Oxidative stability of Menhaden/Soybean oil blends

With the approval of menhaden oil pending, the food industry is trying to incorporate marine oils high in omega-3 fatty acids into food systems. The main problem obstructing its use as a food ingredient is fishy/painty flavors which occur with low levels of oxidation. The purpose of this study was to follow the formation of volatile compounds in menhaden/soybean oil blends and to correlate total volatiles with sensory odor scores. Specially Processed Menhaden Oil (SPMO) was supplied by Zapata Haynie Corporation (Reedville, VA). Blends of 0%, 10%, 20%, and 100% menhaden oil were stored for 15 weeks at 22 C, in the dark, with air in the headspace. Peroxide Value (PV) was measured. The amounts of pentane and total volatiles produced were measured using the Shimadzu static headspace attachment for the Shimadzu GC-9A capillary gas chromatograph. Total volatiles also were followed using direct injection volatile analysis. Retention times for selected volatiles were compared with those of known standards. Sensory analysis was completed using a modified version of the AOCS oil odor/flavor scorecard, with a panel of 12 trained judges. There was a significant increase in PY for each blend over the 15 week period (p<0.05). Pentane and total volatiles for the 0%, 10%, and 20% oils increased toward the end of the study but not significantly. Odor intensity scores did not increase over the 15 week period for any of the oils. The fifteen-week study period may not have been long enough for sufficient development of volatiles in the 0%, 10%, and 20% oils. The inclusion of the 100% menhaden oil altered the perceptions of the sensory panel since it had a much stronger fishy/painty odor. This caused the differences in the other oils to be overshadowed and poor correlations between sensory evaluation scores and PV and volatiles were obtained. Conditions responsible for the development of off-flavors in menhaden/soybean oil blends need further study before the commercial use of marine oils in food products is feasible.