高压脉冲电场结合冷冻浓缩生产浓缩绿茶汤工艺优化

    Concentrated green tea soup produced by pulsed electric field and freeze concentration

    • 摘要: 为解决茶饮料生产过程中因热力加工导致茶叶香气物质损失的关键难点问题,寻找一种保留香气成分的低温加工新技术,采用高压脉冲电场(pulsed electric field,PEF)和冷冻浓缩分别对茶汤进行提取和浓缩,得到最佳工艺参数,并用气相色谱-质谱(gas chromatograph-mass spectrometer,GC-MS)与固相微萃取(solid-phase micro-extraction,SPME)相结合的方法测定高压电场提取的茶汤与热水浸提的茶汤以及冷冻浓缩得到的浓缩茶汤与真空蒸发浓缩得到的浓缩茶汤在香气成分方面的差异。试验结果表明:脉宽2.5 μS时,PEF技术生产绿茶汤的适宜条件为料液比1:30、电场强度35 kV/cm、脉冲个数8个、脉冲频率2 700 Hz;以4℃的溶液初温、150 r/min的刮刀转速、冷媒温度为?15~?18℃条件浓缩效果最佳;香气成分分析表明PEF集成冷冻浓缩比真空蒸发浓缩更能保留茶汤的香气成分。研究结果可为高压脉冲电场及冷冻浓缩的应用提供技术依据。

       

      Abstract: Abstract: Instant tea powder is completely soluble solid. It has emerged as a new and fast growing product in the world.. The tea powder basically keeps the original color, aroma, and taste of the tea. It has advantages of convenience, health, nutrition, elegance, quality control, and high stability, which is deeply favored by consumers at home and abroad as well as tea beverage manufacturers. However, tea aroma losses during thermal processing of tea beverage production. In this paper, the application of integration of pulsed electric field (PEF) and freeze concentration technology on tea soup was studied. The hot water extraction was substituted by the PEF extraction to extract green tea soup, vacuum evaporation was substituted by freeze concentration to concentrate the tea. The optimum conditions of the above two technologies were investigated. Using the combination of gas chromatography(GC-MS) mass spectrometry and solid-phase micro-extraction (SPME), the differences of the tea soup extracted by pulse electric field (PEF) and hot water on the aroma composition were investigated respectively, the same analysis was done for concentrated tea soup by freeze concentration and vacuum evaporation,. The optimal conditions of PEF extraction were given as; pulse width of 2.5 μs, electric field strength of 37 kV/cm, pulse number of 10, pulse frequency of 2 700 Hz and solid-liquid ratio of 1:30. The results of freeze concentration were best under the following conditions: initial solution temperature at 4℃, scraper speed at 150 r/min and coolant temperature at -15~-18℃. Compared with the hot water extraction, extraction of tea polyphenols by PEF was almost the same. The method of GC-MS with SPME was used to analyze aroma compounds of tea soup extracted by PEF and hot water respectively. The results indicated that PEF extraction technology could effectively keep the main aroma of tea soup. It was better than hot water extraction. The results of SPME /GC-MS indicated that freeze concentration technology could effectively keep most of aroma compounds of tea soup. It was better than vacuum evaporation. Both methods have potential applications in industrial production.

       

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