Study On Volatile Conponents During Fermentation Process Of Sweet Flour Paste

The fermentation process of sweet flour paste which was long production period and little yield is influenced by traditional methods.And the quality of the product were unstable because the products were affected by the season and climate of processing.So the industrialization development of sweet flour paste was limitted.In the study,the influences between fermentation conditions and the changes of volatile components were extracted by HS-SPME and analysed GC-MS.And the relations of between the changes of volatile components and features flavoring compositions was studied during fermenting process of the traditional paste. The results were as follows:ⅠTo optimize extraction conditions in sweet flour pasteThe kinds of volatile components from sweet flour paste which were extracted by three methods(solvent extraction,simultaneous distillation extraetion and headspace -solid-phase microextraction)were Compared.The results showed that HS-SPME was the best extraction method for extracting volatile components in sweet flour paste. Optimization of HS-SPME by response surface method showed that extracting temperature 63℃,extraction time 53min,Nacl 1.05 g and pH 4.1,empty volume 6mL,mass concentration of 0.5 g/mL,desorption time 4min and speed 937r/min. 52 compounds were acquired under the optimal conditions,and total content and species of esters were the highest.ⅡInfluence on volatile components produing under different fermentation conditionsVolatile components from sweet flour pastes,which were fermented by different conditions(microbial,fermentation temperature,light,add yeast quantity,brine concentration and raw materials),were extracted by HS-SPME and analysised GC-MS. The results showed that Aspergillus oryzae was beneficial to produce alcohols and ketones.Aspergillus niger was beneficial to produce phenolics and hydrocarbons. Rhizopus oryzae was beneficial to produce esters and aldehydes.Mixed Koji did not benefit for producing most volatile components.The optimization of per-fermentation temperature was 20℃.And under the optimum per-fermentation temperature,the contents of esters,alcohols,ketones and hydrocarbons were the highest. It were helpful for esters forming when later fermentation temperatures were 35℃or 40℃,and it was beneficial to esters forming when later fermentation temperatures were 40℃and 45℃.It was advantageous to esters,aldehydes,hydrocarbons and furans formed under light conditions. It was significant helpful to esters formed by adding yeast with 1.4%. The higest contents of seven species were adding salt concentration with 12%.After the fermentation of 25 days,the contents of esters,alcohols, ketones and hydrocarbons producing by flour fermenting were more than by wheat fermenting.ⅢStudy on the typical of aroma component by GC-OTwo sweet flour paste made in lab and two sweet flour pastes bought from supermarket were detected by HS-SPME-GC-MS/GC-O.The result showed the relationship from 28 odours and volatile components.Aromatic characteristics were boiled potato,almond,fruit,flowers and picees.The main faover components were ethyl benzoate,ethyl caprylate,phenylacetaldehyde and 2-pentylfuran which were the fragrance of flowers,and phenylacetic acid ethyl ester and phenylethyl alcohol which were the fragrance of wheat,and ethyl laurate which was the fragrance of peanut,and benzaldehyde which was the fragrance of almond flavour,and 4-Hydroxy-3-methoxystyr ene which was the fragrance of pungent aroma,and furfural which was the fragrance of boiled potato.ⅣDynamic detected on volatile components during fermentation processingThe volatile components of fermentation processing in sweet flour paste were analysed by HS-SPME-GC-MS. The results showed that hydrocarbons were the main volatile components in flour,and esters were the main volatile components in sweet flour paste and Koji. Relative Content of esters and alcohols were the highest in Koji(the second day).The kinds of esters were more and more ,but relative Content of alcohols were gradually less during fermentation processing.Aldehydes and phenols were detected rarely in raw material,and relative contents of aldehydes were increasing slowly during fermentation processing,but major content of phenols were increasing in Koji. Ethyl benzoate,ethyl caprylate,ethyl laurate,benzaldehyde,and phenylacet -aldehyde were formed in 2 days,and Phenylacetic acid ethyl ester,Phenethyl alcohol,2-Pentylfuran and Furfural were formed in 7 days.