Common methods of analysis for meat and poultry products

Water AOAC

1. Oven drying– weigh 2 - 5g. into cellulose thimbles or aluminum

pans

– dry at 100 - 102oF for 16 - 18 hrs.

– cool in dessicator

– reweigh

– weight lost calculated and reported ~ $2000

AOAC oven options

2. - convection at 125oF for 2 - 4 hrs.

3. - vacuum at 95 - 100oF for 8 - 12 hrs.

4. - microwave at 80% - 100% power for 3 - 5 minutes

– Note: special design (CEM Corp.) - $30,000

Rapid methods - water

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

2. Near infrared transmission (NIT)

– 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

INFRATEC

tecator 1265 MEAT ANALYZER

CFS MultiTrack/Wolfking Continuous Fat Analyzer

– Gives simultaneous measures of fat, water and protein

– ~ 20 measurements per minute

– from CFS (Wolfking) technical literature

• Wolfking indicates SD of 0.3%

• Cost is ~$95,000

3. Guided microwave spectrometry (GMS)

– 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

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

Fat

Rapid methods - fat

1. Cooked / fat release– Hobart - only for fresh ground beef

– 15 minutes

– “good as a guess”

Rapid methods – product formulation

– Heat rendering

– Highly variable, SD ~ 2% or more

– Cost ~ $1000

• Hobart F-101

2. Modified Babcock

– 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

3. X-ray absorption - Anyl-Ray

– 13 lb. sample

– Nondestructive

4. Visual image analysis

– Computerized scan of surfaces for white fat exposed

Supercritical fluid extraction

– CO2 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

SMART Trac

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

Sample Moisture Calculated ID (%) Fat %

1 51.11 30.892 51.32 30.933 51.37 30.854 51.21 30.725 51.24 30.67

Average 51.25 30.81Standard Deviation 0.101 0.112

• 30.79 % Reference Fat from Soxhlet

- from CEM technical literature

Hot Dogs-Regular

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

Number of Caviezel measurement as % Product

samples of official method

Raw meat 5 103.7

Cooked sausage 13 101.9

Uncured sausage 14 101.7

Cooked, cured meats 9 105.0

Sausage with vegetable fat 5 99.3

- from Büchi technical literature

AOAC 1. Kjeldahl - developed in 1883

– acid digest to NH4+ for N content

– calculate protein as N x 6.25

- Beware -

Protein

2. Combustion - developed in 1970’s

– 800 - 900o C oven to convert protein to N2

– Measures N2 by thermal conductivity again, calculate protein as N x 6.25

– No waste products– Sample preparation critical due to small sample

size

3. CEM Sprint™ Rapid Protein Analyzer

– 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

Rapid methods - protein

– 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

W + F + P + A = 100%By:

Or: use M : P ratios if appropriate (fresh meat M : P = 3.7 : 1)

AOAC– 5 g. sample weighed into crucible

– 550oC (~ 900oF - 1000oF) 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

Ash

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%

Other methods for 460/560 products

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

3. Color / sensory