Nut

ritio

n La

belli

ng a

nd

Prox

imat

e An

alys

is

Food

Con

stitu

ents

:M

ACRO

NU

TRIE

NTS

(Tot

al c

alor

ies,

CH

O, f

at, p

rote

in

cont

ents

:Dai

ly R

efer

ence

Val

ues:

DR

V)M

ICRO

NU

TRIE

NTS

(Vita

min

s,m

iner

als:

% o

f Ref

eren

ce

Dai

ly I

ntak

es-R

DI)

Are

nutr

ition

ally

impo

rtan

t fo

r th

eir

effe

cts

on c

hron

ic a

nd d

efic

ienc

y di

seas

es

Exam

ples

:RD

I an

d D

RVRD

IVi

tam

inA.

....5

000

IUVi

tam

inC.

...60

mg

Vita

min

D...

..400

IUVi

tam

inE.

.....3

0IU

Iron

.....

.....1

8mg

Zinc

......

......

15m

g

DRV*

Fat.

......

......

....6

5gSa

tura

ted

FA...

20g

Chol

este

rol..

..300

mg

Tota

lCH

O...

....3

00g

Fibe

r....

......

....2

5gPr

otei

n....

.....5

0g*C

alor

ie...

......

2000

Nut

ritio

nal C

laim

sFr

eeLo

wRed

uced

/less

/lean

/ligh

tG

ood

Sour

ce/c

onta

ins/

prov

ides

Mor

e/ad

ded/

extr

a/pl

us/

Hig

h/ric

h/ex

celle

nt s

ourc

eM

odifi

ed(S

ee:

Tabl

es3.

5-3.

9 in

tex

tboo

k)

Hea

lth C

laim

sCa

lciu

m a

nd o

steo

poro

sis

Sodi

um a

nd h

yper

tens

ion

Die

tary

fat

and

can

cer,

CH

DFi

ber

and

canc

er, CH

DSu

gar

alco

hols

nad

den

tal c

arie

sFo

late

and

neu

ral d

efec

ts

PRO

XIM

ATE

AN

ALY

SIS

I. M

oist

ure

II. C

arbo

hydr

ates

and

Crud

e Fi

ber

II. L

ipid

s

IV. P

rote

ins

V. A

sh

Purp

ose

of P

roxi

mat

e A

naly

sis:

Esti

mat

ion

and

det

erm

inat

ion

of h

ow m

uch

of t

he

maj

or f

ood

com

pone

nts,

whi

ch a

re M

oist

ure,

CH

O,

Lipi

ds, P

rote

ins,

Ash

, Cru

de F

iber

,exi

st in

a g

iven

fo

od. T

he p

roxi

mat

e an

alys

es t

here

fore

are

:

1. M

oist

ure

Ana

lyse

s2.

Cru

de F

at A

naly

ses

3. C

rude

Pro

tein

-(N

on-p

rote

in n

itro

gen

als

o in

clud

ed)

mos

t pr

otei

ns

cont

ain

16%

ni

trog

en.

Ther

efor

e th

e ge

nera

l “p

rote

in

fact

or”

is

100/

16=6

.25.

If

we m

ulti

ply

the

perc

ent

nitr

ogen

by

6.2

5 ,w

e ob

tain

crud

e pr

otei

n.

4. A

sh -

resi

due

afte

r bu

rnin

g al

l or

gani

c m

ater

ial.

Som

e m

iner

als

beco

me

vola

tile

at

high

tem

pera

ture

s of

bur

ning

and

ther

efor

eca

n be

los

t. A

lso

som

e m

iner

als

occu

r in

the

for

m o

f sa

lts

of o

rgan

ic a

cids

lik

e ci

trat

es w

hich

con

tain

car

bon

and

are

lost

.5.

CH

O a

nd C

rude

Fib

erTo

tal

carb

ohyd

rate

= 1

00 -

[moi

stur

e +

crud

e fa

t +

crud

e pr

otei

n +

ash]

.Cr

ude

fibe

r:re

sidu

e le

ft

afte

r al

kalin

e an

d ac

id

dige

stio

nof

org

anic

mat

ter

If w

e su

btra

ct t

he t

otal

of

1-5

from

100

, we

get

the

nitr

ogen

fr

ee

extr

act

by

diff

eren

ce.

Doi

ng

this

no

rmal

ly u

nder

esti

mat

es n

itro

gen-

free

ext

ract

.

MOIS

TURE

and

Tota

l so

lids

ANALY

SIS

Ch.8

I. I

mpo

rtan

ce o

f W

ater

II.P

rope

rtie

s of

Wat

er

III.

Cla

ssif

icat

ion

of H

2O D

eter

min

atio

ns-D

irec

t M

etho

ds:D

ryin

g an

d D

isti

llati

on

-M

etho

ds M

easu

ring

Phy

sica

l Pro

pert

ies

-Met

hods

Bas

ed o

n Co

lliga

tive

Prop

erti

es

-M

etho

ds M

easu

ring

Che

mic

al P

rope

rtie

s

I. I

mpo

rtan

ce o

f W

ater

WA

TER

has

grea

t im

port

ance

in f

oods

, bec

ause

:1.

Of

its

econ

omic

impo

rtan

ce t

o th

e pr

oces

sor

and

the

cons

umer

, pe

rmit

ting

mat

eria

l ba

lanc

es,

yiel

d an

d lo

ss

calc

ulat

ions

, al

so

for

real

izin

g le

gal

stan

dard

sto

prot

ect

cons

umer

s ,

sinc

e fo

od

com

pani

es

want

to

se

ll as

m

uch

wate

r as

la

w pe

rmit

s.

2. O

f it

s ef

fect

son

sta

bilit

y, t

here

fore

qua

lity

issu

es,

sinc

e hi

gh m

oist

ure

leve

ls a

ccel

erat

e al

l ty

pes

of f

ood

dete

rior

atio

n(ch

emic

al,

enzy

mat

ic,

mic

robi

al).

3. I

t pe

rmit

s un

ifor

m e

xpre

ssio

n of

ana

lyti

cal

resu

lts,

fo

r fo

od

labe

lling

and

for

regu

lati

ons

conc

erni

n g f

ood.

WATER

Wat

er F

unct

ions

Impo

rtant

pro

perti

es o

f wat

er:

1.U

nive

rsal

solv

ent (

salt,

vita

min

s, su

gar,

gase

s, pi

gmen

t)

2.C

apab

le o

f ion

izin

g (H

3O+ ,

OH

- )

3.A

ffec

ts th

e te

xtur

e

4.En

ters

che

mic

alre

actio

ns (h

ydro

lysi

s of p

rote

in =

n a

min

o ac

ids)

5.St

abili

zest

he c

ollo

ids b

y hy

drat

ion

6.N

eces

sary

for m

icro

-org

anis

ms g

row

th

REA

CTI

ON

RA

TES

IN F

OO

D A

S A

FU

NC

TIO

N O

F W

ATE

R A

CTI

VIT

Y

MO

ISTU

RE

AN

ALY

SIS

WH

Y D

O W

E N

EED

MO

ISTU

RE

AN

ALY

SIS?

1.M

ater

ial b

alan

ce

2.M

eetin

g th

e st

anda

rds o

f pro

duct

3.Pr

oduc

t sta

bilit

y (p

reve

nt d

eter

iora

tion,

mol

d,

bact

eria

, ins

ect d

amag

e)

4.Ex

pres

s the

com

posi

tion

on D

ry W

eigh

t Bas

is

5.Ec

onom

ic im

porta

nce

(H2O

is c

heap

)

WA

TER

DET

ERM

INA

TIO

N M

ETH

OD

S

1.D

ryin

g m

etho

ds

2.D

istil

latio

n m

etho

d

3.C

hem

ical

met

hods

4.Ph

ysic

alm

etho

ds

As a

gen

eral

rule

in a

ll an

alys

es, c

hoos

e th

e fa

stes

t sim

ple

conv

enie

nt m

etho

d w

hich

will

giv

e re

sults

with

in th

e de

sire

d ra

nge

of a

ccur

acy

-sav

ings

on

time,

labo

r cos

ts,

will

qui

ckly

cov

er c

apita

l exp

endi

ture

.

CO

NSI

DER

ATI

ON

S IN

SEL

ECTI

NG

TH

E M

ETH

OD

S O

F W

ATE

R A

NA

LYSI

S

1.Fo

rm o

f wat

er p

rese

nt (f

ree

vs. b

ound

wat

er)

Exam

ple:

% w

ater

in m

ilk v

s. no

n-fa

t drie

d m

ilk.

2.N

atur

e of

pro

duct

:

Vol

atile

com

poun

ds

Hea

t sta

ble

-los

s of s

ome

food

com

poun

ds

Uns

atur

ated

fat -

oxid

atio

n -w

eigh

t.

3.H

ow fa

st y

ou c

an a

naly

ze sa

mpl

e.

4.A

ccur

acy

and

repr

oduc

ibili

ty.

5.A

vaila

bilit

y an

d co

st o

f equ

ipm

ent.

The

moi

stur

e co

nten

t of

fo

ods

vari

es

grea

tly

betw

een

food

pro

duct

s -

e.g.

Prod

uct

Moist

ure

cont

ent

%M

ilk87

-91

Melon

s92

-94

Milk

pow

der

4Cu

cumbe

rs96

Butt

er a

nd m

arga

rine

~15

Mea

t an

d fish

50-7

0

•The

re a

re m

any

alte

rnat

ive

met

hods

,thu

s m

any

diff

eren

t pr

inci

ples

of

op

erat

ion.

Ch

oice

of

m

etho

d de

pend

s on

fol

lowi

ng c

rite

ria:

Spee

d -

reso

urce

sav

aila

ble

–de

sire

d le

vels

of

accu

racy

/ pr

ecis

ion

–ope

rati

ng c

osts

•If

you

work

at

a ro

utin

e la

bora

tory

, yo

u pr

efer

qu

ick

met

hods

. H

owev

er, f

or r

efer

ence

labo

rato

ry

accu

racy

is m

ost

impo

rtan

t. F

ollo

wing

are

ste

ps t

o be

fo

llowe

d fo

r de

term

inin

g th

e ov

eral

l co

mpo

siti

on o

f a

food

sam

ple

or c

onte

nt o

f a

spec

ifie

d co

mpo

nent

:

KIN

DS

OF

WA

TER

-D

EGR

EE O

F W

ATE

R

BIN

DN

ESS

Mon

olay

erW

ater

is b

ound

in fo

od -

rest

ricte

d in

its m

ovem

ent

due

to c

harg

es, h

ydro

gen

bond

, phy

sica

l ent

rapm

ent.

Har

d to

re

mov

e fr

om fo

od.

Nev

er b

e ab

le to

rem

ove

wat

er c

ompl

etel

y.

Mul

tilay

erW

ater

-add

ition

al la

yer o

f wat

er a

roun

d fo

od

parti

cle.

Not

as h

ard

to re

mov

e as

the

mon

olay

er.

Mob

ile o

r Fre

e W

ater

-con

sist

ed w

ith id

eal s

olut

ion.

Form

s of

Wat

er in

foo

ds a

nd t

heir

Pro

pert

ies

Wat

er m

ay o

ccur

in s

ever

al f

orm

s in

foo

ds:

1. Fr

ee H

2O (

with

in t

he p

ores

of

mat

eria

l in

the

int

er

gran

ular

spa

ces)

:A

s so

lven

t fo

r m

olec

ular

dis

pers

ion

of

solu

tes,

col

loid

s,

etc.

Whe

n it

exi

sts

as a

sol

vent

, it

can

be

thou

ght

of a

s fr

ee w

ater

, not

bou

nd t

o an

y th

ing

and

ther

efor

e av

aila

ble

for

chem

ical

re

acti

ons,

m

icro

bial

gr

owth

, an

d ph

ysic

al

chan

ges.

It

can

be

obta

ined

by

evap

orat

ion;

ıt

reta

ins

its

usua

l pr

oper

ties

as

solv

ent,

it is

ava

ilabl

e to

mic

roor

gani

sms.

2. A

dsor

bed

wate

r ca

n ex

ist

in m

ono

or p

olym

olec

ular

laye

rs

on

the

inte

rnal

or

ex

tern

al

surf

aces

of

m

olec

ules

in t

he f

ood.

It

is h

eld

tigh

tly

in c

ell w

alls

or

on p

arti

cula

rly

prot

eins

and

sta

rche

s wh

ich

have

str

ong

tend

enci

es f

or f

orm

ing

such

inte

ract

ions

wit

h wa

ter.

Beca

use

fat

is h

ydro

phob

ic, i

t do

es n

ot u

sual

ly in

tera

ct

with

the

wat

er p

hase

in

food

, ho

weve

r, t

here

are

ph

osph

olip

ids

and

lipop

rote

ins

that

ass

ocia

te a

t lip

id-

wate

r in

terf

aces

.

Thes

e ca

n ac

t as

em

ulsi

fier

s. V

an d

erwa

lls f

orce

s ar

e ef

fect

ive

for

phys

ical

ly a

dsor

bed

H2O

(is

fou

nd i

n a

m

ono

laye

r on

the

sur

face

of

mac

rom

olec

ules

).

3.

Wat

er

of

Hyd

rati

on:

Som

etim

es,

wate

r ca

n be

ch

emic

ally

bo

und

to

cert

ain

com

poun

ds

like

lact

ose

(for

min

g a

stab

le

mon

ohyd

rate

), sa

lts

(tar

tara

te),

prot

eins

(h

ydro

gen

bond

ed)

and

poly

sacc

hari

des

(hyd

roge

n bo

ndin

g). T

his

boun

d wa

ter

may

var

y fr

om 0

.5

to

30%

of

th

e to

tal

wate

r pr

esen

t.

This

wa

ter

is

part

icul

arly

dif

ficu

lt t

o re

mov

e fo

r an

alyt

ical

pur

pose

s.

Chem

ical

ly b

ound

wat

er i

s in

th

e fo

rm o

f wa

ter

of

hydr

atio

n or

cry

stal

izat

ion,

It

is u

nava

ilabl

e as

sol

vent

.

Ex:

MgS

O4.3

H2O

: H

ere,

H2O

is

com

plet

ely

diff

eren

t fr

om t

he o

ther

for

ms.

~6%

of

H2O

in a

nim

al t

issu

es,

~10%

of

H2O

in f

ruit

sis

in t

his

form

.

III.

Cla

ssif

icat

ion

of H

2O D

eter

min

atio

ns

Prin

cipl

es o

f m

etho

ds u

sed

for

moi

stur

e de

term

inat

ion:

I.D

IREC

T M

ETH

OD

S:Th

ese

are

base

d on

sep

arat

ion

of w

ater

fro

m f

ood

solid

s an

d m

easu

ring

the

loss

in w

eigh

t or

the

vol

ume

of

wate

r re

mov

ed.

A. O

ven

Dry

ing

Met

hods

: Var

y gr

eatl

y in

con

diti

ons

for

dryi

ng( o

ver

dess

ican

ts o

r in

atm

osph

eric

or

vacu

um

oven

s) B. D

istilla

tion

Tec

hnique

s:

Co

-dis

tilli

ng w

ater

wit

h a

high

boi

ling

poin

t s

olve

nt t

hat

is i

mm

isci

ble

with

wa

ter.

II

.Met

hods

bas

ed o

n ch

emic

al r

eact

ions

of

wate

r.II

I.M

etho

ds

mea

suri

ngso

me

phys

ical

(a)

or

colli

gati

ve(b

)pro

pert

y th

at i

s co

rrel

ated

to

moi

stur

e co

nten

t

IA. D

ryin

g M

etho

ds

Thes

e ar

e es

sent

ially

the

rmal

met

hods

. M

oist

ure

los

is a

fun

ctio

n of

tim

e an

d te

mpe

ratu

re. I

n m

ost

case

s,

dr

ying

m

etho

ds

rely

on

gr

avim

etri

c di

ffer

ence

bef

ore

and

afte

r dr

ying

, us

ing

heat

tr

ansf

er b

y co

nduc

tion

on

conv

ecti

on.

Dry

ing

met

hods

have

adva

ntag

es o

f be

ing:

-Sim

ple

-Fas

t(in

frar

edm

etho

d),

-Han

dlin

g la

rge

num

ber

of s

ampl

es-

Inex

pens

ive

(equ

ipm

ent)

Prin

cipl

es g

over

ning

moi

stur

e lo

ss:

*Hea

t tr

ansf

er r

ate

(sel

dom

a li

mit

ing

fact

or)

*Tem

pera

ture

**S

urfa

ce a

rea

of p

rodu

ct, p

arti

cle

size

*D

iffu

sion

of

wate

r th

roug

h pr

oduc

t*V

apor

pre

ssur

e di

ffer

ence

s (R

H a

t su

rfac

e vs

. pro

duct

), nu

mbe

r of

sam

ples

in o

ven,

air

ex

chan

ge r

ate

in o

ven,

vac

uum

app

lied

or

not,

ai

r m

ovem

ent

in d

ryer

, etc

.

*1 m

ole

of s

olut

e di

ssol

ved

in 1

liter

wat

er

rais

es it

s bo

iling

poi

nt b

y ~0

.5ºC

.Thu

s bo

iling

po

int

elev

atio

n co

ntin

ues

duri

ng m

oist

ure

rem

oval

pro

cess

.

DR

YIN

G M

ETH

OD

S–

DR

Y T

HE

FOO

DS

UN

DER

TH

E SP

ECIF

IC C

ON

DIT

ION

S

Type

s of O

ven,

Tem

pera

ture

, Tim

e.

Adv

anta

ges:

Sim

ple,

Rel

ativ

ely

rapi

d, A

naly

sis o

f lar

ge

num

ber o

f sam

ples

at a

tim

e.

Dis

adva

ntag

es:L

oss o

f oth

er o

rgan

ic c

ompo

unds

or g

ases

fo

rmed

by

ther

mal

dec

ompo

sitio

n of

org

anic

co

mpo

unds

.

Oxi

datio

n of

oil.

Erro

r Sou

rce:

Cru

st fo

rmat

ion

from

suga

r.

1. A

ir-ov

en M

etho

d---

put t

he sa

mpl

e (1

0g) i

n fla

t, ta

rred

dis

h -

spec

ified

tim

e an

d te

mpe

ratu

re (1

50C

for 1

hr)

-m

easu

re th

e lo

ss o

f w

ater

.

2. V

acuu

m o

ven

Met

hod

---u

se it

if y

ou d

o no

t wan

t to

expo

se

to h

igh

tem

pera

ture

. U

se 5

0 m

m H

g an

d ar

ound

100

C.

Food

rich

in

fruc

tose

mus

t be

drie

d at

70C

or b

elow

.

3. H

ot p

late

Met

hod

---r

apid

, qua

lity

cont

rol,

use

som

e tim

e, p

ut

in v

acuu

m a

t 100

C, c

ool i

n de

sicc

ator

s, "M

ojon

nier

".

4. M

oist

ure-

bala

nce

---ba

lanc

e in

ove

n w

ith IR

ligh

t and

hea

t.

Mea

sure

the

moi

stur

e lo

ss.

DR

YIN

G M

ETH

OD

S

•Dis

adva

ntag

es:

•Pre

cautıv

e m

easu

res

have

to

be

take

n to

avo

ıd

deco

mpo

siti

onof

sol

ute

com

pone

nts:

Exam

ple:

Fr

ucto

se

cont

aini

ng

food

s

may

de

com

pose

wi

th

unco

ntro

lled

heat

ing

sinc

e fr

ucto

se is

des

troy

ed a

bove

the

100

°C,

•Sol

utio

n: A

pply

vac

uum

, red

uced

tem

pera

ture

and

lo

nger

dry

ing

tim

e.e.

g. A

lso

may

pla

ce i

n va

cuum

de

sicc

ator

over

co

ncen

trat

ed

sulf

uric

ac

id,

phos

phor

us p

ento

xide

, or

mag

nesi

um p

erch

lora

te).

•Ove

n m

etho

ds a

re n

ot g

ood

for

prod

ucts

tha

t ha

ve a

lot

of b

ound

wat

er.

•Dri

ed f

ruit

s co

ntai

n a

lot

of b

ound

wat

er a

nd w

ill

lose

onl

y 75

% o

f th

eir

moi

stur

e by

dry

ing

met

hods

. D

ehyd

rate

d fi

nely

gro

und

carr

ots

requ

ire

6-9

mon

ths

in a

vac

uum

ove

r M

g pe

rchl

orat

eto

att

ain

cons

tant

we

ight

.

DRY

ING

met

hods

have

man

y ot

her

disa

dvan

tage

s:

It i

s no

t sp

ecif

ic f

or a

ll ty

pes

of w

ater

, th

eref

ore

may

lead

to

mis

take

n ca

lcul

atio

nsO

ptim

al d

ryin

g te

mpe

ratu

re m

ay n

otbe

att

aine

dD

ryin

g ca

n be

de

stru

ctiv

e

to

othe

r co

mpo

nent

s (n

onde

stru

ctiv

e vs

. des

truc

tive

met

hods

)

Hea

t So

urce

s us

ed a

re a

ir-o

vens

, va

cuum

-ove

ns,

mic

rowa

ve o

vens

, in

frar

ed o

vens

and

la

mps

. In

id

eal

dryi

ng p

roce

dure

for

the

det

erm

inat

ion

of

wate

r,

weig

ht

loss

es

shou

ld

resu

lt

from

qu

anti

tati

ve

and

rapi

d vo

lati

lizat

ion

of

wate

r on

ly. T

his

depe

nds

larg

ely

upon

:

*Air

mov

emen

t in

the

dry

ing

cham

ber

*Vac

uum

in t

he c

ham

ber.

Fact

ors

infl

uenc

ing

resu

lts

(the

rat

e of

eva

pora

tion

of

wat

er in

ove

ns).

a-D

iam

eter

or

surf

ace

area

of

cont

aine

rs.

b-D

epth

of

cont

aine

rsc-

Mat

eria

l of

con

tain

ers

(Al;

porc

elai

n et

c.D

ryin

g ra

te is

hig

hest

in A

l dis

hes)

d-Po

siti

on a

nd n

umbe

r of

con

tain

ers

in t

he o

ven.

*Des

sica

nts

like

P 2O

5; ca

lciu

m c

arbi

de, s

ilica

gel

will

sp

eed

dryi

ng..

e-D

ryin

g is

a f

unct

ion

of t

ime,

tem

pera

ture

and

wate

r va

por

pres

sure

. The

refo

re in

ord

er t

o be

abl

e to

dec

reas

e th

e te

mpe

ratu

re,

we h

ave

to e

ithe

r in

crea

se t

he t

ime

or a

pply

vac

uum

.In

vacu

um o

vens

, wa

ter

vapo

r pr

essu

re

of

air

in

oven

ca

n be

ef

fect

ivel

y us

ed a

t m

uch

lowe

r te

mpe

ratu

res

thus

av

oidi

ng d

ecom

posi

tion

s or

des

truc

tion

s.

Vacu

um i

s ge

nera

lly a

pplie

d in

2 s

teps

,i.e.

Firs

t go

dow

n to

~3

10 m

m H

gfo

r 30

min

utes

,and

the

n at

tain

<15

mm

H

g. T

ypic

al v

acuu

m le

vels

for

spe

cifi

c co

mm

odit

y ty

pes

are:

100

mm

Hg

for

frui

ts, o

ils, n

uts;

50 m

mH

g fo

r su

gars

an

d su

gar

prod

ucts

; 25

mm

Hg

for

cere

als

and

eggs

.

*Dry

ing

tim

e is

inve

rsel

y re

late

d to

dry

ing

tem

p.

Espe

cial

ly i

n dr

ying

cer

eals

, n

orm

al o

vens

req

uire

14

hour

s wh

erea

s m

icro

wave

ove

ns

requ

ire

3-10

min

utes

fo

r 10

gr

sam

ples

whe

n p

ower

inpu

t ~1

00 w

atts

. *I

n in

frar

ed o

vens

dry

ing

is e

ven

fast

er.

How

ever

th

ere

is

a ri

sk

of

surf

ace

carb

oniz

atio

nsi

nce

the

fila

men

t of

the

IR

lam

p(~5

00W

)de

velo

ps ~

2000

° K,

th

ereb

y m

ight

lead

to

surf

ace

carb

oniz

atio

n

Dry

ing

Cond

itio

ns

Ove

ns i

n wh

ich

ther

e is

hot

air

cir

cula

tion

or

an

iner

t at

mos

pher

e wi

th

vacu

um

(70-

130°

C)is

ap

plie

d fo

r a

spec

ifie

d ti

me

unti

l su

cces

sive

we

ighi

ngs

diff

er b

y <3

mg.

Goal

: Re

ach

high

est

tem

pera

ture

wi

thou

t de

com

posi

tion

or

ch

emic

alre

acti

on

(Tem

pera

ture

-tim

eop

tim

isat

ion)

Type

s of

Equ

ipm

ent:

Hot

Air

Ove

ns-

Eith

er w

orki

ng o

n co

nvec

tion

or

forc

ed a

ir,

it

shou

ld b

e ac

cura

te a

nd u

nifo

rm i

n te

mpe

ratu

re.

So f

irst

rul

e in

dry

ing

is:u

se a

GO

OD

ove

n.-

May

hav

e ba

lanc

es b

uilt

into

ove

n,so

per

mit

ting

se

mi-a

utom

atic

assa

ys-

Som

e ha

ve h

umid

ity

sens

ors

to d

eter

min

e wh

en

dryi

ng is

com

plet

e.

Vacu

um o

vens

–Va

cuum

help

s to

get

rid

of

the

1%+

moi

stur

e th

at i

s bo

und

in m

ost

food

s. W

e ca

n us

e lo

wer

tem

ps,r

educ

ed R

H (v

apor

pre

ssur

e in

ove

n).

It

MU

ST H

AVE

LEA

KS t

o re

duce

VP

,For

th

is a

im, a

ir is

pas

sed

thro

ugh

a dr

yer

such

as

con

c. H

2SO

4or

dri

erri

te..

*Opt

imal

Tim

e-Te

mp

com

bina

tion

: i.e

.16

hrs

at 1

00°C

is m

ost

com

mon

.

*Col

d tr

ap i

s es

sent

ial

for

colle

ctin

g th

e wa

ter

from

sam

ple

to p

rote

ct t

he v

acuu

m

pum

p an

d re

duce

RH

.

Oth

er o

vens

:M

icro

wave

:Ve

ry r

apid

hea

t tr

ansf

er/d

ryin

g:i.e

.6-

8 m

in

for

10g

sam

ple

of m

eat.

Bui

lt-in

bal

ance

s. A

ir e

xcha

nge

syst

ems.

But

requ

ires

ce

ntra

lly

loca

ted

and

even

ly

dist

ribu

ted

sam

ples

.In

frar

ed:

(Fila

men

t T:

2000

-250

0K)

mor

e ra

pid

heat

tr

ansf

er,t

hus

shor

tens

tim

e,bu

t m

ay b

e to

o fa

st a

nd b

urn

sam

ple.

Use

IR

lam

p ca

. 10

cm f

rom

sam

ple.

Thi

n be

d of

fo

od 1

0-15

mm

. Dry

ing

tim

es s

houl

d be

10-

20 m

in m

ax.

Acc

urac

y Pr

oble

ms

1. S

ampl

ing

erro

rs.

2. R

eten

tion

of

wate

r by

ads

orpt

ion,

occ

lusi

on o

r ch

emic

al

com

bina

tion

mak

es lo

ss b

y va

pori

zati

on d

iffi

cult

. Rea

chin

g a

cons

tant

wei

ght

does

not

alw

ays

guar

ante

e th

at a

ll wa

ter

has

been

rem

oved

. 3.

The

re m

ight

be

barr

iers

to

wate

r di

ffus

ion

in f

ood

role

of

dif

fusi

on in

dry

ing.

4.

Chem

ical

de

com

posi

tion

re

acti

ons

poss

ible

es

peci

ally

for

sug

ars

like

fruc

tose

and

sucr

ose

5. O

ther

vol

atile

s

6. E

ffec

ts o

f O

xida

tion

7. A

bsor

ptio

n of

wat

er f

rom

air

:

A.

Ads

orpt

ion

of m

oist

ure

from

air

in

dryi

ng

oven B.

Ads

orpt

ion

of w

ater

fro

m t

he a

ir d

urin

g we

ighi

ng.

Proc

edur

al C

onsi

dera

tion

s

1. Pr

epar

atio

n of

Sa

mpl

e:

Dif

fere

nt

for

Liqu

id

prod

ucts

-Br

ead

vs.F

ruit

s

2. D

ryin

g Co

ndit

ions

: reg

ulat

ion

of t

empe

ratu

re t

o ±

1°C

may

yi

eld

a 0.

1%

diff

eren

ce

in

moi

stur

e co

nten

t.Th

e va

cuum

requ

ired

fo

r di

ffer

ent

prod

ucts

is d

iffe

rent

:100

mm

Hg

is id

eal f

or f

ruit

s,

nuts

, oils

, and

fat

s;50

mm

Hg

for

suga

r an

d su

gar

prod

ucts

, 25

mm

Hg

for

cere

al f

oods

, egg

s, a

nd e

gg

prod

ucts

.3.

Pre

para

tion

of

the

dryi

ng d

ish:

The

dry

ing

dish

sh

ould

be

pre-

drie

d an

d he

ld i

n a

desi

ccat

orun

til

use.

I.B.

Dis

tilla

tion

Proc

edur

es:

Refl

ux

Dis

tilla

tion

with

im

mis

cibl

e so

lven

ts

(Ent

rain

men

t)

This

typ

e of

met

hod

is u

sed

for

sam

ples

whi

ch

cont

ain

othe

r vo

lati

le c

ompo

nent

s.

Ex:S

pice

s

Prin

cipl

e:A

so

lven

t im

mis

cibl

e wi

th

wate

r is

ad

ded

to s

ampl

e an

d th

e m

ixtu

re (

H2O

+ s

olve

nt)

is b

oile

d o

ff a

s an

aze

otro

pic

mix

ture

. U

pon

cool

ing,

the

2 p

hase

s wi

ll se

para

te (

volu

met

ric

dete

rmin

atio

n).

Dep

endi

ng

on

your

pu

rpos

e,

your

so

lven

t's

dens

ity

has

to b

e ei

ther

hig

her

or lo

wer

than

th

at o

f wa

ter.

App

arat

usty

pes:

p. 9

2-95

.

Dis

tilla

tion

was

ori

gina

lly d

evel

oped

as

a ra

pid

met

hod

for

food

qua

lity

cont

rol,

howe

ver,

for

fo

ods

that

mig

ht d

ecom

pose

on

heat

ing,

you

ca

n on

ly

get

appr

oxim

ate

resu

lts

from

di

still

atio

n m

etho

ds.

Dis

tilla

tion

is

pref

erre

d fo

r ce

real

s, n

uts,

oils

, wa

xes,

and

pow

dere

d pr

oduc

ts.

Col

d

DIS

TILL

ATI

ON

MET

HO

D

Con

dens

er

Gra

duat

ed T

rap

Sam

ples

& S

olve

ntH

eatin

g M

antle

Solv

ent

Tolu

ene

Ref

luxi

ng &

Wat

erSe

para

tion

Met

hod

Col

d w

ater

Ther

e ar

e th

ree

gene

ral t

ypes

of

dist

illat

ion:

1. D

irec

t di

still

atio

n fr

om im

mis

cibl

e liq

uids

with

ve

ry h

igh

boiln

g po

int

–e.

g. m

iner

al o

il.

2. D

irec

t di

still

atio

n wi

th im

mis

cibl

e liq

uids

tha

t ha

ve b

oilin

g po

ints

nea

r th

at o

f wa

ter

e.g.

tol

uene

or

xyl

ene.

3. R

eflu

x di

still

atio

n wi

th a

n im

mis

cibl

e liq

uid

–to

luen

e(B.

P.11

0ºC)

, xyl

ene(

B.P.

137

ºC)o

r te

trac

hlor

oeth

ylen

e

Prob

lem

s th

at c

an b

e en

coun

tere

d wh

en u

sing

en

trai

nmen

t di

still

atio

n in

clud

e:

1. In

com

plet

e re

cove

ry o

f wa

ter

as a

res

ult

of

emul

sion

s be

twee

n wa

ter

and

solv

ent.

2. D

rops

of

wate

r cl

ingi

ng t

o th

e co

nden

ser

or

side

of

the

rece

ivin

g tr

ap.

3. D

ecom

posi

tion

of

sam

ple

–m

ore

prob

lem

s wi

th h

igh

boili

ng p

oint

sol

vent

s.4.

Tol

uene

may

con

dens

e to

o so

on i

n th

e tr

ap

and

thus

doe

sno

t ca

rry

muc

h wa

ter

over

int

o th

e tr

ap.

II.C

hem

ical

Met

hods

1. Ka

rl F

isch

er M

etho

d:Ve

ry p

opul

ar m

etho

d, b

ut

Karl

-Fis

cher

Ti

trat

ion

is

seld

om

used

in

hi

gh

moi

stur

e fo

ods.

For

low

moi

stur

e fo

ods

like

cand

ies,

cho

cala

te,

drie

d fr

uits

and

veg

etab

le,

bake

ry d

ough

s, b

aked

pro

duct

s re

aste

dco

ffee

, fa

ts a

nd o

ils, s

ugar

ric

h fo

ods

orfo

ods

rich

bot

h in

re

duci

ng

suga

rs

and

prot

eins

, KF

is

th

e pr

efer

red

met

hod.

Prin

cipl

e: R

educ

tion

of

iodi

ne (

I°→

I-)

to

ioda

teby

SO

2in

pre

senc

e of

H2O

(see

pp.

130

-1).

2 H

2O+

SO2

+ I 2

→2H

I +C

5H2S

O4

Wit

hout

wa

ter

in

the

med

ium

, th

is

redo

x re

acti

on w

illno

t oc

cur.

(see

Fig

.8.6

)

The

basi

c re

acti

on t

akes

pla

ce in

two

sta

ges:

1)(C

5H5N

).I2+

(C5H

5N).S

O2+

(C5H

5.N)+

H2O

→2(

C 5H

5N).H

I+(C

5H5N

).SO

3

2)(C

5H5N

).SO

3+CH

3OH

→(C

5H5N

HSO

4CH

3)Ev

en

thou

gh

the

stoi

chio

met

ry

is

not

exac

t,

at

the

turn

ing

poin

t of

the

tit

rati

on,

for

each

mol

e of

H2O

in

sam

ple,

the

am

ount

of

spen

t KF

Rea

gent

will

co

ntai

n:1

mol

e of

Iod

ine

1 m

ole

of S

O2

3 m

oles

pyr

idin

e1

mol

e m

etha

nol.

So t

his

is b

asic

ally

the

com

posi

tion

of

the

KF R

eage

nt.

1ml r

eage

nt c

orre

spon

ds t

o 3.

5mg

wate

r.Th

e en

dpoi

ntin

volv

es a

cha

nge

in

Redo

xpo

tent

ial,

whic

h ca

n au

tom

atic

ally

be

dete

cted

wit

h us

e of

ele

ctro

des.

Th

ere

now

are

also

aut

omat

ed K

FTit

rato

rsby

Mer

ck.

Ex.:F

ored

ible

oil

indu

stry

,whe

re n

o wa

ter

is d

esir

ed i

n pr

oduc

t, K

F ti

trat

ion

is u

sed

for

auto

mat

ic c

ontr

ols

for

any

trac

e wa

ter.

CH

EMIC

AL

MET

HO

DS

Kar

l Fis

her M

etho

d---

Stan

dard

tech

niqu

e fo

r low

moi

stur

e fo

ods.

Espe

cial

ly g

ood

for r

educ

ing

suga

rs a

nd p

rote

in-r

ich

food

s an

d go

od fo

r foo

ds w

ith h

igh

vola

tile

oils

.

H2O

SO2

I

2

H2S

O4

HI

++

+2

2Th

eory

:

KA

RL

FISH

ER M

ETH

OD

Kar

l Fis

her R

eage

nt:

Dis

solv

e 13

2 g

of Io

dine

+ 4

25 m

l of P

yrid

ine

+ 42

5 m

l of

MeO

H+

105

g of

SO

2.

Titra

te12

0 m

g of

H2O

with

Car

l Fis

her R

eage

nt.

Cal

cula

ted

Con

cent

ratio

n =

mg

H2O

/ml o

f Rea

gent

=5

mg/

ml o

f Rea

gent

% H

2O =

Con

c. x

ml R

eage

nt /

mg

of S

ampl

e x

100

KA

RL

FISH

ER M

ETH

OD

NNNNNN

NNNN

N

NN

H2O

CH3O

H

HSO

4CH

3

I 2SO

2H

ISO

3

SO3

++

+2

+

+

Brow

n M

ahog

any

Colo

r

1. 2.

Met

hod

of c

hoic

e fo

r m

any

low-

moi

stur

e fo

ods

like

drie

d fr

uits

an

d ve

geta

bles

, ca

ndie

s,

choc

olat

e, r

oast

ed c

offe

e, o

ils a

nd f

ats.

The

met

hod

has

been

app

lied

to i

nter

med

iate

m

oist

ure

food

s (b

aker

y do

ughs

, ba

ked

prod

ucts

, fa

t-ri

ch c

akes

, an

d fo

ods

with

hig

h le

vels

of

vola

tile

oils

).

Met

hano

l, su

lfur

dio

xide

, and

pyr

idin

e ar

e ad

ded

in e

xces

s so

tha

t al

l wat

er m

olec

ules

rea

ct.

The

amou

nt

of

iodi

nere

duce

d by

wa

ter

is

titr

ated

by K

F re

agen

t. T

he r

eage

nt h

as t

o be

st

anda

rdis

ed a

gain

st d

isti

lled

wate

r fo

r fi

ndin

g it

s wa

ter-

equi

vale

nce

fact

or,

KFRe

q(ho

w m

uch

wate

r 1

ml o

f KF

rea

gent

will

cor

resp

ond

to).

Prob

lem

s:

1. Ex

trac

tion

m

ay

not

be

com

plet

e or

de

com

posi

tion

may

tak

e pl

ace

duri

ng e

xtra

ctio

n.

Ther

efor

e, f

ound

valu

es w

ill b

e to

o lo

w.

2. I

nter

fere

nce

from

:a)

Asc

orbi

c ac

id w

hich

is o

xidi

zed

by K

arl F

isch

er

reag

ents

to

de

hydr

oasc

orba

tean

dwa

ter(

so

titr

atio

n m

easu

res

both

wat

er a

nd a

scor

bic

acid

).b)

Car

bony

l co

mpo

unds

rea

ct w

ith

met

hano

l to

fo

rm a

ceta

lsan

d re

leas

e wa

ter,

and

fou

nd w

ater

valu

es w

ill b

ehi

gher

tha

n th

e re

al s

itua

tion

.c)

Rea

ctio

n wi

th m

erca

ptan

s, b

icar

bona

tes,

and

ca

rbon

ates

can

cau

se f

adin

g en

dpoi

nts.

d)po

lyun

satu

rate

d fa

tty

acid

s wi

ll re

act

with

I,

yiel

ding

hig

h wa

ter

valu

es.

2.

Gene

rati

on o

f ac

etyl

ene

gas

CaC 2

+ H

2O –

––––

––> C

H=

CH +

CaO

The

amou

nt o

f ac

etyl

ene

gas

that

is

form

ed

afte

r re

acti

on

with

wa

ter

is

mea

sure

d by

a

mon

omet

er.

This

pro

cedu

re h

as b

een

used

for

de

term

inin

g wa

ter

cont

ents

of

powd

ered

foo

d pr

oduc

ts

like

cere

als,

fl

ours

, an

d co

ttag

e ch

eese

.

3. C

obal

t Ch

lori

de P

aper

:

CoCl

2+

H2O

---

----

--->

CoC

l 2*

6 H

2O(d

ry:b

lue)

(w

et:p

ink)

Filt

er p

aper

s ar

e so

aked

in

solu

tion

of

CoCl

2an

d dr

ied.

The

sam

ple

is g

roun

d an

d a

smal

l qu

anti

ty i

s sp

read

on

the

pape

r. T

he s

ampl

e is

cov

ered

to

allo

w co

lor

chan

ge.

Sem

iqua

ntit

ativ

ees

tim

ates

of

free

wat

er in

foo

d ca

n be

obt

aine

d by

mea

suri

ng t

he r

ate

of c

olor

cha

nge

on

the

filt

er p

aper

. Thi

s m

etho

d is

use

d on

hig

h su

gar

food

s su

ch a

s ra

isin

s.

III.

AM

ETH

OD

S M

easu

ring

Phy

sica

l Pro

pert

ies:

Som

etim

es

ther

e is

ne

ed

for

nond

estr

ucti

ve

anal

yses

(i.e.

plan

tbr

eede

rs d

on't

wan

t to

los

e th

eir

very

val

uabl

e sa

mpl

es).

Exam

ples

of s

uch

nond

estr

ucti

ve m

etho

ds

are

spec

tros

copi

c m

etho

ds

like

NM

R (N

ucle

ar

mag

neti

c Re

sona

nce)

,

and

Die

lect

rom

etry

. H

owev

er,

thes

ety

pes

of m

etho

ds a

re n

ot v

ery

spec

ific

, th

ey n

eed

stan

dard

izat

ion

(indi

vidu

al)

wher

e yo

u ha

ve t

o pr

epar

e yo

ur o

wn g

raph

ics

us

ing

stan

dard

s, s

om

ay b

e co

nsid

ered

to b

e ra

ther

“em

piri

cal”.

M

any

para

met

ers

like

the

tem

pera

ture

of m

easu

rem

ent

affe

ct m

easu

red

valu

es.

Belo

w is

gi

ven

a su

mm

ary

of

thes

e m

etho

ds.

PHY

SIC

AL

MET

HO

DS

1. In

frar

ed M

etho

d:A

bsor

ptio

n M

etho

d --

-m

easu

ring

the

abso

rptio

n of

OH

gr

oup

at w

avel

engt

h of

2.8

µ.

Com

mon

Met

hod

-1pp

m(s

ensi

tivity

)0

2040

6080

100

1530456075

% M

oist

ure

by O

ven

Met

hod

% IR Transmission at 2.8µ.

*Spe

ctro

scop

ic m

etho

ds -

Nea

r In

frar

ed:

NIR

→ne

ar ın

frar

ed r

efle

cten

ce:

*Pri

ncip

le;

Reso

nant

fre

quen

cy o

f pr

oton

s in

H

2O

is

diff

eren

t fr

om

that

of

pr

oton

s in

m

acro

mol

ecul

es.

•Use

d wa

vele

ngth

s ar

e 3.

0 an

d 6.

1 um

(f

unda

men

tal

vibr

atio

n fr

eque

ncie

s of

wat

er)

1.93

um (

com

bina

tion

abs

. ba

nd)

and

1.45

um

(fir

st o

vert

one

of t

he O

H s

tret

chin

g)O

ne a

dvan

tage

is t

hat

r

esul

ts d

o no

t ne

ed

expe

rt i

nter

prat

atio

n.A

noth

er i

s it

s ex

celle

ntse

nsit

ivit

y –

can

mea

sure

dow

n to

few

ppm

. Als

o ve

ryra

pid.

Dis

adva

ntag

e ar

e ve

ry e

xpen

sive

equ

ipm

ent

and

very

cri

tica

l sam

ple

prep

arat

ion

step

.

*Gas

Chro

mat

ogra

phic

Met

hods

:Th

e wa

ter

in

sam

ple

can

be

extr

acte

d in

tom

etha

nol

and

anal

ysed

by G

C, w

hich

is v

ery

good

at

sepa

rati

ons

–us

e a

Poro

pack

colu

mn

(bes

t fo

r se

para

tion

of

pola

r m

ater

ials

. W

ater

will

eas

ily b

e se

para

ted

from

met

hano

l an

d m

easu

red

usin

g a

univ

ersa

l de

tect

or (T

CD:t

herm

al c

ondu

ctiv

ity

dete

ctor

)•Q

uant

ific

atio

n -A

stan

dard

cur

ve u

sing

dif

fere

nt

rati

osof

wat

er t

o m

etha

nol

shou

ld b

e pr

epar

ed

and

resu

lts

are

extr

apol

ated

fr

om t

his

stan

dard

cu

rve.

•Adv

:Can

run

aut

omat

ed s

yste

ms-

rapi

dity

•Acc

urat

e/pr

ecis

e (li

mit

ed t

o ex

trac

tion

) •L

ittl

e or

no

inte

rfer

ence

s•D

isad

v:Co

st o

f in

stru

men

t,an

d ex

pert

ise

need

ed

for

relia

ble

inte

rpre

tati

ons.

*Nuc

lear

Mag

neti

c Re

sona

nce

Prin

cipl

e:

Hyd

roge

n nu

cleu

s ab

sorb

s en

ergy

in

sp

ecif

ic r

adio

fre

quen

cy. W

hile

the

re a

re n

umer

ous

form

s (b

indi

ng) o

f H

nuc

lei,

met

hod

can

disc

rim

inat

e be

twee

n wh

atth

eH

is b

onde

d to

e.g

. OH

.

•Wor

kswe

ll fo

r lo

w m

oist

ure

cont

ents

, bu

t sp

ectr

um g

ets

too

com

plic

ated

for

hig

h m

oist

ure

prod

ucts

.•A

dv:

Can

dete

rmin

e/di

stin

guis

h bo

und

wate

r –

one

of t

he f

ew s

uch

met

hods

,-

Rapi

d (1

min

), -

Non

dest

ruct

ive

sinc

e no

nthe

rmal

, no

deco

mpo

siti

on,a

ndac

cura

te.

•Dis

adv:

Hig

h co

stan

d so

phis

tica

tion

in o

pera

tion

NM

R:

Mea

sure

the

hydr

ogen

nuc

lei

H2

nucl

ei o

f wat

er w

ill v

ibra

te (s

pin-

orie

ntal

) in

a fi

xed

mag

netic

fiel

d an

d pr

oper

radi

o fr

eque

ncy.

Abs

orpt

ion

of ra

dio

freq

uenc

y by

the

hydr

ogen

nuc

leus

.

Rap

id/N

on-d

estru

ctiv

e/A

ccur

ate

NU

CLE

AR

MA

GN

ETIC

RES

ON

AN

CE

SPEC

TRO

MET

ER

R-F

Tr

ansm

itter

Det

ecto

r

Sam

ple

Tran

smitt

erC

oil

Rec

eive

r Coi

l

2040

6080

100

0

% M

oist

ure

by O

ven

Met

hod

Relative Detector Response

Nuc

lear

Mag

netic

Res

onan

ce S

pect

rom

eter

*Ele

ctri

cal C

ondu

ctiv

ity:

Empi

rica

lre

lati

onsh

ips

have

be

en

deve

lope

d be

twee

n m

oist

ure

cont

ent

and

elec

tric

al c

ondu

ctiv

ity.

Con

duct

ivit

yof

sam

ple

depe

nds

on:

-M

oist

ure

cont

ent↑

↑-

Salt

con

tent

-

Pack

agin

g -T

empe

ratu

re-

Text

ure

App

licat

ion:

20 g

of

prep

ared

sam

ple

is p

ut in

a s

teel

cup

, a

curr

ent

is p

asss

ed t

hrou

gh t

he v

esse

l, an

d co

nduc

tivi

ty is

re

ad. T

he m

oist

ure

cont

ent

is t

o be

ext

rapo

late

d fr

om t

he

std

curv

eto

be

pr

epar

ed

with

di

ffer

ent

but

know

n m

oist

ure

cont

ents

.A

dv:s

peed

;D

isad

v:sa

mpl

edi

men

sion

s/pa

ckin

g in

ce

llan

d ot

her

com

pone

nts

will

alli

nflu

ence

the

con

duct

ivit

y

Met

hods

bas

ed o

n sp

ecif

ic g

ravi

ty a

nd d

ensi

ty

1.Sp

ecif

ic g

ravi

ty a

nd d

ensi

ty o

f liq

uid

sam

ples

can

be

mea

sure

d us

ing

a py

cnom

eter

, wh

ich

is r

elat

ed t

o th

e wa

ter

cont

ent

of s

ampl

e.

Ther

e ar

e ta

bles

tha

t re

late

den

sity

or m

ost

com

mon

ly s

peci

fic

grav

ity

to s

olid

s co

ncen

trat

ion

; but

the

se s

houl

d al

l be

reco

rded

at

the

sam

e te

mp.

2. A

Wes

tpha

lba

lanc

eca

n be

use

d wh

ich

is b

ased

on

Arc

him

edes

' pr

inci

ple,

“Th

e sa

me

body

will

dis

plac

e eq

ual w

eigh

ts o

f al

l liq

uids

in

whic

h it

flo

ats”

. W

B wi

ll yi

eld

both

den

sity

and

sp

ecif

ic g

ravi

tyva

lues

, t

houg

h sp

ecif

ic g

ravi

ty i

s th

e ea

sies

t to

ob

tain

. The

bal

ance

has

a s

inke

r su

spen

ded

on a

thi

n wi

re t

hat

hang

s fr

om t

he e

nd o

f th

e ba

lanc

e.U

sing

A a

nd B

whe

re A

= t

he w

eigh

t of

the

sin

ker

in a

ir,B

= t

he w

eigh

t of

the

sin

ker

in p

ure

wate

r, a

nd

C =

the

weig

ht o

f th

e si

nker

in t

he

liqui

d, w

ater

con

tent

of

liqui

d sa

mpl

e ca

n th

en b

e ca

lcul

ated

.

Erro

rs c

an b

e ca

used

by

surf

ace

tens

ion

on t

he w

ire

and

by a

ir b

ubbl

es

atta

ched

to

the

wire

or

sink

er.

3.

Spec

ific

gr

avit

y by

hydr

omet

ry:

This

is

th

e si

mpl

est

way

to d

eter

min

e sp

ecif

ic g

ravi

ty, a

gain

bei

ng

base

d on

Arc

him

edes

' pr

inci

ple.

Con

cern

s ab

out

this

m

etho

d in

clud

e:-

clea

nlin

ess

of t

he h

ydro

met

er-

tem

pera

ture

(liq

uid

volu

me,

the

refo

re d

ensi

ty w

ill

chan

ge w

ith

tem

pera

ture

), -a

lar

ge e

noug

h co

ntai

ner

shou

ld b

e ch

osen

so

that

th

ere

is n

o ph

ysic

al i

nter

fere

nce

from

the

con

tain

er

hold

ing

the

flui

d.

Som

e co

mm

on h

ydro

met

ers

are:

A. S

acch

arom

eter

s B.

Bal

ling

C. B

rix

D. B

aum

e'hy

drom

eter

s[0°

Baum

e=

Pure

wat

er,

10 B

aum

e'=

10%

sal

t (N

aCl)]

, E.

Lac

tom

eter

s

Exam

ple:

LACT

OM

ETER

S:Sp

ecif

ic g

ravi

ty o

f “n

orm

al”

milk

is 1

.029

-thi

s co

rres

pond

s to

29º

in l

acto

met

er r

eadi

ng. S

o,

to g

et s

peci

fic

grav

ity

of m

ilk,

you

divi

de

lact

omet

er d

egre

es b

y 10

00 a

nd a

dd 1

. Tot

al

solid

s in

milk

can

the

n be

fou

nd a

ccor

ding

to

the

follo

wing

equ

atio

n:

Tota

l sol

ids

= 0.

25 L

+ 1

.2 F

wher

e L

is t

he l

acto

met

er r

eadi

ng,

and

F is

pe

rcen

t fa

t in

the

milk

.

REFR

ACT

OM

ETRY

:Pr

inci

ple:

Opt

ical

dens

ity

of s

olut

ions

as

well

as

the

refr

acti

on w

ill c

hang

e wi

th c

hang

ing

wate

r co

nten

ts.S

ome

refr

acto

met

ers

may

rea

d as

RI

(dim

ensi

onle

ss)

and

som

e di

rect

ly i

n %

sol

uble

so

lids(

1°Br

ix=R

I of

1%w/

w su

cros

e so

lution

)).

Refr

active

Ind

ex:

RI c

an v

ary

betw

een

1.300

and

1.700

at

20°

C[wi

th s

odiu

m D

line

(λ=

589

ηm

)].

RI a

lso

vari

es w

ith:

-Tem

pera

ture

–C

once

ntra

tion

–W

avel

engt

h of

ligh

t (if

oth

er t

han

Sodi

um D

line

)

III.

BM

ETH

OD

S Ba

sed

on C

ollig

ativ

ePr

oper

ties

:

III.

b.1.W

ATE

R A

CTIV

ITY

(aw)

Know

ing

only

the

wat

er c

onte

nt o

f fo

ods

may

not

be

en

ough

.

Ano

ther

very

im

port

ant

conc

ept

rela

ted

to

moi

stur

e is

“w

ater

acti

vity

-aw

”,wh

ich

is d

efin

ed a

s:A

w= (P

) / (P

o)

= ER

H/1

00“T

he

rati

oof

eq

uilib

rium

va

pour

pres

sure

of

sa

mpl

e (P

) to

the

equ

ilibr

ium

vap

our

pres

sure

of

pure

wat

er (P

o) a

t th

at s

ame

tem

pera

ture

”M

etho

ds

for

mea

suri

ng

aw

are

base

d on

co

lliga

tive

(phy

sico

chem

ical

)pr

oper

ties

of

wate

r:W

hen

solu

tes

are

adde

d to

H2O

, vap

our

pres

sure

↓

osm

otic

pr

essu

re↑,

fr

eezi

ng

poin

t↓,

boili

ng

poin

t↑.

•Mea

sure

men

t of

wat

er a

ctiv

ity

in f

oods

.

1. D

irec

tly

mea

sure

Aw

–a.

cla

ssic

al (m

anom

etri

c) m

easu

rem

ent

ofth

e va

por

pres

sure

or

by u

sing

hyg

rom

eter

s wi

th a

sen

sor

cont

aini

ng h

ygro

scop

ic m

ater

ial

like

LiCl

, th

e co

nduc

tivi

ty o

f wh

ich

will

chan

ge a

ccor

ding

to

the

rela

tive

hum

idit

y in

the

cha

mbe

r ab

ove

sam

ple,

or

psyc

hrom

eter

s.b.

Dew

poi

nt -

mir

rors

2.M

easu

rem

ent

of E

RH (e

quili

briu

m r

elat

ive

hum

idit

y)

Sim

ples

t a

ppar

atus

use

s s

alt-

impr

egna

ted

filt

er p

aper

s. H

ere

the

prin

cipl

eis

:S

alt

will

not

diss

olve

H2O

unl

ess

surr

ound

ing

hum

idit

y le

vel

rise

s to

a p

oint

whi

ch i

s eq

ual

to t

he s

peci

fic

satu

rati

onm

oist

ure

cont

ent

of t

he s

alt

(sta

ndar

d an

d co

nsta

nt v

alue

s fo

r ea

ch

type

of

sa

lt).

Filt

er

pape

rs

are

dipp

ed

into

va

riou

s sa

tura

ted

solu

tion

s wi

th k

nown

ERH

leve

ls, d

ried

and

aff

ixed

insi

de t

he u

pper

lid

of

the

petr

i dis

h;sa

mpl

e is

pla

ced

in lo

wer

dish

, cov

ered

wit

h lid

an

d eq

uilib

rate

d fo

r 20

gho

urs

at 2

0C. A

w of

sam

ple

is b

etwe

en t

he

wet

pape

r of

hig

hesr

aw

and

dry

pape

r of

lowe

st a

w.

The

vapo

rpr

essu

re (

Aw)

of

wate

r ab

ove

a fo

od is

rel

ated

to

its

moi

stur

e co

nten

t. B

ut

the

rela

tion

ship

is n

onlin

ear

for

man

y fo

od

prod

ucts

and

lar

ge e

rror

s ca

n oc

cur

unle

ss

you

linea

rize

the

data

us

ing

a tr

ansf

orm

atio

n.Yo

u ca

n pr

epar

e an

is

othe

rm f

or t

he s

peci

fic

food

but

thi

s wi

ll be

tim

e co

nsum

ing,

and

hyst

eres

ism

ay le

ad

to e

rror

s.

II.b

.2.F

reez

ing

poin

t el

evat

ion

or d

epre

ssio

n:W

hen

wate

r is

add

ed t

o a

food

, th

ere

will

be a

fr

eezi

ng p

oint

dep

ress

ion

, whi

ch c

an b

e m

easu

red

and

is v

alid

for

upp

er a

w le

vels

(>0.

8).

Exam

ple:

F.P.

(fre

ezin

g po

int)

of

unad

ulte

rete

dm

ilk

≅0.5

5ºC.

Each

1%

ad

ded

wate

r ch

ange

s th

e fr

eezi

ng p

oint

of

milk

by

.005

5 ◦

C. P

erce

nt a

dded

wa

ter

can

thus

be

calc

ulat

ed u

sing

the

equa

tion

:

One

mol

al o

f an

y sp

ecie

s de

crea

ses

FP b

y 1.8

6º∆t

(tc-

t 1)=

-1.8

6*m

olal

con

cent

rati

onW

here

m: M

olal

ity

of s

olut

ion

(mol

es s

olut

e/kg

sol

vent

) Tc

= A

vg.f

reez

ing

poin

t of

nor

mal

milk

(-0.

55C)

, an

d T 1

= th

e ob

serv

ed f

reez

ing

poin

t%

add

ed w

ater

= 1

00(T

c-T 1

)/Tc

REPO

RTIN

G RE

SULT

S (C

h.4,

p.6

5-67

)Th

e re

fere

nce

basi

s ch

osen

is

of

ut

mos

t im

port

ance

.The

re a

re t

he f

ollo

wing

alt

erna

tive

s:1

AR(

as r

ecei

ved)

or

-as

is b

asis

:exp

ress

ed o

n un

trea

ted

sam

ples

(als

o so

met

imes

as

“f

resh

weig

htba

sis”

(g/1

00g

tiss

ue).

2.O

D(o

ven-

drie

d) o

r dr

ym

atte

rba

sis:

expr

esse

d on

con

tent

s

exc

ludi

ng w

ater

Sinc

e m

oist

ure

cont

ents

can

var

y gr

eatl

y, i

t is

be

st t

o re

port

it in

dry

mat

ter

basi

s in

ord

er t

o be

abl

e to

mak

e co

mpa

riso

ns.

3-Ed

ible

por

tion

bas

is(S

kinn

ed e

ggs

or W

hole

eg

gs) i

.e. 1

00 g

rof

ski

nned

egg

s4-

Arb

itra

rily

se

lect

ed

basi

s:

See

next

3

exam

ples

Ex 1

:In

cere

als

→a

refe

renc

e po

int

is 1

4% H

2Oco

nten

tis

ta

ken

to e

xpre

ss t

he n

utri

ent

cont

ents

Ex

2:

Qua

ntit

y of

am

ino

acid

sca

n be

exp

ress

ed a

s m

g pe

r ea

ch 1

6 gr

of N

.Ex

.3: a

s --

--g/

100

gof

a s

peci

fic

nutr

ient

–nu

trie

nts

5. P

er s

ervi

ng –

(g /

ser

ving

)6.

...

.../l

ot s

ize

–for

man

ufac

turi

ng o

pera

tion

s7.

In

“sta

ndar

dize

dun

it”s

–

RDI-

reco

mm

ende

d da

ily in

take

s(I

U o

f vi

tam

ins)

,-

....a

ctiv

ity

in s

yste

m (e

nzym

es),

-.....

meq

=02/

g of

pro

duct

–(t

itra

tion

s)8.

“wei

ght”

or “v

olum

e”ba

sis:

For

exam

ple,

ppm

can

deno

te

both

m

g/kg

–we

ight

basi

s(m

ost

com

mon

)or

m

g/L

–vo

lum

e ba

sis.

(air

sa

mpl

ing

or b

ever

age

form

ulat

ions

g/1

10 o

r g/

100

L)

Calc

ulat

ions

in c

onve

rtin

g fr

om o

ne b

asis

to

anot

her

basi

s:

Exam

ple:

Sam

ple

com

posi

tion

is 1

0%

H2O

; 30

%

fat

on (

asis

)ba

sis.

To

calc

ulat

e ho

w m

uch

fat

this

will

cor

resp

ond

to o

n “d

ry m

atte

r” b

asis

:

So

the

sam

ple

cont

ains

33

.33%

fat

on

dry

mat

ter

basi

s.

33.33

)10

100

(10

030

=−

=x

Fatdm

2. F

rom

% O

D (o

ven

drie

d) to

AR

(as

rece

ived

):

%Y O

D =

%

Y AR

x 10

0 (1

00 -

% lo

ssO

D)

3. F

rom

AR

to A

M (a

rbitr

ary

moi

stur

eba

sis)

:

%Y

= %

Y AR

(100

-ar

bitr

ary

moi

stur

e %

) 10

0 -%

moi

stur

e AR

The

“Uni

ts”

used

in e

xpre

ssin

g an

alyt

ical

resu

lts

have

to b

e SI

uni

ts (m

etric

).Li

st o

f com

mon

ly u

sed

SI u

nits

is g

iven

in y

our

text

-boo

k on

pag

e 36

-37.

The

pref

ixes

used

den

ote

the

follo

win

g :

giga

: 109

kilo

: 103

nano

: 10-9

mic

ro: 1

0-6m

ega

: 106

Sign

ifica

nt f

igur

es:

Judg

emen

t of

the

num

ber

of m

eani

ngfu

l dig

its in

a r

esul

t

Rep

orte

d va

lue

shou

ld o

nly

con

tain

sig

nif

ican

t di

gits

(all

know

n t

o be

tru

e, j

ust

th

e la

st o

ne

in d

oubt

)6

4.7

2, 6

.47

2,0

.64

72

, 6.4

07

all

hve

4 s

.d.

43

3.8

+3

2.6

6=

40

1.1

4→R

oun

ded

off→

40

1.1

(th

e n

umbe

r h

avin

g th

e le

ast

sign

ific

ant

figu

re d

icta

tes

it.)

Zero

s ??

?C

onve

rt t

o ex

pon

enti

al f

orm

: If

zer

os c

an b

e om

ited

, th

en t

hey

ar

e n

ot s

ign

ific

ant:

70

00

→7

X1

03

: z

eros

not

sig

nifi

can

t7

00

0.0

→7

.00

0X

10

3 :

zero

s si

gnif

ican

tR

oun

din

g u

p: <

5:d

rop

figu

re;

>5

:dro

p fi

gure

an

d in

crea

se p

revi

ous

num

ber

by 1

Q-V

alu

e fo

r re

ject

ion

of

resu

lts=

X2

-X1

/WX

1:q

ues

tion

able

val

ue,

X2

:nex

t cl

oses

t va

lue,

W:T

otal

spr

ead

of

valu

es.

E

xam

ple:

>0

.76

if t

her

e ar

e 4

obs

erva

tion

s

“EX

PERT

WIT

NES

S”RE

PORT

S:In

som

e co

untr

ies,

cer

tifi

cate

of

anal

ysis

by

an

expe

rt w

itne

ss i

s a

lega

lly v

alid

doc

umen

t.

In

som

e ot

hers

, th

e co

urt

is e

mpo

were

d to

acc

ept

or

to

reje

ct

it.

Re

port

fo

rmat

sh

ould

be

pr

epri

nted

fo

r fa

ster

an

d m

ore

unif

orm

pr

oces

sing

. Th

e re

port

sho

uld

cont

ain

:

•pro

per

sam

ple

iden

tifi

cati

on (

type

, qu

anti

ty,

pack

agin

g, la

belli

nget

c.);

•ana

lysi

s m

etho

d us

ed,

•res

ults

•I

nter

pret

atio

nof

res

ults

.

Mul

tiva

riat

e A

naly

sis

and

Chem

omet

rics

Insi

ght

& U

nder

stan

ding

Thes

e pr

oced

ures

ar

e de

sign

ed

to

extr

act

usef

ul i

nfor

mat

ion

from

lar

ge o

r co

mpl

ex d

ata

sets

. M

ulti

vari

ate

met

hods

ha

ve

broa

d ap

plic

atio

n in

man

y as

pect

s of

pra

ctic

al f

ood

scie

nce

incl

udin

g m

icro

biol

ogy,

ch

emis

try

and

engi

neer

ing.

Expe

rim

ent

Des

ign

Stat

isti

cal

expe

rim

ent

desi

gn

tech

niqu

es

use

expe

rim

enta

l re

sour

ces

(tim

e,

mat

eria

ls,

equi

pmen

t)

effi

cien

tly

to

colle

ct

data

fo

r de

velo

pmen

t of

mod

els.

Mod

elin

g an

d Si

mul

atio

n

Mod

els

can

be

deve

lope

d us

ing

regr

essi

on

or

othe

r m

etho

ds a

nd u

sed

to f

ind

true

opt

ima

in

qual

ity

or

cost

, or

to

se

ek

acce

ptab

le

com

prom

ises

in p

erfo

rman

ce o

f se

vera

l fac

tors

.

Thes

e te

chni

ques

hav

e ap

plic

atio

n in

ana

lyti

cal

met

hod

deve

lopm

ent

and

prod

uct

and

proc

ess

opti

miz

atio

n.

They

ar

e pa

rtic

ular

ly

usef

ul

for

gene

rati

ng

proc

ess

scal

e-up

da

ta,

and

ofte

n m

inim

ize

surp

rise

s du

ring

tra

nsfe

r to

ind

ustr

ial

scal

e op

erat

ion.

Com

posi

tion

/Pro

pert

y Re

lati

onsh

ips

Rela

tion

ship

s be

twee

n pr

oduc

t co

nsti

tuen

ts o

r in

gred

ient

s an

d pr

oper

ties

can

be

disc

erne

d,

and

in m

any

case

s co

ntro

lled

or o

ptim

ized

. The

pr

oper

ties

may

incl

ude

sens

ory

(fla

vor,

te

xtur

e, t

urbi

dity

, per

ceiv

ed c

olor

, etc

.) or

ph

ysic

al (f

irm

ness

, lig

ht s

catt

erin

g, f

oam

, etc

.) pr

oper

ties

or

cost

.

Stru

ctur

e/Fu

ncti

on R

elat

ions

hips

Impr

ovin

g un

ders

tand

ing

of

rela

tion

ship

s be

twee

n th

e st

ruct

ure

of m

olec

ules

(i.e

., am

ino

acid

com

posi

tion

of

pept

ides

) an

d th

eir

biol

ogic

al

(fla

vor)

or

phys

ical

beh

avio

r (f

oam

, ha

ze)

can

lead

to

impr

oved

ingr

edie

nts

and

prod

ucts

.

Patt

ern

Reco

gnit

ion

proc

edur

es a

re u

sefu

l fo

r di

scer

ning

whi

ch o

f a

num

ber

of m

easu

rem

ents

ca

n di

scri

min

ate

betw

een

clas

ses

of s

ampl

es o

n a

desi

red

basi

s; t

he r

esul

ts c

an t

hen

be u

sed

to

clas

sify

new

sam

ples

. A

pplic

atio

ns i

nclu

de t

he

iden

tifi

cati

on o

f sa

mpl

es a

s to

cul

tiva

ror

gro

wing

ar

ea, o

r de

tect

ion

of a

dult

erat

ion.