No abstract

HPLC methods are described for the determination of free and total furfurals in liquid and powdered infant milk formulas. (Hydroxymethyl)furfural, furfural, furyl methyl ketone, and methylfurfural were determined simultaneously in one run. Identical HPLC conditions were used to measure free and total furfural compounds, although there were slight differences in sample preparation. The chromatographic technique involved the separation of the furfural compounds in a C 18 column using an isocratic mobile phase (water-acetonitrile) and a variable-wavelength absorbance detector. Linearity, precision, recovery, and sensitivity were always satisfactory. Detection limits ranged from 0.01 to 0.05 µg/mL, and determination limits ranged from 0.02 to 0.06 µg/mL of liquid infant milk or 15% (P/V) reconstituted powdered infant milk. In addition, we report the levels of furfural compounds in 12 commercial infant milk formulas (powdered and liquid) produced in Spain. (Hydroxymethyl)furfural and furfural were higher in infant milk formulas than in powdered cow milks. Levels of total furfural compounds were the same in powdered and liquid infant milk formulas. However, levels of free furfurals were higher in powdered than in liquid infant milks.

Biogenic amines were determined by using high-pressure liquid chromatography during spoilage of raw Engraulis encrasicholus (anchovies), during ripening and shelf life. Histamine, cadaverine, tyramine, and putrescine were extensively formed at the beginning of spoilage, while β-phenylethylamine and tryptamine were formed only at advanced stages of spoiling. Serotonin, spermine, and spermidine levels were constant throughout spoilage. Seventeen lots of anchovies were evaluated through the typical ripening process. Each ripening process lasted 18 to 22 weeks, Only a slight formation of biogenic amines was observed during the first period of ripening (2 to 4 weeks). According to our results, ripening had little influence on the formation of amines, and therefore the amount of amines in the final products depends primarily on the levels of these substances in the raw material. During shelf-life studies, anchovies packed in brine were more stable, from the point of view of biogenic amine formation, than anchovies packed in oil. High formation of tryptamine and histamine was observed in both products when they were stored at room temperature. Refrigerated storage prevents amine formation.

The progress of the Maillard reaction in two infant milks (liquid and powdered forms of the same commercial brand) was monitored for 9 months of storage at 20, 30, and 37°C. An increase in furfural compounds [hydroxymethylfurfural (HMF) and furfural (F)] was observed while no changes in available lysine occurred during storage at any temperature. In reconstituted powdered infant milk, at the three storage temperatures, the contents of free and total HMF ranged from 10.3 to 23.5 µmol/L and from 15.0 to 34.7 µmol/L, respectively. The content of free and total F ranged from 1.1 to 5.3 µmol/L and from 1.8 to 6.8 µmol/L, respectively. Free and total HMF content in liquid infant milk ranged from 0.6 to 1.6 µmol/L and from 9.0 to 12.2 µmol/L, respectively. The content of free and total F ranged from 0.3 to 0.6 µmol/L and from 1.4 to 2.3 µmol/L, respectively. Although free and total HMF and F were always higher in powdered milk than in liquid infant milk, in the latter the ratio total HMF/free HMF was more than 10 times that in powdered infant milk. On the basis of the increase in furfural compounds and by using the sum of free HMF and free F, an equation has been derived by which the shelf life of such products can be predicted.

Two infant milks claimed to have the same final composition in liquid and powdered form respectively were stored for 12 mo at 20, 30, and 37 °C. Vitamin E, thiamin, riboflavin, pyridoxine, folic acid, and nicotinamide remained constant at the three temperatures. However, there were statistically significant losses of vitamin A (approximately 35%) in samples stored at 37 °C. No differences were observed in vitamin stability between the two infant milks studied. Final levels of vitamin A were always higher than the minimum set by Spanish legislation. Vitamin A overfortification (approximately 200%) was more than that needed to compensate for losses during storage.