冻融破乳方法对水代法提取油茶籽油的影响

为提高水代法提取油茶籽油的提油率,将油茶籽经过脱壳、粉碎、过筛、加水过胶体磨、离心分离得到乳状液,经冻融破乳后离心分离得油茶籽油。以提油率为指标,探究了加热冻融、乙醇冻融、调pH冻融、加盐冻融等冻融破乳方法对水代法提取油茶籽油的影响,并通过共聚焦激光扫描显微镜对破乳前后乳状液的微观结构进行了观察。结果表明：乙醇冻融和加盐冻融使油茶籽的提油率降低;调pH可提高提油率,在pH为8时提油率为92.17%;加热冻融法是最佳的冻融破乳方法,在加热温度60℃、加热时间20 min条件下,提油率最高,达到92.57%;加热冻融处理后油滴聚集,粒径明显增大。采用加热冻融法对乳状液进行破乳可有效提高水代法提取油茶籽油的提油率。     

复合无磷保水剂对反复冻融鲟鱼片理化特性及微观结构的影响

为研究反复冻融条件下复合无磷保水剂对鲟鱼片理化特性及微观结构的影响,以蒸馏水处理作为空白对照组,将碳酸氢钠、柠檬酸钠和山梨糖醇浸泡的鲟鱼片作为处理组,分别进行5 次冻融,并对不同处理组鲟鱼片的解冻损失率、蒸煮损失率、pH值、硫代巴比妥酸（thiobarbituric acid,TBA）值、肌原纤维蛋白溶解度、Ca2＋-ATPase活性、质构特性等指标进行测定,同时比较鲟鱼片的微观组织结构。结果显示,随着冻融次数的增加,鲟鱼片的解冻损失率、蒸煮损失率、TBA值均显著上升（P＜0.05）,保水剂速冻处理组上升速率低于缓冻处理组低于空白对照组;各组鱼片pH值均呈现出先下降后升高趋势;水分含量、肌原纤维蛋白溶解度、Ca2＋-ATPase活性、硬度和弹性均显著降低（P＜0.05）,保水剂处理组各项指标下降速率均低于空白对照组;组织切片图显示保水剂处理能较好地保持鲟鱼片的微观组织结构。因此,使用由碳酸氢钠、柠檬酸钠和山梨糖醇复合的无磷保水剂对反复冻融条件下鲟鱼片的品质劣变有明显抑制作用。     

Antibacterial activity and action target of phenyllactic acid against Staphylococcus aureus and its application in skim milk and cheese

Phenyllactic acid (PLA) has been demonstrated to possess antibacterial activity and capacity to prolong food shelf life. However, studies on the performance of PLA in inhibiting Staphylococcus aureus and its effectiveness when applied to dairy products are largely lacking. Here, antibacterial activity (planktonic and biofilm states) of PLA against S. aureus CICC10145 (S. aureus_45) were investigated. The results showed that PLA inhibited growth of S. aureus_45 and formation of S. aureus_45 biofilm. Next, the antibacterial action target of PLA was uncovered from both physiological and phenotypic perspectives. The results showed that PLA decreased cell metabolic activity and cell viability, damaged cell membrane integrity, triggered leakage of intracellular contents (DNA, proteins, and ATP), and caused oxidative stress damage and morphological deformation of S. aureus_45. In practical application, the antibacterial activity of PLA against S. aureus_45 cells was further confirmed in skim milk and cheese as dairy food models, and the antibacterial effects can be adequately maintained during storage for 21 d, at least at 4°C. These findings suggested that PLA could be a potential candidate for controlling S. aureus outgrowth in dairy foods.     

熊果苷的药理作用及机制研究进展

熊果苷由于具美白、祛除色素的特性以及抗氧化、抗微生物、抗炎活性等药理作用,被广泛应用于化妆品和制药行业.近年来,熊果苷在改善葡萄酒香气等食品领域中也有一定的应用,对其安全性、营养价值等方面的研究报道越来越多.随着人们对食疗和保健的重视,许多药品也向着药食同源的方向发展,故熊果苷在食品、保健品方面具有广阔的开发前景.该文...     

可得然胶功能性质及其在食品中的应用研究进展

可得然胶是一种微生物胞外多糖,具有良好的凝胶性、持水性、增稠性及冻融稳定等特性,在食品工业中得到广泛的应用。随着可得然胶应用研究的不断深入,近年来有关可得然胶的报道越来越多。本文综述了可得然胶的来源、化学结构及功能特性,重点阐述了可得然胶在各类食品加工领域应用的最新进展,以期为可得然胶进一步在食品加工中的应用提供理论参考。     

Characteristic tryptic peptides and gelling properties of porcine skin gelatin affected by thermal action

Thermal action in extraction process had effects on characteristic tryptic peptides identification and gelling properties of porcine gelatin. SDS-PAGE, HPLC-LTQ/Orbitrap high-resolution mass spectrometry, texture analyser and rheometer were used to evaluate collagen depolymerisation degree, characteristic tryptic peptides and gelling properties of gelatins prepared in various thermal actions. Results showed that with increasing temperature and time, depolymerisation degree enlarged, while gel strength, gelling and melting temperature decreased. Mass spectra showed that 47 and 49 common characteristic tryptic peptides were identified in gelatins extracted at 50 °C and 100 °C with various times, respectively. Moreover, 34 common characteristic tryptic peptides were identified in all gelatin samples. Further comparison between this work and our previous investigations yielded 20 common characteristic tryptic peptides, which stably exist in various thermal actions. These common characteristic tryptic peptides may be very helpful for the accurate authentication of porcine gelatin.     

油莎豆油不同提取方法的比较

全面比较了油莎豆油的溶剂浸提法、水酶法和水酶-冻融技术这3种提取方法,探索不同提取方法的提取机理,为油莎豆油提取产业化生产提供指导。研究比较了3种油莎豆油提取方法的提取率、油品理化性质、油莎豆粕粉扫描电镜图。结果表明,水酶法和水酶-冻融技术相对溶剂浸提法更具开发潜力。     

芝麻素对细菌作用方式的研究

采用滤纸片法和平板培养法研究了芝麻素的抗菌活性,同时以大肠杆菌为指示菌,用生长曲线法、琼脂块再培养法对芝麻素抗细菌作用的方式进行了研究。结果表明,芝麻素抗细菌作用显著,最低抑制浓度(MIC) 为0．1%,既可抑制细菌的生长,又有杀菌作用,但以杀菌作用为主。用相差显微镜进行观察,可见到加有芝麻素的培养液中细菌形态有明显的改变,菌体密度不均匀；芝麻素的抗菌作用优于同浓度的苯甲酸钠。     

酸性热致大豆分离蛋白聚集体制备高冻融稳定性类蛋黄酱乳液

本文对酸性（pH 3.0）热致大豆分离蛋白聚集体（AHSPI）的平均粒径（Dh）、表面电位（ζ）、表面疏水性（H0）与溶解度进行了表征与测定,并用酸性（pH 3.0）天然大豆分离蛋白（ANSPI）、中性（pH 7.0）热致大豆分离蛋白聚集体（HSPI）作为对比分析,同时选用了AHSPI代替蛋黄制备高冻融稳定性的类蛋黄酱乳液,探讨了不同蛋白浓度对类蛋黄酱乳液的外观质地、微观结构、流变性质、DSC特性的影响。结果表明：AHSPI的平均粒径（204.67 nm）及H0（79418）均大于ANSPI与HSPI（pH 7.0）,但ζ电位绝对值（35.93 mV）小于ANSPI与HSPI（pH 7.0）,溶解度（89.47%）较HSPI（pH 7.0）更好。用AHSPI制备的类蛋黄酱乳液经过3次冻融循环保持稳定的最低浓度可达0.3 wt%,冻融前后乳液结构保持不变,只是乳液粒径的略微增大,流变性质表明类蛋黄酱乳液具有以弹性为主的凝胶网络结构,随着蛋白浓度的增大,油滴粒径逐渐减小,粘弹特性增强。DSC热分析表明：随着蛋白浓度的增加,类蛋黄酱乳液的结晶凝固点降低（-18→-28 ℃）,而蛋黄酱即使具有低于冷冻温度（-20 ℃）的结晶凝固点（-27.89 ℃）,仍发生了冻融破乳现象,类蛋黄酱乳液较好的界面稳定性赋予了其较好的冻融稳定性,为开发一类天然低胆固醇高冻融稳定性的酱类乳液提供了研究基础。     

白茶药理作用及保健功效研究进展

综述了白茶的药理作用及保健功能。