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
36
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/3323245.html
相关试题推荐
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
With2005fastbecoming"theyearofthenaturaldisaster",itistimetore
With2005fastbecoming"theyearofthenaturaldisaster",itistimetore
随机试题
NoEnglishmanbelievesinworkingfrombooklearning.Hesuspectseverything
[originaltext]M:IhadprepareddinnerforeightpeoplebeforeMarycalledands
高中地理《岩石圈的物质循环》 一、考题回顾 二、考题解析 【教
A.只有1条 B.只有2条 C.至少有3条 D.不存在
在Word编辑环境中,不是以对象的形式插入到文档中的是()。A.特殊字符 B.
小儿能量代谢与成人的主要不同点是A.基础代谢所需能量少,活动所需能量多 B.基
国外某研究机构针对网上购物行为进行调查,随机抽取2万名网络购物消费者,对其进行“
2017年12月表中所列矿砂及其精矿种类中,有几类的进口均价超过5000
下列关于阿仑膦酸钠的描述中,正确的有A.本品属于第一代氨基二膦酸盐类骨代谢调节剂
男童身高80cm,前囟已闭,头围47cm,乳牙16枚,能用简单的语言表达自己的需
最新回复
(
0
)