46C-25 |
Evidence of accelerated lipid oxidation during high-intensity ultrasonic processing |
R. SESHADRI1, E. Spencer, S. Marsch3, and J. Weiss. (1) Colloidal and Interfacial Food Science Laboratory, University of Tennessee, 2605 River Drive, Knoxville, TN 37996, (2) Universidad Autónoma de Querétaro, Av. Lomas No. 528-5, Colonia Lomas de Espanita, Irapuato, 36613, Mexico High-intensity ultrasound is increasingly being used in the food industry as an alternative processing technology. Two important application of power ultrasound are directly related to lipids: (a) emulsification (b) improved extraction of lipids from oil seeds. At present, no studies have been conducted that investigated the effect of high intensity ultrasound on the quality of the processed lipids. The objective of this study was to investigate the effect of application time and intensity level of power ultrasound on the lipid oxidation of sunflower oil. Sunflower oil was obtained from ACH Food Companies Inc, Memphis, TN. 100 ml of bulk oil was sonicated at intensity levels ranging from 0.2–40 W/cm2 for 0, 5,15 and 30min. respectively. The samples were kept at 25°C using a waterbath during sonication. The fatty acid content was analyzed using a HP 6890 gas chromatograph (Supelco SP-2380 Silica Capillary Column). TBA test were conducted following a standard procedure (AOCS Methods 5th edition). All chemicals were purchased from Sigma Chemicals. Thiobarbituric acid tests demonstrated that both sonication time and intensity level of ultrasound had an influence on malonaldehyde (MA) formation in ultrasonically treated sunflower oil. At intensity levels of 15 W/cm2, the MA content increased by a factor of more than 10 as the sonication increased from 0 to 30 minutes. As the sonication intensity increased, MA formation reached a maximum at approx. 5W/cm2. GC analysis of the fatty acid profile using hexane as a standard with identified peaks of methyl myristate, methyl palmitate, methyl palmitoleate, methyl stearate, cis-9-oleic methyl ester, methyl linoleate and methyl linolenate however remained inconclusive and showed only slight differences between sonicated and non-sonicated sunflower oil. Application of ultrasound for prolonged periods of time (> 15 minutes) and at high power levels may accelerate lipid oxidation and result in substantially decreased oil quality.
Session 46C, Food Chemistry: Lipids, antioxidants and emulsifiers
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