At QUB, work has progressed in WP-3 with volatile organic compounds (VOCs) and mycotoxins analysis. The VOC content in raw milk uses solid phase micro extraction (SPME) coupled to GC-MS/MS. The study so far has identified many compounds in the milk, and currently the data is being processed to categorise the various chemical components into groups. These groups will eventually be used to determine correlations with parameters such as farm location, feed type and breed. Milk quality can also be determined by identifying signature chemicals that indicate decomposition and degradations of the milk.

Naturally occurring ketones, aldehydes, carboxylic acids and alkanes, as well as compounds such as vanillin and levo-menthol have been found in the raw milk. Compounds like vanillin could have been added artificially to the feed to improve the cows appetite, consequently changing the aroma of the milk. Potential quality markers looked at here range from fatty acid composition (C4:0 to C18:0), both as saturated fatty acids and the branched fatty acid composition, and also terpenes, as they are responsible for the natural aroma qualities of the milk.

Compound information is generated using deconvolution software as well as the NIST mass spectral database.

Shown below are raw milk VOC chromatograms. Differences  in chemical composition and intensities of individual chemicals can be seen (as highlighted in red).

Extracted data can be processed according to season (i.e. differences in S1 to S5 on the same farm), differences in farms within the same season, and comparison of farms between different countries

One such category are Terpenes, which are responsible for flavours and aroma. The following have been identified in the samples: Carene, Limonene, Neophytadiene and Phellandrene. The example shows terpene content changing over the sampling time period, which may be as a result of the change in animal diet.

Animal health can be measured from compounds such as acetone. Acetone levels in the milk can indicate ketosis, and symptoms of ketosis in cows include loss of appetite, milk production loss, and an increase of periods of illness.

Also underway in WP-3 is the mycotoxin analysis on beef and chicken liver samples. Mycotoxins are natural toxins produced by moulds, and can be a problem for food safety. The mycotoxin quantitative analysis workflow is using a 30+ mycotoxin method that contains 13 regulated and 14 emerging mycotoxins, and is the most up to date regarding mycotoxins of concern to human health. So far, the analysis has revealed several common types of mycotoxins found in the liver samples, such as 15-AcDON, Beauvericin and Enniatin B.