Validation of photographs usage to evaluate meat visual acceptability of young bulls finished in feedlot fed with or without essential oils

Forty ½ Brown Swiss × ½ Nellore crossbred bulls were distributed into three experimental groups: CON - diet without addition of essential oils; CLO - diet with average 5,000 mg/animal/day of clove essential oils and CIN - diet with average 5,000 mg/animal/day of cinnamon essential oils to evaluate three methodologies of visual acceptability: with steaks directly in Trays and Sequential and Random photos. Seventeen consumers evaluated visual appearance of meat using a 9-point structured hedonic scale. CON group presented higher shelf-life than essential oils groups. Trays and Sequential scores were similar in the majority of days; thus digital images could be used to evaluate colour evolution. However, Random photos resulted in lower scores and slower acceptability decrease than Trays and Sequential photos (p < 0.05) among the second and fifth day of display. Random photos presented a lower and more constant standard deviation than Trays and Sequential photos (p < 0.01) indicating that this methodology promoted a higher standard situation for meat colour evaluation.