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
20
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] The industry of producing hundreds of artificial flavors and fragrances probably appeared in______.
选项
A、2000
B、1953
C、1909
D、1810
答案
C
解析
细节题型。见第一段第三句:Since the early twentieth century, success in reproducingthese substances has created a new industry that…符合“二十世纪早期”条件的选项只有C,所以是答案。
转载请注明原文地址:https://tihaiku.com/zcyy/3936479.html
相关试题推荐
Norwayis,quitenaturally,payinggreatattentiontodevelopmentsinEuropeand
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Thefirstrecordeduseofnaturalgastolightstreetlampsitwasinthetowno
Thefirstrecordeduseofnaturalgastolightstreetlampsitwasinthetowno
OneofthemostbeautifulnaturalwondersintheUnitedStatesmustcertainlybe
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
Naturalflavoringsandfragrancesareoftencostlyandlimitedinsupply.Fo
随机试题
[originaltext]W:Steve,canyoutellmehowlongyou’vebeenapubowner?M:We
中性点经消弧线圈接地是为了( )。A.根除断续电弧接地过电压 B.限制断续电弧
当土为中密的砂土,深度在5m以内的沟槽边坡的坡顶无荷载时最陡坡度是()。A.1
试讲题目1.题目:志愿填报,海阔天空 2.内容: 职业“投币机”活动规则
下面不属于病史主诉的为A.治疗过程 B.症状 C.病程 D.停经天数 E
不符合脑死亡的判断标准的是A:对刺激无感受性及反应性 B:运动、无呼吸 C:
A.AB.BC.CD.D
某9层钢结构办公建筑,房屋高度H=34.9m,抗震设防烈度为8度,布置如题24-
男性,65岁,因心搏骤停进行心肺复苏术。下述叙述正确的是( )。A.尽管有心室
心室肌0期除极化的描述,错误的是A.由快Na+通道激活开放弓 B.阈电位水平大
最新回复
(
0
)