低聚木糖的模拟移动床色谱分离研究

研究了用模拟移动床色谱分离高含量低聚木糖的工艺。首先通过单柱固定床实验来选择适合低聚木糖分离的固定相,比较了不同类型的离子交换树脂对低聚木糖和单糖混合液的分离度和分离效率．筛选出DIAION—UBK530Na树脂为合适的分离介质;然后运用真实移动床模型,近似确立模拟移动床色谱分离工艺的初始操作参数．在理论分离原理的指导下,优化分离条件,在阀切换时间为300s、进料流量和洗脱流量分别为3．5mL／min和5ml/min、提取液和提余液流量分别为3．8mL／min和4．7mL／min、同时循环流量控制在8．9mL／min的条件下．使分离后的低聚木糖、单糖纯度均在90％以上,收率分别达到91．55％和92．18％。     

发酵牛肉调味基料替代亚硝酸盐在红肠中的应用

在传统调味基料制备工艺基础上,增加微生物发酵环节制成发酵牛肉调味基料(Fermented beef flavor,FBF),将其按照不同添加比例应用于红肠的加工中,设计5组试验:阴性对照NC组(不添加亚硝酸盐)、阳性对照PC组(添加亚硝酸盐),分别添加2%、6%和10%发酵牛肉调味基料的样品组制成红肠,真空包装后,20 ℃条件下贮藏,在贮藏过程中对其进行品质评价。结果表明:发酵牛肉调味基料对红肠除具有明显提高风味作用(气味和滋味得分均不低于NC组)外,还起到良好的发色和抗氧化作用,添加发酵牛肉调味基料的试验组红肠的红度值与PC组无显著差异,当其添加量为2%时,红肠在贮藏过程中的TBARs值始终低于1.0 mg/kg,具有较强的抗氧化性。微生物多样性分析结果发现,发酵牛肉调味基料的添加对红肠中的优势腐败菌属(葡萄球菌属)具有明显抑制作用,其货架期比NC组明显延长,与PC组的保质期相当。可见,FBF具有应用于红肠中替代亚硝酸盐的潜力。     

1-MCP处理维持软枣猕猴桃活性氧的代谢平衡

为了明确1-MCP处理对软枣猕猴桃冰温(-0.5±0.3℃)贮藏0～60 d期间活性氧(ROS)代谢的影响,以"龙成二号"为研究试材,采用1.0μL/L 1-甲基环丙烯(1-MCP)进行熏蒸处理,探究其对果实生理、活性氧代谢、抗坏血酸-谷胱甘肽循环的影响.结果表明:在贮藏60 d时1-MCP处理组果实呼吸强度为44.1...     

发酵牛肉调味基料在牛肉饼中的应用效果

冷冻牛骨肉末经热-压浸提、酶解、发酵和美拉德反应后制成发酵牛肉调味基料（fermented beef flavoring,FBF）,以新鲜牛前肩肉为原料,加入不同比例腌制剂制成牛肉饼,分别为阴性对照（negative control,NC）组（既不添加NaNO2又不添加FBF）、阳性对照（positive control,PC）组（添加不同比例的NaNO2）及实验组。对牛肉饼进行感官评价后于20 ℃条件下贮藏,测定贮藏期间牛肉饼的红度值（a*）、pH值、硫代巴比妥酸反应物（thiobarbituric acid reactive substance,TBARs）值及亚硝酸盐残留量。结果表明：与NC组相比,PC组和实验组牛肉饼色泽红润,口感香嫩,风味得到明显改善;只添加FBF的实验组牛肉饼a*较高,TBARs值和亚硝酸盐残留量较低;同时添加NaNO2和FBF的牛肉饼口感、色泽及风味等品质均有所提高,且20 g/kg FBF和0.05 g/kg NaNO2复配制成的牛肉饼品质最好。     

预处理方式对甘薯变温压差膨化干燥产品品质的影响

为研究预处理方式对甘薯变温压差膨化干燥的影响,以甘薯为原料,探讨膨化初始含水量、糖煮处理和冻融处理对甘薯膨化干燥产品硬度、表观密度和感官等的影响。结果表明:甘薯膨化初始含水量为75%～80%,用40%麦芽糖浆液煮沸处理2min,-18℃下冷冻处理12h再室温(20℃)自然解冻,在膨化温度为100～105℃、抽真空干燥温度75～80℃条件下所制备的甘薯膨化产品具有良好的色泽和酥脆性。试验表明运用糖煮和冻融预处理可明显改善甘薯膨化干燥产品的酥脆性和色泽。     

Rosemary as antioxidant in pressure processed chicken during subsequent cooking as evaluated by electron spin resonance spectroscopy

The potential of rosemary (Rosmarinus officinalis L.) to inhibiting lipid oxidation in minced chicken breast and thigh muscle processed at 600 MPa for 10 min during subsequent heat treatment was investigated using electron spin resonance (ESR) spectroscopy and electrochemical detection of oxygen consumption. Chicken breast cooked at 95 °C was found to have significantly higher rate of formation of free radicals and oxygen consumption rate than the samples cooked at 70 °C and 120 °C and this intermediate cooking temperature was used to evaluate the effect of pressure on oxidation during subsequent cooking. Rosemary was found effective in retarding lipid oxidation since the pressurized, minced chicken breast and thigh with rosemary added showed lower rate of oxygen consumption and lower tendency of free radical formation following heat treatment than the samples without rosemary. Pressurized chicken thigh showed a higher susceptibility to oxidation than chicken breast upon subsequent heat treatment. Oxidation in pressurized and subsequently heat-treated chicken breast was from a higher tendency of radical formation concluded to be in an earlier phase of oxidation compared to thigh subjected to the same treatment.Industrial relevanceHigh-pressure processing has a great potential for microbial control of raw chicken meat as a “fresh” chill-stored, convenience product for wok cooking. While raw chicken meat is oxidatively stable, high-pressure treatment at 600 MPa and above induces lipid oxidation resulting in off-flavors during subsequent cooking. Addition of 0.1% dried rosemary to minced chicken thighs or breasts prior to high-pressure processing inhibit lipid oxidation during subsequent cooking and could form the basis for product development.     

Physicochemical properties and structure of starches from Chinese rice cultivars

Starches from 10 different non-waxy rice cultivars in China were isolated and investigated for their physicochemical properties including the swelling power, solubility, syneresis, thermal, rheological and textural properties, and structure. The range of amylose content in 10 rice starches was between 18.1 and 31.6%. The branch chain length distribution of amylopectin revealed that the proportions of short (DP6–11), medium (DP12–17), and longer chains (DP18–23) were 4.6–11.1%, 47.0–51.6% and 25.3–31.8%, respectively. The relationships between different properties of rice starches were determined using Pearson correlation analysis. Amylose content was negatively correlated to swelling power (r = ?0.632, p ≤ 0.05) and positively correlated to gel hardness (r = 0.776, p ≤ 0.01). The percentage of short chains (DP6–11) was negatively related to the transition temperatures (T_o, T_p and T_c), T_oG′ and T_G′max, while the percentage of medium chains (DP12–23) was positively related. Various branch chain length amylopectins played different roles in rheological behavior of starch dispersions. The percentage of short chains (DP6–11) was positively correlated to G′ and G″(r = 0.832 and r = 0.775, respectively, p ≤ 0.01), and negatively correlated to tanδ peak (r = ?0.717, p ≤ 0.05). However, the percentage of longer chains (DP18–23) showed a negative relation with G′ and G″ (r = ?0.794, p ≤ 0.01; r = ?0.741, p ≤ 0.05), and a positive relation with tanδ peak (r = 0.668, p ≤ 0.05).     

拉伸温度对纤丝干酪流变学特性及微观结构的影响

用小型单螺杆拉伸机制作纤丝干酪,研究拉伸温度对纤丝干酪流变学性质和微观结构的影响。扫描电镜观察结果表明,干酪凝块经过拉伸过程后由无定型的三维结构转变为近乎平行排列的线性纤维状结构,拉伸温度越高蛋白质网络结构越致密。这一结果与通过离心法测定纤丝干酪可榨乳清含量结果一致,说明经过热烫拉伸处理后酪蛋白矩阵持水力增大,且拉伸温度越高酪蛋白矩阵持水力越大。干酪从25 ℃升温至80 ℃的动态流变学温度扫描结果表明,拉伸温度低于50 ℃时制作的纤丝干酪加热后流变学性质不稳定。干酪从0.1-10 Hz动态流变学频率扫描结果表明,纤丝干酪表现出较强的粘弹性以及剪切稀化特性,且随着拉伸温度的升高,这种特性表现的愈加明显。TPA分析结果表明,拉伸温度对纤丝干酪硬度影响最显著。