Animal Science, Department of


First Advisor

Chris R. Calkins

Date of this Version


Document Type



A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Animal Science (Meat Science & Muscle Biology), Under the Supervision of Professor Chris R. Calkins. Lincoln, Nebraska: August 2020.

Copyright (c) 2020 Felipe Azevedo Ribeiro


In order to tightly control dry aging environmental conditions, we designed and built a computerized dry aging system that is capable of measuring and precisely controlling relative humidity (RH; ± 1%), temperature (± 0.5 °C), air flow (± 0.015m3/min), and mass loss (± 5 g). This dissertation addressed the effects of RH and ultimate pH on meat quality and sensory attributes of dry-aged beef. In study one, we learned that wet-aged steaks had higher L* (P = 0.01), a* (P = 0.03), and b* values (P < 0.001), lower discoloration scores (P < 0.05), and lower TBARS (thiobarbituric acid reactive substance) values (P = 0.03) than dry-aged treatments. Under prolonged retail display (RD), dry aging of beef has the potential to reduce color and lipid stability compared to wet aging. In study two, a faster rate of moisture loss was found on the first three days of aging at 50% RH (P < 0.001) when compared to 85% RH. Lower RH results in accelerated moisture loss at the beginning of the aging process without significantly affecting the total amount of moisture loss. Trim loss, yield, and microbial counts were not affected by RH levels (P > 0.05). Pseudomonadales dominates the dry-aged loins while Enterobacteriales was the most abundant in the wet-aged samples. Lower RH tended to associate with more desirable flavor notes. In study three, meat with high pH (pH = 6.69) had the lowest L*, a*, and b* values (P < 0.05) throughout RD, and also the lowest TBARS values at 4 and 7 days of RD (P < 0.001), regardless the aging method. Ultimate pH did not affect rate (P = 0.51), total moisture loss (P = 0.96), trim loss (P = 0.69) and yield (P = 0.75) during dry aging. Clostridialeswere only observed on WET-DC samples, which also had a higher abundance of Lactobacillales. Flavorcharacteristics of dark cutters were not improved by dry aging. Regarding tenderness, our results showed that aging method (wet or dry), RH level (50, 70 or 85%), and ultimate pH did not have an effect on Warner-Bratzler shear force (P > 0.05).

Advisor Chris R. Calkins