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
40
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] From the passage we can learn that ______.
选项
A、natural flavorings and fragrances are not quite dear
B、the limitation of natural flavorings and fragrances is clear
C、the supply of natural flavorings and fragrances is adequate to meet the demand
D、the cost of producing natural flavorings and fragrances is high
答案
D
解析
细节题型。见第一段第一句:Natural flavorings and fragrances are often costly and limited in supply.因此选项D为答案。
转载请注明原文地址:https://tihaiku.com/zcyy/3325552.html
相关试题推荐
Damsarecostly,butoncetheyhavebeenbuilt,______electricityverycheaply.A
Thelimitedgaincouldhardlyserveasarelievingjustificationforthetremend
Norwayis,quitenaturally,payinggreatattentiontodevelopmentsinEuropeand
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
随机试题
"Blockpatrol(巡逻,巡逻队),""communitywatch""civilianpatrol."Theymay
Inatelephonesurveyofmorethan2,000adults,21%saidtheybelievedthe
Theconversationistakingplaceatafriend’shouse.[br][originaltext]M1Hi
烧伤后肥厚性瘢痕压力治疗,错误的是A.弹性包裹 B.紧身服(套) C.管形加
请按所提供的教材设计1课时的教学简案。 要求: (1)写出一
1948年7月,某国率先向世人宣布:它已经向国民提供了“从摇篮到坟墓”的社会福
Thechangeinthatvillagewasmiraculou
肾小球滤过膜损伤或通透性增加时可发生()。A.多尿 B.少尿 C.血尿多
腺样囊性癌多见于哪个腺体A.下颌下腺 B.舌下腺 C.唇腺 D.腭部小腺体
镀锌钢导管、可弯曲金属导管和金属柔性导管连接处的两端宜采用( )固定保护连接导体
最新回复
(
0
)