Study On Quick-freezing And Fresh-keeping Technology Of Stachys Sieboldii

Stachys sieboldii is a perennial Labiatae Stachys herb medicinal plants,nutrient rich and has some medicinal value.Rich in water,carbohydrate,protein,vitamins,choline and other nutrients,can regulate intestinal flora,enhance immunity,promote the absorption of trace elements,not only taste crisp,also has a unique flavor.But it is not storable,easy spoilage,influence the appearance and quality.The preservation technology research on Stachys sieboldii more useing pickled at present,Few reports has been research about frozen preservation technology of Stachys sieboldii,Curing technology can easy to make the nutrients serious loss,affect its nutritional value and medicinal value.So this paper takes the high quality Stachys sieboldii as raw material,study the effect of Stachys sieboldii quality on frozen pretreatment,quick freezing method,freezing-preservtion method and thawing method.Seeking the best quick-freezing technology of Stachys sieboldii,the main conclusions are as follows:(1)Effects of different blanching time on the quality of Stachys sieboldii:Fixed water consumption and single blanching of the material by boiling bath,Determination the change of enzyme activity,nutrient determination and texture properties of Stachys sieboldii on different blanching time to research the impact on the quality of it.The results showed that blanching treatment can effectively inhibit pectinase and polyphenol oxidase activity.The activity of pectinase was decreased and the activity of polyphenol oxidase was basically inactivated after 60 s,can effectively control the enzymatic browning of Stachys sieboldii;With the increase in blanching time,Stachys sieboldii ingredients gradually decreased.Blanching 30 s-60 s when the downward trend is more gentle,blanching 70 s after the decline in the trend is morerapid,indicating that the blanching time is too long is not conducive to the nutritional quality of Stachys sieboldii.(2)Effects of freezing method and frozen storage temperature on the quality of Stachys sieboldii: Quick-frozen the Stachys sieboldii by using-30 ? and-77 ?refrigerator frozen,liquid nitrogen frozen,then preserve under refrigerator of-15 ?,-20 ? and-25 ?.Research the impact on the quality of Stachys sieboldii by determination its nutrient composition,texture characteristics and ice crystal of freezing method and frozen storage temperature.The results show that The ice crystals are tiny and uniform distribution in frozen Stachys sieboldii tissue by liquid nitrogen frozen,no obvious damage to the cell structure,organization is more intact.The more freezing and frozen storage temperature low,physiological and biochemical reaction is slower in the tissue of Stachys sieboldii and less loss of nutrients,hardness and other texture characteristics are also more ideal,the hardness reaches 175.2 N under-25 ? and quick frozen by liquid nitrogen frozen.(3)Effects of different thawing methods on the quality of Stachys sieboldii:microwave thawing,ultrasonic thawing,water bath thawing,air thawing and 4 ?refrigerator thawing are used to thawing the frozen Stachys sieboldii.Research the impact on the quality of Stachys sieboldii by measuring the thawing time,drip loss,nutrient composition,texture properties and other indicators and combined with sensory evaluation.The results show that the different thawing time of different methods required as follows:microwave thawing<ultrasonic thawing < water bath thawing <air thawing<4 ? refrigerator thawing,microwave thawing and ultrasonic thawing are fast thawing and the others are slow thawing.It has great effect of 5 kinds of thawing methods on texture characteristics of Stachys sieboldii(p<0.05),the effect of microwave thawing on the hardness of Stachys sieboldii was the least(176.7 N),and it has lower juice loss rate,less nutrients loss,higher comprehensive sensory score of Stachys sieboldii(93.657).(4)The quality changes during frozen of Stachys sieboldii:tracking measured the nutrition quality,texture properties and combining with sensory evaluation to evaluate the quality changes during frozen storage of Stachys sieboldii within 6 months.Theresults show that lower temperature freezing can better preserve the hardness of Stachys sieboldii.During the storage period,the content of Vc,soluble solid and pectin decreased slowing.the content of reducing sugar in 7 day has a brief rise and decreased later.The sensory score is 81.293 points of Stachys sieboldii after frozen 6months.Indicating that the low temperature storage can better preserve the appearance and quality of Stachys sieboldii.In summary,it not only can effectively inhibit the enzyme activity of Stachys sieboldii,but also less loss nutrient when blanching 60 s,can provide high-quality Stachys sieboldii follow-up study for frozen.The lower the freezing and preserve temperature,the less the loss of the nutrient components after the thawing,and can maintain its hardness and other physical properties.No obvious damage to the cell structure by liquid nitrogen frozen,Can reduce the damage of Stachys sieboldii cell rapid freezing process,more suitable for quick-frozen Stachys sieboldii.Microwave thawing time is short,less loss of juice and nutrients,higher comprehensive sensory score,more suitable for thawing of Stachys sieboldii.Low temperature freezing can effectively reduce the decline of quality of Stachys sieboldii,extend the shelf life of it.