Effect of vitamin C addition to ground beef from grass-fed or grain-fed sources on color and lipid stability, and prediction of fatty acid composition by near-infrared reflectance analysis

Research was conducted to determine the effect of postmortem vitamin C addition (VITC) versus no VITC (CONTROL) to ground beef from grass-fed (GRASS) or grain-fed (GRAIN) sources on color and lipid stability during 8 days of illuminated display at 4 °C. The use of near-infrared reflectance (NIR) spectroscopy to predict the fatty acid composition of ground beef and its potential to discriminate samples from different nutritional backgrounds were also evaluated. Total lipid content of ground beef was 53% lower (P<0.05) for GRASS than GRAIN. Ground beef from GRASS had greater (P<0.01) percentages of saturated (SFA) and polyunsaturated (PUFA) fatty acids, and lower (P<0.01) percentages of monounsaturated (MUFA) fatty acids than GRAIN. For GRAIN, VITC reduced (P<0.01) lipid oxidation, and resulted in darker (P<0.01) and redder (P<0.01) color of the ground beef from 2 to 8 days of display compared to CONTROL. For GRASS, lipid oxidation did not differ (P>0.05) for VITC and CONTROL. VITC improved (P<0.01) color stability by prolonging more red color in GRASS during 8 days of display. Results from partial least squares modeling showed accurate predictions using NIR for total saturated [standard error of performance (SEP=1.16%), coefficient of determination on the validation set (r2=0.87)] and unsaturated (SEP=1.18% and r2=0.90) fatty acid contents of ground beef, as well as the composition of stearic, oleic, and linolenic (SEP=1.2%, 1.27%, and 0.07%; r2=0.91, 0.92, and 0.93, respectively). However, the composition of other individual fatty acids was poorly predicted. VITC was effective in retarding pigment oxidation in ground beef from both GRAIN and GRASS; however, VITC reduced lipid oxidation in GRAIN samples only, despite higher PUFA percentages in GRASS. NIR can be used to predict accurately the content of total saturated and unsaturated, and stearic, oleic, and linolenic fatty acids in ground beef. NIR showed potential to discriminate meat samples originating from different feeding production systems.