Piet De Vegt

Doctor of Philosophy, (Food Technology)
Study Completed: 2015
College of Health


Thesis Title
The Microflora of Raw Milk and the Impact of Milk on their Survival at Low pH

Read article at Massey Research Online: MRO icon

Mr De Vegt investigated the bacteria found in raw milk, and developed a high-throughput acid tolerance test to determine which of these bacteria were most likely to reach the lower intestinal tract and have an influence on our health. A total of 363 bacterial species were isolated. Of these, 70 were found to be able to survive at acid levels typically found in the stomach. When milk was included in the investigation, the number of bacteria able to survive increased to 186, meaning 116 extra isolates were able to withstand the same acidity. In the second part of this work, Mr De Vegt investigated how milk protected bacteria when exposed to the extreme acidity found in the stomach. He found that certain combinations of proteins and salts found only in milk helped protect these bacteria from pH values as low as 2.5.

Professor Steve Flint
Dr Helen Withers