Chemical and lipid composition of buffalo meat as affected by different cooking methods

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Chemical and lipid composition of buffalo meat as affected by different cooking
methods

M. Juárez1, S. Failla2, A. Ficco2, F. Peña1, C. Avilés1 & O. Polvillo1
1MERAGEM Research Group, University of Cordoba (Spain), Edif. Gregor Mendel, Campus Rabanales,
14071, Cordoba. (Spain), Email: juarez@us.es.
2C.R.A.- PCM Monterotondo, 00015, Rome (Italy), Email: sebastiana.failla@entecra.it.

Abstract
Buffalo meat is considered in Italy as an alternative product for its good nutritional characteristics. The
influence of three cooking methods (boiling, grilling and frying) on the chemical and lipid composition of
buffalo meat was evaluated. All the treatments reduced the moisture and increased protein, ash and fat
content. That increase in fat content was higher after frying due to the incorporation of fat from olive oil. The
lipid fraction proportions were affected by boiling, in which phospholipids increased, and by frying, in which
glycerides increased. Grilling had no effect on lipid fraction proportions. Fried meat had lower saturated fatty
acid content in all the lipid fractions considered due to the incorporation of mono-unsaturated (C18:1) and
poli-unsaturated fatty acid (C18:2) from oil. That incorporation of oil fatty acids caused a decrease of n-3
fatty acids and conjugated linoleic acid relative content. Grilling decreased trans fatty acid content in the free
fatty acid fraction, and frying did it in the glycerides fraction. Boiling and grilling increased thiobarbituric
acid reactive substances, while frying had no effect on them.

Introduction
Human nutritionists are recommending a higher intake of polyunsaturated fatty acids (PUFAs) and especially
of n-3 fatty acids at the expense of n-6 fatty acids (Department of Health, 1994). Besides the beneficial
effects of PUFA for human health , the conjugated linoleic acid (CLA) isomers have received much attention
for their health promoting effects (Pariza et al., 2001). On the other hand, trans fatty acids have deleterious
health effects (Stender and Dyerberg, 2004), and recommendations to decrease their intake have been
promoted during the last decade (WHO, 2003).
Buffalo meat is considered in Italy as an alternative healthy product for its good nutritional characteristics.
However the nutritive value of buffalo meat can be affected by cooking methods. The effects of different
cooking methods on nutritive values of different meats have been previously studied (Vasanthi et al., 2007).
Therefore the aim of this project was to study the influence of three cooking methods (boiling, grilling and
frying) on the chemical and lipid composition of buffalo meat.

Material and methods
Sampling and cooking
Ten male buffalos were reared at the same farm and under the same production system until they reached the
slaughter weight (380 kg). At the abattoir, samples from longissimus dorsi muscle were collected, sliced,
packed and aged for three days at 2ºC.
The samples were cooked by frying, boiling, and grilling. Olive oil was used for pan-frying. The temperature
of oil during the frying process was 180ºC and the internal temperature of the meat reached 84±1.7ºC. For
the boiling process, the samples were dipped into boiling water until 85±3.2ºC internal temperature was
reached. The grilling process was carried out with an electrically operated grill at 180ºC until an internal
temperature of 89±0.7ºC was reached. After the cooking processes, the samples were homogenised using a
kitchen blender.
Meat quality analysis
AOAC methods (1990) were used for moisture, protein and ash determinations. The lipids were extracted
and purified according to the method of Folch et al. (1957). Total intramuscular lipids were separated into
neutral lipids (glycerides), free fatty acids (FFAs) and polar lipids (phospholipids) according to the method
described by Pinkart et al. (1998). Contents of fractions were quantified, and the results were expressed as a
percentage of the total weight obtained. The fatty acid composition of each fraction was determined by gas
liquid chromatography of methyl esters, prepared in basic conditions (KOH:methanol) for glycerides and
phospholipids and acidic conditions (H2SO4:methanol) for the FFAs. The gas chromatograph was a Varian
3900 equipped with a flame ionization detector and the column was an Agilent HP-88 column (Agilent
Technologies Spain, S.L., Madrid) (100 m, i.d. 0.25 mm x 0.2 ?m). Fatty acid proportions from the three

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fractions were expressed as percentage of the total fatty acids. Finally, the extent of lipid oxidation was
assessed by the thiobarbituric acid substances (TBARS) method described by Bruna et al. (2001).
Statistical analysis
Significant differences between means of experimental data were determined by ANOVA using Statistica
7.0 software (StatSoft Inc., www.statsoft.com ).

Results and discussions
Table 1 shows proximate composition, lipid fraction percentage and TBARS content. Changes in moisture,
protein, ash and fat contents were found to be significant (P<0.001) for all cooking methods. The treatments
reduced the moisture and increased protein, ash and fat content. That increase in fat content was higher after
frying due to the incorporation of fat from olive oil. The lipid fraction proportions (P<0.001) were affected
by boiling, in which glycerides decreased and phospholipids increased, and by frying, in which glycerides
increased and phospholipids decreased. The decrease of glycerides fraction during boiling may be due to the
thermal hydrolysis and the increase of that fraction during frying was due to the incorporation of
triglycerides from olive oil. That increase in the amount of phospholypids leads to a decrease in the
percentage of the other two fractions. Regarding to FFAs content, the levels found after the three cooking
methods were lower than those of raw meat. It may be due to the migration of FFAs from muscle to other
locations, as water or oil. The loss of volatile FFA and the deactivation of enzymes occurred during heating
may also explain the decrease of FFAs.
Boiling and grilling increased thiobarbituric acid reactive substances (P<0.001), while frying had no effect
on them. The increase in the TBARS values after boiling and baking could be due to the high temperature.
However, during frying the malonaldehyde eventually formed could be lost either by dissolution in the
frying oil or due to formation of adducts with proteins (Weber et al., 2008).

Table 1. Proximate and lipid fraction composition (%) and TBARS content (mg malonaldehyde/kg meat) of
raw and cooked buffalo meat
Raw
Boiled
Grilled
Fried
Sig
Moisture 73.54±0.215a 63.79±0.263b 61.23±0.301c 56.50±0.476d ***
Ash
1.13±0.007d 1.32±0.014c 1.97±0.024b 2.27±0.062a ***
Protein 18.33±0.082d
26.87±0.105c 28.12±0.102b 29.73±0.071a ***
Fat 1.72±0.153c
3.20±0.212b
3.44±0.177b
6.30±0.282a
***
Glycerides 52.54±0.402b 41.63±0.360c 54.31±0.443b 62.53±0.559a ***
FFA 17.44±0.276a
13.66±0.290b
14.29±0.395b 13.61±0.437b ***
Phospholipids 30.01±0.978b 44.70±1.256a 31.39±1.102b 23.85±0.770c ***
TBARS 1.32±0.010c 1.50±0.053b 1.92±0.081a 1.39±0.031c
***
Sig.: Significant differences; *** = p<0.001

Table 2 shows the fatty acid composition in the three lipid fractions. Fried meat had lower SFA content
(P<0.001) in the three fractions due to the incorporation of MUFA (C18:1) and PUFA (C18:2) from oil. That
incorporation of oil fatty acids caused a decrease of n-3 fatty acids and CLA relative contents (P<0.001).
Grilling decreased trans fatty acid content (P<0.001) in the FFAs fraction. Frying decreased trans fatty acid
percentage in the glycerides fraction. Möllenken (1998) concluded that trans fatty acids would be difficult to
form unless a severe cooking condition was used. Therefore, if trans fatty acids were not formed during
frying, the decrease of its percentage would be again explained by the incorporation of other fatty acids from
oil.

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Table 2. Fatty acid indices (% of total fatty acids) of glycerides, free fatty acids and phospholipids fractions
of raw and cooked buffalo meat
Raw Boiled Grilled Fried Sig
Glycerides

SFA 49.78±0.182b
52.07±0.446a
52.46±0.246a 40.84±0.342c ***
MUFA 46.74±0.291b 43.69±0.439c 43.47±0.338c 53.69±0.280a ***
PUFA 3.53±0.116c 3.97±0.147b 3.80±0.190bc 5.71±0.179a ***
CLA 0.34±0.049a 0.30±0.013a 0.31±0.031a 0.06±0.005b ***
n6/n3 6.66±1.160c 8.63±0.878b 7.68±0.529bc 27.90±1.802a ***
Trans 1.00±0.101a 1.11±0.095a 1.17±0.114a 0,57±0,045b ***

Free Fatty Acids

SFA 90.62±0.808a
89.02±2.088a
90.75±1.436a 84.08±0.529b
***
MUFA
5.24±0.414b 6.59±1.371b 5.67±0.971b 11.5±0.261a ***
PUFA 4.11±0.561ab 4.33±0.778a 3.55±0.382b 4.54±0.407a **
CLA 0.17±0.073a 0.10±0.018b 0.09±0.275b 0.01±0.002c ***
n6/n3 8.08±0.239a 6.84±0.397b 6.79±1.452b 6.70±1.556b ***
Trans 1.37±0.278a 1.55±0.473a 0.76±0.243b 1.56±0.107a ***

Phospholipids

SFA 39.76±0.952a
35.57±0.349b
39.31±0.609a 36.44±0.797b
***
MUFA 19.74±0.883 19.81±0.467 19.45±0.460 20.25±0.620 ns
PUFA 40.49±1.579b 44.52±0.579a 41.31±0.712ab 43.07±1.109a ***
CLA 0.11±0.002a 0.13±0.034a 0.09±0.009a 0.07±0.057b ***
n6/n3
8.49±1.469 8.15±0.769 10.39±1.782 8.66±1.003 ns
Trans 0.50±0.074a 0.35±0.046b 0.46±0.076ab 0.44±0.053ab *
Sig: Significant differences. ns = p>0.05; * = p<0.05; ** = p<0.01; *** = p<0.001

Conclusions
All the cooking methods evaluated changed proximate composition, oxidation parameters and fatty acid
profile of the Buffalo meat. Changes in proximate composition were more prominent in fried meat. Only
boiled and grilled meat had increased levels of TBARS, indicating oxidative changes, but they did not reach
threshold levels for preventing human consumption. The fat content in fried samples significantly increased
due to absorption of fat by the meat. Fatty acid profile was greatly affected by cooking methods. There were
significant increases in PUFAs of glycerides, phospholipids and FFA in meat after frying. However CLA and
n-3 fatty acid relative content decreased, leading to a worse n-6/n-3 ratio. No trans fatty acid formation was
observed for any culinary treatment.

References
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