Effects of Age on Chemical Composition and Tenderness of Muscle <i>Longissimus thoracis</i>of Martina Franca Donkey Breed

The aim of this study was to determine the effects of age on chemical composition and tenderness of donkey meat. These characteristics were determined on Longissimus thoracis samples taken from 40 entire donkey males of Martina Franca breed slaughtered at 12 (Group 1, n = 20) and at 18 months (Group 2, n = 20) of age. Tenderness was evalu-ated at two and seven days post slaughter using a Warner-Bratzler shear force device. The chemical composition showed a significant increase in protein content (P < 0.05) in the meat of donkeys slaughtered at 18 months of age (22.3 g/100 g) compared to the meat of younger animals (21.4 g/100 g). Intramuscular fat content was significantly lower (P < 0.05) in Group 1 (2.41 g/100 g) compared to Group 2 (3.71 g/100 g). Shear force values at seven days post slaughter were significantly (P < 0.01) lower (5.15 ± 0.31 kg/cm2) in Group 1 compared with the results obtained at two days post slaughter (6.25 ± 0.53 kg/cm2). In Group 2 shear force values obtained seven days post mortem were higher (5.88 ± 0.23 kg/cm2) compared with Group 1 after the same ageing period but significantly (P < 0.05) lower if compared with those (6.53 ± 0.23 kg/cm2) determined in the same animals two days post slaugher.

A Letter to Martina

Dear Martina,How are you doing recently? I miss you very much. I have something good to tell you. I am gonig to England to study in your school next term, and we’ll meet each other then.Will you please help me look for an apartment? I hope to find a clean and bright house,Iwhich is not very far from our school.

‘72杨’韧皮部的构造与理化性能

将‘72杨’、杉木和毛竹的木质部进行对比试验,观察并测试‘72杨’韧皮部的解剖构造以及理化特性,为其高值化利用提供基础数据。使用场发射环境扫描电镜、X射线衍射仪、傅里叶变换红外光谱仪等设备和NREL标准对‘72杨’韧皮部的微观结构、结晶度、化学成分等物化性质进行测定与分析。研究结果表明,‘72杨’韧皮部中韧皮薄壁细胞和筛管分子占细胞总面积的(81.9±1.8)%,结构相对简单。‘72杨’韧皮部气干密度为0.358 g/cm3,绝干密度为0.321 g/cm3;而木质部的相应密度较高,分别为0.497和0.482 g/cm3;‘72杨’韧皮部结晶度仅为19.4%,比木质部低8.7%。‘72杨’韧皮部纤维素、半纤维素、木质素的含量分别为28.7%,11.1%,24.1%,均低于木质部中相应成分的含量,且木质化程度低,半纤维素以木糖为主。此外,由红外谱图发现‘72杨’韧皮部含有单宁、酚类、胼胝质等物质。‘72杨’韧皮部具有低密多孔、结构疏松、结晶度低、木质素含量低、抽提物含量高等特点。因此,‘72杨’韧皮部特别有利于机械(能耗低)或化学(抗降解屏障低)降解以及物化改性(多孔、可及性强),可提取酚类、单宁、胼胝质等物质用于工业应用,研究结果可为‘72杨’韧皮部的高值化利用提供重要的理论依据。