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
2023-12-31
58
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] ______, a substance can be synthesized.
选项
A、Upon identifying the basic components of it
B、Once chemically analyzed
C、When gas chromatography is used
D、If spectroscopy is adopted
答案
B
解析
细节题型。见第二段倒数第二句(见75题答案),所以选项B为答案。
转载请注明原文地址:https://tihaiku.com/zcyy/3321923.html
相关试题推荐
Physics,oneofthenaturalsciences,______energyandmatter.A、dealwithB、are
AcollegegraduatewhoAistrainedinoneofthenaturalBsciencesormathematic
Thelimitedgaincouldhardlyserveasarelievingjustificationforthetremend
Norwayis,quitenaturally,payinggreatattentiontodevelopmentsinEuropeand
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
随机试题
Theabilityoffallingcatstorightthemselvesinmidairandlandontheir
[originaltext]Whatwillthewomangivetotheman?[/originaltext]A、Hernewdesi
[originaltext]W:So,Greg,youarequitetheworldtravelerIhear.M:Um,yeah
[originaltext]Scientistshavediscoveredthespeciesofsongbirdthatperformsa
在对铁路网进行规划时,节点选择的原则有()。A.生态型城市和内陆型城市 B
关于神经症的睡眠障碍,以下叙述中正确的是()A.失眠一般分为两种形式:入睡困难
(2020年真题)Y公司是一家在深圳证券交易所上市的民营企业,主要从事药品研发和
下列属于微观经济学中的“俱乐部产品”的是()。A、公共绿地 B、免
肾脏近曲小管及集合小管对水的重吸收受支配的激素是A.抗利尿激素B.ACTHC.性
A.漏出液B.脓性胸腔积液C.血性胸腔积液D.血性腹腔积液E.脓性腹腔积液细菌性
最新回复
(
0
)