Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2001
Publication Date: 3/6/2002
Citation: BOLTON, G.E., SANDERS, T.H. EFFECT OF ROASTING OIL ON THE STABILITY OF ROASTED HIGH-OLEIC PEANUTS. JOURNAL OF THE AMERICAN OIL CHEMISTS' SOCIETY. 2002. V. 79. P. 129-132. Interpretive Summary: Improvement in the shelf life of roasted peanuts is of significant concern to peanut processors and optimum roast flavor is important to consumers. Peanuts with high oleic acid to linoleic acid ratio (O/L) have been developed which have significantly improved shelf life. Many peanuts are oil roasted and commercially available conventional oil is not high O/L oil. This study was conducted to determine the shelf life potential of hig O/L peanuts oil roasted in high O/L oil versus conventional oil. The study demonstrated that high oleic acid peanuts roasted in conventional oil had significantly decreased shelf life compared to those roasted in high O/L oil. The comparisons were made by examining the change in oil composition of the roasted peanuts and characteristics of peanuts during a 20-week storage at 30 C. The data indicate that manufacturers using oil roasted high O/L peanuts should use high O/L oil to gain maximum increase in shelf life.
Technical Abstract: Lipid degradation related off flavor is a limiting factor in shelf-life of peanut products. Use of peanuts with high oleic acid/linoleic acid (O/L) ratio (ca. 30) has the potential to improve shelf-life of roasted peanuts and peanut products. Use of conventional O/L ratio peanut oil (ca. 2) to roast high O/L peanuts may result in less than optimum shelf-life improvement. To determine the full potential for shelf-life improvement of oil roasted high O/L peanuts a study was conducted to examine the effects of roasting high O/L peanuts in high O/L or conventional peanut oil. High O/L peanuts were roasted at 177 C to Hunter L values of 49 plus or minus 1. O/L ratios of roasting oils were 23.2 and 1.5 for high O/L and conventional oils, respectively. Roasted peanuts were stored at 30 C for 20 weeks. Samples were taken at regular intervals to examine peroxide value (PV), oxidative stability index (OSI), moisture content and water activity (aw). Oil content in both treatments was 2-3 percent higher after roasting. O/L ratio of high O/L roasted peanuts was 27.9 vs. 13.6 for the conventional oil roasted peanuts. PV of conventional oil roasted peanuts was significantly higher than high O/L roasted peanuts after 4 weeks of storage. After 20 weeks of storage PV of conventional oil roasted peanuts was 10.8 compared to 5.3 for the high O/L roasted peanuts. OSI values were 88.5 and 52.4 immediately after roasting for the high O/L roasted vs. conventional oil roasted peanuts. Values for both treatments decreased but differences were similar throughout the storage period. Shelf-life of high O/L peanuts is decreased when roasted in conventional O/L peanut oil vs. high O/L peanut oil.