Upload
others
View
2
Download
0
Embed Size (px)
Citation preview
Most economical to reduce microbial populations
Also inactivates certain enzymes but …
induces chemical reactions
Acid catalyzed reactions – unsaturated terpenes
Maillard reaction – complex mixture of products
Thermal decompositions/reactions
produce sulfur volatiles
Formation of sulfur volatiles – degrades flavor
dimenthyl sulfide
methanethiol
hydrogen sulfide
Non sulfur volatiles formed
4-vinyl guaiacol (ferulic acid)
alpha-terpineol (limonene)
Furaneol (sugars + ascorbic acid)
0
1
2
3
4
5
Gra
pefr
uit- o
Passio
n F
ruit- o
Mo
ldy- o
Cooked
- o
Me
dic
ine
- o
Gra
pefr
uit-r
Passio
n F
ruit -
Mold
y-r
Co
oke
d-r
Me
dic
ine
-r
Sw
eet
Acid
Bitte
r
Canned OJ vs Fresh Squeezed OJ
0
1
2
3
4
5
Gra
pefr
uit-o
Passio
n F
ruit-o
Mo
ldy-o
Cooked
-o
Me
dic
ine
-o
Gra
pefr
uit-r
Passio
n F
ruit -
r
Mold
y-r
Cooked
-r
Medic
ine
-r
Sw
eet
Acid
Bitte
r
Gra
pefr
uit-o
Passio
n F
ruit-o
Mo
ldy-o
Cooked
-o
Me
dic
ine
-o
Gra
pefr
uit-r
Passio
n F
ruit -
Mold
y-r
Cooked
-r
Medic
ine
-r
Sw
eet
Acid
Bitte
r
Canned OJ (blue) Fresh Squeezed OJ (red)
No Naringin!!
1.8
1-M
eth
an
eth
iol
2.2
7- D
ime
thyl
su
lfid
e
4.3
9- 2
-me
thyl-
3-f
urn
ath
iol
9.0
0-N
ot
aro
ma
ac
tive
15
.15
16
.92
18
.33
2 4 6 8 10 12 14 16 18
Time (min DB-5)
PF
PD
Re
sp
on
se
5.3
0- M
eth
ion
al
3.6
3- 3
-me
rca
pto
-2-b
uta
no
ne
6.6
6-D
ime
thyltr
isu
lfid
e
13
.61
-1
-P
MT
Pérez-Cacho, P. R.; Mahattanatawee, K.; Smoot, J. M.; Rouseff, R., Identification of sulfur volatiles in canned orange juices lacking orange flavor. Journal of Agricultural and Food Chemistry 2007, 55, 5761-5767.
CH3
CH3 SH
CH3
Widely distributed in Foods
Are found in many chemical forms
Typically found at trace concentrations
Have extremely potent aromas
Are difficult (BUT IMPORTANT) to measure
GC-olfactometry
Sulfur specific GC detectors - PFPD
Sulfur in Cooked Foods
Sulfur in Fruits
N
S
N
S
SS
S
CH3S
CH3 CH3S
SCH3
CH3S
H
sulfide dissulfide thiol
thiazole thiazolines thrithiolane
Sulfur Structures
Sulfur Off-Flavor Structures
Sulfur Off-Flavors
Relative Aroma Strength
Rough rule – many exceptions
Compound Odor
Description
Odor Threshold (µg/L)
Hydrogen sulfide Rotten egg, sulfurous 10
Methional Cooked potato 1.8
2-Acetylthiazole popcorn 1
Methanethiol Sulfurous 0.2
Dimethyl disulfide cabbage 0.16
2-Acetylthiophene sulfury 0.08
2-Furfurylthiol Roasted, coffee like 0.005
2-Methyl-3-furanthiol Boiled meat 0.005
Bis(2-methyl-3-furyl)-disulfide beef like 0.00002
Sulfur Aroma Thresholds
How to measure at trace levels?
Atomic Emission
Sulfur Chemilluninesence
Flame Photometric detection
Pulsed Flame Photometric Detection, PFPD
Selected Ion Monitoring, SIM
PF
PD
Res
po
nse
(S
qrt
mo
de)
H2S
S
O2
MeS
HD
MS
E
MS
(IS
)
2-M
eth
iop
hen
e
Met
hio
nal
DM
TS
IPD
S (
IS)
2,8-
epit
hio
-cis
-p-m
enth
ane
1-p
-men
then
e-8-
thio
l
8-S
H-p
-men
than
-3-o
ne
(IS
)
DM
DS
3-S
H h
exyl
ace
tate
11
14 15
1716 18
400 600 800 1000 1100 14001200 1500900700 1300
Bis
-2-m
eth
yl-3
fury
l-d
isu
lfid
e *
ZB-5 column
Sulfur compounds in GFJ (canned RFC)
3-M
eth
iop
hen
e
PFP
D R
esp
on
se (
Sqrt
)
Time
2-M
eth
iop
hen
e D
MD
S
DM
TS
3-M
eth
iop
hen
e
Met
hio
nal
3-S
H h
exyl
ace
tate
2,8
-ep
ith
io-c
is-p
-men
than
e
1-p
-men
then
e-8
thio
l
H2S
SO2
MeS
HD
MS
CS 2
Thermal generation of GFJ VSC’s
Fresh Juice
Heated @ 90°C 2 hrs
Heated @ 90°C 6 hrs
Heated @ 90°C 15 hrs
Mechanism for 1-PMT formation
SH
H S H
+-limonene
citrus
1-p-menthen-8-thiol
Grapefruit – character impact
+H+
Thiam ine (vitam in B1)
N H2N
N N
S
O H
+
bis (2-m ethyl-3-furyl)-disulfideO
S S
O
threshold = 2 parts in 1014
parts w ater
Thiamine Decomposition
Dreher, J. G.; Rouseff, R. L.; Naim, M., GC-Olfactometric Thermal Degradation of Thiamin in Model Orange Juice. Journal of Agricultural and Food Chemistry 2003, 51, 3097-3102.
CH3
S COOH
NH2
CH3
SCHO
methionine methional
Tasteless-odorless Cooked potato
MethionineCysteine Glutathione
S-Methyl Methionine
OH
O
NH2
SH NHHOOC
O
NH2
SH
NH
O
COOHSOH
NH2
O
SOH
NH2
O
+
Non-pathogenic bacteria
Associated with fruit juice off-flavorsflavor defect in apple and orange juices
Produces flat/sour type spoilagestorage temperature critical
no gas produced
Off-aromamedicinal
antiseptic
disinfectant
Aro
ma
Inte
nsi
tyFI
D R
esp
on
se
can
dy,
sw
eet,
fru
ity
alco
ho
l
ber
gam
ot
cucu
mb
erfr
esh
,flo
wer
pu
nge
nt,
spo
ilage
,gar
bag
e
pap
er
sco
tch
tap
e
bee
f b
roth
oil
y,fr
ied
sco
tch
tap
ean
ise ?
ho
spit
al
oily
,fri
edcl
ove
mild
ewy
clea
ner
h
erb
ace
ou
s
ran
cid
oil
mea
ty
swea
ty
10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0
Time - Minutes
GU
AIA
CO
L
2,6
-D
CP
2,6
-D
BP
me
dic
ine
me
dic
ine
me
dic
ine
,an
tise
pti
c
A. Cycloheptanicus Day 28
0
1
2
3
4
5
6G
C-O
Aro
ma P
eak H
eig
ht
Day 0 Day 14 Day 28
2,6-DBP
2,6-DCP
guaiacol
0
1
2
3
4
5
6
GC
-O A
rom
a P
eak H
eig
ht
Day 0 Day 14 Day 28
2,6-DBP
2,6-DCP
guaiacol
Incubation Time (Days)
Perez-Cacho, P. R.; Danyluk, M. D.; Rouseff, R., GC-MS quantification and sensory thresholds of guaiacol in orange juice and its correlation with Alicyclobacillus spp. Food Chemistry 2011, 129, 45-50.
Gocmen, D.; Elston, A.; Williams, T.; Parish, M.; Rouseff, R. L., Identification of medicinal off-flavours generated by Alicyclobacillus species in orange juice using GC-olfactometry and GC-MS. Letters Applied Microbiology 2005, 40, 172-77
min0 10 20 30 40 50 60 700
10
20
30
40
50
Met
hio
nin
e
MM
S
Fresh Satsuma juice
Time (min)
Flu
ore
scen
ce I
nte
nsit
y
ASP
ASn Gln
Thr
Arg
Lys
L-a-ala
Phe
Ser
SOH
NH2
O
+
Screen incoming juices for precursors
mandrins have highest MMS
orange and grapefruit lower MMS
Sakamoto, K.; Inoue, A.; Nakatani, M.; Kozuka, H.; Ohta, H.; Osajima, Y., S-
methylmethionine sulfonium in fruits of citrus hybrids. Bioscience Biotechnology and
Biochemistry 1996, 60, 1486-1487.
Direct “at risk” juices to ref. storage
Pass juice through cation exchange resinManabe, T., Dimethyl sulfide as a factor of off-flavor in heat-induced Satsuma
mandarin orange (Citrus unshiu) juice and its precursor. Hiroshima Nogyo Tanki
Daigaku Kenkyu Hokoku 1979, 6, 145-52.