Sensory profiles and the effect of age feeding regime and aging on the eating quality of selected beef cuts

Abstract

The main purpose of this study was to determine, describe and compare the eating quality of selected beef cuts; loin, rump and ribeye produced in Namibia. These cuts originate from carcasses of different age classes, feeding regime and post-mortem aging periods. The determination of the eating quality of this beef will aid MEATCO in understanding consumers’ responses in relation to the sensory attributes of these beef cuts. To date, the eating quality of this beef has not been determined or described by scientific means. Eating quality of beef refers to the overall beef eating experience and it can be affected by various pre- and post-mortem factors. Eating quality is an important component of beef meat quality, but highly variable due to variations in tenderness and flavour, which are dependent on the intrinsic and extrinsic factors of the animal. This variability contributes to consumer dissatisfaction. As a result the prediction of eating quality of beef at the consumer level is of utmost importance to the producers of beef meat in order for them to remain competitive in the market. The study was conducted in two phases, Phase 1 of the study involved descriptive sensory evaluation, where a trained panel was used to evaluate the beef samples. The sensory attributes that were applicable to the beef samples were first identified by the trained panel with the aid of the panel leader. From this, a lexicon and evaluation form were developed. The trained panel used a category scale to rate the intensity of the identified sensory attributes. Phase 2 of the study involved physical evaluation, whereby measurements of shear force resistance were determined using the Warner Bratzler shear force device mounted on a Universal Instron Machine. Added to this cooking and thawing losses were also measured by using a measuring scale. The results of the sensory evaluation show that the trained panel could distinguish the difference between the two grain fed groups (AG and ABG) and the young free-range group (AF) on one side and the older free-range groups (ABF, B4 and B6) on the other. The former groups scored higher for the attributes such as tenderness, overall flavour and aroma whereas the latter groups scored higher for juiciness and other flavour undertones e.g. green, livery, rancid and sour. Age class of the animals was found to have had an effect on tenderness related attributes and juiciness, whereas feeding regime had an effect on overall flavour and flavour undertones. However prolonged post-mortem aging had a minimal effect on the sensory attributes. There were no differences found between the 36 and 55 days aged samples. From this study it can be suggested that even though extreme post-mortem aging results in acceptable tenderness levels for all age classes and feeding regimes, the consumer may still pick up flavour differences between the different age classes and feeding regimes. Marketing this beef as a single product line may therefore result in an inconsistent eating experience for the consumer.