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Microbially induced changes in the volatile constituents of fresh chilled pasteurised milk during storage

Paper ID Volume ID Publish Year Pages File Format Full-Text
19856 43136 2014 10 PDF Available
Title
Microbially induced changes in the volatile constituents of fresh chilled pasteurised milk during storage
Abstract

•Relationship between microbial numbers and volatile organic compounds is not linear.•VOC concentrations change once a threshold number of bacteria are exceeded.•Bacterial numbers in milk may not accurately reflect consumer (odour) perception.•VOC detection plus bacterial numbers data improves understanding of shelf-life.

Off-odours caused by volatile organic compounds (VOCs) are often the first indicators consumers have of milk spoilage. In this study the VOCs associated with three types (trim, 0.25–0.40% fat; lite, 1.40–1.50% fat; and full-cream, 3.18–3.28% fat) of fresh chilled pasteurised milk (FCPM), held for up to 17 days at 4.5 ± 0.5 °C, were measured using proton-transfer-reaction mass spectrometry (PTR-MS). The chemical identification of VOCs in the headspace of the milk was supported by SPME–GC–MS analysis. Bacterial numbers (aerobic plate count at 25 °C) in the milk were also estimated. Replicate sets of milk types treated with sodium azide (NaN3) to inhibit microbial activity were investigated. The relationship between microbial numbers and VOCs was not linear; rather the concentrations of VOCs only started to change after a threshold number of bacteria ranging from 106–108 CFU mL−1 was reached. This combined approach provided new insights on the effect of microbial growth on FCPM shelf-life.

Keywords
PTR-MS; Volatile organic compounds; Milk spoilage; Microbial activity; Shelf-life
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Microbially induced changes in the volatile constituents of fresh chilled pasteurised milk during storage
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Publisher
Database: Elsevier - ScienceDirect
Journal: Food Packaging and Shelf Life - Volume 2, Issue 2, December 2014, Pages 81–90
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us