Water
AOAC
1. Oven drying
– weigh 2 - 5g. into cellulose thimbles or aluminum pans
– dry at 100 - 102 o
F for 16 - 18 hrs.
– cool in dessicator
– reweigh
– weight lost calculated and reported ~ $2000

2. - convection at 125 o
F for 2 - 4 hrs.
3. - vacuum at 95 - 100 o
F for 8 - 12 hrs.
4. - microwave at 80% - 100% power for
3 - 5 minutes
– Note: special design (CEM Corp.)
- $30,000

1. Rapid heating / balances
– Ohaus, Mettler, others - infrared, halogen, microwave sources of heat
15 - 30 minutes
~ $1000
 3-4 %

METTLER LJ16 Moisture Analyzer: for rapid and simple routine drying

– NIR common for grain
–
Must be calibrated
– Nondestructive, multi-component measurement
– Now available for in-line use
– $40,000 - 60,000

Near infrared (NIR)
– Broad, multiple – component analyses (fat, water, protein simultaneously)
– Measurement of near infrared absorption by functional organic groups – ketones, alcohols, esters, ethers, aldehydes, etc.
– “fingerprints” pure compounds, mixtures must be calibrated to known standards
– calibration is critical
– Transmission (as opposed to reflectance) instruments show very good performance

Near infrared (NIR)
(continued)
– Cost is $50,000 for table top instruments
– Measurement time < 1 second
– Continuous monitoring of composition on commercial mixers and grinders

tecator
INFRATEC

1265 MEAT ANALYZER

CFS MultiTrack/Wolfking Continuous
Fat Analyzer
– Gives simultaneous measures of fat, water and protein
– ~ 20 measurements per minute

• Wolfking indicates SD of 0.3%
• Cost is ~$95,000
– from CFS (Wolfking) technical literature

– Similar strengths and weaknesses as NIT but not as well established
– Nondestructive, multi-component, in-line use

Guided microwave spectrometry (GMS)
– Microwave absorption to measure changes in conductivity and dielectric constants
– Available for in-line measurements (GMS 44) and on grinders (GMS 46) from Weiler

Guided microwave spectrometry (GMS)
(continued)
– Multi component measurements including salt and temperature
– Fat at 2 measurements per second
– 25,000 lbs/hr on grinders
– SD indicated by Weiler as 0.2%-0.4%
– Matrix sensitivity to air and to ice crystals
– Cost is ~ $115,000

Fat
AOAC
1. Ether extract (Soxhlet)
– dried 2 -5 g. sample
– extract with di-ethyl ether or petroleum ether
(hexane) --- 8 - 12 hrs.
– cool in dessicator, reweigh
– calculate fat as % weight lost of wet sample weight
– does not include phospholipids

1. Cooked / fat release
– Hobart - only for fresh ground beef
– 15 minutes
– “good as a guess”

Rapid methods – product formulation
• Hobart F-101
– Heat rendering
– Highly variable, SD ~ 2% or more
– Cost ~ $1000

– Acid digestion, release fat
– Measure fat layer
– Calibrated bottle for 9 or 18 g. samples

Modified Babcock
– Acid hydrolysis, volumetric measurement
– Sensitive to variations in samples and procedure
– Capable of SD of 0.75%
– Cost $7.00/bottle plus centrifuge

– 13 lb. sample
– Nondestructive

– Computerized scan of surfaces for white fat exposed

Supercritical fluid extraction
– CO
2 at elevated pressure and temperature
– Fast (20-30min), no solvent residue
– Matrix-sensitive, moisture absorbers may need to be included with samples
– Performance can be good but may be affected by sample matrix

– Instruments available from LECO and others
– Cost ~ $30,000

Q C Assistant
– Software by Least Cost Formulations, LTD
– % fat from database predicted by water content
(indirect)
– Licensed for $3,000
– Offered with CEM microwave oven for moisture
(AOAC approved) as “Profat 2  ”
–
SD of 0.5% - 0.7%
– Cost = $21,000+

NMR
– Newest innovation in fat analyses
– Based on proton response to oscillating magnetic field, similar to magnetic resonance imaging (MRI) used for medical applications
– Water typically causes interference
– CEM microwave oven plus NMR
– Smart Trac 


– results in 4-5 minutes
– no solvents
– no calibration
– direct measure of fat
– effective over wide range
– cost ~ $65,000

Hot Dogs-Regular
Sample
ID
1
2
3
4
5
Average
Standard Deviation
Moisture
(%)
51.11
51.32
51.37
51.21
51.24
51.25
0.101
•
30.79 % Reference Fat from Soxhlet
Calculated
Fat %
30.89
30.93
30.85
30.72
30.67
30.81
0.112
from CEM technical literature

Additional methods
– Ultrasound
– In beef, intramuscular fat correlation was reported as about 0.88 with standard errors of about 0.8
– In pork, correlations appear to be about
0.5-0.7
– May be useful for live measurement
– Electrical conductivity (TOBEC)
– Not widely applied beyond carcasses and primals.

Advanced Methods for fat
– Caviezel
– Total lipid measured as total fatty acids
– Includes triglycerides, phospholipids, sterols, free fatty acids
– Meets FDA definition of total fat for labeling
– N-butyl alcohol extraction, saponification, separation, quantitation by GC
– AOAC peer-verified status
– Correlation coefficients of 0.99, SD of 0.47% reported

Advanced Methods for fat
– Caviezel
(continued)
– Automated system available from Büchi
• Requires about 2 hours
• Cost $88,000
($55,000 for manual sampling)

Measurement of Fat in Meat with Caviezel
Method and Büchi System
Product
Number of samples
Raw meat
Cooked sausage
5
13
Uncured sausage 14
Cooked, cured meats 9
Sausage with vegetable fat 5
Caviezel measurement as % of official method
103.7
101.9
101.7
105.0
99.3
from Büchi technical literature

AOAC
1. Kjeldahl - developed in 1883
– acid digest to NH
4
+ for N content
– calculate protein as N x 6.25
- Beware -

. Combustion - developed in 1970’s
– 800 - 900 o C oven to convert protein to N
2
– Measures N
2 by thermal conductivity again, calculate protein as N x 6.25
–
No waste products
– Sample preparation critical due to small sample size

– Introduced in 2008
– Specific protein tagging solution with colorimetric(?) measurement
– Direct protein measure, avoids false high values from nonprotein nitrogen, i.e. melamine in pet foods, milk products
– AOAC approved

– Can estimate protein given results for water and fat
– assume 1% ash for fresh meat
– 2 - 4% ash for processed meat depending on specific product
By:
W + F + P + A = 100%
Or: use M : P ratios if appropriate
(fresh meat M : P = 3.7 : 1)

Ash
AOAC
– 5 g. sample weighed into crucible
– 550 o C (~ 900 o F - 1000 o F) oven for 8 - 12 hrs.
– Remaining weight (after cooling) is mineral or ash % of original sample weight
– Relatively constant at about 1% for fresh meat
– Salts (i.e. processed meats) increase ash content

For analytical methods at any level,
– Remember performance
– Know method capability…and limitations
– Monitor for deviations during use

1. Salt
– Quantab indicating strips
AOAC - however - precision ± 10%
– 10 g. sample + 90 ml hot water
– cool, insert strip, read when finished
– remember dilution factor i.e. 0.24 x 10 = 2.4%

2. pH
– Measure of H ion concentration or acidity
– pH = - log [H + ] log relationship means that pH 4 is 10x as acidic as pH 5 and 100x as pH 6
– Cannot numerically average pH values pH 4 + pH 5
 pH 4.5
2