本文研究了沙葱自然发酵过程中主要菌群和典型发酵菌株的生长及其与沙葱中呈味氨基酸变化的关系.游离氨基酸含量用氨基酸自动分析仪分析,对影响感官的游离氨基酸按照氨基酸的味觉强度进行分类.结果表明:沙葱未发酵前呈味氨基酸中以鲜味氨基酸(Glu、Asp、Lys)含量高,发酵初期以植物乳杆菌为优势乳酸菌,各种呈味氨基酸含量均逐渐降低.主发酵期植物乳杆菌、发酵乳杆菌和嗜酸乳杆菌数量较多,苦味氨基酸含量(Leu、Val、Arg、Ile、Trp、Met)、甜味氨基酸(Ser、Thr、Gly、Ala、His、Pro)和鲜味氨基酸含量相近.发酵后期以干酪乳杆菌为优势乳酸茵,甜味氨基酸含量占总呈味氨基酸含量比例更大.整个发酵过程中芳香族氨基酸(Tyr、Cys、Phe)含量较低且变化不大,发酵中后期7～15d沙葱的滋味最好.

[Objective] To compare and analyze the quality of spiced beef storing in different temperature,and define safety storage period of spiced beef.[Method] The quality of spiced beef in common marketing storage conditions was studied,as well as the variation law of microorganism with time and temperature.[Result] Storing at normal temperature,physical state and microorganism content of spiced beef varied with time prolong;the variation rate under lower and stable temperature was lower.High quality period and quality guarantee period of spiced beef under 4 ℃ was 8 and 14 d;High quality period,quality guarantee period and retirement period under 7 ℃ was 6,8,12 d;under 10 ℃ was 4,6,8 d,respectively.[Conclusion] The study can provide reference basis for defining spiced beef safety storage period.

Structural characterization and physio-chemical properties of 6 long jujube polysaccharides were explored by infrared spectroscopy,optical rotation meter and viscometer.Infrared spectroscopy showed that long jujube polysaccharide had typical functional groups of polysaccharides.Optical rotation tests revealed the specific rotation degrees for 6 long jujube polysaccharides of +44.0,+27.0,+30.0,+19.0,+36.0 and +22.0,respectively.Their solubility was greatly affected by temperature.A low solubility at low temperature was observed.The viscosity of six long jujube polysaccharides was increased with increasing concentration,but was reduced with increasing temperature and the temperature effect was reversible.Moreover,the viscosity was also negatively related to shearing force.

The relationships between microbial and physiochemical properties for chilled mutton were investigated and predictive models for the growth of the major pathogenic bacteria Pseudomonas were established.Total bacterial colony,pH,total volatile basic nitrogen(TVB-N) and Pseudomonas count were measured during chilled storage of mutton at 4 ℃.The results showed that pH initially rose and then fell,TVB-N increased slowly at the early stage of storage and rapidly at the later stage.Gompertz models and square-root models describing the growth of Pseudomonas at 4,7,10,15 ℃ and 20 ℃ were fitted with Matlab 7.0 software.The growth models at 4 ℃ and 10 ℃ were valiated.Accuracy was observed within 20%,indicating good prediction capability.

Total plate count(TPC) can reflect the spoilage condition of spiced beef.In this study,bacterial growth models which describe TPC in spiced beef at constant temperatures and a predictive model for the shelf life of spiced beef were established.Commercial spiced beef samples were stored at 4,7 or 10 ℃ and measured for TPC changes during storage.The primary growth models established in this study indicated a goodness of fit above 95%,and the secondary square root model showed a good linear relationship between temperature and growth rate with R2 of 0.998 and residual error fluctuating about zero.Moreover the shelf life prediction model was also validated.

[Objective] To filter the antitumor polysaccharide from long jujubes,so as to provide references for developing new jujube products.[Method] Purity of the obtained six long jujube polysaccharides were detected with Sepharose CL-6B and HPLC.At the same time inhibition rate of Bel7402,BGC823 and KB by six long jujube polysaccharide were determined and comparatively analyzed.[Result] The six types of polysaccharides were all single component.When the concentration was 400 mg/L,inhibition rate of the three tumour by LJU-3 were separately 61.29%,68.77% and 72.16%,which was the highest than that of other five long jujube polysaccharides and higher than 50%,all of this explained the inhibitive effect of LJU-3 against the three tumour was moderate sensitive or high sensitive.IC50 value of LJU-3 to Bel7402,BGC823 and KB were 198,178 and 167 mg/L with IC50 software,so LJU-3 was considered as the antitumor polysaccharide in long jujube polysaccharide.[Conclusion] The study provided references for the furthur study on the antitumor activity of polysaccharides from long jujube.