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
2025-01-31
16
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/3936485.html
相关试题推荐
______scientistshaveobservedincreasedpollutioninthewatersupply.A、LateB、
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
With2005fastbecoming"theyearofthenaturaldisaster",itistimetor
With2005fastbecoming"theyearofthenaturaldisaster",itistimetor
With2005fastbecoming"theyearofthenaturaldisaster",itistimetor
With2005fastbecoming"theyearofthenaturaldisaster",itistimetor
随机试题
Astheplanecircledovertheairport,everyonesensedthatsomethingwaswr
ListL:4,5,6,7,7,8,xListLconsistsof7numbers.Whichofthefollowing
PoorpeoplehaveI.Q.’ssignificantlylowerthanthoseofrichpeople,andt
膜迷路包括:A.膜半规管 B.以上都不是 C.球囊 D.椭圆囊 E.膜蜗
钢筋拉伸试验一般应在(10-35)℃环境温度条件下进行。
涎腺多形性腺瘤之所以称为混合瘤是因为()A.肿瘤内既有涎腺上皮,又有
()是指以生存为给付保险金条件,按约定分期给付生存保险金,且分期给付生存
《隔离开关分合闸位置“双确认”改造技术规范》中视频监控应具有对一次主设备状态实时
合约基准价的高低是根据提出需求的一方的需求来确定的。( )
新拌砂浆的流动性用()表示,保水性用()表示。A.沉入度、分层度 B.坍落度、
最新回复
(
0
)