Hexanal as biomarker for milk oxidative stress induced by copper ions

Abstract

Milk flavor varies greatly due to oxidative stress during storage. Several studies have documented the use of volatile biomarkers for determining milk oxidation, but only a few have focused on the development of inline procedures enabling the monitoring of milk oxidative stress. In this work, oxidative stress was induced in pasteurized milk samples by spiking increasing concentrations of copper ions (from 0 to 32 mg·L). During storage (4°C), hexanal evolution was monitored by a proton transfer reaction mass spectrometer. The mass fragment m/z 83 was selected as a biomarker for hexanal determination. Its intensity evolved with a sigmoidal trend, showing a maximum rate proportional to the Cu content in milk. The proposed approach is simple, fast (up to 120 sample/h), sensitive (8.8 μg·m per μM hexanal in the sample), with low limit of detection (0.5 μM, determined as 3 times the standard deviation divided by the slope of a calibration line), precise (<6%), with good recovery (99-104%), and noninvasive. The method can be used for laboratory screening of milk susceptibility toward oxidation or for quality control in the processing line.

Rapid and noninvasive quality control of anhydrous milk fat by PTR‐MS: The effect of storage time and packaging

“…Recently, Asaduzzaman et al monitored milk oxidative stress by following hexanal evolution at 4°C by PTR‐MS. In particular, the mass peaks at m / z 101 and m / z 83 corresponding to the protonated molecular ion and to the fragment obtained from the loss of a water molecule were indicated as biomarker for hexanal determination . In our experiment, both these mass peaks ( m / z = 101.096 and m / z = 83.085) showed a significantly higher concentration in the BIB sample than in the CT sample at all the time points.…”

“…In particular, the mass peaks at m/z 101 and m/z 83 corresponding to the protonated molecular ion and to the fragment obtained from the loss of a water molecule were indicated as biomarker for hexanal determination. 31 In our experiment, both these mass peaks (m/z = 101.096 and m/z = 83.085) showed a significantly higher concentration in the BIB sample than in the CT sample at all the time points. At 45 days (data not shown), the AMF stored in the BIB showed already higher levels, which means that this difference was originated during the first days of the storage and is then maintained.…”

Rapid and non‐invasive multivariate approach for the quality control of raw milk from mountain areas based on proton transfer reaction mass spectrometry data

“…Such a threshold reduced the number of monitored ions to 39, only. Among those, the most abundant ions found in all milk samples were m/z 45 (acetaldehyde MH + ion), m/z 47 (ethanol and formic acid MH + ions), m/z 55 (hexanal fragment ion), m/z 57 (fragment ions of carboxylic acid and alcohols), m/z 59 (acetone MH + ion), m/z 61 (acetic acid MH + ion and fragment ion of ethyl acetate), m/z 73 (2‐butanone MH + ion), m/z 87 (diacetyl, pentanal and pentanone MH + ions), and m/z 89 (acetoin, butanoic acid, ethyl acetate and pentanol MH + ions) . The identification of all the ions in this study is tentative and relies on previously reported literature.…”

“…The headspace was replaced by clean air by passing it through an activated charcoal filter. The analytical method and instrument operation conditions were adopted from a previously validated method for milk headspace analysis . The instrument was operated in scan mode over the range of m/z 21 to 200 with a dwell time of 100 ms per m/z value.…”

“…The analytical method and instrument operation conditions were adopted from a previously validated method for milk headspace analysis. 21 The instrument was operated in scan mode over the range of m/z 21 to 200 with a dwell time of 100 ms per m/z value. The data were corrected for background and transmission.…”