Changes in Lipid Oxidation and Fatty Acids in Altay Sheep Fat during a Long Time of Low Temperature Storage

The Effects of Sheep Tail Fat, Fat Level, and Cooking Time on the Formation of Nε-(carboxymethyl)lysine and Volatile Compounds in Beef Meatballs

This study aimed to determine the effects of fat type (sheep tail fat (STF) and beef fat (BF)), fat levels (10, 20, or 30%), and cooking time (0, 2, 4, and 6 min, dry heat cooking at 180 °C) on the carboxymethyl lysine (CML) content in meatballs. pH, thiobarbituric acid reactive substance (TBARS), and volatile compound analyses were also performed on the samples. The use of STF and the fat level had no significant effect on the pH value. The highest TBARS value was observed with the combination of a 30% fat level and STF. CML was not affected by the fat level. The highest CML content was determined in meatballs with STF at a cooking time of 6 min. In the samples cooked for 2 min, no significant difference was observed between STF and BF in terms of the CML content. STF generally increased the abundance of aldehydes. Aldehydes were also affected by the fat level and cooking time. A PCA provided a good distinction between groups containing STF and BF regardless of the fat level or cooking time. Pentanal, octanal, 2,4-decadienal, hexanal, and heptanal were positively correlated with CML.

Transcriptome Analysis Reveals Genes Involved in Thermogenesis in Two Cold-Exposed Sheep Breeds

Thermogenesis plays an important role in the survival of sheep exposed to low temperatures; however, little is known about the genetic mechanisms underlying cold adaptation in sheep. We examined 6 Altay (A) and 6 Hu (H) six-month-old ewe lambs. Altay sheep are raised in northern China and are adapted to dry, cold climates, while Hu sheep are raised in southern China and are adapted to warm, humid climates. Each breed was divided into two groups: chronic cold sheep, exposed to -5 °C for 25 days (3 A^c; 3 H^c), and thermo-neutral sheep, maintained at 20 °C (3 A^w; 3 H^w). The transcriptome profiles of hypothalamus, tail-fat and perirenal fat tissues from these four groups were determined using paired-end sequencing for RNA expression analysis. There are differences in cold tolerance between Hu and Altay sheep. Under cold exposure of the lambs: (1) UCP1-dependent thermogenesis and calcium- and cAMP-signaling pathways were activated; and (2) different fat tissues were activated in Hu and Altay lambs. Several candidate genes involved in thermogenesis including UCP1, ADRB3, ADORA2A, ATP2A1, RYR1 and IP6K1 were identified. Molecular mechanisms of thermogenesis in the sheep are discussed and new avenues for research are suggested.

Effects of rendering and α-tocopherol addition on the oxidative stability of horse fat

Oxidative stability of horse fat rendered at 70 °C, - 0.1 MPa under vacuum and 110 °C, 0.1 MPa from horse fatty tissues was investigated after the addition of α-tocopherol at 0, 30, 60, and 150 mg/kg during storage at 60 °C in the dark. Peroxide values of initial horse fat rendered at 70 °C under vacuum ranged from 6.10 to 7.40 meq/kg. After 14 days, those of horse fat with α-tocopherol at 0, 30, 60, and 150 mg/kg increased to 142.40, 34.10, 39.37, and 58.23 meq/kg, respectively. Acid values and thiobarbituric acid values of horse fat rendered at 70 °C were lower than those of horse fat at 110 °C. Unsaturated fatty acids contents of horse fat rendered at 70 °C and 110 °C were 58.04 and 57.15%, respectively. These results indicate that rendering at 70 °C under vacuum improved the oxidative stability of horse fat and the addition of α-tocopherol helped to prevent lipid oxidation.