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

Abstract

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 5,000mg/animal/day of clove essential oils and CIN - diet with average 5,000mg/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.

Acceptability by sensory and visual analyses of meat from Nellore heifers fed with natural additives and finished in feedlots

“…Thus, the addition of essential oils and blend to the diets of heifers finished in high‐grain feedlots improved the visual acceptance of the meat. Essential oils have a natural antioxidant effect, 14, 31, 32 and their incorporation into cell membranes may delay the oxidation of myoglobin. Essential oils capture free radicals that are formed during lipid oxidation, delaying the conversion of the cherry red pigment (oxymyoglobin) to the brown pigment (methemioglobin) 33 .…”

“…Essential oils capture free radicals that are formed during lipid oxidation, delaying the conversion of the cherry red pigment (oxymyoglobin) to the brown pigment (methemioglobin) 33 . The addition of essential oils as nutritional supplements in ruminant diets can therefore improve animal performance, health, and welfare, as well as meat quality 11, 14, 32 . Natural essential oils added to the diet not only improve the oxidative stability and the sensorial properties of the meat but also enhance the nutritional value and the health benefit of meat products 11, 34 .…”

“…To produce images under standardized conditions, photographs were taken as described by Passetti et al 14 . The steaks were photographed each day until day 11 of the evaluation, using a Nikon Coolpix P500 digital camera mounted on a photographic stand containing two D65 fluorescent light tubes as the standard illuminant.…”

“…Images were stored and transferred to a computer as JPEG files. A GretagMacbeth mini Colour‐Checker (Colour–Confidence, Birmingham, UK), which contains 24 colored patches, was photographed with each meat sample to check color reproduction capability as described in Passetti et al 14 …”

“…Visual assessments are a gold standard for estimating consumer perceptions of meat, 12 but they are complex, expensive, and time consuming. Difficulties related to the use of meat in consumer surveys could be overcome through the use of photographs for color evaluation 13‐15 . The use of such images has reduced the number of representative samples required to explain the variations in color on the surface of meat.…”