Free and Bound Volatile Chemicals in Mulberry (Morus atropurpurea Roxb.)

Mulberry (Morus atropurpurea Roxb.) is a popular and desirable fruit that is widely cultivated in China. Despite its popularity, the free volatile chemicals and glycosidically bound volatiles (GBVs) of mulberry have been minimally studied. To this end, we have investigated these compounds in 4 mulberry cultivars via solid phase extraction (SPE) and headspace solid phase microextraction with gas chromatography–mass spectrometry (HS‐SPME‐GC‐MS). A total of 55 free volatile chemicals and 57 GBVs were identified and quantified. In 3 of the cultivars (“YFS,” “T10,” and “D10”), the GBVs were found in higher amounts than their free counterparts, corresponding to a ratio of 1.2 to 1.8. The characteristic aromas were determined by their odor activity values (OAVs) and by generating an aroma series (AS). A total of 20 volatile compounds had OAVs ≥ 1.0. In particular, ethyl butanoate, hexanal, (Z)‐3‐hexenal (E)‐2‐hexenal, (E)‐2‐nonenal, and eugenol had relatively high OAVs and were considered to be the key aromas contributing to the mulberry flavor. Consequently, mulberry was characterized by a variety of herbaceous scents having a background of sweet, spicy, fruity, and floral notes. The free volatiles exhibited strong herbaceous notes, whereas the GBVs were responsible for the sweet and spicy qualities of the fruit. Based on our results, 2 cultivars (“YFS” and “D10”) are proposed to be good candidates suitable for the further development of mulberry‐based food products due to their complex and desirable aromas.     

凤凰单丛香气及糖苷类香气前体变化研究

目的测定凤凰单丛加工过程的挥发性香气化合物和糖苷类香气前体的含量变化,并讨论糖苷类香气前体与挥发性香气化合物的含量变化的关系。方法采用溶剂辅助风味蒸发法(solvent assisted flavor evaporation,SAFE)联合气相色谱-质谱联用仪(gas chromatography and mass spectrometry,GC-MS)检测技术分析挥发性物质的变化,再采用衍生法并结合GC-MS定量分析糖苷类香气前体的变化。结果共检测出挥发性香气物质79种,其中包含醇类29种、酯类11种、烯类25种、苯类3种、醛类3种、酮类5种、以及其他化合物3种,以醇类物质的含量最多。在干燥样中,含量最高5种的香气物质为α-法尼烯(24.05%)、橙花叔醇(22.63%)、芳樟醇(11.58%)、吲哚(4.28%)、脱氢芳樟醇(2.95%)。共检测到糖苷类香气前体14种,其中包括6种葡萄糖苷和8种樱草糖苷。其含量在加工过程中都有增加,糖苷类香气前体总量从550.73μg/g增加到843.06μg/g,增加了52.99%。结论糖苷类香气前体的总量相较于鲜叶有明显的增加,对应配基的游离态香气化合物的相对含量没有增加,凤凰单丛香气的形成并非来自于糖苷类香气前体的水解。茶叶中的糖苷类物质有与之相应的前体反应合成糖苷类物质,这个反应一直持续到茶叶加工完成,这也是茶样中糖苷类香气前体在加工过程中持续增加的原因。     

Contribution of Free and Glycosidically Bound Volatile Compounds to the Aroma of Muscadine Grape Juice

Free and glycosidically bound volatile compounds were isolated and identified from muscadine grape juice. Most abundant in free and bound form was the muscadine character-impact aroma compound 2,5-dimethyl-4-hydroxy-3(2H)-furanone (Furaneol). Other aroma compounds, such as o-aminoacetophenone and 2-phenylethanol were found in free and bound forms. A high level of 2-phenylethanol was intheglycosideformand many bound monoterpenes were identified. p-Vinylguaiacol, a potential off-flavor in muscadine juice was found at a low level in bound form. Enzymatic hydrolysis of glycoside precursors could lead to release of volatile compounds with both potentially positive and deleterious effects on the overall aroma.     

酶对生姜风味的影响

就几种酶对生姜风味的影响作了相关的阐述。首先对生姜中以自由态和键合态形式存在的风味物质进行了介绍，并阐述了β-糖苷酶对其的影响，同时还介绍了香叶醇脱氢酶对生姜风味的影响。