臺灣博碩士論文加值系統

　　本研究之目的在，探討濃縮胡蘿蔔汁之製程條件及對品質的影響。採用瑞士Unipektin公司P151-3S中間工廠型三效蒸發器及其所附設的香氣回收設備來濃縮胡蘿蔔汁，並將回收到的香氣冷凝水分別再以分餾蒸餾法或滲透法濃縮後，回添於還原胡蘿蔔汁中。
　　胡蘿蔔汁香氣成分的總回收率隨蒸發率的提高而增加，而蒸發率受進料流速及一效發罐的蒸發溫度所影響。以蒸發率高低、低香氣胡蘿蔔汗的色澤及冷凝液香氣強度品評結果，作為釐定香氣成分回收條件之依據，所選用的一效蒸發罐溫度為101℃，進料流速為每小時54公升，可得蒸發率為48.96%之香氣冷凝液。經熱脫附冷/捕捉法配合氣相層析儀分析鑑定出terpinolene、m-xylene及β-bisabloene等十一種揮發性成份，其中碳氫化合物含量佔總量的98%。選用HR-98薄膜，以逆滲透法濃縮胡蘿蔔香氣冷凝液，濃縮香精中揮發性成份總量約為11586mg/kg，其中含量較量較高且具代表性的分別為m-xylene、hexanal及camphene等。當操作溫度或壓力昇高時，透流率會隨之昇高。以oldershaw column分餾蒸餾香氣冷凝液，所得濃縮香精中揮發性成份總量約為7300mg/kg，並生成了胡蘿蔔煮熟味之代表性化合物nonanal。將濃縮香精回添於還原胡蘿蔔汁中，以三角試驗難事法時行官能品評試驗，兩種濃縮方式間並不具顯著性差異。
　　低香氣胡蘿蔔原汁經三效濃縮後，可溶性固形物含量提高至56° Brix，將濃縮汁稀釋還原至6° Brix以時行品質分析。結果顯示，蔗糖、葡萄糖及果糖的含量皆減少，羥化甲基糠醛（5-HMF）的含量為1.2ppm。比較高低兩種不同濃縮倍數的還原胡蘿蔔汁：還原自低濃縮倍數（36°Brix）的胡蘿蔔汁其色調較偏紅，總類胡蘿蔔素含量也較經三效濃縮再還原的胡蘿蔔汁高。而官能品評試驗結果顯示：還原自低濃縮倍數的胡蘿蔔汁其整體風味喜好性為最佳，進行統計分析後得知，整體風味喜好性和香氣強度呈負相關的關係。
　　結合以上結果，良好品質的濃縮胡蘿蔔汁其濃縮終點之可溶性固形物含量應在40° Brix以下；而蒸發濃縮過程中，所回收到的香氣冷凝液再配合逆滲透法製成濃縮香精，可回添入濃縮胡蘿蔔汁中或另供食品工業上的其他用途。

　　The purposes of this research are, to investigate the evaporation condition of carrot ( Daucus sarota L. var. Sativa DC.) juice and the effect on the quality of concentrated product. Carrot juice was concentrated by the Unipektin P151-3S pilot-scale triple effect evaporator with aroma recovery plant. The recovered aroma condensate was also concentrated by fractionation column or reverse osmosis, then added back to the reconstituted carrot juice.
　　The higher evaporation rate of carrot juice resulted in the increase of the total volatile compound recovery. The evaporation rate depends on the inlet juice feed rate and 1-effect evaporator temperature. The determination factors of optimum condition for aroma recovery were the evaporation rate, color of the aroma stripped carrot juice and the aroma intensity of condensate. the aroma recovery of carrot juice proceeding at 101℃ and 54L/hr. ( feed rate) resulted in 48.96%evaporation rate. The aroma condensate was further concentrated by the reverse osmosis process. The permeate flux was higher as the operation temperature and pressure raised. The recovered condensate was also fractionated by the oldershaw column. Both the final volume concentration ratio were 10. The two concentrated aroma condensate were added to the reconstituted carrot juice separately. Sensory evaluation result indicated that there is no signifficance difference between these two aroma concentration methods.
The aroma stripped carrot juice was concentrated to 56° Brix by the 3-effect evaporator. Comparing with the original fresh carrot juice, the amount of sucrose, glucose and fructose in the reconstituted juice after dilution were decreased. The content of browning intermediates: 5-HMF was 1.2 ppm. Total carotenoids, redness and overall flavor likeness were all higher in the juice reconstituted from 36° Brix concentrate. According to the correlation analysis, the higher overall flavor likeness was associated with weaker aroma intensity.
　　The end concentration point of high quality concentrate should below 40° Brix. The recovered aroma condensate can be further concentrated to aroma essence by reverse osmosis. The aroma concentrate can be incorporated with the carrot concentrate to enhance its flavor. It can also use alone for other purposes in the food industry.