Study On The Technology Of Vacuum Frozen Drying Sweet Pepper

Vacuum Freeze-dried grains of green sweet pepper as emerging dehydratedvegetable products, are becoming more and more popular in the international anddomestic markets, since the products are nutritious as the fresh material, have highrecovery rate, and can be ready to serve. The dehydrated green sweet pepper aftervacuum freeze-drying can keep its original flavor and nutrients, which caneffectively solve some problems, such as, the sample size decreased, the texturehardened and volatile components loss seriously, etc. However, the problems offading during long-term storage restricted the development of technology ofvacuum Freeze-dried in China.In order to obtain the optimum conditions of vacuum freeze-dried, we studiedthe conditions of blanching experiments, protecting green tests, freeze-driedexperiments and storage tests to provide technical support for the production ofvacuum freeze-dried green bell pepper. The main conclusions were as follows:(1) Blanching and soaking could effectively prevent browning and modifyqualities. Selecting the green sweet pepper of good maturity and color, fruit weightof130~150g, flesh thickness of5.0~5.5mm, and the fruit vertical stems of7~9cm, horizontal stems of7.0~7.5cm. After washing and peeling section, rawmaterials were cut into pieces of1.5×1.5cm. It was found that blanching in95°Cfor70s could make enzyme inactive completely to prevent browning effectivelyand approve retention rate. After blanching, retention rate and recovery rate ofchlorophyll among freeze-dried products were both approved when soaked in themixture solution contained5%NaCl,4%glucose and0.4%CaCl2for20minutes in20°C.(2) Energy consumption could be cut down by optimizing parameters offreeze-drying. On conditions that the eutectic temperature was no more thaneutectic point (2.2°C), the heating temperature must be as high as possible toshorten the cycles of producing. The technology parameter of freeze-drying wasthat the grain of sweet pepper was quick-frozen in-20°C, and the vacuum of thefreeze-drying process in30Pa, sublimation drying in5°C for3h and resolution drying in40°for1.5h. The quality of freeze-dried Sweet Pepper was improvedevidently.(3) Vacuum Freeze-dried grains of green sweet pepper are particle satiated andthe color outside is bright. Also, it has better efficiency in rehydration. We put the0.07mm thickness pepper into150×100mm lightproof PE bags and with the vaccumpacking the storage effects is good under5℃.