Chemical Composition and Oxidative Stability of Roasted and Cold Pressed Pumpkin Seed Oils

In the present study, the effects of three production processes (pressing of roasted pumpkin seed paste, pressing of unroasted ground pumpkin seeds and pressing of unroasted ground pumpkin seeds while cooling the press) on the properties of pumpkin seed oils produced from two seed varieties (husked and naked) were investigated. Oils produced with roasting had a higher initial peroxide value (PV), twofold higher total phenol content and better oxidative stability while cold pressed oils had higher tocopherol content. Fatty acid and triacylglycerol compositions were not significantly affected by the processing conditions. Oxidative stability of the oils positively correlated with oleic acid content and negatively correlated with linoleic and linolenic acid contents. The lack of correlation in oxidative stability with tocopherol and polyphenol contents suggests that improvement in oxidative stability of roasted oils could have been caused by antioxidative Maillard reaction products or inactivation of oil degrading enzymes. In addition, oils produced from husked seeds had significantly higher linoleic acid, triacylglycerols (TAG) containing mainly linoleic acid (LLL, OLL and PLL), tocopherol and phenol contents while oleic acid and TAG containing mainly oleic acid (LOO and OOO) contents and oxidative stability were lower. Principal component analysis (PCA) of the analytical data confirmed the observed differences between oils from two varieties and three production processes.

[1]  S. Wada,et al.  Influence of the position of unsaturated fatty acid esterified glycerol on the oxidation rate of triglyceride , 1983 .

[2]  Y. Younis,et al.  African Cucurbita pepo L.: properties of seed and variability in fatty acid composition of seed oil. , 2000, Phytochemistry.

[3]  M. Murkovic,et al.  Stability of pumpkin seed oil , 2000 .

[4]  H. Yoshida,et al.  Microwave roasting effects on the oxidative stability of oils and molecular species of triacylglycerols in the kernels of pumpkin (Cucurbita spp.) seeds , 2006 .

[5]  V. Gökmen,et al.  Impacts of roasting oily seeds and nuts on their extracted oils , 2010 .

[6]  Danny R. Bedgood,et al.  Endogenous biophenol, fatty acid and volatile profiles of selected oils , 2007 .

[7]  Michal Holcapek,et al.  Triacylglycerols profiling in plant oils important in food industry, dietetics and cosmetics using high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. , 2008, Journal of chromatography. A.

[8]  D. Gorbet,et al.  Polyphenolic content and sensory properties of normal and high oleic acid peanuts , 2005 .

[9]  D. Firestone.  Liquid chromatographic method for determination of triglycerides in vegetable oils in terms of their partition numbers: summary of collaborative study. , 1994, Journal of AOAC International.

[10]  M. Murkovic,et al.  Changes in chemical composition of pumpkin seeds during the roasting process for production of pumpkin seed oil (Part 1: non-volatile compounds) , 2004 .

[11]  C. Paquot.  1.121 – Determination of Moisture and Volatile Matter Content , 1979 .

[12]  M. Andjelkovic,et al.  Phenolic compounds and some quality parameters of pumpkin seed oil , 2010 .

[13]  P. Raspor,et al.  Stereospecific analysis of triacylglycerols as a useful means to evaluate genuineness of pumpkin seed oils: lesson from virgin olive oil analyses. , 2010, Journal of agricultural and food chemistry.

[14]  S. Nakić,et al.  Chemical characteristics of oils from naked and husk seeds of Cucurbita pepo L. , 2006 .

[15]  T. Gutfinger,et al.  Polyphenols in olive oils , 1981 .

[16]  P. Cabras,et al.  Determination of antioxidant compounds and antioxidant activity in commercial oilseeds for food use , 2007 .

[17]  M. Murkovic,et al.  Variability of fatty acid content in pumpkin seeds (Cucurbita pepo L.) , 1996, Zeitschrift fur Lebensmittel-Untersuchung und -Forschung.

[18]  E. Dimić,et al.  Shelf Life of Cold-Pressed Pumpkin (Cucurbita pepo L.) Seed Oil Obtained with a Screw Press , 2010 .

[19]  H. Yoshida,et al.  Relationship between oxidative stability of vitamin E and production of fatty acids in oils during microwave heating , 1991 .

[20]  Jaehwan Lee,et al.  Effects of roasting conditions of sesame seeds on the oxidative stability of pressed oil during thermal oxidation , 2010 .

[21]  Se-Wook Oh,et al.  Chemical composition and oxidative stability of safflower oil prepared from safflower seed roasted with different temperatures , 2004 .

[22]  P. Lewicki,et al.  Chemical Composition and Oxidative Stability of Selected Plant Oils , 2010 .

[23]  V. Gökmen,et al.  Changes in oxidative stability, antioxidant capacity and phytochemical composition of Pistacia terebinthus oil with roasting. , 2011, Food chemistry.

[24]  B. Rabrenović,et al.  Cold-Pressed Pumpkin Seed Oil Antioxidant Activity as Determined by a DC Polarographic Assay Based on Hydrogen Peroxide Scavenge , 2011 .