The aim of the study was to quantify microbiological, biochemical and sensory changes in full cream raw milk
(RM) processed with high temperature short time (HTST) pasteurisation (P), ultraviolet light treatment (UV)
and a combination of UV light treatment and HTST pasteurisation (UVP) in commercial scale production of
Cheddar cheese. The three treatments have been compared at a similar level ofmicrobial efficacy. No significant
differenceswere reported on themacro-nutrient composition, however a 35% and 18% reduction in cholesterol in
the UV and UVP treatments were observed. HTST treatment (UVP and P) reduced riboflavin and Vitamin B12 in
milk by ~31% and ~18% respectively, with no reduction in riboflavin and Vitamin B12 observed after the UV
treatment alone. Lipid oxidation and lipolysis results indicated a significant difference between raw and UVP
treated milk (p b 0.05). Protein oxidation results indicated no significant differences except for methionine
sulfone, which increased by 67.24% and 87.93% respectively for UV and UVP treatments. Some differences
were noted with sensory results, most noticeably on the ‘tallowy’ flavour descriptor for the UV treated milk,
however customer acceptance of UV treated milk will ultimately determine the acceptability of UV technology
as an alternative or adjunct to commercial thermal treatment of milk in cheese production.
Industrial relevance: UV light has been proposed as a non-thermal alternative or adjunct to traditional heat treatment
for the reduction ofmicro-organisms in fluids. UV technology presents numerous benefits over traditional
preservation, such as use of heat treatment, for example: lowcost of installation andmaintenance, lower production
cost and the reduction of carbon emissions when compared to traditional thermal pasteurisation systems.
Furthermore UV technology also offers alternative processing technology in developing countries where
production of milk and cheese are done on a small scale. Known limitation for the efficacy of UV as a processing
option was its low penetration depth into turbid liquids, such as milk, and the possible negative impact on
organic compounds when over-exposed to UV light. New optimised reactor design features of the swirl tube
Surepure Turbulator™, could potentially negate these negative effects associated with UV treatment due to
improved uniformity of treatment. This technology would provide and affordable and accessible processing
solution to not only enhance the safety and extend shelf-life of the milk being produced, but will also increase
final product quality of secondary dairy products such as Cheddar cheese produced from UV treated milk.
These advantages could positively impact on the safety, profitability and sustainability of the agro-industrial
sector within such regions.