Abstract #290

Section: Dairy Foods
Session: Dairy Foods Symposium: Biofilm Formation on Dairy Separation Membranes
Format: Oral
Day/Time: Tuesday 10:30 AM–11:00 AM
Location: 327
Recorded Presentation is being recorded
# 290
The role of biofilms in the quality of dairy products in whey processing plants.
S. Flint*1, S. N. M. Zain1, R. Bennett1, 1Massey Institute of Food Science and Technology, Massey University, Palmerston North, New Zealand.

Whey originates from microbial fermentation processes such as cheese and casein manufacture and is loaded with microorganisms from those operations. Thermalization is used to reduce bacterial numbers in whey before processing, however, bacteria that survive this are able grow within the manufacturing plant and contaminate the product. In hot processing plants, the growth of thermotolerant bacteria such as Streptococcus thermophilus can reach high levels on manufacturing plant surfaces blocking ultrafiltration modules. The current cold UF systems operating at 10°C solved that problem, however we are still facing microbial quality issues. Scrapings from ultrafiltration membranes reveal a variety of bacteria – many of which cannot survive thermalization and are hypothesized to enter via the water used for dialysis or cleaning. Control of water quality is therefore important. One problem that persists in today’s whey manufacturing plants is the growth of spore-forming bacteria that survive thermalization. Bacillus licheniformis is a common contaminant which we assume originates from raw milk but propagates as biofilm on manufacturing plant surfaces. Although many strains cannot ferment lactose, they grow readily on stainless steel surfaces in the presence of whey. Their growth is limited to zones close to their optimum growth temperature of 37°C before whey concentration and dialysis as growth is influenced by ions and protein concentration. They produce spores and protease, potential problems in whey products. The challenge is to manipulate conditions to prevent biofilm growth of B. licheniformis in manufacturing plant.

Key Words: Lactobacillus plantarum, Klebsiella, cation

Speaker Bio
Steve Flint is Professor of Food Microbiology and Safety at Massey University, Palmerston North, New Zealand. His specialist research field is understanding the development and control of biofilms in the food industry with a current focus on sporeforming bacteria, bacteria producing enzymes in the dairy industry and Listeria and Yersinia biofilms across the wider food industry. Steve spent 20 years in the dairy industry before continuing his career as a university academic. He has published over 120 papers and over 150 conference presentations.