PORK AND PORK QUALITY                             PIH-125


               Composition and Nutritive Value of Pork

Burdette C. Breidenstein, Oklahoma City, Oklahoma
Robin Kline, Des Moines, Iowa

Alden M. Booren, Michigan State University
Wayne and Carmen Jorgensen, Dover, Arkansas
April C. Mason, Purdue University
Herbert W. Ockerman, The Ohio State University

     Human use of pork as a food dates back to prehistoric times.
Drawings  on the walls of caves in Europe portray wild pigs being
hunted even before the development  of  a  written  language.  As
civilization  advanced  and  animals were domesticated to provide
for a more predictable and consistent food supply,  the  pig  was
highly  valued  as a source of very palatable human food. For the
ensuing centuries, a number of  societies  have  placed  a  heavy
reliance  on pork as a major dietary component, and it has served
them well as a source of major nutrients.

     ``Fat as a pig'' was, for centuries, an apt description  for
one  who  was  overweight. However, over the past thirty or forty
years improvements in leanness achieved through genetic means and
the  development of improved feeding and other management regimes
have resulted in a much leaner profile for the typical pig. As  a
result,  the pig has generally become much leaner since World War
II. In the modern era, there have  been  a  number  of  consumer-
driven changes in pork production. In responding to emerging con-
sumer demands, the pork industry, shortly  after  World  War  II,
began  to  modify  pork  composition by reducing its fatness with
corresponding increases in leanness and all  that  this  implies.
Consumers  have  become much more diet conscious with emphasis on
nutrition and health, but still are very interested in the tradi-
tional  quality  attributes  of flavor, tenderness, juiciness and
texture that pork provides.

     Common wisdom suggests that pork produces a  high  level  of
appetite satiation, or a feeling of appetite satisfaction. Simon-
son (1982) reports that persons on a  meat-containing  diet  com-
pared  to  those  on either a self-designed vegetarian diet or on
diets individually designed for them by a professional dietitian,
lost  weight more slowly. However, the persons who were on a non-
vegetarian diet had less weight fluctuation, fewer  dropouts,  no
feeling  of  hunger,  experienced  few physical and psychological
problems and had improved work productivity. This generally  sup-
ports  the contention that meat consumption, including pork, pro-
vides a good level of appetite satisfaction.

     The pork producer has increasingly recognized  his  role  in
supplying human food and the responsibility that this recognition
brings with it, and of the increasing need  to  keep  abreast  of
changing  consumer  needs and desires. Producers have, therefore,
become much more aware of the validity of the desire by consumers
for  a  healthier and a safer diet. Recognizing the corresponding
increases in  demand  for  reasonably  priced  ``healthy''  meat,
requiring  a  minimum  of  time  and  effort  in the kitchen, has
spawned a number of new products using pork as  a  raw  material.
The  development of scientific parameters, and the use of comput-
ers, has permitted the industry to more consistently produce pro-
ducts which are more finely attuned to existing and emerging con-
sumer desires and demands. Such developments have resulted  in  a
triumph  for  hog  producers and resulted in the development of a
hog that is both ``producer'' and ``consumer'' friendly.


     The primary tissues which constitute pork include lean, fat,
bone  and  soft connective tissue. The paramount reason, however,
for raising pigs in the modern era, is the ability of the pig  to
convert  plant  materials to lean tissue for use as a human food.
The lean tissue must obviously contain  sufficient  intramuscular
fat  to  insure  acceptable taste appeal. While many of the other
components of the animal contribute significantly to its economic
value,  we  must not lose sight of the primary role of the pig in
the food supply chain, namely  the  production  of  lean  tissue.
Table  1 provides composition information relative to the contri-
bution of the various tissues to the traditional primal cuts.

Table 1. Lean, fat, bone and skin of primal cuts expressed as a %
of total carcass lean, fat, bone and skin respectively.*
                      Lean      Fat     Bone     Skin       cut
Leg (ham)              28.8     14.5     17.6     12.0      21.5
Loin                   24.2      6.7     25.6     --        17.0
Blade Boston           13.9      5.1      4.2     --         8.7
Arm picnic             11.4      6.0     11.6      8.8       9.5
Belly                   9.7     16.0     --       15.0      10.6
Jowl, spareribs,
  Neck bones, feet      7.4      6.5     41.0     15.5      11.6
  and tail
Non-specific            4.7     45.2     --       48.8      21.1
TOTALS                100.1    100.0    100.0    100.1     100.0
*Source:  Forrest (1989).

     A hot, (pre-rigor) pork carcass weighing 172 pounds would be
expected  to  have  originated from a live hog weighing about 235
pounds. Typically that carcass might be expected to have a  back-
fat  thickness  at  the  10th rib of about 1.3 in. and a loin eye
area of about 4.5 sq. in. According to Forrest et al. (1989) that
typical  pork  carcass  contains about 48 to 50% of its weight in
the form of knife-separable lean,  about  32  to  33%  in  knife-
separable fat, about 5 to 6% skin and about 1.5 to 2.0% shrink or
product unaccounted for.  The  authors  estimate  this  separable
lean  to  consist  of  about 10% extractable lipids and 19 to 20%
protein based on Anderson (1983). Anderson  (1983)  also  reports
the trimmable fat tissue to contain 4.5 to 5.0% protein and about
76% extractable lipids. One can then conclude that the total soft
tissue  contains  about  36  to 37% extractable fat and 13 to 14%
protein. One can also conclude that this 235 lb. pig  produces  a
172  lb. carcass before chilling and that it contains about 80 to
84 lb. of chilled separable lean.

Table 2. Extractable fat content of fresh pork.*
                   Raw pork         Cooked pork, lean only
                   lean only         g of fat/3 oz serving
Tissue origin,      g/100 g                        Pan
Primal cut          tissue    Braised   Broiled   fried   Roasted
Leg (ham), whole     5.41       --        --       --       9.4
Loin, sirloin        6.75      11.1      11.5      --      11.2
 center loin         7.15      11.6       8.9     13.5     11.1
 center rib          7.53      12.3      12.7     13.0     11.7
 blade               11.03     17.5      18.2     16.9     16.4
 whole               7.54      12.4      13.0      --      11.8
Blade Boston         9.28      15.0      15.7      --      14.3
Arm picnic           6.16      10.4       --       --      10.7
Spareribs            23.60     25.8       --       --       --
*Source -- Anderson (1983) - USDA HB 8-10.

     Table 2 presents the fat content/100 g of lean tissue  on  a
raw  basis  (g/100g  separable  lean)  as  well  as  g/85g cooked
separable-lean tissue. The Atwater conversion factor  to  convert
lipids to energy is 9.02 kcal/g of lipids and 4.27 kcals/g in the
case of protein, according to Anderson (1983).  Thus  in  85g  (3
oz.)  of  cooked  lean  from  the primal cuts, they range from 87
kcals originating from fat, out of a total of 187 kcals  for  the
lean  of  the  fresh leg (ham), to 148 from fat out of a total of
235 kcals from a serving of cooked lean from the blade portion of
the loin.

     The absolute fat content of the lean is  higher  for  cooked
than  for  raw tissue. This is believed to be due to two factors:
1) the weight reduction in  cooking  brought  about  by  moisture
losses  and  2) the transfer of subcutaneous or intermuscular fat
following rendering which occurs during the cooking process.   It
is  believed  that  this rendered fat invades the lean tissue and
thus becomes a part of the cooked lean,  insofar  as  extractable
fat  is  concerned.   It may well be useful, therefore, to remove
fat tissue before cooking as a means of reducing the contribution
of pork lean to dietary fat.

Table 3. Fatty acid profile1 of cooked pork lean.
                        Components            Fatty acids (FA's) 2
                    of 3 oz cooked lean  Expressed as a % of total FA's
                     Total Total fatty
Primal cut of lean  lipids    acids                        SFA's-stearic
tissue origin          g        g      MUFA's3PUFA's4SFA's5     acid
Leg, rump portion     9.47     8.79     48.4   11.1   37.3      25.5
  Shank portion       9.28     8.61     50.9    9.9   36.1      24.7
Loin, sirloin roast  11.24    10.29     47.5   10.4   39.0      26.4
  Rib chops, broiled 12.08    11.42     49.9    9.3   39.2      26.5
  Blade roast        16.61    15.79     47.9    8.9   40.7      26.8
Blade Boston
  Steak braised,     15.34    14.03     47.7    9.5   39.6      26.0
Arm picnic roast     10.63    10.18     50.1   10.0   36.7      24.9
1 Source - Slover et. al (1987).
2 FA's = Fatty Acids
3 MUFA's = Monounsaturated Fatty Acids
4 PUFA's = Polyunsaturated Fatty Acids
5 SFA's = Saturated Fatty Acids

Nutritive Value

     Challenges to the inclusion of pork in  the  U.S.  diet  are
concentrated  on  its fat, saturated fatty acids, cholesterol and
sometimes on its sodium content.  Most of the  reputable  dietary
guidelines,  according  to  the National Research Council (1988),
recommend curtailing human consumption of fat so that it  contri-
butes no more than 30% of caloric intake and that saturated fatty
acid intake be limited to less than 10% of caloric intake. It  is
then  further  recommended that dietary cholesterol be limited to
an average of not more than 300 mg/day.  Finally,  the  safe  and
adequate  intake  of sodium of 1100 to 3300 mg per person per day
(equivalent to about 2.8 to 8.5g of salt per day) is  also  typi-
cally recommended. Table 2 presents the lipid content for a 3 oz.
serving of a number of cuts of fresh pork as reported by Anderson
(1983). The fresh leg and the loin cuts, with the possible excep-
tion of the blade portion of the loin, and the Blade Boston would
certainly  be  acceptable  in fat content to most American consu-
mers. Fatty acid profiles derived  from  Slover,  et  al.  (1987)
shown  in  Table  3,  indicate that saturated fatty acids (SFA's)
constitute less than 40% of the fatty acids of all except one  of
the major pork cuts. Of the major pork cuts presented in Table 3,
the caloric contribution provided by fat ranges from a low of  84
calories to a high of 148 kcals per 3 oz. serving.  Spare ribs is
an exception in that it provides 233 kcals per 3 oz.  serving  of
cooked  lean  and  fat. If one were on a diet which provided 2000
kcals/day, the fat in a 3 oz. serving of  cooked  lean  from  the
primary  cuts, would provide between 4.25 and 7.5% of the caloric
requirements. From the data presented in Table 3, one can  deter-
mine  that  saturated fatty acids provide between 33 kcals and 68
kcals per 3 oz. serving of cooked pork lean. On the premise  that
stearic  acid  does not elevate serum cholesterol, as reported by
Bonanome and Grundy (1988), the  caloric  contribution  of  SFA's
that may elevate serum cholesterol is reduced to a range of 24-45

     Fresh pork is a nutrient-dense food, meaning simply that  it
makes  a  greater contribution to a number of nutrient needs than
to the energy requirements. In the case of pork in the 2000  kcal
diet,  it is nutrient-dense for an adult male with regard to pro-
tein, iron, zinc, thiamin, riboflavin, niacin  and  vitamin  B12.
Thus  one can properly describe pork as a very nutritious food in
that it is nutrient dense in more than four nutrients.

     Pork is a versatile food, and a high proportion of  pork  is
consumed  as  processed  meat. It is therefore, important to look
also at the processed meat component of the diet. Pork is a popu-
lar  meat  for  about  85%  of  the  U.S.  population.  While The
National Livestock and Meat Board estimates that only  12-15%  of
beef  and  lamb is eaten in processed form, between 65 and 75% of
pork is eaten in the  cured  and  processed  state  according  to
Breidenstein  and  Williams  (1986)-with  the  remainder eaten as
fresh.  The contribution of fresh pork to nutrient needs is  well
supported  by the nutrient profiles for fresh pork lean contained
in Table 4 as is true for processed pork as well.

Pork Consumption

     The composite of consumed pork in the United States in  1987
is presented in Table 4. Americans ingested about 1.5 oz. of pork
per person per day in a combination of fresh and processed forms.
Of that total the authors perceive that about 25% was consumed as
fresh product, whereas, the remaining 75% was  consumed  as  pro-
cessed  meat. In such a composite, as Table 4 shows, pork remains
a nutrient dense food in a 2000 kcal diet, providing only  6%  of
that daily energy need. In this regard, pork contributes a higher
percentage of the required iron, zinc, thiamin, riboflavin,  nia-
cin,  vitamin  B12  and  protein  than  its contribution to those
energy needs.

Table 4. Nutrient profile of pork as perceived to be ingested.
                              100 g                  Avg. daily
                 _________________________________    nutrient
Item              Fresh    Processed  Composite*   contribution**
Kcals             266.88     278.00     275.32         119.65
Protein, g         27.37      16.29      18.96           8.24
Lipids, g          16.61      22.62      21.17           9.20
Cholesterol, mg    96.12      57.00      66.44          28.88
Iron, mg            1.18       1.61       1.51           0.65
Zinc, mg            3.32       1.98       2.30           1.00
Sodium, mg         71.23    1077.00     834.21         362.55
Thiamin, mg         0.79       0.41       0.50           0.22
Riboflavin, mg      0.38       0.21       0.25           0.11
Niacin, mg          5.54       3.62       4.09           1.78
Vitamin B12, mcg    0.95       1.15       1.10           0.48
*Derived by (Fresh Profile  x  0.2414)  +  (Processed  Profile  x
**Based on daily ingestion of fresh and processed pork.


     The pig, as a member of the human food  chain,  has  evolved
into  a  highly  efficient  converter  of  grains and other plant
source materials into foods which are very  nutritious  and  also
highly  satisfying  to  the human palate. The most obvious change
which has occurred over  the  past  four  decades  has  been  the
increased  leanness  of  the  animal. As plant-source edible oils
have become much more available and at  very  economical  prices,
the demand that the pig produce edible food fats has been dramat-
ically reduced. The consumer demand for lower fat meats has  also
helped  accelerate  this  trend. Kauffman and Breidenstein (1983)
have estimated that the pig has increased in  leanness  by  about
23%.   Others  have estimated the improvement to be even greater.
The highly important characteristic about this change is that  it
has occurred while retaining the eating qualities expected by the
consumer. Thus, the pork  producer  can  take  great  justifiable
pride in producing food that is truly ``consumer friendly.''

Anderson,   B.   A.   1983.   Composition    of    foods:    Pork
products*raw*processed*prepared.  Agriculture  Handbook No. 8-10.
United States Department of Agriculture, Human Nutrition Informa-
tion Service.

Bonanome, A. and S. M. Grundy. 1988. Effect  of  dietary  stearic
acid  on  plasma  cholesterol and lipoprotein levels. New England
Journal of Medicine, May 12.

Breidenstein, B. C. and J. C. Williams. 1986. Contribution of red
meat to the U.S. diet. National Live Stock and Meat Board.

Forrest, J. C. 1989. Personal communications.

Kauffman, R. G. and B. C. Breidenstein. 1983. A red meat  revolu-
tion:    Opportunity  for  progress.  Food  and  Nutrition  News.
National Live Stock and Meat Board, September/October.

National Research Council.  1988.  Designing  foods.  Washington,
D.C.; National Academy Press.

Simonson, M. 1982. An overview: Advances in research  and  treat-
ment of obesity. Food and Nutrition News. National Live Stock and
Meat Board, March/April.

Slover, H. T., R. H. Thompson, Jr., C. S. Davis and G. V. Mervia.
1987. The lipid composition of raw and cooked fresh pork. Journal
of Food Composition and Analysis 1, 38-52.

NEW 6/90 (5M)


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