Effect of different concentrations of ammonium hydroxide on the stability of color, meat lipid, some indexes of proteins degradation and palatability attributes of Awassi rams meats during frozen storage

Abstract

The aim of the study was to examine the effect of different concentrations of ammonium hydroxide (NH4OH) on the stability of color, meat lipid, tyrosine/ tryptophane index and palatability attributes of Awassi rams meats during frozen storage. postmortem directly, the carcasses were fabricated. The longissimus dorsi muscle (LD) and Semimembranosus muscle (SM) were removed from both sides of the Awassi rams carcasses to represent two major valuable cuts, the loin and the leg respectively, then these muscles were randomly divided into four treatments. Then immersed in ammonium hydroxide solutions at concentrations 0.25, 0.5 and 0.75% and control treatment (distilled water) for 30 min at ratio (1: 1, meat: solution). The treated and untreated of meat samples were covered tightly and seperately with nylon bags and chilled kept 4 C° for 24 hours and then frozen stored -18 C°. were used for the chemical, biochemical changes and sensory properties to meats awassi rams were monitored. The results are indicated the presence significant differences (P<0.05) among treatments in met-myoglobin formation and TBA values in both muscles of LD and SM stored at -18 C°. treated samples with 0.5 and 0.75% ammonium hydroxide were reported lower percent in forming Met-Mb and inhibition in TBA values. With index lower TBA values in both muscles LD and SM. It observed that the LD muscles had lower Met-Mb formation percent and TBA values compared with SM muscles for each treatment. the results showed that there were higher (P<0.05) in total tyrosine/ tryptophan index (T.T/T) and protein tyrosine/ tryptophan (P.T/T) and non protein tyrosine/ tryptophan (N.P.T/T) in LD and SM muscle among treatments. the results showed improve of Sensory properties in LD and SM muscles when treated with ammonium hydroxide at concentration 0.5 and 0.75% especially (Tenderness, Juiciness and overall acceptability). It could be concluded that using of ammonium hydroxide is led to color and lipid stability, also could contribute effectively to the meat tenderization of aged rams meats.