红枣挥发性物质在烘干过程中的变化研究

    Variation of Volatile Compounds of Chinese Dates During Toast

    • 摘要: 新鲜成熟的团枣在25~75℃逐渐烘干,当温度在4 h升高到50℃后,控制升温速率为每4 h升高5℃,直到75℃。取鲜枣100 g及从50℃开始每隔5℃取样100 g,去核、切碎,分别用95%乙醇浸泡,蒸去乙醇得膏,然后用除去过氧化物的乙醚萃取,醚液用无水硫酸钠干燥,低温下蒸发除去乙醚后得到挥发性物质,再用气相色谱—质谱联用仪测定了上述样品的挥发性化学成分。结果表明,新鲜成熟的团枣的挥发性成分主要为13种酯类,以棕榈烯酸乙酯、肉豆蔻烯酸乙酯、亚油酸乙酯、棕榈酸乙酯、油酸乙酯、月桂酸乙酯、肉豆蔻酸乙酯等的含量较高,且其含量随着温度的升高和时间的延长而逐渐略有减少;5-羟甲基-2-呋喃甲醛和5-羟基-5,6-二氢-麦芽酚在55℃以上检出,2-呋喃甲醛在65℃以上检出,随着烘干温度逐步升高和时间增长其残留含量逐渐增高;65℃时干枣的品质最好,烘干红枣的最高温度不宜超过70℃。

       

      Abstract: Fresh ripe Tuan date,a kind of Chinese date, was gradually toasted between 25℃ and 75℃. The furnace temperature program including a step-up period from 25℃ to 50℃ within 4h, then temperature increases at 5℃/4h from 50℃to 75℃. Fresh date of 100 g and the samplings of 100 g taken every 5℃ beginning with 50℃ was soaked in 95% ethanol respectively. After distillation of ethanol the residue was extracted by using ethyl ether (3×60 mL) and dried with sodium sulfate. The volatile compounds were obtained by distillation of ethyl ether and analyzed by GC-MS. The results showed that the volatile compounds were mainly 13 esters, including ethyl palmitoleate, ethyl myristoleate, ethyl lipoleate, ethyl palmitate, ethyl oleate, ethyl laurate, and ethyl myristate, etc. The contents of those esters were decreased as the furnace temperature was increased. Otherwise, the content of 5-hydroxymethyl-2-furancarbonaldehyde, 5-hydroxyl-5,6-dihydrogen-meltol found begining with 55℃ and 2-furancarbonaldehyde found begining with 65℃ was increased as the furnace temperature was increased. 3-hydroxyl-2-on-butane, ethyl malate and ethyl decanoate are possible to contribute to fresh date smell, and 5-hydroxymethyl-2-furancarbonaldehyde, 5-hydroxyl-5,6-dihydrogen-meltol and 2-furancarbonaldehyde to the special charred smell. The dried date toasted at 65℃ was provided with best quality. The furnace temperature should not be higher than 70℃ during the toast process.

       

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