预处理加工对西兰花茎叶汁挥发性成分的影响

Fig.2 Effect of pretreatments on the volatile components of broccoli stem and leaf juice

为研究热烫、冻融、超声3种预处理方式对西兰花茎叶汁挥发性成分的影响,本试验利用顶空固相微萃取-气相质谱联用仪对不同预处理加工后的西兰花茎叶制成的西兰花茎叶汁中挥发性成分进行测定。结果表明,西兰花茎叶汁的主要异味成分为己醛、庚醛、壬醛、(E)-2-己烯醛、(E,E)-2,4-庚二烯醛、1-戊醇、1-辛醇、1-己醇、(E)-3-己烯-1-醇、甲硫醇、2-乙基噻吩、硫氰酸甲酯、二甲基二硫醚、β-紫罗酮、6-甲基-5-庚烯-2-酮。与超声预处理相比,热烫和冻融处理可以较好地降低西兰花茎叶汁中挥发性成分的种类和含量。与未进行预处理的对照组相比,热烫处理的西兰花茎叶汁中虽然检出了甲硫醇和二甲基二硫醚,但醛类含量减少,酯类含量增加,此外,与冻融处理相比,热烫硫化物含量更低。本研究为西兰花茎叶的果蔬汁开发提供了理论依据。

In order to investigate the effects of three pretreatments(blanching, freeze-thaw and ultrasonic treatment) on the volatile components of broccoli stem and leaf juice, the headspace solid-phase microextraction-gas chromatography mass spectrometry was used to determine these volatile components in the juice produced from broccoli stem and leaf treated with different pretreatments. Results showed that the main odorous components of broccoli stem and leaf juice were hexanal, heptaldehyde, nonanal,(E)-2-hexenal,(E, E)-2,4-heptadienal, and 1-pentanol, 1-octanol, 1-hexanol,(E)-3-hexen-1-ol, methyl mercaptan, 2-ethylthiophene, methyl thiocyanate, dimethyl disulfide, β-lonone, and 6-methyl-5-hepten-2-one. Blanching and freeze-thaw treatment could effectively reduce both the types and contents of volatile components in broccoli stem and leaf juice than ultrasonic treatment. Compared to the control group that had not been pretreated, methyl mercaptan and dimethyl disulfide were determined in the broccoli stem and leaf juice treated with blanching, the aldehydes content was lower and the esters content was increased. Besides, the sulphide content of blanching group was lower than that of freeze-thaw treated group. This study provided a techique basis for the development of fruit and vegetable juices.