cutting edge fat quality

7/30/2019 Cutting Edge Fat Quality

1/4

Pork Fat Quality

F I R S T Q U A R T E R 2 0 1 0

N e v e r s t o P i m P r o v i N g

As commercial pigs have become leaner over

the past 20 years, at quality has become one

o the key traits dening overall carcass value.

Fat quality has received heightened awareness

over the past ew years as eed prices have

increased, resulting in least-cost ormulated

diets using ingredients that may compromise

at quality. Many actors can contribute to

at composition (and quality). Some o these

actors include: genetics, diet, leanness/

atness, growth rate, age/body weight, gender

and anatomical at location (7,15). O these

actors, diet is the key actor that we can use

to quickly infuence at

quality, as the non-diet

actors are less easible

to alter substantially to

improve at quality. This

issue o Cutting Edge

addresses the biological,

dietary and commercial

aspects o at quality and

means to control them inproduction systems.

Effect of Fat Quality on

Pork Products

Fat quality can be best defned by the frmness

o the at. Sot at oten leads to at layer

separation in loins and may be partially

responsible or muscle separation in the ham

and shoulder (10). Sot at in bellies has been

implicated in causing reduction in slicing yields;

however, most large-scale commercial sliceyield studies do not indicate that slice yield is

decreased by sot at. It is generally agreed

upon that sot at causes problems with product

appearance when packaged (9). Sot at can

lead to bacon that has an oily/wet appearance

that may oten be transparent, oers no slice

defnition when packaged under vacuum, and

leads to aster oxidation rates (rancidity).

Sot at can also lead to product appearan

issues with sausage and can lead to redu

yields in emulsion products like bologna (

Generally, sot at produces reduced prod

workability and appearance with an

increased propensity or rancidity to deve

Biology of Fat

An understanding o at chemistry is

essential to understanding basic at quali

Fat is composed o at (triglycerides =

glycerol + atty acids), water, and protein

Fatty acids can be

classied into thre

categories based

on their chemical

structures (or

saturation level): 1

saturated atty aci

- no double bonds

2) mono-unsatura

atty acids - onedouble bond; and

polyunsaturated a

acids - two or mo

double bonds. Th

saturation o atty acids dictates the melt

point o a at (rmness), with a highly

saturated at having a higher melting poin

(rmer) than an unsaturated at.

Dietary ats and carbohydrates are the

sources o long chain atty acids or

synthesis o ats in mammals (13). Dietaats are readily converted to carcass at a

carcass at ormed in this manner takes

the general characteristics o the dietary

(sot dietary at = sot carcass at). Dieta

carbohydrates are converted to body at

through a process called de novo atty

acid synthesis, orming predominantly

Due to the severe economic crisis our

industry has been enduring over the last

two years, it is plausible to assume that a

close collaboration between the many seg-

ments o our industry will only be acceler-

ated. That evolution will, in turn, enhance

the industrys ability to better develop and

implement strategies to sustainably produce

the most desirable carcass (raw materi-

als) at the least cost. This issue o Cutting

Edgeaddresses the biological, dietary and

pork processing aspects o at quality and

discusses the means to economically bal-

ance pig growth rate, eed conversion ratio

and lean deposition with desirable carcass

at content and quality.

Andrzej A. Sosnicki, PhD.

Director, Perormance Validation Program

For additional information about the

results reported here, please contact

Neal Matthews, [email protected]

and Steve Jungst, [email protected]

Cutting

EDgE

Fat quality has

received heightened

awareness over the past

few years as feed prices

have increased, resulting

in least-cost formulated

diets using ingredientsthat may compromise

fat quality.


2/4

Fatty Acid OSF ISF INMF ITMF

C14:0 0.07 0.15 0.18 0.09

C16:0 0.50 0.30 0.79 0.32

C16:1 0.20 0.36 0.22 0.20

C18:0 0.54 0.51 0.51 0.40

C18:1 0.26 0.28 0.44 0.36

C18:2 0.44 0.32 0.39 0.44

Melting point 0.56 0.61 - -

Heritability Estimates

OSF = outer subcutaneous fat; ISF = inner subcutaneous fat; INMF = inter-muscular fat; ITMF = Intramuscular fat.

Adapted from Suzuki et al.(18)

Table 1. Heritability Estimates of Fatty AcidsAdapted/calculated from Scott et al.(16)

Figure 1. Effect of Fatness on Iodine Value

60.00

67.50

75.00

82.50

90.00

Iodin

eValue

saturated and monounsaturated atty acids (13), which yield a

rmer carcass at. Although dietary carbohydrates are used to

synthesize atty acids, most mammals, including the pig, are

not able to incorporate a double bond past the 9 position in a

de novo synthesized atty acid (13). Thus, pigs can only orm

saturated and monounsaturated atty acids rom carbohydratesand require the essential atty acids (polyunsaturated atty

acids, such as linoleic acid) rom a at source in the diet to

incorporate polyunsaturated atty acids into the at o the

carcass (13). Dietary at additions will alter or even shut down

de novo at synthesis (13). Thus, as the percentage o at is

increased in the diet, de novo atty acid synthesis is urther

inhibited, resulting in less saturated at deposition (soter).

Furthermore, as the atty acid prole o dietary at becomes

less saturated (soter), pig body (and carcass) at also becomes

less saturated (soter).

Metrics of Fat Firmness

The current standard measure o at rmness is iodine

value. Iodine value is a measure o the unsaturation o ats

and is expressed in terms o the amount o iodine absorbed

by a at sample. Basically, the iodine value (IV) determines

the unsaturation level o the at through the number o double

bonds in the atty acids.

Saturated at = low iodine value = rm at

Unsaturated at = high iodine value = sot at

Most commonly in the pork industry, iodine value is

determined by direct chemical methods (i.e. Hanus

method), atty acid analysis [IV = (C16:1*0.95)+(C18:

1*0.86)+(C18:2*1.73)+(C18:3*2.62)+(C20:1*0.79)],

or through Near Inra-Red (NIR) methods. The atty acid

analysis method is currently the most common method

o analysis, but NIR analysis will likely become more

prevalent in the uture due to reduction in labor intensity

and speed o sample determination.

Other objective measures o at rmness may include

assessing the linoleic acid content (C18:2) o at, because

it is the most prevalent polyunsaturated atty acid in pork

at and oten dictates its iodine value. Many companies

the bend/bar/fex method o assessing rmness o bellie

or loins, which involves draping the belly/loin over a bar

assessing the rmness by measuring the amount o dro

over the bar. Minolta colorimeter readings can be used

assess at color because higher levels o linoleic acid shogive the at a more yellowish color. Within the pork indu

subjective rmness assessments have also been used to

assess rmness o products such as loins, bellies, and b

These subjective measures are normally user-dened an

unique to the plant/company in which they are develope

Genetic Effects on Fat Firmness

Pig genotype has been shown to have an eect on at

rmness by numerous researchers (2,5,12,16,18). Herit

estimates (i.e. proportion o the total phenotypic variation

in a population or a trait that is attributable to the additieect o the genes) have been reported or several atty

indicating there is genetic variation or atty acid compos

and at quality (Table 1).

Some o the atty acids (C16:0, C18:0, C18:1, and C18:

and the melting point o at have been ound to have low

(i.e. 0.40

heritabilities (18). Although dierences between genotyp

exist, most o the dierence due to at rmness between

genotypes can be attributed to atness o the genotype (

Adapted/calculated from Scott et al.(16)

Table 2. Genotype Effectson Leaness and Fat Firmness

Trait L X L W Hybrid

Carcass weight, kg 134.93 132.03

Backfat thickness, mm 39.48 29.22

Iodine Value 65.22 69.69

Trait L W Duroc Hampshire

Carcass weight, kg 68.5 67.3 71.8

Lean percentage, % 54.3 56.0 56.8

Iodine Value 61.8 66.0 66.0

**Adapted/calculated from Lo Fiego et al. (12).

**Adapted/calculated from Barton-Gade (2).


3/4

Typically as the degree o atness increases, the at becomes

more saturated or rmer. For example, it was ound that the

dierence between lean and obese pigs (selected or either

lower or higher levels o backat thickness derived rom the

same population o pigs) had a dramatic eect on atty acids,

which equates to around 9 IV units dierence (16; Figure 1).Other research has also ound similar results when comparing

genetic lines having dierent atness/leanness levels (2,12;

Table 2) or when assessing the eect o backat on iodine

value (8; Figure 2). Furthermore, some reports have indicated

that aster growing animals have rmer at (7). The dierence

in at rmness between most modern genetic lines should

be minimal, assuming comparisons are made on animals

with similar backat levels (or % lean), live weights, and/or

nutritional planes.

Other Non-Nutrition Effects on Fat FirmnessAnatomical location o the at can also infuence its rmness.

This has been demonstrated when comparing at rom the

jowl and backat, or even when comparing the individual at

layers o backat (1,3; Figure 3). Gender can also have an

eect on at quality, which is to be expected because gilts are

typically leaner than barrows and, as previously mentioned,

leaner animals generally have soter at. The dierence

between barrows and gilts or iodine value is typically1-2

IV units. Research has evaluated the eect o age or body

weight on atty acid composition. It has been shown that

rom 70 to 220 days o age, saturated atty acids increase

and unsaturated atty acids decrease, implying at becomes

rmer as a pig gets older (15). Reports have indicated

improvements in at rmness up to the 250 to 265-lb. range

(1,11). Correa et al., (7) indicated little dierence in atty

acid composition at weights o 236, 254, or 276 lbs., but

data rom Lo Fiego et al., (12) indicated that at rmness was

improved up to 350 lbs.

Nutritional Effects on Fat Firmness

Pig diets are one o the most important actors in ensuring

or changing the atty acid prole rom the standpoint that

the diet can be altered more readily than non-dietary

infuences on at quality. The importance o nutrition

can probably be best exemplied by the volume

o research that is conducted concerning dietary

infuences o at quality vs. the research assessing

non-dietary eects on at quality. This literature is

replete with research evaluating dietary at sources,

inclusion levels o at sources, and eed ingredients

that can potentially aect at quality (i.e. at sources,

DDGS, CLA or ractopamine). For the most part, these

studies agree with the previously mentioned general

at biology principles as related to dietary at (i.e.

as the percentage o at is increased in the diet, de

novo atty acid synthesis is urther inhibited, resulting in less

saturated/soter at and as the atty acid prole o dietary

at becomes less saturated/soter, carcass at becomes less

saturated/soter).

The iodine value product (IVP) concept (6) is based on these

principles and is calculated using the ormula: IVP = (iodinevalue of the feed source fat) X (% of fat in the feed source)

X 0.10. Table 3 contains IVPs o some selected dietary

ingredients. Formulas have been developed that estimate

the iodine value o carcass at based on the iodine value

product o the diet. The ollowing equation developed by PIC

Adapted/calculated from: Ellis and McKeith (8)

Figure 2. Effect of Backfat Thickness on IV

60.0

61.8

63.5

65.3

8mm 12mm 16mm

67.0

Iodine

Value

Table 3. Iodine Value Productof Selected Feed Ingredients

Ingredient % Fat

Feed Ingredients

Corn 125 3.9 49

Soybean meal130 3.0 39

Wheat 125 1.6 20

Peanut meal 92 6.5 60

Corn distillers grain 125 7.9 99

Bakery product 86 7.3 63

Common Fat Sources

Beef tallow 44 99.0 436

Choice white grease 60 99.0 594

Lard 64 99.0 634

Poultry fat 78 99.0 772

Restaurant grease 75 99.0 743

Alternative Fat Sources

Corn oil 125 99.5 1244

Soybean oil 130 99.5 1294

Coconut oil 10 99.5 100

Palm oil 50 99.5 498

Iodine Valueof the fat

Iodine ValueProduct

50.00

60.00

70.00

80.00

90.00

IodineValue

Adapted from Apple et al. (1)

Figure 3. Effect of Fat Location on Iodine Value

Inner Backfat Layer Middle Backfat Layer Outer Backfat Layer

50.00

60.00

70.00

80.00

90.00

IodineValue

Adapted from Benz et al. (3)

Backfat Jowl


4/4

cutting edge fat quality

Documents