1/2006 - Potravinárstvo

Effect of heating parameters on oxidative stability of oils
Oxidative stability is an important parameter in evaluating
the quality of oils and fats and is greatly affected by their
fatty acid composition and minor components such as
tocopherol and tocotrienols. Induction period (IP, h) for
fresh as well as heated oils was in order: flaxseed oil <
walnut oil< linola oil. It is correlated with polyunsaturated
fatty acids content (especially with linolenic acid). The large
degree of linolenic acid in flaxseed oil reduced its stability.
Obtained results are with agreement with other authors, who
compared oxidative stability of different cold-pressed oils.
Bozan at al. (2008) stated that flaxseed oil exhibited the
lower oxidative stability in comparison with safflower and
poppy oils. Savage at al (1999) showed that walnut oils
were more unstable in the Rancimat test when compared to
hazelnut oil and that their oxidative stability depended
significantly on walnut variety. Such results suggest that
minor components play very important role and their natural
composition could significantly influence this quality
parameter. Because of that its quite popular to stabilize oils
with addition of natural or synthetic antioxidants (Rudnik at
al. 2001; Tabee at al. 2008).
Thermal degradation of fatty acids as well as other
compounds significantly decrease oxidative stability of oils
– especially rich in polyunsaturated fatty acids. This
changes could be correlated with colour changes, but it
should be followed by additional tests.
CONCLUSION
It has been stated that heating effected colour of all
examined oils. The changes, observed as colour darkening,
increased with heating time and temperature. During heating
of oils decreased L and b values and increased a value. The
biggest colour changes were observed for walnut oil while
the most stable colour had low-linolenic flaxseed oil. At the
same conditions (180ºC/120min) ∆E of walnut oil was 3
times higher than of linola oil.
Oxidative stability of oils decreased with increasing heating
temperature and time. At highest heating temperature the
oxidative stability of high-linolenic flaxseed and walnut oils
decreased 2 times faster than low-linolenic flaxseed oil. The
best properties, regardless of heating temperature and time,
exhibited low-linolenic flaxseed oil (linola).
REFERENCE
BOZZAN BERRIN, TEMELLI FERAL. 2008. Chemical
composition and oxidative stability of flax, safflower and poppy
seed and seed oils. In Bioresource Technology, 2008, 99, s.
6354-6359.
CHOO W. S., BIRCH E. J., DUFOUR J. P. 2007.
Physicochemical and stability characteristics of flaxseed oils
during pan-heating. In Journal of American Oil Chemist’s
Society, 2007, 84, s. 735-740 .
CHOO, WEE-SIM., BIRCH, JOHN, DUFOUR, JEAN-
PIERRE. 2007. Physicochemical and quality characteristics of
Potravinárstvo
cold-pressed flaxseed oils. In Journal of Food Composition and
Analysis, 2007, 20, s. 202-211.
HOSSEINIAN F. S., ROWLAND G. G., BHIRUD P. R.,
DYCK J. H., TYLER R. T. 2004. Chemical composition and
physicochemical and hydrogenation characteristics of highpalmitic
acid solin (low-linolenic acid flaxseed oil). In Journal
of American Oil Chemist’s Society, 2004, 81, s. 185-188.
MASKAN MEDENI. 2003. Change in colour and
rheorogical behaviour of sunflower seed oil during frying and
after adsorbent treatment of used oil. In European Food
Research Technology, 2003, 218, s. 20-25.
OOMAH B. DAVE, SITTER LAURIE. 2009. Characteristics
of flaxseed hull oil. In Food Chemistry, 2009, 114, s. 623-628.
RUDNIK E., SZCZUCINSKA A., GWARDNIAK H.,
SZULC A., WINIARSKA A. 2001. Comparative studies of
oxidative stability of linseed oil. In Thermochimica Acta, 2001,
370, s. 135-140.
SABUDAK TEMINE. 2007. Fatty acid composition of seed
and leaf oils of pumpkin, walnut, almond, maize, sunflower and
melon. In Chemistry of Natural Compounds, 2007, 43, s. 465-
467.
SAVAGE G. P., DUTTA P. C., McNEIL D. L. 1999. fatty
acid and tocopherol contents and oxidative stability of walnut
oils. In Journal of American Oil Chemist’s Society, 1999, 76, s.
1059-1063.
SIKORSKA, EWA, CAPONIO, FRANCESCO, BILANCIA,
MARIA T., SUMMO, CARMINE, PASQUALONE
ANTONELLA, KMELINSKII, IGOR V., SIKORSKI,
MAREK. 2007. Changes in colour of extra-virgin olive oil
during storage. In Polish Journal of Food and Nutrition
Sciences, 2007, 57, s. 495-498.
TABEE ELHAM, AZADMARD-DAMIRCHI SODEIF,
JÄGERSTAD MARGERITA, DUTTA PARESH. 2008.
Effects of α-tocopherol on oxidative stability and phytosterol
oxidation during heating in some regular and high-oleic
vegetable oils. In Journal of American Oil Chemist’s Society,
2008, 85, s. 857-867.
TZANG BOR-SHOW, YANG SHUN-FA., FU SHIH-GUEI.,
YANG HUI-CHUN. , SUN HAI-LUN., CHEN YI-
CHEN.2009. Effects of dietary flaxseed oil on cholesterol
metabolism of hamsters. In Food Chemistry, 2009, 114, s.
1450-1455.
WIESENBORN D., KANGAS N., TOSTENSON K., HALL
C., Chang K.2005. Sensory and oxidative quality of screwpressed
flaxseed oil. In Journal of American Oil Chemist’s
Society, 2005, 82, 887-892.
WRONIAK, MAŁGORZATA , KRYGIER KRZYSZTOF.
2006. Oleje tłoczone na zimno. In Przemysł Spożywczy, 2006,
7, s. 30-32.
Contact address:
Agnieszka Kita (PhD, DSc), Department of Food Storage and
Technology, Wrocław University of Environmental and Life
Sciences, ul. Norwida 25, 50-375 Wrocław, Poland, tel.: +48
71 3205038, e-mail: Agnieszka.Kita@wnoz.up.wroc.pl fax:
+48 71 3205221,
Ewa Płuciennik (MSc), Department of Food Storage and
Technology, Wrocław University of Environmental and Life
Sciences, ul. Norwida 25, 50-375 Wrocław, Poland
ročník 4 34 1/2010