Study On Process Of Vacumm Freeze-Dried Okra

Okra was known as "green ginseng"because of its high nutritional value and health benefits.And the Okra also contains many nutrients and physiologically active ingredient.But Okra pods have high moisture content and high water lose rate because of strong respiration, so the Okra are difficult to storage and transportation, resulting in the okra rot because of not timely sales and economic losses. The Okra of vacuum freeze-dried rehydration good, long storage life, easy to carry and also addressing the storage issues.Vacuum freeze-dried Okra improve the deep processing of okra and greatly increase the added value of okra. In this study, a commercially available fresh okra local as raw materials, to ensure product quality and reduce processing costs,a key technology of vacuum freeze-dried of Okra were studied aims to provide some technical reference in industrial production of vacuum freeze-dried okra.Main research finding was following:(1) Okra which contains a special sticky substance may hinder moisture to escape.The Okra was sliced can shorten the drying time, but may result in some loss of the active substance. Selecting the green local commercial Okra of good color, the same batch size uniform size (diameter of about 1-2cm, length about 11～13cm) for the study. Prior to pre-freezing,the okra will be cut into four at the same longitudinal section for shorten the drying time and reduce the loss rate of polysaccharide gum.(2) Blanching could prevent browning,and soaking solution could modify qualities. The Okra were blanched 90s at 95℃hot water respectively.After being blanched at hot water,the Okra were soaked in the solution made up of 5%Nacl,9%sucrose and 0.3% Cacl2 for 30min at thetemperature of 20℃,and the liquid-ratio of solution was 3:10.Next,after the soaking,the Okra was cutted into 4 slices in portriat.The techniques could prevent browning efficiently,maintain a certain fragility,and improve recovery rate of dehydrated Okra.(3) Energy consumption could be cut down by optimizing parameters of freeze-drying.Okra outer skin, flesh, seed rate of water loss, the eutectic point, a total different melting points. Eutectic point three parts were-15.44 ℃,-15.09 ℃,-14.17 ℃, in order to ensure complete freeze okra, select a pre-freezing temperature -25 ℃; to ensure the pre-freezing the structural damage is small, it is determined pre-freezing time 6h. Third Part of the eutectic point were 6.31 ℃,7.34 ℃,8.02 ℃, the sublimation drying want to set a suitable temperature, to ensure the temperature of each part does not exceed its eutectic point of the premise, as far as possible to improve the heating plate temperature, shorten the drying time. Okra pods after parameter optimization of vacuum freeze-drying process, freeze-drying process is determined as follows:loading 400g, proper control of the degree of vacuum, a heating plate temperature of 10 ℃, holding 10h complete sublimation drying, then heating plate temperature was raised to 35 ℃, holding 2h complete analytical dried okra this time final moisture content of less than 5%.