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
2024-01-02
25
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 identit3, 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] It can be inferred from the passage that ______
选项
A、vanillin is easier to synthesize than benzaldehyde
B、not all synthetic flavors are harmless
C、in general, the less components there are in a fragrance, the harder it is to synthesize
D、synthesized substances must be tested for safety only if they are used in food
答案
B
解析
见第三段第一句:Many of the chemical compounds…and are as harmless or harmful as the natural substances.由此推断出:有些化学合成物(其中也包括香料)与其自然界存在的物质一样是无害的,有些则是有害的。因此选项B为答案。
转载请注明原文地址:https://tihaiku.com/zcyy/3326010.html
相关试题推荐
Manypartsoftheworldarelosingimportantnaturalresources,suchasforests,a
Thelimitedgaincouldhardlyserveasarelievingjustificationforthetremend
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Thefirstrecordeduseofnaturalgastolightstreetlampsitwasinthetowno
随机试题
June15DearSi
某工程由A、B、C、D四个施工过程组成,施工顺序为:A—B—C—D,各施工过程的
()教育是思想政治教育的核心。A.政治立场 B.理想信念 C.道德品质 D
患者多处骨折,颈部超声检查如图所示,最可能的诊断是 A.甲状腺腺瘤 B.甲状
锅炉省煤器使用的管子一般采用()。A、无缝钢管 B、螺旋缝钢管 C、焊接钢管
人在每一瞬间,将心理活动选择了某些对象而忽略了另一些对象。这一特点指的是注意的(
下列关于上市公司向不特定对象公开募集股份的特例规定,表述正确的有()。A:最近三
学生学习“功=力×距离”,这种学习属于()。 A.辨别学习 B.符号学习
下列属于5-HT受体阻断剂类止吐药的是A.昂丹司琼 B.格拉司琼 C.雷莫司
下列各项中,属于在记录审计过程时应当特别注意的重点方面有()A.具体项目或事项
最新回复
(
0
)