TY - JOUR
T1 - Reduction of Staphylococcus aureus and quality changes in apple juice processed by ultraviolet irradiation, pre-heating and pulsed electric fields
AU - Walkling-Ribeiro, M.
AU - Noci, F.
AU - Cronin, D. A.
AU - Riener, J.
AU - Lyng, J. G.
AU - Morgan, D. J.
PY - 2008/12
Y1 - 2008/12
N2 - Apple juice inoculated with Staphylococcus aureus (SST 2.4) was processed by a hurdle sequence including ultraviolet irradiation (UV; 30 min, 20 °C), pre-heating and pulsed electric fields (PEF). Four different levels of pre-heating temperature (35-50 °C), electric field strength (28-40 kV cm-1) and total treatment time (25-100 μs), were used in an orthogonal design, evaluating their impact on S. aureus. Selected physical and chemical quality attributes were measured and compared to conventional pasteurisation (26 s, 94 °C). A higher reduction (P < 0.05) of S. aureus was achieved with a hurdle approach (UV; 46 °C (PEF inlet) and 58 °C (PEF outlet); PEF 40 kV cm-1 and 100 μs) in comparison to conventional pasteurisation (9.5 vs. 8.2 log10, respectively). Bacterial inactivation was not affected by pre-heating temperature (P ≥ 0.05), while increasing electric field strength and treatment time both induced a reduction in bacterial numbers (P < 0.05). An analysis of the normalised energy densities for all UV/PEF processing conditions indicated a maximised energy efficiency at higher electric field strengths and shorter treatment times. Treatments showed little effect on the measured quality attributes.
AB - Apple juice inoculated with Staphylococcus aureus (SST 2.4) was processed by a hurdle sequence including ultraviolet irradiation (UV; 30 min, 20 °C), pre-heating and pulsed electric fields (PEF). Four different levels of pre-heating temperature (35-50 °C), electric field strength (28-40 kV cm-1) and total treatment time (25-100 μs), were used in an orthogonal design, evaluating their impact on S. aureus. Selected physical and chemical quality attributes were measured and compared to conventional pasteurisation (26 s, 94 °C). A higher reduction (P < 0.05) of S. aureus was achieved with a hurdle approach (UV; 46 °C (PEF inlet) and 58 °C (PEF outlet); PEF 40 kV cm-1 and 100 μs) in comparison to conventional pasteurisation (9.5 vs. 8.2 log10, respectively). Bacterial inactivation was not affected by pre-heating temperature (P ≥ 0.05), while increasing electric field strength and treatment time both induced a reduction in bacterial numbers (P < 0.05). An analysis of the normalised energy densities for all UV/PEF processing conditions indicated a maximised energy efficiency at higher electric field strengths and shorter treatment times. Treatments showed little effect on the measured quality attributes.
KW - Apple juice
KW - Hurdle approach
KW - Non-thermal optimisation
KW - PEF
KW - Staphylococcus aureus
KW - UV
UR - http://www.scopus.com/inward/record.url?scp=46049089975&partnerID=8YFLogxK
U2 - 10.1016/j.jfoodeng.2008.05.001
DO - 10.1016/j.jfoodeng.2008.05.001
M3 - Article
AN - SCOPUS:46049089975
SN - 0260-8774
VL - 89
SP - 267
EP - 273
JO - Journal of Food Engineering
JF - Journal of Food Engineering
IS - 3
ER -
