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.

rrouseff@ufl.edu