Date of Award


Degree Name

MS in Agriculture - Dairy Products Technology


Dairy Science


Rafael Jimenez- Flores


In food processing, inadequate surface sanitation procedures lead to the formation of biofilms in which bacteria attach and aggregate in a hydrated polymeric matrix of their own synthesis. Formation of these sessile communities and their inherent resistance to existing sanitation procedures and agents are at the root of the risk of bacterial infections for consumers. Due to this existing problem, an effective method for reducing biofilm formation in dairy processing equipment is necessary for dairy products processing. Ultraviolet Pulsed light Technology has shown a positive effect in eliminating microorganism populations on food products. The objective of this work is to evaluate the effect of Pulsed light Technology on a biofilm of different dairy component matrices (e.g. Water (control); whey protein isolates (WPI), lactose, and sweet whey). This evaluation will be performed using the three strains of spore forming Bacillus species most common in commercial milk powder (B. subtilis, B. coagulans, and B. licheniformis). The matrix in which the evaluation was made consisted on allowing the attachment of endospores to on to a square 2.5cm x 2.5cm ASI 304 stainless steel coupon. Four Xenon light treatment levels (no treatment, 5 bursts, 10 seconds, 20 seconds and 30 seconds) were applied to the coupon surfaces using the Xenon model RC847 machine. The attachment of Bacillus to stainless steel in water as matrix was 1000 to 3000/ sq cm as measured in our laboratory. Results showed that there was a significant difference in spore reduction depending on the matrix of the biofilm and with the intensity of the Xenon treatment. Reduction in spores ranged from 1 to 4.7 logarithmic reduction cycles depending on the material of the biofilm, the strain of spores and the intensity of treatment. We conclude that there is significant potential to use this technology in maintaining low spore counts in commercial dairy powders.

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