Development of an apparatus inactivating B. subtilis spore in
Orange juice using High Electric Field AC
Kunihiko Uemura, Isao Kobayashi and Takashi Inoue*
National Food Research Institute, *Pokka co.
1. Introduction
Heat treatment is commonly used to inactivate microorganisms in liquid foods in order to
improve food safety and extend shelf life. However, heat treatment to kill spores also causes thermal
damage to the food, which can adversely affect the flavor and lead to loss of nutrients. We developed an
apparatus to apply a high electric field AC (HEF-AC) that inactivates heat-resistant microbe spores in
liquid food while preserving the freshness of raw food.
Contact E-mail address: [email protected]
1)K. Uemura and S. Isobe, J. Food Eng., 53, 203(2002). 2) K. Uemura and S. Isobe, J. Food Eng., 56, 325(2003).
3)T. Inoue, Y. Kawahara , S. Ikeda, S. Hijikata , S. Isobe and K. Uemura, JSFE., 8, 123(2007).
Block diagram
○:Inactivate more than 3-log. △:Inactivate more than 2-log. ×:Inactivate less than 1-log.
Tempera
ture
S.cerevisiae
E.coli B.Subtilis B.cereus A.acidocaldarius
Geo.stearothermophilus
65℃ ○ △
70℃ ○ ○
110℃ × ×
115℃ △ △ ×
120℃ ○ ○ ○ ×
130℃ ○ ○ ×
135℃ △
140℃ ○
2. HEF-AC setup1),2)
3. Inactivation of B.subtilis spore3)
HEF-AC system appearanceElectrode
Inactivation of selected microorganism
4. Improvement in quality of Orange juice
Teflon
block
1mm
32mm
6mm
Titanium
electorode
Scale up
Throughput:
2,000L/h
•Inline test
•Long run
test
-6
-5
-4
-3
-2
-1
0
100 110 120 130
Inaciv
ating
effect
of B
.subtil
is
Log(N
/N0)
Temperature [°C]
0.3s
0.6s
0.9s
Holding time
FHEF-AC = 0.006 min
0
0.2
0.4
0.6
0.8
1
1.2
Raw HEF-AC UHT
β-c
aro
ten
e [m
g/L
]
0
50
100
150
200
250
300
350
400
Raw HEF-AC UHT
Hesp
eri
din
[m
g/L
]
38
39
40
41
42
43
44
45
Raw HEF-AC UHT
Asco
rbic
acid
[m
g/L
]
0.E+00
2.E+08
4.E+08
6.E+08
8.E+08
1.E+09
Raw HEF-AC UHT
Lim
on
en
e[A
RE
A]
0.E+00
2.E+05
4.E+05
6.E+05
8.E+05
1.E+06
Raw HEF-AC UHT
Lin
alo
ol [
AR
EA
]
-0.5
0
0.5
1
1.5
Fragrance
Orange feel
Aftertaste
Color
Refreshed feel
Total
Test way：7 steps
（-3～+3）absolute scale
■ ：HEF-AC
◆ ：UHT
Sensory evaluationComponents analysis
-2
-1.5
-1
-0.5
0
0 5 10 15 20
Inactivation e
ffect
of
B.s
ubtil
is
log(N
/N0)
Electric field [kV/cm]
Temperature and holding time Electric field effect
Temperature : 115°C
NaCl consentration : 0.0025%～0.15%
In Progress
