Dynamics of ageing processes in different beef muscles

Abstract

The purpose of the study was to investigate the dynamics of ageing processes in different beef muscles at temperature of 1 °C during 28-day period and its effect on chemical (nonprotein nitrogen (NPN) and connective tissue) and instrumental parameters (Warner-Bratzler (WB) share force of roasted muscles), as well as sensory parameters, such as colour of raw, tenderness, juiciness, smell and flavour intensity of to the internal temperature of 60 °C roasted beef muscles (temperature of plate 220 °C). The total of six muscles (Psoas major (PM), Longissimus lumborum (LL), Semimembranosus (SM), Biceps femoris (BF), Semitendinosus (ST) and Triceps brachii (TB)) of normal meat quality were 24 h post mortem included in this study. Muscles originated from six commercially slaughtered animals of Simmental breed, three of them were heifers (22 to 30 months, hot carcass weight from 234 kg to 264 kg) and three bulls (21 to 23 months, hot carcass weight from 359 kg to 364 kg). In general, the content of NPN significantly increased by ageing. Regarding the dynamics of proteolysis the muscles at 14 days of ageing can be ranked from the lowest to the highest increase of NPN as follows: TB <ST <SM <PM <BF <LL. The content of connective tissue was not affected by ageing, but the content of soluble connective tissue increased by ageing in TB muscle. All sensory properties of roasted samples were improved during 28-day period. WB share force decreased during ageing for approximately 28%. To ensure the overall sensory quality of beef (tenderness have to be evaluated with 6 points for extra beef quality or 5 points for I. and II. category, and for other properties 5 points are required) is sufficient ageing at the temperature 1 °C for PM 7 days, for LL between 14 and 28 days, for TB and ST 28 days, for SM and BF more than 28 days.