methodologies to evaluate meat … to evaluate meat composition and quality ... tpa :texture profile...

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TECHNIQUES TO EVALUATE MEAT COMPOSITION AND QUALITY

TECHNIQUES TO EVALUATE MEAT TECHNIQUES TO EVALUATE MEAT COMPOSITION AND QUALITYCOMPOSITION AND QUALITY

Dr. Ma. ÀNGELS OLIVERDr. Ma. ÀNGELS OLIVER

Finca Camps i Armet, s/n

17121 Monells (Girona)

MEAT QUALITY CAN BE DEFINED WITH THE FOLLOWING PARAMETERS:

Co lo r

Water Holding Capacity

Texture

Intramuscular fat and fatty acid composition

pH

During the early post-mortem changes in muscles of slaughtered animals,

the pH falls from around 7.0 – 7.2 in the muscle of a living animal to 5.5 – 5.8

This final value is called ultimate pH (pHu), and its values are reached at

different post mortem times depending on species, muscle type and stress,

during the pre-slaughter period.

The reason for the pH fall is the formation of lactic acid from glycogen in the

anaerobic glycolysis.

Muscle pH: is the key in the conversion of muscle to meat

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pH

Normal

pH evolution during p.m. period in the LD beef muscle

Normal

DFD

5,5

6

6,5

7

0 10 20 30 40 50

Time (hours)

pH

pH evolution in some pig genetic lines

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5,5

6

6,5

7

pH45 pH3 pHu

pH

pH meters

pH how to measure

To predict PSE meat: at 45 min post-mortemTo predict DFD meat: at 24 h post-mortem

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Methods toevaluate:

SUBJETIVES

OBJETIVES

COLOR

Colour is a very important quality characteristic of the meat

Consumers related meat colour to the sensory properties of a product, or to fresheness .

Factors influencing meat colour:

- Pigment content (myoglobin and haemoglobin)- Ante and post-mortem conditions- Form and type of storage

Lighness= 42Lighness=36

Colour diferences related to ante-mortem treatment

COLOR

SIRLOIN: 24 h p.m.

DARFRESH: SKIN, vacuum;BLOOM :SKIN+MAP;

MAP: MODIFIED ATMOSFERE

Pakaging systems

COLOR

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DETERMINATION OF MEAT COLOUR OBJECTIVE METHODS

Lightness: is the atribute that better reflex the pH drop and final pH of themeat (100 to 0).Coordinate aCoordiante b

COLOR

CIE Colour space

Diffuse-reflected spectrophotometry:Colour, colour stability and quality defects

Hunter Lab System , 1958

CIELAB System, 1976

Instrumental methods

COLOR

Light illuminating : illuminant C illuminant D Standard observers: 2º and 10 º CIE, 1931, CIE 1967

COLORIMETERS AND SPECTROPHOTOMETERS: 400-730 nm visible region of the spectrum

Medium values of lightness (L*) and Chroma (C*) of 11 meat samples measured by CM200, CM2002, CM2600d, IS-CAS140B

Poultry

Rabbit

GoatPork VealLamb

Mutton Beef 12 m

CowBeef 17 m

DFD20

30

40

50

60

70

0 10 20 30

C*, Chroma

L*, L

ight

ness

COLOR

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Pigment content : HORNSEY method

COLOR

It is the ability of the meat to retain its water during

cutting, heating and pressing

WATER HOLDING CAPACIY

DRIP LOSS : is the amount of exudate in the meat surface


HOW TO PREDICT

Electrical conductivity (Oliver et al.1990)

Impedances (Madsen et al, 1999; Oliver et al., 2001)

HOW TO QUANTIFY THE DRIP LOSS:

On line Method (Rasmussen and Andersson, 1996)

Reference Method BY OCDE (Honikel, 1996)

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(Honikel)



(Rasmusen)

TECHNOLOGIES:Texturometers: Instron

OF THE MEAT

muscle fibresconnective tissueintramuscular fatwatermuscular pH

Warner-Brazler: shear force: (Moller, 1980)

different type of test

TPA :texture profile analysis: (Bourne, 1978)

The objective is to try to mesure the tenderness of themeat by objective test:

- Instrumentaly or Sensory panel

This is a simple word that means a very difficult concept.

TEXTURE

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3 cm

1,5 cmShear Force (N)

t (s)

Total Energy(Kg.cm)

Modul (N/cm)

Shear Value (N)

Si ↑ Shear Value HardnessSi ↑ Modul ElasticitySi ↑ Total Energy Chewiness

↑

↑

↑

OF THE MEAT

TEXTURE

WARNER-BRATZLER TEST: STANDARISATION ON THE PREPARATION OF SAMPLES AND COOOKING METHOD

TPA (Texture profile analysis)

TEXTURE


TEXTURE

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SPRINGINESSCOHESIVENESSCHEWINESSGUMMINESSHARDNESS


TEXTURE

Intramuscular fat and fatty acid

composition contributes to the caloric

content of meat, but also have an effect

on the texture and the flavour

of the meat

Both components (quantity of fat and its

quality) affect consumers´health

INTRAMUSCULAR FAT AND FATTY ACID COMPOSITION

Chemical methodology How to quantify:


a) Reference Method (1986)Acid hydrolysis + ether extractionPhospholipids + Tryglicerids (Method 1) Ether extraction without acid hydrolysis Tryglicerids(Method 2)

Method 1 = 1.2 x method 2 (ether extraction only)

b) Folch method (1957)Extraction of fat using 3 : 1 mixture of chloroform : methanolExtraction of all lipids

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NIT Near Infrared TransmitanceNIR Near Infrared Reflectance

(from 800 to 2500 nm.)(Indirect methods, they need an equation of Calibration)

Gas Chromatography (Díaz, 1994)

HOW TO QUANTIFY

Gispert et al. (1997)Windham y Morrison (1998)

Physical Methodologies

HOW TO PREDICT


NIT o NIR tecnhology


% of Intramuscular fat


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GRIN IN AUTOCTHONOUS BREED :BLACK MAJORCA PIG AND IBERIAN PIG


% INTRAMUSCULAR FAT > 8%

FATTY ACIDS:OLEIC ACID> 55%LINOLEIC ACID<15%

FATTY ACID COMPOSITION OF THE MEAT IN DIFFERENT SPECIES

BEEF LAMB PIG RABBIT IDEAL VALUE

FATTY ACIDSSaturated (%) 41% 44% 35% 38% «MUFA (%) 46% 40% 40% 22% »PUFA (%) 5% 5% 20% 36% <15%

Cholesterol mg/100 g 70 70 60 60 «n-6/n-3 2 1 8 11 4<

P/S 0,1 0,1 0,5 0 0,5 o >


[email protected]

THANK YOU FOR YOUR ATTENTION

methodologies to evaluate meat … to evaluate meat composition and quality ... tpa :texture profile...

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