Young Scholar Presentation: Effects of Feeding Antioxidants to Steers Fed Microalgae (Aurantiochytrium limacinum CCAP 4087/2) on Color Stability and Palatability of Longissimus Lumborum Steaks

Previous research reports feeding increasing levels of microalgae to beef heifers increased concentrations of 20:5n-3 and 22:6n-3 fatty acids, but steak color stability was reduced and sensory panelists detected more off-flavors (Phelps et al., 2016). A follow up study was conducted to evaluate effects of feeding antioxidants to steers fed microalgae (MA; Aurantiochytrium limacinum CCAP 4087/2, Alltech, Inc., Nicholasville, KY) on color stability and palatability of Longissimus lumborum (LL) steaks. Steers (n=40) were blocked by initial BW (638±29 kg) and assigned to one of four treatments: 10% flaxseed diet (FLAX), FLAX diet plus 100 g∙steer^-1∙d^-1 MA (ALGAE), 100 g∙steer^-1∙d^-1 MA plus antioxidants (103 IU/d vitamin E and Sel-Plex; Alltech Inc.) fed throughout feeding (AOX), and 100 g∙steer^-1∙d^-1 MA plus antioxidants fed for the final 10 d of feeding (LATE). On d-45 steers were harvested, LL were removed after 48 h and aged 14 d. After aging, each LL was fabricated into steaks for simulated retail display and trained sensory panel analyses. Treatment did not affect steak juiciness, tenderness, or beef flavor (P>0.15), but impacted (P<0.01) off-flavor intensity of steaks. Steaks from FLAX steers had decreased off-flavor scores compared to steaks from ALGAE and AOX steers (P<0.03), but did not differ (P=0.07) from LATE steaks. Off-flavor scores of steaks from ALGAE steers were not different from steaks from AOX and LATE steers (P>0.10), but steaks from AOX steers had greater (P=0.04) off-flavor scores than steaks from LATE steers. There were treatment×day interactions for surface metmyoglobin and visual panel discoloration score (P<0.01). From d 0-5, there were no treatment differences for surface metmyoglobin percentage or discoloration score (P>0.10). On d-6, steaks from ALGAE steers had more metmyoglobin and a greater discoloration score than steaks from AOX and LATE steers (P<0.01), but were similar to FLAX steaks (P=0.18). From d 7-10, steaks from ALGAE steers had more metmyoglobin and a greater discoloration scores compared to steaks from the other treatments (P<0.03). Also from d 7-9, metmyoglobin percentage and discoloration score of steaks from AOX steers were similar to steaks from LATE steers (P>0.06), but AOX steaks had less metmyoglobin and reduced discoloration score compared to steaks from FLAX steers (P<0.04). When antioxidants were supplemented in diets containing microalgae, color of LL steaks was improved, but antioxidants did not combat off-flavors.