lycopene extract from tomato

8/3/2019 lycopene extract from tomato

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Lycopene is a pigment principally responsible for the

characteristic deep-red color of ripe tomato fruits and

products.

It, as a natural source of antioxidants, has attracted

attentions due to its biological and physicochemical

properties.Recent epidemiological studies have suggested that the

consumption of tomatoes and tomato-based food products

reduce the risk of cancer


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Because of presence of 11 conjugated carbon-carbon double

bonds, lycopene is susceptible to chemical change when exposed

to light, heat and oxygen.

During food processing, lycopene may undergo degradation

and isomerization simultaneously, and the formation of cis

isomer of lycopene reduce it colour intensity and biological

activity.

In tomatoes product, all trans-, 13-cis, 15-cis lycopene are

reported to occur.

Resonance effect of cis-lycopene lower than all trans, the

antioxidative ability of the former should be inferior to the latter.

Thus, to develop a method for all trans-lycopene and its cis

isomers in food products is extremely important.


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Ripe tomato fruitwere immersed inboiling water for

1-2 min

Rapidlycooled, then

hand-peeled

The peels werepartially dried in

air for a few

hours and storedat 4C

The skins were

hand-separatedfrom the seeds and

other impurities

Each peel sample

was characterizedfor moisture andtotal lycopene

content

Moisture wasdetermined by ovendrying at 105C to

constant weight


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Approximately 0.05 g of tomato powder (weight measured exactly to

1/1000 g) was added to 10 ml of ACS grade acetone in a 250 ml glass

beaker.

The solution was agitated gently for 1 minute, followed by vacuum-

filtration through a 5.5 cm paper filter.

The filter paper was transferred to the original 250 ml beaker along

with 10 ml acetone. The solution was agitated and filtered as before.

This step was repeated for a total of 4 filtrations of the powder.

A total of 40 ml acetone was used, but evaporation caused the final

solution to be less than 40 ml. Volume of solution was noted before

injection into the HPLC.

All steps were performed in subdued light, as suggested by Thurnham

et al. (1988).


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Based on

2 phasessystem

Analogous

to the theoryof TLC

Most commonadsorbents aresilica gel and

alumina

The sample isapplied to the

top of thecolumn

Equilibriumestablished betweensolute adsorbed on

alumina and elutingsolvent flowingdown through the

column


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(nonpolar liquid phase, polar modified solid phase) Retention of an analyte under normal phase

conditions is primarily due to interactions between

polar functional groups of the analyte and polar

groups on the sorbent surface

Hydrophilic interactions

polar-polar interactions

hydrogen bonding

pi-pi interactionsdipole-dipole interactions

dipole-induced dipole interactions


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Mobile phase :

Hexane

Tetrahydrofuran stabilised

with 0.025% BHT

N-Ethyl-diisopropylamine

Lycopene standard (purity

95% or higher; available from

CaroteNature GmbH)

Apparatus:

Spectrophotometer with a 1-cmcuvette

HPLC system with a suitable

pump, A phenyl-hexyl silicon

column (250 4.6mm i.d.5 m

particle size) , injector,

thermostated column

compartment, and integrator

Column: Two serially-connected

two stainless steel

columns (250x4.0 mm)

Stationary phase: Nucleosil 300-5, 5 m (Macherey-Nagel or

equivalent)

Detector: UV/VIS or VIS


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HPLC standard solution:

Accurately weigh between 5.5 and

6.5 mg of the lycopene standard

into a 100-ml volumetric flask.Dissolve in 5 ml of

tetrahydrofuran stabilised with

BHT and make up to volume with

hexane. This is a standard solution

for the HPLC assay.

Spectrophotometric determination

of lycopene:

Measure the absorbance of the

spectrophotometric standard solutionin a 1-cm cuvette at the wavelength

of maximum absorption

(approximately 470 nm). Use hexane

as the blank

HPLC conditions:

Flow rate: 0.8 ml/min

Injection volume: 20l

Pressure: approx. 80 bar

Column temperature: 20

Detection: 470 nm

Mobile phase: 0.15% solutionof N-ethyl-diisopropylamine in

hexane (v/v)

Run time: 30 min


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Amount of Nucleosil 300-5used should weigh at least30 times as much as the

sample

The column should have aheight at least 10 times of

the diameter when packed

The sample is

adsorbed onto a smallquantity of adsorbent

as a pure liquid

When elution, narrow bandof sample separate into

several bandscorresponding to no. of

components in the mixture

It is essential that thecomponents move through thecolumn as a narrow horizontalband to come off the column inthe least volume of solvent and

not overlap with othercomponents of the mixtures

The column should bevertical and the

packing should beperfectly uniform


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Number of plate, N


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Retention factor, k


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Resolution, R


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Separation factor,


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lycopene extract from tomato

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