The Brazil based researchers, whose findings were published in Food Control, claim that LIBS differs from traditional nutrient quantifying methods in that it could allow direct analysis at the processing line.
Chronic calcium deficiency, resulting from inadequate intake or poor intestinal absorption, is one of several important causes of reduced bone mass and osteoporosis, argue the authors.
Some kinds of grain derivate products, such as breakfast cereals, can be enriched with calcium, hence becoming a high-calcium nutrient, and the researchers said that, in this regard, determining the Ca amount in manufactured cereals is important for quality control procedures.
They explain though that conventional calcium analysis methods comprise taking a sample from the substance to be inspected or from a processing line product; transporting it to an inspection device or to a laboratory and preparing it for chemical analysis and determination, with this stage involving transformation of the sample into an appropriate form for analysis such as from solid to liquid.
“This step is usually the most time consuming analytical procedure, in addition to generating toxic residues and increasing the probability of sample contamination for the analysis,” stress the researchers.
They said that, in contrast, LIBS makes use of a high energy laser pulse to simultaneously prepare the sample and generate its compositional ‘fingerprint’ and the system can be employed on samples regardless of their being solid, liquid or gas, with no or little pre-treatment procedures.
The researchers note previous studies reported matrix effects as a result of employing LIBS methods and they said that experimented with conventional calibration in order to minimize these.
To perform the calibration curve, seven commercial cereals containing Ca in a range of 16.00 mg kg-1 to 3734 mg kg-1 were considered, they reported.
The authors said the Ca amounts provided by the manufacturers were evaluated by using inductively coupled plasma optical emission spectrometry (ICP OES).
And their results show that the precision of the LIBS measurements was of eight per cent and its accuracy, observed by using a corn bran standard reference material, was higher than 99 per cent, added the team.
The researchers added that despite samples showing some differences in composition such as, distinctive sugar amounts, the presence or absence of chocolate and different grain compositions, the matrix effect did not result in appreciable scattering of calibration curves.
The authors claim their study demonstrates that LIBS can be an excellent tool for assessing nutrient distribution in commercial breakfast cereals, in addition to being fast and preventing complicated and dangerous sample pre-treatment processes.
“These features represent a favourable differential when compared to other techniques. The proposed LIBS method seems to be a good alternative to be used in production control systems and also in quality inspection departments,” concluded the researchers.
Source: Food Control
Published online ahead of print: 10.1016/j.foodcont.2010.04.004
Title: Determination of Ca in breakfast cereals by Laser Induced Breakdown Spectroscopy
Authors: E. C. Ferreira, E. A. Menezes, W. O. Matos, D. Milori, A. Nogueira, L Martin-Neto