Changes of protein oxidation,lipid oxidation and lipolysis in Chinese dry sausage with different sodium chloride curing salt content

The effect of sodium chloride(NaCl)curing salt content on protein oxidation,lipid oxidation and lipolysis of Chinese dry sausage was investigated.Two groups Chinese dry sausages with 2%and 4%(m/m)salt content were studied.The degree of protein oxidation increased during the processes in two groups sausages,while the content of phospholipids decreased,neutral lipids and free fatty acids increased.The degree of protein oxidation,lipid oxidation and lipolysis in 4%NaCl content group was higher than those in 2%NaCl content group,while 4%NaCl content group has higher lipase activity.In conclusion,4%NaCl may facilitate the protein oxidation,lipid hydrolysis and oxidation in Chinese dry sausage,and the protein oxidation had strong correlation with lipid oxidation and lipolysis.The results could provide a basis for improving the technology of industrial production.

Time-dependent categorization of volatile aroma compound formation in stewed Chinese spicy beef using electron nose profile coupled with thermal desorption GC–MS detection

In the present study,flavor profiles of Chinese spiced beef in the cooking process were comparatively analyzed by electronic nose,gas chromatography–mass spectrometry(GC–MS)with a thermal desorption system(TDS),and solid-phase microextraction(SPME).A total of 82 volatile compounds were identified,and 3-methyl-butanal,pentanal,hexanal,-xylene,heptanal,limonene,terpinene,octanal,linalool,4-terpinenol,-terpineol,and(E)-anethole were identified as the characteristic flavor compounds in Chinese spiced beef.Variation in the content of volatile components produced by different cooking processes was observed.In general,a cooking time of 4 h resulted in optimal flavor quality and stability.Results indicated that the electronic nose could profile and rapidly distinguish variation among different cooking time.The volatile profiling by TDS-GC–MS and responses from the electronic nose,in combination with multivariate statistical analysis,are a promising tool for control the cooking process of spiced beef.

Effect of proteolytic starter culture isolated from Chinese Dong fermented pork(Nanx Wudl)on microbiological,biochemical and organoleptic attributes in dry fermented sausages

The effect of a proteolytic starter culture isolated from Nanx Wudl,on microbiological,biochemical and organoleptic attributes of dry fermented sausages was investigated during processing.Based on preliminary screening,the combination of Staphylococcus xylosus SX16 and Lactobacillus plantarum CMRC6,showing excellent proteolytic activity in vitro,was selected as the multi-strain starter(starter LS).For comparison,the single-strain starter culture of L.plantarum CMRC6(starter LB)and non-inoculated control were also tested.During fermentation,lactic acid bacteria and staphylococci dominated the microbiota and suppressed the Enterobacteriaceae growth in LS-inoculated sausages.The addition of LS starter accelerated acidification and proteolysis during ripening,improving the contents of total free amino acids and several essential free amino acids(Phe,Ile and Leu).Volatile compounds analysis revealed that LS-fermented sausage showed the highest abundance of 3-methyl-1-butanol,probably due to the inoculated S.xylosus.The inoculation of LS starter improved the sensory properties of sausages,especially the flavor attribute.Therefore,S.xylosus SX16 and L.plantarum CMRC6 are promising candidates for inclusion as multi-strain starters in the manufacture of gourmet fermented dry sausage.

Predominant yeasts in Chinese Dong fermented pork(Nanx Wudl)and their aroma-producing properties in fermented sausage condition

Yeasts are one of the predominant microbial groups in fermented meats.In this study,yeast communities of Chinese Dong fermented pork(Nanx Wudl)were investigated and the technological properties of 73 yeast isolates were evaluated.Through culture-dependent and high-throughput sequencing methods,the main yeast species identified included Pichia membranifaciens,Kazachstania bulderi,Millerozyma farinosa,Candida zeylanoides,Kazachstania exigua,Candida parapsilosis and Saccharomyces cerevisiae.Among these yeasts,P.membranifaciens,M.farinosa,K.exigua and K.bulderi were detected in fermented meats for the first time.A total of 73 yeast isolates was investigated for their lipolytic and proteolytic activities.All yeast species showed lipolytic activity,while proteolytic activity against meat protein was only detected in S.cerevisiae.Assay of aroma-producing potential was performed in a model simulating fermented sausage condition.Inoculation of yeast strains increased volatiles production,especially esters and alcohols.The highest ester production was observed in S.cerevisiae Y70 strain,followed by K.exigua Y12 and K.bulderi Y19.C.zeylanoides Y10 and S.cerevisiae Y70 were the highest producers of benzeneethanol and 3-methyl-1-butanol.S.cerevisiae Y70 with its highest production of branched alcohols and esters could be a promising candidate as aroma enhancer in the manufacture of fermented sausages.

Development of volatiles and odor-active compounds in Chinese dry sausage at different stages of process and storage

The effect of process and storage on the volatiles and odorant profi le of Chinese dry sausage was evaluated,as well as its physicochemical parameters.Microbial esterification and wine(27.54%–43.35%),and lipid oxidation(11.30%–34.92%)played a key role in flavor profile during process and storage.A significant increase of each volatile was detected during process except gradual decrease of volatiles from spices,while a gradual decrease of each volatile was detected during storage except signifi cant increase of volatiles from lipid oxidation and esterifi cation.15 and 6 odor-active compounds were respectively correlated(P<0.05)with the process and storage time.Level of heptanal,1-octen-3-ol,the ethyl of 2-methylbutanoic,3-methylbutanoic,butanoic,benzoic,hexanoic,heptanoic,octanoic and decanoic acid were best discriminators of process stage,while(E)-2-nonenal,ethyl hexanoate,ethyl heptanoate,and methyl decanoate,were marker compounds of storage time.An objective method was established to evaluate the stages of process and storage for samples.

Relative Content of Phenoxyethanol and p-Hydroxyacetophenone in Water Phase of Oil-water Systems and Teir Relevant Control Parameters

In emulsion system, micro-organisms survive in water phase, thus concentration of preservative in water phase directly reflects to anti-fungi efficacy. As preservative easily migrates into oil phase, it reduces preservative efficacy. A common solution is to increase preservative amount in the whole system. However this way always brings safety issues as preservative is a major allergen. Another effective but safety way is to prohibit preservative migrating into oil phase. In cosmetic research area, phenoxyethanol （PE） and p-Hydroxyacetophenone （p-HAP） pair gradually emerges to be a popular preservative candidate. Thus this new preservative system has been focused as the research object in this work. The relative contents （C） of both PE （CPE） and p-HAP （Cp-HAP） in water phase has been carefully determined. Eight commonly used oils have been further employed to check CPE and Cp-HAP in different oil-water system. The other infuence parameters such as polyols, processing parameters are also investigated. Results shows squalane, petrolatum, silicone oil and hydrogenated polyisobutene might be good oil phase candidates for formulation when using PE and p-HAP preservative system. In these oil systems, PE and p-HAP are mainly located in water phase. Besides, increasing percentage of 1, 3-butylene glycol, shortening homogenization time or adding preservatives at the end of processing under lower temperature could effectively increase effective content preservatives in water phase, either.