豆乾營養豐富，為延長保存時間往往添加大量防腐劑，造成食品安全衛生問題。本研究利用欄柵技術，結合數種抑菌因素，應用在豆乾加工，以達到減少防腐劑濫用，並延長保存期限的效果。試驗針對（1）黃豆浸漬時溫度（4及30℃）及有無臭氧處理（0及2 ppm/min）、（2）豆漿中添加0～5,000 ppm有無UV處理之肉桂、（3）使用0～0.40% （w/v）葡萄糖酸內酯（glucono-δ-lactone, GDL）作為凝固劑之可行性及（4）冷卻過程使用0～15 ppm臭氧冷卻0～80 min對微生物抑制效果等加以探討。研究結果發現，4℃浸漬可有效抑制微生物生長；而GDL濃度增加有抑菌功效，但豆乾質地較傳統豆乾差。肉桂粉濃度越高，則抑菌效果越佳；而利用臭氧冷卻亦可有效降低產品微生物量。歸納豆乾製作之欄柵條件為：黃豆使用4℃浸漬20小時，以0.4% GDL為凝固劑，並添加0.1%以紫外線照射過之肉桂粉製成之豆乾胚，經滷煮後，利用15 ppm臭氧吹冷40 min。
Dried soybean curd contains plenty of nutrients which make it putrefactive easily; therefore, manufacturers usually add preservatives to increase the shelf life. This investigation used the hurdle technology, by gathering several bacteria inhibition factors, to extend the shelf life of dried soybean curd. The bacteria inhibition factorsused in this study are: (1) different soaking temperatures (4 and 30℃) and ozone treatments (0 and 2 ppm/min); (2) addition of different concentrations of cinnamon (0~5,000 ppm), treated with or without UV in soymilk; (3) different (glucono-δ-lactone, GDL) concentrations (0~0.40% (w/v)) as a coagulant; (4) different concentrations of ozone (0~15 ppm) and cooling time (0~80 min) of the dried soymilk curd. The results showed that soybean soaked in 4℃ for 20 hours can effectively inhibit microbial growth. Increasing of the concentration of GDL could enhance the inhibitory effect on microorganism; however, the quality of the texture of dried soybean curd was decreased. The results also indicated the higher the concentration of cinnamon powder added, the better the inhibitory effect on the microorganisms. Ozone treatment was an effective process to inhibit the microorganisms during the cooling process of dried soybean curd. In summary, the optimal process for dried soybean curd is: soak the soybean in 4℃ for 20 hours, and coagulate the soymilk with 0.4% GDL. Meanwhile, 0.1% cinnamon powder treated with UV radiation was added during coagulation. The half product was boiled in brine and then cooled by applying 15 ppm ozone for 40 min.
