Siti Md Zain

Doctor of Philosophy
Study Completed: 2018
College of Health


Thesis Title
Biofilm formation by B. licheniformis isolated from whey protein concentrate 80 powder as a potential source of product contamination

Read article at Massey Research Online: MRO icon

Contamination of whey products with bacteria canbean economic problem for the dairy industry. Ms Zain investigated sixwhey protein concentrate powder(WPC80)samples containinghigh bacterial counts and identifiedthe predominant microflora was the mesophilicthermotolerantbacterium Bacilluslicheniformis. These bacteria most likely contaminate the whey powder from the internal surfaces of the dairy manufacturing where the bacteria grow as biofilms. The largest surface area in a whey product manufacturing plant is during ultrafiltration where they whey is concentrated and purified. This process, however, runs at a temperature of 10°C, a temperature where B. licheniformis is unable to grow. B. licheniformisappearsto be poorly adapted to thriving in whey product manufacturing plant. However, a search revealed specific stages early in the manufacturing process where the temperatures and nutrients are suitable for B. licheniformisgrowth. This understanding is helpful in targeting control measures to prevent the contamination of WPC80.

Professor Steve Flint
Dr Hong Soon Tay
Mr Rod Bennett


S. N. Md Zain., (2013). The role of biofilm development on ultrafiltration membranes in the contamination of whey products. 2nd Symposium on Food Science & Technology, IFNHH, Massey University, Palmerston North, New Zealand. 15 November 2013. Oral presentation.