首页
登录
职称英语
Natural flavorings and fragrances are often costly and limited in supply. Fo
Natural flavorings and fragrances are often costly and limited in supply. Fo
游客
2024-01-01
9
管理
问题
Natural flavorings and fragrances are often costly and limited in supply. For example, the vital ingredient in a rose fragrance is extracted from natural rose oil at a cost of thousands of dollars a pound; an identical synthetic substance can be made for 1% of this cost. Since the early twentieth century, success in reproducing these substances has created a new industry that today produces hundreds of artificial flavors and fragrances.
Some natural fragrances are easily synthesized; these include vanillin, the aromatic ingredient in vanilla, and benzaldehyde, the aromatic ingredient in wild cherries. Other fragrances, however, have dozens, even hundreds of components. Only recently has it been possible to separate and identify these ingredients by the use of gas chromatography and spectroscopy. Once the chemical identity is known, it is often possible to synthesize them. Nevertheless, some complex substances, such as the aroma of fresh coffee, have still not been
duplicated
satisfactorily.
Many of the chemical compounds making up these synthetics are identical to those found in nature, and are as harmless or harmful as the natural substances. New products must be tested for safety, and when used in food, must be approved by the U. S. Food and Drug Administration.
The availability of synthetic flavors and fragrances has made possible a large variety of products, from inexpensive beverages to perfumed soap to used cars with applied " new car odor. " [br] From the passage we can learn that______.
选项
A、natural flavorings and fragrances are not quite dear
B、the limitation of natural flavorings and fragrances is clear
C、the supply of natural flavorings and fragrances is adequate to meet the demand
D、the cost of producing natural flavorings and fragrances is high
答案
D
解析
细节题型。见第一段第一句:Natural flavorings and fragrances are often costly andlimited in supply.因此选项D为答案。
转载请注明原文地址:https://tihaiku.com/zcyy/3323237.html
相关试题推荐
"GeothermalEnergy"→Geothermalenergyisnaturalheat
"GeothermalEnergy"→Geothermalenergyisnaturalheat
"GeothermalEnergy"→Geothermalenergyisnaturalheat
"GeothermalEnergy"→Geothermalenergyisnaturalheat
"GeothermalEnergy"→Geothermalenergyisnaturalheat
"GeothermalEnergy"→Geothermalenergyisnaturalheat
EnergyfromNaturalGas1.Muchoftheworldgetsitsene
EnergyfromNaturalGas1.Muchoftheworldgetsitsene
EnergyfromNaturalGas1.Muchoftheworldgetsitsene
EnergyfromNaturalGas1.Muchoftheworldgetsitsene
随机试题
Accordingtothepassage,whenthreepeoplelookoutthesamewindow,______.[b
Itusedtobethecasethatifyouleftyourcarinthesunonahotsummer’
Thefirehascausedgreatlosses,butthefactorytriedto________theconseque
某平原区二级公路工程项目,设计图纸简单,全部工程项目工期预计1年。根据该项目的特
高校精品课程建设的根本保证是()。A.改革教学内容和课程体系 B.建设高水平
供电企业的用电营业机构统一归口办理用户的()和报装接电工作。A.用电安全检查
某研究者欲了解某地正常成年男性和女性的红细胞总体平均水平是否有差异,随机抽样测定
患者女,32岁,气粗息涌,喉中痰鸣如吼,胸闷胁胀,咳呛阵作,咳痰色黄或白,粘浊稠
实喘的基本病机是( )。A.外邪扰肺,肺气上逆 B.肺气胀满,不能肃降 C
A.单体酶B.单纯酶C.结合酶D.同工酶E.变构酶催化的化学反应相同,酶蛋白的分
最新回复
(
0
)