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Refractive Index and Density Measurements of Peanut Oil for Determining Oleic and Linoleic Acid Contents

Journal of the American Oil Chemists' Society volume 90, pages 199–206 (2013)Cite this article

Abstract

Peanut seed are approximately 50 % oil of which >80 % is either oleic or linoleic acid. The oleic/linoleic acid (O/L) ratio largely influences oxidative stability and hence peanut shelf life. Traditional peanut seed have O/L ratios near 1.5–2.0; however, many new cultivars are “high oleic” with O/L ratios ≥9. During peanut seed handling, contamination among lots may occur. A cost effective method to rapidly differentiate peanut seed based on O/L ratio is needed across multiple segments of the industry, and measurements of oil density and oil refractive index (RI) were evaluated for this potential. Fatty acid profiles of samples from normal and high oleic seed lots, and blends of these oils, were determined by traditional gas chromatography analysis and this data compared to corresponding oil density and RI measurements. Oleic acid content, linoleic acid content, density and RI were all strongly linearly (R 2 > 0.98) correlated for oil blends with O/L ratios from ~2 to 16. Threshold density or RI values both showed excellent potential for rapidly differentiating samples with an O/L ≥ 9; however, sample volume requirements preclude density measurements on single seed.

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Authors and Affiliations

  1. USDA ARS - Market Quality and Handling Research Unit, North Carolina State University, Department of Food, Bioprocessing and Nutrition Sciences, 236C Schaub Hall, Raleigh, NC, 27695, USA

    Jack P. Davis

  2. Technical Center, The Hershey Company, 1025 Reese Ave, Hershey, PA, 17033, USA

    Daniel S. Sweigart

  3. USDA ARS - Market Quality and Handling Research Unit, 226 Schaub Hall, Raleigh, NC, 27695, USA

    Kristin M. Price

  4. USDA ARS - Market Quality and Handling Research Unit, North Carolina State University, Department of Food, Bioprocessing and Nutrition Sciences, 236D Schaub Hall, Raleigh, NC, 27695, USA

    Lisa L. Dean

  5. USDA ARS - Market Quality and Handling Research Unit, North Carolina State University, Department of Food, Bioprocessing and Nutrition Sciences, 236A Schaub Hall, Raleigh, NC, 27695, USA

    Timothy H. Sanders

Authors
  1. Jack P. Davis
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  2. Daniel S. Sweigart
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  3. Kristin M. Price
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  4. Lisa L. Dean
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  5. Timothy H. Sanders
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Correspondence to Jack P. Davis.

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The use of trade names or instruments in this publication does not imply endorsement by the United States Department of Agriculture-Agricultural Research Service.

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Davis, J.P., Sweigart, D.S., Price, K.M. et al. Refractive Index and Density Measurements of Peanut Oil for Determining Oleic and Linoleic Acid Contents. J Am Oil Chem Soc 90, 199–206 (2013). https://doi.org/10.1007/s11746-012-2153-4

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  • DOI: https://doi.org/10.1007/s11746-012-2153-4

Keywords

  • Density
  • Refractive index
  • Peanut
  • Peanut oil
  • High oleic
  • O/L ratio