Color of orange juices in relation to their carotenoid contents as assessed from different spectroscopic data

Abstract

The

color

of

orange

juice

influences

consumers’

choice,

hence

much

importance

has

been

given

to

the assessment

of

this

attribute

for

decades.

The

instrumental

measurement

of

orange

juice

color

can

be harnessed

for

the

rapid,

quality-control

oriented

estimation

of

its

carotenoids,

which

are

health promoting

compounds.

In

this

work

we

compared

and

analyzed

different

spectroscopic

data

that

can

be used

for

these

purposes,

like

the

reflectance

spectra

of

orange

juices

and

the

absorption

spectra

of

their carotenoid

extracts.

Additionally,

we

have

revisited

the

Kubelka–Munk

theory

and

have

concluded

that its

parameters

are

suitable

to

assess

the

carotenoid

content

of

the

samples,

but

not

as

much

as

the

CIELAB color

coordinates.

In

this

regard,

we

have

observed

that

K/S

is

the

Kubelka–Munk

parameter

best correlated

with

the

carotenoid

content

of

the

orange

juices

surveyed

(r

=

0.84),

although

better correlations

were

observed

when

the

CIELAB

coordinate

a*

was

considered

(r

=

0.86

and

0.88

for measurements

with

white

and

black

background,

respectively).

However,

in

our

opinion,

this

fact

should not

lead

to

dismissing

the

usefulness

of

the

Kubelka–Munk

theory

to

estimate

carotenoid

contents,

since its

application

can

lead

to

obtaining

valuable

information

about

the

absorption

and

scattering

properties of

the

samples.