Typical NIR spectra of unpeeled and peeled fruit

1
STUDY OF NIR REFLECTANCE PROPERTIES OF BILBERRY
G. Zsivánovits1, J. Felföldi2 1Canning Research
Institute of Plovdiv, Agricultural Academy of
Bulgaria, Sofia4000 Plovdiv, 154 Blvd. Vassil
Aprilov, e-mail zsivig_at_yahoo.co.uk 2Dept. of
Physics and Control Corvinus University of
Budapest, Hungary1118 Budapest, Somloi ut
14-16, e-mail jozsef.felfoldi_at_uni-corvinus.hu

• The aims of that research were
• to find non-destructive method for measuring the
  anthocyanin content of bilberry fruits.
• to find out how vary the anthocyanin content in
  the peel and in the pulp.

• The methods of that research were
• photometric method, to find the total anthocyanin
  content in the visible range.
• NIR reflectance method to study the unpeeled and
  peeled fruits.

About Anthocyanins Anthocyanin - pink, purple,
violet or blue water-soluble pigments colouring
leaves, flowers and other parts. These pigments
are sensitive to acidity or alkalinity (pH)
turning red in acid and blue in alkali.
Anthocyanins are polyphenolic (see structure).
The color of an individual anthocyanin will vary
from red (acidic conditions) to blue to yellow
(alkaline conditions). The final tissue color is
ultimately dependent upon several factors
including the type and concentration of
anthocyanin pigments present, pH, and the
presence of other metabolites (such as ions,
sugars, hormones). Anthocyanin synthesis
requires light. Low levels of anthocyanin are
present in dark grown plants (0.35 nmol/g) but
the amount increases rapidly after exposure to
light (5 nmol/g after 6 days).
About Bilberry Fruit(Vaccinium
myrtillus) Bilberry is a name given to several
species of low-growing shrubs in the genus
Vaccinium that bear tasty fruits. The species
also known as European blueberry, blaeberry,
whortleberry, whinberry myrtle blueberry,
fraughan etc. Bilberry has been used for
centuries, both medicinally and as a food in jams
and pies. Bilberry fruit contains chemicals known
as anthocyanosides, plant pigments that have
excellent antioxidant properties. They scavenge
damaging particles in the body known as free
radicals, helping to prevent or reverse damage to
cells. This herb is becoming more important to
the aging populations of the world. This fruit
and its extracts have marvelous anti-aging
properties. Bilberry was first studied for its
effects on poor night vision. Indeed, regular use
of the fruit results in quicker adjustment to
darkness and glare and improved visual acuity
both at night and in bright light during the day.
Bilberry may be useful in the prevention and
treatment of glaucoma since it strengthens
connective tissue and prevents free radical
damage. In modern times, the bilberry has become
a very popular nutritional supplement and it has
been found helpful in maintaining vision
health. Anthocyanins are very potent antioxidants
and they appear to play a very important role in
maintaining the integrity of our blood vessels,
both large and very small. They appear to help
maintain proper blood flow in many of our vital
organs.
Photometric method for total anthocyanin
content
Ratio 14 A (A520nm A 700nm)pH 1.0
(A520nm A700nm)pH 4.5 MW (molecular weight)
449.2 g/mol for cyanidin-3-glucoside
(cyd-3-glu) DF dilution factor established in
D ? pathlength in cm ?? 26 900 molar
extinction coefficient, in L ??mol1 ??cm1, for
cyd-3-glu 103 factor for conversion from g to
mg.
Compressed and filtered solution
pH 1.0 buffer (potassium chloride, 0.025M).
pH 4.5 buffer (sodium acetate, 0.4M).
Spectrophotometer, 520 and 700 nm
Instrument for the NIR experiments PMC
Spectralyzer 10-25 Measured wave grade 1000-2500
nm, with gap 2 nm.
Typical NIR spectra of unpeeled and peeled
fruit The spectra of the unpeeled and
peeled fruits show, there are large differences
in the total anthocyanin content of the peel and
the pulp. Although there are differences in other
parts, which means in other ingredients as well.
Based on our calculations the measured
bilberry samples contains 266.42.5 mg/L
anthocyanins.
Calibration of the photometric method
Calibration of the NIR Spectralyzer for total
anthocyanin content
Typical NIR spectra of bilberry solutions
The chosen wavelength grades, based on the best
correlations by PLS regression method
Anthocyanin content in the fruits

• Conclusions and questions for the future
• The NIR method is useful to measure the
  anthocyanin content.
• Two wavelength grade were found for the
  anthocyanins.
• Can be more selective the NIR method for
  anthocyanins?
• There are differences between the anthocyanide
  content of the peel, and the pulp.
• These fruits have very short shelf-life, and the
  process methods usually separate the peel and the
  pulp, to prepare juice. How it is possible to
  keep over these value ingredients for the period
  when there is no fresh bilberry?

Acknowledgement The authors say thanks to the
Bulgarian Agricultural Academy and to the
Corvinus University of Budapest, Dept. of Physics
and control for supporting my short collaboration.