RAPID METHODS FOR "HE DETERMINATION OF MOISTURE AND FAT I N MEATS*

J. D . PETTINATI, C . E . SWIFT AND E. H. COHENW Eastern Regional Research Center

Agricultural Research Service U ,S . Department of Agriculture

Philadelphia, Pennsylvania l9ll8

Analysis t o determine the moisture, fa t and protein content of meat and meat products has become increasingly necessary i n meat industry operations. regulation of product composition and Labeling. These requirements found both government and industry unprepared t o analyze a large volume of meat and meat products with the needed accuracy, speed and economy. I n varying degrees the problem i s shared by regulatory agencies, processors, purveyors, and wholesale d is t r ibu tors , as well as large-scale purchasers, such a s the U.S. Armed Forces, t he USDA, and supermarket, restaurant, and convenience- food chains. inspected plants alone suggests the magnitude of the need. standard methods a re time consuming; t h e only a l te rna t ives a re t o choose from a considerable number of methods of varying accuracy, speed, cost and simplicity. However, m 3 s t of these have not been systematically evaluated and lack any o f f i c i a l s t a t u s .

The increased demand f o r analyses resul ted from str ingent

The f a c t that there a re more than 10,000 federal ly or s t a t e Existing

The spec i f ic needs 3f d i f fe ren t elements of the industry vary widely. The r e l a t ive need f o r ana ly t ica l r e su l t s depends on the operations involved and many include analyses f o r fa t only, f a t and moisture, o r the l a t t e r and protein as well . The accuracy and speed needed and the significance of any given fixed. costs vary depending on types, ra tes , and volumes of production. A t the present state of development, methods m y be grouped in four categories:

1. standard, with main emphasis on accuracy

2 . screening, time-saving as compared with standard

3 . r e l a t ive ly rapid, of t he order of 1 5 min

4 rapid, 5 min or l e s s .

* Presented a t t he 26th Annual Reciprocal Meat Conference of the American Meat Science Association, 1973.

we Present address: Office of Research and Monitoring, U.S. Environmental Protection Agency, Region 111, Philadelphia, Pennsylvania 19106.

224

Most processors lack the technical and f inanc ia l means of investigating the avai lable methods t o make judgements, or t o develop ana ly t ica l capabi l i t i es independently. u n t i l a few highly effect ive, widely applicable mthods can be developed and/or ident i f ied . avai lable methods that w i l l provide the industry with guidance i n t h e select ion of methods and form a basis f o r methods standardization; i n addition, a high p r i o r i t y m u s t be given t o a continued e f f o r t t o develop improved methodology.

This urgent problem w i l l continue t o e x i s t

Immediate demands a re f o r an unbiased evaluation of

During the course of our investigations, we made a survey of methods A wide var ie ty of a l te rna t ives of analysis f o r m i s t u r e and f a t content.

are available t o the meat analyst as a re described i n the sc i en t i f i c l i t e r a t u r e , trade journals and indus t r i a l l i t e r a t u r e w i t h evidence of varying value as t o t h e i r usefulness. Characterist ics of methods, such as time needed f o r analysis , s implici ty of performince, hazards, and costs of equipment a re often, but not always, s a t i s f a c t o r j l y established or evident; however, others, par t icu lar ly accuracy and appl icabi l i ty t o d i f f e ren t types of meats and meat products, a re not . A l l of these character is t ics must be considered i n evaluating available methods. These fac tors a l s o serve as guidelines i n identifying and select ing the more promising methods fo r fur ther development leading to t h e i r standardization and acceptance by organizations such as the AOAC and ASTM.

Our review of moisture and fat analyses of meat has been published (1) in which methods a re compared according t o the important factors mentioned above. discussion represents an updating i n which we have organized only par t of t he data reported i n the l i t e r a tu re , since discussion of t he en t i re l i t e r a t u r e is beyond our present scope, and we have included some of our recently published data t o permit comparisons of character is t ics of the methods. Also, t h i s w i l l permit recognition of promising methods and t o some extent, an ordering of values; however, u n t i l addi t ional research can be done, t h i s ordering must be ten ta t ive and somewhat a rb i t r a ry .

The review is already outdated somewhat and the present

For the present comparison, some of the charac te r i s t ics of 10 moisture and 2 1 f a t methods a re tabulated. The methods are grouped according t o s imi la r i ty of type t o simplify examination of the da ta . average difference abtained re la t ive t o reference method. deviations re la t ive t o reference method express the combined var ia t ions obtained using the experimental and reference methods. reference f o r the experimental methods, an estimate of the standard deviation associated w i t h only the reference methods may be useful. standard deviations obtained i n collaborative tests w i t h AQAC moisture (8) and fa t (15) analyses (most generally used f o r reference) were to.& moisture and i 0 . 4 6 fa t within laboratory, and ?0.63$ moisture and 20.5746 fat between laborator ies .

Accuracy i s the Standard

A s a frame of

The

MOISTURE METHODS

I n table 1, data on four different methods are shown:

1.

2.

a high temperature oven procedure (2)

a hot plate procedure evaluated a t our laboratory (3)

3 . a refractometric measurement of isopropanol extract of meat ( 4 )

4. a gas-liquid chromatographic procedure using a methanol extract of m e a t ( 5 ) .

The column headings i n t h i s tab le and of others that follow are: time required t o perform a single analysis as reported i n the publication, s i ze of sample fo r one analysis, nunber of individual analyses reported, and a tabulation of accuracy. An o f f i c i a l method (6) of analysis w a s used f o r comparison, or reference, i n the majority of the reports surveyed. The data shown as difference (method vs standard) i n the tables , a re e i the r as reported i n the or iginal a r t i c l e o r t is calculated from the data or iginal ly reported. resu l t s obtained on each sample analyzed by the evalusted and reference methods, w i t h appropriate signs t o indicate the posit ive or negative relationship of t he evaluated t o the reference mthod. The range of differences are the largest differences between results by the evaluated and reference methods. f romthe differences between individual or repl icate r e su l t s by the two methods and is equivalent t o a standard deviation of the errors (7) . the investigator reported a single r e su l t on each sample, by each method, no notation is made i n the tables; otherwise, the number of repl icate analyses reported a re shown with the data.

The mean differences ( 4 ) are the mean of the differences between

The standard deviations ($) are the values calculated

When

O f the 4 methods sham i n t ab le 1, Method 3 is the most rapid and i t s accuracy and standard deviation appear very acceptable.

I n tab le 2, data on the use of three methods involving use of infrared radiation a r e shown:

1.

2.

the Dynatronic- infrared radiation oven ( 3 )

the U l t r a - X infrared radiation lamp (9)

3. the O h a u s infrared radiation lamp evaluated by one analyst (3) and collaboratively by 10 laboratories (8).

- Reference t o brand or f i r m name does not consti tute endorsement by the U . S . Department of Agriculture over others of a similar nature not mentioned.

226

TABU 1. MOISTUIiE ANALYSIS METHODS

Method vs. Standard, Method Saznple $ moisture

Time weight N o . of Mean No. T n X (min) (gJ analyses d i f f . Range of D i f f . S.D.

1 Oven, 200Oc 15 25 25 0 -0.4 to t0.5 0.2

2 Hot p la te , 200W 30-45 10 24 0.7 -0.9 to +0.7 0.7

3 Refractometry, 5-10 20 36 -0.05 -0.19 to +0.16 0.3

6 rep l ica te analyses

isopropanol e x t . 6 rep l i ca t e analyses

4 G-L Chranatog. 10 2 74 0.3 -1.4 to +1.5 0.3 methanol ext . 5-6 rep l ica te analyses

TABW 2 . INFRARED ( I R ) RADIATION MOISTUFE METHODS

Method vs . Standard, Method Sample $ moisture

Time No. of Mean No. Type ( m i d wei(5ht (I3 anaiyses d i f f . Range of d i f f . S . D .

1 I R rad. oven 40-60 I-2 24 0.1 -0.6 t o ~ 0 . 6 0.5 (Dynatronic ) 6 rep l ica te analyses

2 I R rad. lamp 15-25 2.5 23 -0.5 -1.7 to +2.2 1.0 (Ultra -X )

(Ohaus ) 6 rep l ica te analyses 3 A I R rad. lamp 30-45 10-20 24 0.4 -0.3 t o +0.4 0.3

3B Same, 10 40 10 180 0.6 -3.54 to +3.21 1.0 co1laSorator.s

227

Method 2 appears t o be the most rapid of these. However, i t s standard deviation is marginal and would very l ike ly be hieper i n a collaborative study, as proved t o be the case when Method 3 w a s studied by one laboratory ( A ) and collaboratively (B) . t o be the most useful of t h i s group of semi-rapid methods f o r screening analysis.

Thus, Method 3 rather than Method 2 appears

I n tab le 3, data on analysis using three azeotropic d i s t i l l a t i o n methods a re shown:

1.

2.

use of butyl ether as d i s t i l l i n g solvent (10)

use of 2-0ctanol as the d i s t i l l i n g solvent (11)

3 . use of %-xylene o r cumene as d i s t i l l i n g solvents evaluated a t our laboratory (12) and collaboratively by 10 laboratories (13).

Method 2 i s the most rapid of these 3 methods but i t s standard deviation i s higher than fo r Method 3B and would be even higher i f determined i n a collaborative study. Thus, u n t i l Method 2 is studied collaboratively, Method 3 f o r which accuracy is w e l l established, may tenat ively be considered as providing the best results froanthis group of semi-rapid methods.

TABU 3 . AZEOTROPIC DISTILLATION METHODS

Method vs . standard, Method Sample $ moisture

t No. of Mean No. Solvent Time (-1 we? ( g analyses d i f f . Range of Di f f . S.D.

1 Butyl ether 3.20 10 46 1.0 -0.7 t o +2.3 0.8 (Si-Mo-Fat ) duplicate analyses

2 2-Octanol 15 15 19 -0.7 -1.9 t o +1.g 1.1 ( W F )

3A m-Xylene Cumene

30 10 8 -0.3 -0.8 t o +o.i 0.4 30 10 8 +0.3 +o.i t o +0.7 0.3

duplicate analyses

3B Same solvents, 30 10 180 -0.7 -2.58 t o e . 6 2 0.7 10 collaborators 30 10 179 -0.5 -1.75 t o +3.55 0.8

228

FAT METHODS

The methodology for determining fa t content of meats is much more varied than f o r moisture determination. Classif icat ion of the methods can be made under headings of solvent extraction, volume determination by e i the r Babcock type methods or by rendering, spec i f ic gravity, and miscellaneous instrumental methods.

I n t ab le 4, data on th ree d i f fe ren t extraction Ethods a re shown:

1. a modified o f f i c i a l method evaluated by our laboratory (14) and collaboratively by 10 laboratories (15). method consjsted of drying meat samples for 30 instead of 90 m i n and then extracting f o r 45 min instead of 4 hr.

Modification of the

2. carbon te t rachlor ide extraction of t h e residue a f t e r drying a meat sample by an U l t r a - X I R radiat ion lamp (9)

3. gravimetric determination of the fat residue that remains a f t e r solvent removal from a butyl e ther extract of fa t which is obtained during azeotropic d i s t i l l a t i o n of a meat sample (10).

Method 2 i s t h e most rapid of these but the standard deviation of b.$ fat is high considering that it is calculated on means of 4-11 rep l ica te analyses per sample. provide the best accuracy of t h i s group of methods.

Method 1 is not quite as rapid but it appears t o

TABLE 4. SOLVENT EXTRACTION M?ZFE€ODS

Method vs . standard, Method Sample 5 f a t

Time No. of Mean No. Type b i n ) weiy (g analyses d i f f . Range of d i f f . S.D.

IA Modified o f f i c i a l 45-75 3-4 27 0 -0.8 t o +0.2 0.6

1B Same, 10 75 3 -4 180 -0.3 -3.6 t o +2.3 0.7

AOAC t r i p l i c a t e analyses

collaborators

2 Carbon 35-55 2.5 23 -0.1 -2.4 t o +1.8 1.0 te t rachlor ide 4 -11 repl ica te analyses ( u It ra -X )

3 Butyl ether 120- 10 46 -1.0 -2.6 t o +0.7 0.8 ext rac t 150 duplicate analyses

(Si-Mo-Fat )

I n tab le 5 , data on two additional extraction methods are shown:

4 . gravimetric determination of the fat residue that remains a f t e r solvent removal from a g-xylene or cumene extract of f a t obtained during azeotropic d i s t i l l a t i o n of a meat sample, evaluated by our Laboratory (16) and collaboratively by 10 laboratories (13).

5. gravimetric determination of a chloroform extract of meat which is f i rs t solubilized by use of methanol (17).

Method 5 offers t he most rapid determination of fat content of a l l extraction procedures c i ted here and the standard deviation seems exceptionally lar. It should be pointed out t ha t i n the a r t i c l e cited, only two law-fat types of meat were evaluated, veal and lamb, which had 1.7 and 6."$ fat content, respectively. method on samples of higher f a t content needs t o be ascertained. determination by Method 4 is not a s rapid but i ts accuracy and appl icabi l i ty has been more thorouglzly evaluated. as a semi-rapid method.

Therefore, the usefulness of the Fat

It appears useful for screening analyses

TABLE 5. SOLVENT EXTRACTION METHODS, CONTINUED

Method VS. standard, Method Sample 5 fat

Time No. of Mean No. me ( m i n ) wTp analyses d i f f . Range of dif'f. S.D.

4A m-Xylene at. 45-60 10 16 -0.7 -0.9 t o +O.g 0.4 Cumene ext. 45-60 10 16 -0.3 -0.5 t o w.5 0.5

4 repl icate analyses

4B Same solvents, 45-60 10 179 -0.4 -2.0 t o e . 8 0.9 10 collaborators 45-60 10 180 -1.0 -2.6 t o e . 5 0.9

5 Chloroform- 10 100 28 0.3 not available 0.2 methanol duplicate analyses

Babcock type methods can be classif ied as re la t ive ly rapid methods. For this reason and because they a re re la t ive ly easy t o perform and require a low investment i n equipnent, they are widely accepted for meat fa t determination. the chemicals used, are shown:

I n table 6, data on three of the methods, ident i f ied by

1. sul fur ic acid digestion ( l8 , lg )

2. mixed perchloric-acetic acid digestion (1 part 6 6 HClO4 and 1 part g h c i a l HOAC) ( 2 0 )

3 sulflrric acid-hydrogen peroxide digestion (21).

Method 3 is the most rapid of these. Digestion is carried out by heating 9 g samples of meat w i t h 14 ml su l fur ic acid and 1-2 m l of 30$ hydrogen peroxide f o r 2-5 min on a hot p l a t e . stated: f resh or cured, -than any other reagent so far proposed." c r i t i c a l evaluation of this method is required.

The author of t h i s method "This procedure is applicable t o a wider range of meat products,

However, a more

TABLE 6 . BABCOCK TYPE MMlEODS

Method vs. standard, Method Smple $ fat

Time w e i g h t No. of Mean Range of No. Type (min) (g) analyses d i f f . difference S.D.

1 Sulfuric acid 20-30 9 (240 -0.1 -1.0 t o + l e 0 0.3 0.2 -0.6 t o +1.2 0.4

4 or 3 repl icate analyses (18

2 Perchloric- 30 9 19 0 -0.4 t o +0.5 0.2 ace t ic acids 2-8 rep l ica te analyses

3 Sulfuric acid, 10 9 hyd. peroxide

not available 0.7

I n tab le 7, data on three additional Babcocktype procedures a re shown:

4. b c o method (22)

5. hydrochloric acid-dbnethylsulfoxide method (23 )

6. alkaline digestion method (24).

A l l three of these methods were developed t o eliminate the use of su l fur ic acid because of the hazardous nature of a concentrated acid and the charring it may cause with some samples.

In method 4, the use of an enzyme, papain, and reagent mixture is This i s effective i n digesting samples but analysis time is u t i l i zed .

lengthened about 5 min compared with acid digestion methods.

In Method 5 , conc. H C 1 is u t i l i zed f o r a 5-6 min digestion and dimethylsulfoxide i s then added t o dissolve all constituents except, the neutral t r iglycer ides . Heavily spiced products were reported t o give some trouble i n the form of suspended material a t the lower interface of the fat column.

I n Method 6, 2@ sodium hydroxide and antifoam agent a re added t o the sample and the mixture is heated 1-2 min t o obtain digestion. Sodium chloride i s then added t o the digest t o increase the density of the lower phase. acceptable f o r a screen- method. The results fo r 44 analyses of cooked bologna, however, indicated that the estimated fat content and standard deviation were high, being 1% and 1.8 f a t , respectively. s e t s of data, it m i g h t be generalized that the method i s less accurate fo r processed product than f o r f resh meat. The speed of the method is very a t t r ac t ive and fur ther investigation and development is warranted. It appears t o be the most promising of the three modifications of t h e Babcock method.

The accuracy indicated fo r 23 samples of ground beef is quite

From the 2

TABLE 7. BABCOCK TYPE MEXBODS, CONTINUED

Method vs . standard Method Sample % fat

No. of Mean Range of No. Type w7iy analyses d i f f . difference S.D.

4 Papain, urea, 35 9 32 0.2 -0.8 t o +le2 0.4 e t c . (Banco) t r i p l i c a t e analyses

5 Hydrochloric 1 5 9 9 -0.2 -1.3 t o +1.6 0.6 acid, dimethyl -sulf ox ide

6 Sodium hydroxide, 8 9-18 ( 23 -0.1 -1.3 t o +i.8 0.7 1.0 -2.3 t o +3.2 1.2 6-12 repl icate analyses

sodium chloride ( 44

Rendering methods permit f a t content t o be determined by heating samples u n t i l fa t is melted, drained in to a collecting vessel and deter- mined e i the r volumetrically or gravimetrically. three rendering methods a re given:

I n table 8, data on

232

1.

2.

a n inverted hot p la te device (25)

a resistance heating device (26)

3. a microwave oven procedure (27)

Method 3 appears t o be the most a t t r a c t i v e of the 3 methods by v i r tue of the speedy analysis (4 min) and accuracy it provides. only 4 ground beef samples compared w i t h values obtained by o f f i c i a l methods were c i ted i n the patent, however, and more extensive performance data are needed. content is selected w i t h reservation. There is another aspect which makes the uni t , and method, a t t r ac t ive . For f resh meat, a t l e a s t , a f t e r moisture content has been vaporized, and fa t content has been melted and collected i n a vessel, protein and ash content can be determined on the residue that remains. residue.

The r e su l t s fo r

Un t i l more data a re available, t h i s method of determining fat

This i s based on the r e h t i v e l y constant chemical analysis of the

TABLE 8. RENDERING METHODS

Method vs. standard, Method Sample $ fa t

No. of Mean Range of No. Type Time (-1 weiy (g analyses d i f f . difference S.D.

1 Inverted ho-t 15 56.6 64 -2.3 -4.1 t o -0.5 1.0 p la t e (Hobart) (2 02) t r i p l i c a t e analyses

2 Resistance 15 15-25 not available -1.5 t o +l.5 not heating (Goss) a v a i l .

3 Microwave oven 4 70 4 0.3 -0.2 t o +l.Og 0.6 (Hobart)

I n t a b l e 9, determination of fa t content by means of spec i f ic gravity is shown in data on three d i f fe ren t methods:

1. instrumental measurement of spec i f ic gravity of f resh meat and r e l a t ing the measurement d i r e c t l y t o fa t content by cal ibrated relat ionship (28,29)

2 . spec i f ic gravity of heptane extracts of meat samples by means of hydrometers and r e l a t ing the measurement d i r ec t ly t o amount of fa t dissolved in the extract ( 3 0 )

3. instrumental measurement of specif ic gravi ty of tetrachlorethylene ex t rac ts of meat samples (31).

233

The rapid screening provided by Methods 1 and 3 makes both methods very a t t rac t ive . only moderately accurate while Method 3 provides be t te r accuracy. Results by the latter are available for meat and meat products with fat content in the 2-3@ range

From data available f o r Method 1, the method appears

Method vs . Standard, Method Sample $ f a t

Time w e i g h t N o . of Mean Range of No. Type ( m i n ) (g) analyses d i f f . difference S.D.

1 Weight, volume, 3 750 (69 0.1 -2.4 t o +2.4 1.2 temp. (Honeywell) (56 -1.0 -3.4 t o f3.4 1.5

2 Hydrometer and 15 20-40 17 0.3 -0.9 t o +0.8 0.5 heptane ex t .

3 Tetrachloroethylene 4-5 45 68 -0.3 -3.1 t o e.1 0.7 ext . (Foss)

In table 10, data on miscellaneous instrumental methods fo r fat analysis by measurement based on physical chemical principles are shown:

1. X-ray absorption as a variable inversely proportional t o fat content ( 3 2 )

2 . capacitance measurement of o-dichlorobenzene - extracts of meat (33)

3. capacitance measurement of meat extracts using a m i x t u r e of 1- and 2-octanol (11)

4. infrared absorption measurement of ground meat samples (34).

Methods 1 and 4 appear equally a t t rac t ive as rapid methods of analysis. The X-ray instrument uses a dental X-ray source of radiation and the attenuation effected by a meat sample i n the path of the radiation is measured. Samples need not be ground but must be properly compacted, f r ee of salt and of some additives which influence readhgs substantially. Saanples smaller than 13-lb can be measured i f thoroughly mixed and very uniform. A more systematic evaluation including collaborative study of Method 1 is needed. Concerning Method 4, the high standard deviation that was obtained for fa t determination i n meat indicated that the infrared transmission method required fur ther developnent . This requirement led one

of the authors of that report t o a l t e r the instrumental procedure so that attenuated t o t a l reflectance (ATR) was measured i n place of transmission spec t ra . I n a recent report (35) of the a l te red procedure, ATR was used t o analyze the fat, protein, and carbohydrate content of soy beans with good accuracy. Very recently the ATR pr inciple w a s applied t o meat w i t h a t l e a s t useful accuracy (21% fa t ) using instrumentation developed by K. Norris, USDA (36).

TABW 10. MISCELLANEOUS INSTRUMENTAL METRODS

Method vs Standard, Method Sample B fa t

Time weight No. of Mean w e oi. No. Type (min) (gj analyses d i f f . difference S .D.

X-ray absorption 5 5902 12 not -1.5 t o +l.5 0.5 ( AnYl-RaY) (13 lb) ava i l .

Capacitance, 20 50 20 0.2 -1.9 t o +1.2 0.8 o-dichlorobenz . t r i p l i c a t e analyses ext . Capacitance, 30 15 19 0.3 -2.1 to +2.9 1.3 mixed octanol ext

Infrared 5 1 34 not available 1.4 radiat ion absorbance

Instrumental procedures were mentioned i n the preceding tab les when- ever some ana ly t ica l data were avai lable . available, fo r which performance data has not come t o our a t ten t ion are l i s t e d below. of the uni t s i s deferred u n t i l data becomes avai lable .

Other instruments, commercially

The speedy analysis they provide i s a t t r ac t ive but evaluation

The last four instruments on t h i s l i s t can determine moisture, fat , and protein content by means of either near-infrared o r infrared radiat ion.

1. The Model TOO Moisture Gauge (37) measures microwave absorption o r re f lec t ion and can determine up t o 95% moisture content w i t h a claimed accuracy of O.2-O.5$.

2. The Model MR near-infrared analyzer (38) is a noncontacting un i t which u t i l i z e s 2-wavelength absorption and ref lect ion, useful f o r measuring up t o 8oq6 moisture content.

23 5

3 .

4.

5 .

6.

7.

8 .

9 .

An

The Model M - 6 Ground Meat Analyzer ( 3 9 ) measures t o t a l leanness of f resh meat by u t i l i z ing the f ac t that lean meat conducts e l e c t r i c i t y about twenty times be t te r than f a t . Current is induced in a meat sample as it crosses a t e s t volume within a transducer. The change i n transducer character is t ics i s combined with the weight of the sample and lean percent is automatically calculated by the uni t i n seconds.

The Autoanalyzer (40) consists essent ia l ly of uni ts that automate w e t chemistry methods from sampling through t o recording resu l t s of analysis. nitrogen on 80 meat samples p r day and determination of fat content is under developuent .

Unit8 a re i n use which determine t o t a l Kjeldahl

The Minispec P-20 nuclear magnetic resonance instrument (41) is a bench-top uni t that provides a pulsed signal. This type of un i t is potent ia l ly useful f o r measuring both lnoisture and fa t content on the same sample.

The Grain Quality Analyzer (42) is used for analyzing cereal grains. f i l t e r s and a computer which solves th i rd order equations. content of each of the three constituents are displayed by d i g i t a l readout. are made i n 10 sec.

Built into the instrument are three narrow band pass

Accuracy is claimed t o be 0.1s and readings

The

The Model F106 Analyzer (43) u t i l i z e s near-infYared l i g h t and measures the three constituents re la t ive t o a non-absorbing wave-length of light. Extent of application t o meat is not known.

The Miran Infrared Analyzer (44) measures e i ther infrared transmission or the attenuated t o t a l reflectance of products us- a miniaturized un i t .

The Model T-320 Meat Composition Analyzer (45) is the newest of these methods t o be marketed. The three constituents are measured by infrared spectrometry. s t a t e s that a 10 g sample of meat is analyzed i n 10 sec and the r e su l t s a r e displayed i n percent w i t h a guaranteed accuracy of 0.25% fo r non-blended o r pre-blend meat and f o r finished product.

Descriptive l i t e r a t u r e

interim is necessary during which new methods w i l l be developed and both new and presently promising methods w i l l be c r i t i c a l l y evaluated. For present guidance i n the choice of methods, the following l i s t of methods which were singled aut i n the foregoing review may be of value.

1.

2.

3 .

1.

2.

3.

4.

5 .

6 .

7.

a. I n

236

MOISTUIiE ANALYSIS

5-10 min refractometric measurement of isopropanol extracts of meat ( table 1)

infrared radiation lamp drying ( tab le 2 )

azeotropic d i s t i l l a t i o n using m-xylene - or cumene ( tab le

FAT ANALYSIS

modified o f f i c i a l method [ether extraction of dried samples, t ab l e 4 )

10 min chloroform-methanol extraction (bi-phasic extraction, tab le 5 )

10 m i n sulf’uric acid-hydrogen peroxide (modified Babcack, tab le 6 )

8 min alkaline digestion (modified Babcock, incompletely evaluated, t ab le 7)

4 min microwave oven rendering (moisture, fat , protein, and ash content combination method, Hobart, incompletely evaluated, t ab le 8)

4-5 min specific gravity of tetrachloroethylene extracts (Foss- l e t , t ab le 9)

3 min specif ic gravity of meat (Honeywell, t ab le 9)

5 min X-ray absorption of meat (Anyl-Ray, tab le 10)

summary, a selected number of available methods have been grouped according t o s imi la r i ty of type of procedure and some of t h e i r character is t ics were compared i n order t o identify those procedures which more closely meet the needs of the meat industry fo r re la t ive ly rapid and rapid analysis . A precise order of value cannot be given t o the methods discussed because i n many cases methods appear equally sat isfactory. methods ident i f ied as useful require e i ther further developnent or more extensive study including applications t o a broad range of meat products and t o comparative studies by multiple laboratories. a s standards, whether f o r the highest degree of accuracy and r e l i a b i l i t y , o r f o r screening, r e l a t ive ly rapid, or rapid analysis, methods must be subjected t o established procedural s teps . analysis of selected samples, a number of analysts in widely separated laboratories, closely specified procedures, and a standard reference method. A s a r e su l t , variation according t o type of product or constituent level,

Obviously, most of the

To obtain acceptance

Collaborative study lnvolves

variation w i t h i n each laboratory and variation between laboratories can be ascertained. Error analysis of the results of the study i s obtained by applying well-established s t a t i s t i c a l procedures such as those suggested by Youden (46, 47, 48).

It is 3ur recommendation that evaluation of the method; identified as useful. be vigorously pursued t o demonstrate proven usefulness and promote t h e i r acceptance as standards by AOAC ASTM.

1. Pet t ina t i , J. D., C. E. Swift and E. H. Cohen. 1973. Moisture and fat analysis of meat and meat products: a review and comparison of methods. J. Assn. O f f . Anal. Chem. 56:541C.

2. Perrin, C . H. and P. A . Ferguson. 1957. The rapid determination of moisture i n meat products. J. Assn. O f f . Anai. Chem. 40:lOg3.

3. Cohen, E. H. 1971. Comparison of t he Off ic ia l AOkC Method with rapid methods for the analysis of moiGture i n meats. O f f . Anal. Chem. 54:1432.

J. Assn.

4. Addis, P B. and A S Chudgar 1973. Rapid analysis of moisture i n meat by refractometry. J. Food Sci . 38:354.

5. Reineccius, G A. and P. B. Addis. 1973. Rapid analysis of moisture i n meat by gas-liquid chromatography. J. Food Sci . 38:355.

6. Assn. O f f . Anal. %em. 1970. Official Methods of Analysis, 11th ed. Washington, D .C . Sec . 24.003(a).

7. Hoel, P. G. 1963. Elementary S ta t i s t i c s , John Wiley & Sons, Inc., New York and Iondon, p. 149.

8. Pe t t ina t i , J. D., V . G. Metzger, D. Van Horn and E . H . Cohen. 1972. Collaborative study of methods of analysis f o r meat and meat products. moisture methods. 86th Annual Meeting of the Assn. O f f . Anal. Chem., Oct. 9-12, Washington, D.C.

I . Modified AOAC moisture method and other rapid

9 . Bartels, H. and Gerigk. 1964. Testing a rapid method for the determination of water and fat content i n meat products. Fleischwirtschaf't 8:743.

D i e

10. Davis, C . E., H. W . Ockerman and V. €3. Cahill . 1966. A rapid approximate analyt ical method for simultaneous determination of moisture and fat i n meat and meat products. Food Technol. 20:1475.

11.

12.

14.

15.

16.

17

18.

19 9

20.

21.

22.

Everson, C . W . , T . Keyahian and D. M. Doty. 1955. Fat and moisture; rapid methods for determination of fat and moisture content i n meat products. Amer . Meat I n s t . Foundation B u l l . 26, 39 pp.

Cohen, E. H. and C . P . Kinrmelman. 1972. The efficacy of various organic solvents fo r the rapid d i r ec t determination of moisture i n meat and meat products. 1972. J. Assn . O f f Anal. Chem. 55: 574

Pe t t ina t i , J. D . and E. €I. Cohen. 1972. Collaborative study of methods of analysis fo r meat and meat products. determination of moisture and fat i n the same sample. Annual Meeting of the Assn. O f f . Anal . Chem., Oct. 9-12. Washington, D .C

111. Rapid 86th

Cohen, E. H. and C. E. S w i f t . 1971. Effect of reduced drying and J. Assn. O f f . extraction time i n determining meat fat content.

Anal. Chem. 54:1006.

Pet t ina t i , J. D., C . E . S w i f t and E. H. Cohen. 1972. Collaborative study of methods of analysis for meat and meat products. 11. More rapid fat determination by modification of the AOAC method. 86th Annual Meeting of the Assn. O f f . Anal. Chem., Oct. 9-12, Washbgton, D .C .

Cohen, E. H. and C . P. Kinanelman. 1972. Proposed technique for the determination of both moisture and fat i n the same sample of meat or meat product. J. Assn. O f f . Anal. Chem. 55:578.

Prost, E. and H. Wrebiakarski. 1972. Evaluation of Soxhlet's and Bligh and D y e r ' s methods i n the determination of fat i n meat. Z . Lebensm. Unters . Forsch . 149:193.

Windham, E. S . products.

1955. R e p o r t on the determination of fat in meat J. Assn. Off. Anal. Chem. 38:210.

Windham, E. S . 1957. R e p o r t on rapid methods for determination of fat i n meat products. J. Assn. O f f . Anal. Chem. 40:765.

Salwin, H., I . K. Bloch and J. H . Mitchell, Jr. 1955. Rapid determination of fat in meat products. J. Agric . Food Chem. 3:w.

Mehlenbacher, V . C . 1960. "he Analysis of fats and Oils. The Garrard Press, Champaign, Ill.

Anderson, B. B., L. L. Robinsm and J. E . Hodgkins. 1962. The "Banco" t e s t : a rapid method for fat in meat and edible meat products. J. Assn. O f f . Anal. Chem. 45:13.

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23. Whalen, F. 1966. A modified Babcock procedure for rapid determination of fat in meats using dlmethyl sulfoxide. Chem. 49:1225.

J. Assn. O f f . Anal.

24. Moreau, J R , and J Galhidi . 1971. -4 new rapid method. f o r measuring Can. In s t . Food the fat content i n meat and meat products.

Technol. J. 4:19.

25. B e l l i s , D. R., J. L. Secris t and M. J. Linskey. 1967. A comparison of solvent and thermal techniques f o r determining the f a t content of ground beef. J. Food Sci . 32:52l.

26. Goss, D. D. 1965. Method and apparatus for tes t ing meat U.S. Patent 3 ,m,929

27. Davis, K. E 1972. Analysis of comminuted meat products. U .S . Patent 3,673,852

28. Whitehead, R. C . 1970. Fat analysis of boned meat by the specific gravity method. Food Technol. 24:469.

29. Malanoski, A. J. and E. L. Greenfield. 1970. Rapid instrumental fat determination. J. Assn. O f f . Anal. Chem. 53:1080.

30. Bittenbender, C. D. 1970. Fat determination--a new physical method. J. Food Sci. 35:460.

31. Foss American, Inc., R o u t e 82, Fishki l l , N.Y. 12524.

32. Anon. 1961. Electronic u n i t , simple technique permit lean determinations i n three seconds. N a t l . Provisioner 145 (July 29):l8.

33. Furgal, H. P. 3.954. Streamlined assay sharpens product control. Food Engineering 26(2):58.

34. Ben-Gera, I and K. H. Norris . 1968. Direct spectrophotometric determination of fat and moisture in meat products. 33 :64.

J . Food Sc i .

35. Wilson, J. M., A. K r e r and J. Ben-Gera. 1973. Quantitative determination of fat , protein, and carbohydrates of soy products w i t h infrared attenuated t o t a l reflectance. J. Food Sci. 38:14.

36. Anon. 1973. USDA instrument measures f a t i n meat. Chemical and Engineering News 51(25):24, June 18.

37. Microwave Instruments Co ., 31Li 2nd Ave ., Corono de l Mar, Cal. 92625.

38. Moisture Register Co ., 1510 W . Chestnut St., Alhambra, Cal. gl802.

39. EMME Co., 5203 W . Glendale Ave., Glendale, Ariz. 85301.

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40. Technicon Instruments Corp, Tarrytown, N .Y. 10591.

41. B r u k e r Scient i f ic , Inc . , 1. Westchester Plaza, Cross Westchester Industrial Park, Elmsford, N. Y. 10523.

42. Neotec Instruments, Inc ., 6110 Executive Blvd . , Rockville, Md . 20852.

43. Anacon, Inc., 30 Main St., Ashland, Mass. 01721.

44. W i l k s Scientific Corp., 140 Water St., South Norwalk, Conn. 06856.

45. Computer Concepts Corp., 1005 Maryville Pike Southwest, Knoxville, Term. 37920.

46. Youden, W . J. 1967. S t a t i s t i c a l Techniques f o r Collaborative Tests, Assn. O f f . Anal. Chem., Washington, D.C.

47. Youden, W . J. 1951. S t a t i s t i c a l Methods fo r Chemists, John Wiley & Sons, New York.

48. Youden, W . J. 1959. Graphic diagnosis of interlaboratory t e s t resu l t s , Indus t r ia l Qual. Control 15:24.

243.

S . SIMON: Thank you, Joe. We do have t i m e for R f e w questions or comments. Before anyone does take the orport,unity t o speak, I would l ike t o remind them t o s t a t e h i s or her name end the ins t i tu t ion with which he or she may he affiliated. In addition t o th i s , I W O U ! ~ PJSO l i ke t o remind you that there has heen enclosed i n the folder, alcng wtth the writ ing pad, a card on which you a re asked t o w r i t e your qiiestion or your comment and, I guess, these are supposed t o be turned in just, outside this h a l l following tbe meeting. Anyone?

G. SMITH, !l"US: I don't believc you mentioned the Moisturefuge equipnent developed by Anderson Laboratories, Ft . Worth, Texas. i f you have any comment on it.

I wonder

JULIO D. PETTINATI: The Moisturehge might be a method fo r which I have requested information and haven't receAved any. w i t h Anderson laboratories or the method. published on t h e method with analyt ical comparative data, it h a s n ' t come t o my at tent ion as ye t . developed and the amount of work tha t is being applied t o t b j s subject, means that this phase of our work needs constant u m t i n g , nwybe on a six month in te rva l rather than annually.

I ' m not familiar If there has been a paper

The rapidi ty with which methods 8 .r~ being

G . GREEN, DXLTEC Nons: Am I right i n believing that the fjgures

SOP meats may require a more extensive rrsparation used f o r the time required f o r the determination doen liot include the preparation time? than others, i.e., s a l t pork.

J. D. €"ATS: That's generally t rue . Different samples do require different steps Jn preparation. ground. Three times is the usual procedure. Sample prepwehion is common t o a t l e a s t gC$ of the methods. measuring time th8.t I concentrated on fo r comparison.

For fresh mett %hey would a l l have t o be

So in my -per it i s only the actual

T. R. DOCKERTY, NATICK LABORATORIES: delative t o the microwave techniques you talked about, what frequency and power leve l did they use i n these analyses?

J. D. PETTINATI: I t 's one of the two FCC specified wave lengths. Bench top uni ts generally operate a t 2450 megahertz. which you may be familiar w i t h , is used more commonly fo r conveyor b e l t operations.

The 912 wave length,

UNIDENTIFLED: May multiple samples be run on the microwave oven which you ci ted i n your review?

J. D. PETTINATI: I don't know specif ical ly . The patent that was issued last year describing the uni t was written up i n such a way t h a t everyone could cal ibrate h i s own microwave oven i n accordance with the equations l isted. It wasn't too clear, but it was specified that each microwave oven would require calibration, tes t ing, and so for th . I would presume th i s means that multiple samples could be run. There a r e a number

242

of models on the market. that is, a counter top uni t which wouM have a shelf area of about one foot by one foo t .

They a r e similar t o a home type cooking uni t ,

These a re not focused beam type uni t s .

S. SIMON: Paul Graham i s a s s i s t an t professor of food science and technology a t Virginia Polytechnic I n s t i t u t e and Sta te University. B.S. and M.S. degrees i n A n i m a l Husbandry were gained a t Virginia Polytechnic I n s t i t u t e and S ta te University, and his F'h.D. in Food Science a t Caro lha S ta te University. associated with the academic community, he has served i n agr icu l tura l extension work, and as a food science consultant t o the meat industry. H i s present work r e l a t ing t o meat product and processing evaluation serves as a base f o r reviewing today's topic , "Measuring Objectionable Inclusions i n Processed Meats ."

H i s

Although he has been most closely