科研之友
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摘要
The determination of alpha-lactalbumin in various dairy products attracts wide attention in multidiscipline fields because of its nutritional and biological functions. In the present study, we quantified the bovine alpha-lactalbumin in various infant formulas and whey protein concentrates using ultra-high performance liquid chromatography coupled to tandem mass spectrometer in multiple reaction monitoring mode. Bovine alpha-lactalbumin was quantified by employing the synthetic internal standard based on the molar equivalent relationship among the internal standard, bovine alpha-lactalbumin and their signature peptides. This study especially focused on the recovery rates of the sample preparation procedure and robust quantification of total bovine alpha-lactalbumin in its native and thermally denatured form with a synthetic internal standard KILDKVGINNYWLAHKALCSE. The observed recovery rates of bovine alpha-lactalbumin ranged from 95.8 to 100.6% and the reproducibility was excellent (RSD < 6%) at different spiking levels. The limit of quantitation is 10 mg/100 g for infant formulas and whey protein concentrates. In order to validate the applicability of the method, 21 brands of infant formulas were analyzed. The acquired contents of bovine alpha-lactalbumin were 0.67-1.84 g/100 g in these infant formulas in agreement with their label claimed values. The experiment of heat treatment time showed that the loss of native alpha-lactalbumin enhanced with an increasing intensity of heat treatment. Comparing with Ren';s previous method by analysis of only native bovine alpha-lactalbumin, the present method at the peptide level proved to be highly suitable for measuring bovine alpha-lactalbumin in infant formulas and whey protein concentrates, avoiding forgoing the thermally induced denatured alpha-lactalbumin caused by the technological processing.
- 出版日期2012-5-21
- 单位浙江大学
