Studv On The Process Of Lotus Root Kimchi And Its Flavor

Processing lotus root into pickled vegetable products could enrich the taste and flavor of lotus root under the action of microorganisms,effectively retain the nutrients of lotus root and prolong the storage period of lotus root products,which was of great significance for the development of lotus root processing industry in China.This experiment mainly developed the fermentation of sweet-sour and low-salt lotus root pickles by lactic acid bacteria.The pretreatment technology,condiment formula and spice excipient formula were optimized in the process of pickles processing.The suitable hardener was screened.The changes of each index in the fermentation process of pickles with spice excipient and without spice were tracked and compared.Electronic-nose and headspace solid-phase microextraction were used.The flavor components of pickles were detected by GC-MS,and the kinds and contents of pickles were analyzed in detail.The results showed as follows:(1)Single factor and orthogonal experiments were carried out to optimize the slice thickness,blanching time and pre-salting time.Taking evaluation scores and hardness values as indexes,the optimum pretreatment conditions were determined as slice thickness of 5 mm,blanching time of 60 s and pre-salting time of 30 minutes.Single factor and orthogonal experiments were conducted to optimize the sugar,salt and monosodium glutamate additions.The evaluation scores and hardness values were taken as indicators.The optimum formula was determined to be 7.5%sugar,3%salt and 0.4%monosodium glutamate.Three spices,clove,anise and ginger,which had great influence on pickles,were determined by preliminary experiments.The single factor and orthogonal experiments were carried out by using sensory evaluation score and hardness value as indexes.The optimum formula was as follows:clove 0.04%,anise 0.1%,ginger 0.9%.The suitable hardener was screened out as follows:clove 0.04%,anise 0.1%,ginger 0.9%.0.1%calcium chloride.The changes of hardness,chroma,nitrite and salinity of pickles with spices and without spices during fermentation were tracked and determined.It was found that spices could effectively delay the hardness decline of pickles and reduce the browning of pickles.The nitrite content of pickles with spices was much lower than that of national pickles during fermentation and at the end of fermentation.Standard for nitrite content in vegetables.The salt content of kimchi was about 1.37%.Compared with ordinary kimchi products,the salt content of kimchi was lower,which meets people’s demand for healthy low-salt food.(2)Different packaging methods were used to store pickles.The effects of vacuum packaging and ordinary packaging(non-vacuum packaging)on the quality of pickles were studied.The results showed that the properties of vacuum packaging products were more stable.After storage for a period of time,the evaluation scores of vacuum packaging products were better than those of ordinary packaging products,and the hardness value decreased less,the softening rate was lower.Because of deoxidization treatment,the internal browning of lotus root slices was observed.The reaction was inhibited and the chroma value was superior to that of ordinary packaging at all storage periods.Samples of pickles treated with microwave sterilization at 700W(2min,4min,6 min)and pasteurization at 80℃(5min,10min,15 min)were compared.Microwave sterilization 700 W,4 min could better extend the product shelf life,maintain product quality,and less damage to product quality,lower softening rate during storage period,less color change,and in the whole process of sensory change was small,higher score.(3)The parameters of pickle products detected by electronic nose were optimized by selecting three factors:generation time of headspace body,temperature of headspace body and sample quantity.The response values of each sensor of 15s and 80s electronic nose were selected to study the influence of different detection conditions on response values.Through principal component analysis,the distinction and aggregation effects of experimental samples were analyzed,and the best detection parameters were selected.That was to say,the headspace formation time was 30 minutes,the headspace body formation temperature was 35 C,and the sample volume was 20 g.The optimized detection parameters were used to distinguish pickles with different fermentation days and different kinds of pickles sold in the market,and the effect was better.(4)The volatile components of pickled lotus root with different spices were determined by headspace solid phase microextraction(HS-SPME)combined with gas chromatography-mass spectrometry(GC-MS),and compared with those of pickled lotus root without spices.The results showed that the flavor components of pickled vegetables with different spices varied greatly and their contents were different.In the blank group(i.e.the sample group without any spices),45 components were detected,66 substances were detected in the fermentation samples of clove group,55 substances were detected in the fermentation samples of octagonal group,60substances were detected in the fermentation samples of lotus root pickle with ginger group,and 73 species were detected in the fermentation samples of lotus root pickle with three spices groups.Matter.Among them,the volatile components mainly include esters,alcohols,olefins and so on.There were fewer kinds of volatile substances in the blank group.After spices were added,the kinds and relative percentage of flavor substances in pickles changed greatly.These substances were directly introduced through spices,and some substances were produced by spices and a series of reactions under the action of microorganisms.The main components of clove group were eugenol acetate,ethyl acetate,cedar alcohol,alpha-chlorenes,isoeugenol and so on.Some of them were introduced directly into clove.The main ingredients in pickles added with anise group were Terpinyl acetate,D-limonene,anise,cis-anisole and so on.The main components of ginger pickles group were isoprenol acetate,3,7-dimethyl-2-octene-1-ol,ginger alcohol,4-ethyl-4-methyl-3-(1-methyl ethyl)-1-(1-methyl ethyl)-cyclohexene,etc.When three spices were added at the same time,the volatile components in pickles acted on each other to produce new substances.The main components in this group of samples were eugenol acetate,1-methyl-2-(1-methyl ethyl)benzene,anise,4-allyl anisole and so on.These substances enriched the taste of pickles.