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
2025-02-02
12
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] Which of the following is the best title for the passage?
选项
A、How to Synthesize Fragrances
B、Synthetic Substances Are Easy to Make
C、Natural Flavorings and Fragrances
D、Synthetic Flavors and Fragrances
答案
D
解析
主旨题型。阅读全文可知本文是围绕天然调味品和香料供应有限且价格不菲(见第一段第一句),后有了人工合成品替代(尽管有些合成容易,有些困难),使大量生产成为可能;其中主要部分谈的是人工合成品(调味品和香料);因此选项D为答案。
转载请注明原文地址:https://tihaiku.com/zcyy/3940120.html
相关试题推荐
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Thefirstrecordeduseofnaturalgastolightstreetlampsitwasinthetowno
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
随机试题
LastmonthDavewentonholidaytoFrance.HecaughtthetrainfromLondonto
A(i)________todisseminatethevastscientificknowledgeofourtimetononsci
世界上的每个城市都有出租车把游客带到有趣的地方。【T1】伦敦是世界上唯一一个游客们乘坐出租车就会有很有趣的经历的城市。(定语从句)部分是因为那在其他国家
[originaltext]W:TheBrownshavetoleavefortheairportinhalfanhour.M:O
我国当前的安全生产管过体制是()。A.生产经营单位负责 B.职工参与
对钢筋混凝土桥梁进行承载能力检算评定时,钢筋截面折减系数ξs的取值依据是(
组织有异型构造的块根类药材是A.太子参B.黄芪C.何首乌D.大黄E.黄连
体温上升期患者表现为A.畏寒、皮肤苍白、无汗 B.畏寒、皮肤潮红、无汗 C.
某物业项目总建筑面积36万m2,其中有高层住宅21万m2,办公楼10万m2,该物
Todealwiththisproblem,studentssay
最新回复
(
0
)