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
2025-01-28
21
管理
问题
Natural flavorings and fragrances are often costly and limited in supply. For example, the essential 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]
She took a weight
off her mind, Suzen went back to her work.
选项
A、A weight taking
B、A weight been taken
C、With a weight taking
D、With a weight taken
答案
D
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3932896.html
相关试题推荐
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
With2005fastbecoming"theyearofthenaturaldisaster",itistimetor
With2005fastbecoming"theyearofthenaturaldisaster",itistimetor
With2005fastbecoming"theyearofthenaturaldisaster",itistimetor
With2005fastbecoming"theyearofthenaturaldisaster",itistimetor
With2005fastbecoming"theyearofthenaturaldisaster",itistimetor
随机试题
ASocioculturalApproachtoReading,LanguageandLiteracyI.T
Whilewedifferinmanyways,____________(这些差异并无优劣之分).suchdifferencesareneit
[originaltext]W:Icanseebyyourresumeherethatyoustudiedbusinessadmini
[originaltext]Someoftheplanet’smostpreciousanimalsandplantsaredis
Therewasatimeinmylifewhenbeautymeantsomethingspecialtome.Igue
Theconceptofinformationsuperhighwayhasbeenaroundformorethana
自然界中氮的循环 ?一、考题回顾
夫妻双方均患白化病,则其子女发病概率是A.50% B.25% C.100%
各种运输方式内外部的各个方面的构成和联系,就是( )。 A.运输系统
某患者经一疗程链霉素治疗后,听力下降,虽停药几周听力仍不能恢复,这是药物引起的A
最新回复
(
0
)