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Applying Pulsed Ultraviolet (UV) Light to Reduce Surrogates on Beef Suprimal Surfaces
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The objectives of this study were: (1) to evaluate effectiveness of pulsed-UV light in reducing the presence of E. coli Biotype I surrogate microorganisms on beef subprimals, and (2) to evaluate the impact of pulsed-UV light on quality parameters, including color, aroma, purge, pH, and aerobic plate counts (APC) of steaks cut from UV-treated subprimals and aged for 0, 7, 14, and 21 days. Beef striploins were subjected to combinations of distance from the UV light source and conveyor belt speed: (1) light height 5 cm, belt speed = 0.074 m/s; (2) light height 28 cm, belt speed = 0.074 m/s; and (3) light height 28 cm, belt speed = 0.123 m/s. No differences were observed (P > 0.05) in reductions of E. coli surrogates among the three UV treatments, with all reductions less than 1-log. No differences (P > 0.05) in aroma scores among treatment groups were noted, although differences in aroma attribute scores occurred between aging times. Panelists scored samples highest (P < 0.001) for bloody/serumy on d 0 than any other aging time. Conversely, sour dairy and spoiled attributes intensified over time with d 21 samples receiving the highest scores (P < 0.001). Although trained panelists’ responses for lean color score did not differ (P = 0.277) among UV treatments, scores for percent discoloration did (P = 0.014). Notably, percent discoloration scores for d 0 were statistically higher than the other aging times, meaning that discoloration diminished as aging continued. No statistical differences were identified for L*, a*, or b* values across UV treatments. Between aging times, differences were seen (P < 0.001) for a* and b* values, with day 0 having the lowest values for both. When evaluating purge and pH, the surface pH of steaks was higher on days 0 and 7 and began to decrease, showing statistical similarities on days 14 and 21. The amount of purge (g) steadily increased as steaks aged. APC counts were not found to differ due to UV treatment but generally tended to increase as storage times lengthened. All three treatments reduced the E. coli Biotype I surrogate microorganisms by less than 1-log. Further research is warranted to determine if different treatment parameters or combinations of pulsed UV light with the addition of other antimicrobials would result in greater reductions.
Gawlik, Ciarra Jade (2019). Applying Pulsed Ultraviolet (UV) Light to Reduce Surrogates on Beef Suprimal Surfaces. Master's thesis, Texas A&M University. Available electronically from