Page 68 - Analytical method for food addtives

36 Analytical methods for food additives

aqueous NaOH and CH Cl . Acids are converted to trimethylsilyl (TMS) esters
2 2
and determined by GC. Phenylacetic acid is used as internal standard for benzoic
acid. A summary of the procedure for this method is given in the Appendix and the
performance characteristics are given in Table 6.3.
A suitable HPLC method for sorbic acid in foodstuffs was collaboratively
tested on orange squash, cola drinks, beetroot, pie filling and salad cream and is
11
applicable to the determination of 50–2000 mg/kg sorbic acid in foodstuffs. In
this method liquid foods not containing insoluble matter are diluted with methanol.
Other foods are extracted by shaking with methanol, centrifuging and filtering.
The concentration of sorbic acid in the clear extract is measured using reverse-
phase liquid chromatography with UV detection. A summary of the procedure for
this method is given in the Appendix and a summary of the statistical parameters
in Table 6.4.

6.3 Recommendations

There are many methods available for the analysis of sorbic acid in foods and the
decision as to which one should be used depends on the matrix to be analysed. The
majority of methods are for liquids such as beverages, sauces and yogurt; further
method development may be required to adapt these methods to be applicable for
all matrices.

6.4 References
1 ‘AOAC Official Method 983.16. Benzoic acid and sorbic acid in food, gas-chromato-
graphic method. NMLK–AOAC Method’, AOAC Official Method of Analysis (2000)
47.3.05 p 9.
2 ‘Simultaneous determination of sorbic acid, benzoic acid and parabens in foods: a new
gas chromatography–mass spectrometry technique adopted in a survey on Italian foods
and beverages’, De Luca C, Passi S, Quattrucci E. Food Additives and Contaminants
(1995), 12(1), 1–7.
3 ‘Simple and rapid method for the determination of sorbic acid and benzoic acid in foods’,
Choong Y-M, Ku K-L, Wang M-L, Lee M-H. J Chinese Agricultural Chemical Society
(1995) 33(2) 247–261. [Chinese]
4 ‘Simultaneous analysis of preservatives in foods by gas chromatography/mass
spectrometry with automated sample preparation instrument’, Ochiai N, Yamagami T,
Daishima S. Bunseki Kagaku (1996) 45(6), 545–550. [Japanese]
5 ‘Gas chromatographic flow method for the preconcentration and simultaneous determi-
nation of antioxidant and preservative additives in fatty foods’, González M, Gallego M,
Valcárcel M. Journal of Chromatography A (1999) 848, 529–536.
6 ‘Simultaneous gas chromatographic determination of food preservatives following
solid-phase extraction’, González M, Gallego M, Valcárcel M. Journal of Chromatog-
raphy A. (1998) 823(1–2), 321–329.
7 ‘A simple method for the simultaneous determination of various preservatives in liquid
foods’, Lin H J, Choong Y M. Journal of Food and Drug Analysis. (1999) 7(4), 291–304.
8 ‘Effect of pH on the retention behavior of some preservatives-antioxidants in reverse-