketchup contain a
relatively low percentage of cis-isomers (10 %), aggressive food
processing or cooking has been shown to increase cis-isomer
content. The greatest increase in cis-isomer formation was observed
when tomato products were heated in the presence of oil. Thus,
research conducted so far suggests that lycopene cis-isomer
formation is usually not observed at the mild temperatures commonly
employed in most commercial food processing but is enhanced by the
presence of oil at medium or higher processing and cooking
temperatures. The presence of elevated levels of lycopene
cis-isomers in human biological samples compared with fresh
tomatoes may also have biological significance, but this remains
speculative. Cis-isomers may show unique tissue biodistribution
patterns or perhaps distribute differently within cellular
compartments to influence cell functions and responses to
physiological or toxic stimuli in the external or intracellular
environment. Thus, it is hypothesised that modification of the cis-
and trans-lycopene-isomer pattern of foods may allow investigators
to achieve targeted changes in absorption and distribution of
specific carotenoid isomers in order to influence biological
effects and health outcomes. The objective of the present study was
to develop two similar tomato sauces with high and low
cis-lycopene-isomer content by different processing techniques.
Therefore, cis-lycopene has more benefit than trans lycopene.
8Conclusion
The facts about tomatoes definitely point them out to be a
powerhouse of nutrients to be enjoyed as often as possible.
Tomatoes contain masses of vitamin C and are a rich source of
vitamins A and B, as well as potassium, iron, phosphorus and fibre.
Of course not forgetting the commonly known huge amount of lycopene
that tomatoes contain which has been associated with reduced risk
of some cancers.
Lycopene is an antioxidant found in the cell walls of the tomato
and is what makes them red, it is part of the carotenoid family
which are natural compounds that create the colours of fruits and
vegetables. Lycopene has been making headlines of late because of
its anti-carcinogenic properties, the research all indicate that
lycopene in tomatoes increases when tomatoes are cooked, this is
because when a tomato is cooked the cell wall ruptures and releases
more lycopene. A.To sum it up, yes tomatoes do contain more
lycopene when cooked however other valuable nutrients which are
equally as valuable are lost during the heating process, like most
raw foods the lycopene contained in the raw tomato is probably a
sufficient amount thus twice as much lycopene and none or less
vitamin C, B1 and B6 is probably not a good trade off. Additionally
the lycopene content can be increased simply by blending tomatoes,
therefore no need for heating or nutrient loss.
6Reference
http://www.ncbi.nlm.nih.gov/pubmed/17453080http://www.cancer.org/treatment/treatmentsandsideeffects/complementaryandalternativemedicine/dietandnutrition/lycopenehttp://www.therawgreek.com/tomato-a-go-go
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