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1、Chapter20FruitsandVegetables周海璐Fruits,vegetables,andotherplanttissueseitherdirectlyorindirectlysupplyallfoodstohumans.Anestimated（估计）270,000plantspeciesexist.Thenumberofcrops（作物）thatfitintohumans’dietary（饮食）pictureisprobablybetween1,000and2,000species.Fruitsandvegetables
2、takeinawidevarietyofedible（可食用的）plantparts.Fruitsaregenerallythefruitofaplantbutvegetablesincludefruits,leaves,flowers,seeds,stems（茎）,bulbs（球茎）,tubers（块茎）androotsofaplant.Leafyvegetablesaregenerallyhighinwaterandlowincarbohydrates,protein,andfats.Theyfrequentlycontainthe
3、mechanismforphotosynthesis（光合作用机制）.Someexamplesincludespinach（菠菜）,lettuce（生菜）,mustardgreens（芥末菜）,andcabbage（甘蓝）.Seedsvaryinwatercontentandareasourceofcarbohydratesandprotein.Theymaybe“fresh”andhighinwateror“dried”andrelativelylowinwatercontent.Cornandbeansareexamples.Gen
4、eralPropertiesandStructuralFeatures各类蔬菜普遍特性及结构特点Tubers（块茎）aregenerallyhigherincarbohydratesandlowerinwatercontentthanstem,flower,orleafyvegetables.Tubersareenlargedundergroundstems.Potatoesarethebestexample.Stems（茎）areplantportionsgenerallyhighinwaterandfiber.Theyhaverel
5、ativelylittleothernutritionvalue.Asparagus（芦笋）isanexample.Bulbs（球茎）aregenerallyhigherincarbohydratesandlowerinwatercontentthanstems,flower,orleafyvegetables.Bulbslikeonionsandgarlic（大蒜）areenlargementsabovetheroots.Rootslikecarrotsaregenerallyhigherincarbohydratesandlower
6、inwatercontentthanstem,flower,orleafyvegetables.Rootsarethepartofaplantthatgrowdownward（向下）intothesoiltoanchor（固定）theplantandfurnishnourishment（提供营养）byabsorbingnutrients.GeneralComposition一般组成Freshaswellascannedandfrozenfruitsandvegetablesprovideavarietyofvitamins,minera
7、ls,andfiber.Theyarelowinfat(exceptavocados（鳄梨）)andsodium（钠）,andtheyprovidedietaryfiber（膳食纤维）.Whole,unpeeled（未去皮的）fruitishigherinfiberthanpeeled（去皮的）fruitorfruitjuice.TableA-8(P573)providesthecompositionofmanyfruitsandvegetables.Freshandcannedfruitsandvegetablescontainahi
8、ghwatercontent.Obviously,theenergycontentincreaseswhenthefruitisdried.Thecarbohydratecontentishighcompa
