Degree of oxidation depending on the positional distribution of linolenic acid in perilla oil and interesterified products

Interesterified perilla oil (IPO) was produced from rearrangement of fatty acids in perilla oil (PO) using Lipozyme RM IM-catalyzed interesterification. IPO showed a total fatty acid composition similar to PO; however, the positional distributions of ω-3 linolenic acid (ω-3 Ln, ALA) of these two oils were different. Thermal oxidation was performed at 40°C in the dark and oxidative stabilities of PO and IPO were investigated using ¹H NMR. After 20 days of oxidation, the concentration of ALA in IPO (47.9±1.3%) was significantly (p<0.05) higher than in PO (40.4±0.6%). IPO (40.6±5.5 mM oil) produced significantly (p<0.05) lower amounts of aldehydes (secondary oxidation products) than PO (61.6±2.0 mM oil). GC and HPLC results showed that the distribution of ALA in the LnLnLn molecule within TAG species was the main reason for improvement in the oxidative stability of IPO.     

Utilization of cane molasses for docosahexaenoic acid production by Schizochytrium sp. CCTCC M209059

Cane molasses (CM), an agro-industrial by-product, was first examined for docosahexaenoic acid (DHA) production by Schizochytrium sp. Cell dry weight as 21.94 g/L at treated CM cultivation was similar to that at pure glucose (26.7 g/L) cultivation. Batch fermentation at different initial CM concentration showed that DHA percentage could reach 47.51% at 10 g/L CM but only 37.90% at 70 g/L CM. By analyzing the fermentation process, monosodium glutamate might be a positive agent for effective DHA production. Finally, monosodium glutamate and malic acid were introduced to the fed-batch fermentation for effective DHA production.     

食品安全无菌抽样现状及操作规范研究

目的了解食品安全无菌抽样过程存在的问题,为规范无菌抽样工作流程提供参考依据。方法通过问卷调查、专家访谈、现场调研等方法对24家承担上海市食品药品监督管理局食品安全抽检任务的检验机构开展调查和分析,并通过模拟样品运送时间温度和开展实验室验证,确定合适的运输存储条件。结果部分检验机构存在抽样人员管理不到位、取样工具差异性较大、抽样记录不完整、样品运输时间和温度不符合要求等问题。结论建议加强抽样人员管理,提升抽样人员专业水平;无菌抽样关键过程进行视频信息采集,实现抽样过程的电子化记录和信息追溯;提倡样品在储存运输时进行连续温度监控。     

高效液相色谱法检测哌虫啶在稻田水、土壤、 稻米和小麦粉中的残留

目的 建立用高效液相色谱分析田水、土壤、稻米和小麦中哌虫啶残留分析方法。方法 稻田水用二氯甲烷提取,土壤、稻米和小麦用乙腈提取,采用高效液相色谱紫外检测器进行检测。结果 在0.5～10 mg/L范围内,哌虫啶浓度与色谱峰面积呈良好线性关系,相关系数0.9998,哌虫啶的最小检出量为1.0 ng。哌虫啶在田水、土壤、稻米和小麦种的平均添加回收率为73.17%～102.18%,变异系数为3.02%～9.89%。哌虫啶最低检测浓度为0.1 mg/kg。结论 本方法准确可靠,操作简便快速,节约溶剂,对环境污染小,符合农药残留分析的要求。     

极限平衡法与有限元强度折减法在露天矿边坡稳定性分析中的应用对比

阐述了极限平衡法和有限元强度折减法两种边坡稳定性分析方法的基本原理,采用Slide 6.0和Phase2 8.0两款软件对某露天矿西部边坡的稳定性进行分析,对比极限平衡法与有限元法计算出的安全系数。计算结果显示,两款软件计算出的安全系数接近,有限元法为1.0,极限平衡法为1.04~1.06,安全系数均达不到该边坡所要求的最低安全系数1.25,必须对边坡加固。根据软件数值分析出的滑移面用长锚索进行加固,加固后边坡安全系数为1.25~1.41,达到西部边坡的安全要求。经过对边坡稳定性的分析发现,极限平衡法和有限元法计算的安全系数均符合实际工程情况,适用于相似边坡的稳定性分析。     

Antioxidative activities of mao feng tea (Camellia spp.) and kamtae (Ecklonia cava) extracts and their effects on structured lipid from corn and perilla oil

In the study, solvent extracts of kamtae (Ecklonia cava) and mao feng tea (Camillia sinensis) were used for obtaining different fractions of organic solvents (diethyl ether, butanol, and ethyl acetate) and the extracted fractions were studied for their antioxidative activities. The total phenolic contents of the mao feng tea ranged from 1.44 to 5.97 mM GAE/g while kamtae ranged from 1.13 to 4.41 mM GAE/g, respectively. Among them, ethyl acetate fraction showed the highest content of phenolic compounds, resulting in Trolox equivalent antioxidant capacity (TEAC) values as 1,554.54 (from mao feng tea) and 1,097.63 mM Trolox E/g (from kamtae). Also, ethyl acetate fractions from mao feng tea showed the highest DPPH (89.27 RSC%), superoxide anion scavenging activity (46.58%), and ferric reducing antioxidant power (FRAP) (242.2 mg GAE/g) while ethyl acetate fractions from kamtae (K-EA) showed the highest DPPH (82.23 RSC%), superoxide anion scavenging activity (28.82%), and FRAP (162.43 mg GAE/g) among the obtained fractions.     

琼胶寡糖对冻藏南美白对虾蛋白质功能特性的影响

目的 探究琼胶寡糖对冻藏南美白对虾蛋白质功能特性的影响。方法 采用蒸馏水、1.5%和3.0%三聚磷酸钠、1.5%和3.0%琼胶寡糖浸泡南美白对虾,分别在冻藏第0、20、40、60、80和100 d时进行取样,测定其肌原纤维蛋白溶解性、浊度、乳化性(emulsifying activity index, EAI)、起泡性(foaming capacity, FC)和热稳定性。同时,利用苏木精-伊红(hematoxylin and eosin, HE)染色观察肌肉组织微观结构。结果 在冻藏过程中,琼胶寡糖与三聚磷酸钠的作用效果相当,且1.5%、3.0%琼胶寡糖显著改善了虾仁肌原纤维蛋白溶解性、EAI和FC的降低以及浊度的增加情况,增加了其热稳定性。HE染色结果显示,新鲜虾仁内部肌肉组织排列紧密有序,而冻藏100 d后,各处理组虾仁肌肉纤维均有不同程度的扭曲断裂,其中3.0%琼胶寡糖组虾仁肌纤维间的连接仍十分紧密,组织结构最为完整。结论 琼胶寡糖能有效保持冻藏南美白对虾蛋白质功能特性,维持肌肉组织结构,提高虾类品质。本研究为水产品抗冻剂的开发提供了借鉴和参考。     

Emulsifying Properties of Lecithin Containing Different Fatty Acids Obtained by Immobilized Lecitase Ultra-Catalyzed Reaction

Lecitase Ultra and 6 triacylglycerol lipases (lipases PS, M, AH, AY, R, and AK) were immobilized on Amberlite XAD 7HP and used to catalyze the acidolysis reaction between lecithin and capric acid (C10:0) for comparison. The highest molar incorporation value (51.0 mol%) was observed for the immobilized Lecitase Ultra. Further, immobilized Lecitase Ultra was selected for catalyzing acidolysis between lecithin and fatty acids with different chain lengths (C6:0, C8:0, C10:0, C12:0, and C14:0). After reaction, free fatty acids were removed by SPE and the resultant was called modified lecithin fraction 1 (MLF1). The highest molar incorporation value was obtained for C10:0 (51.0 mol%) at 45 °C with a mole ratio of 10/1 (C10:0/lecithin) for 72 h. After removal of lysophosphatidylcholine by solid-phase extraction from MLF1, the resultant modified lecithin fraction 2 (MLF2) was used to prepare an oil-in-water emulsion. All emulsions prepared with MLF2 exhibited significantly higher emulsion stability (ES) values (16.2–17.7) and smaller particle sizes (d ₃₂ 0.40–0.49 μm, d ₄₃ 0.75–1.01 μm) than the emulsion prepared with unmodified lecithin (ES 14.1, d ₃₂ 0.76 μm, d ₄₃, 1.26 μm) (P < 0.05). Furthermore, less clarification and droplet aggregation were observed in emulsions prepared with MLF2 than in lecithin-based emulsions. Overall, the MLF2s showed better emulsifying properties than lecithin.     

麦麸多糖提取工艺及其抑菌活性的研究

通过单因素和L9(33)正交试验对麦麸多糖的微波法提取工艺进行研究,得出提取的最佳工艺条件为:时间90 s、功率320 W、料液比1∶30,在此工艺条件下,麦麸多糖得率为6.57%。通过体外抑菌试验及最小抑菌浓度的测定研究了麦麸多糖的抑菌效果,结果表明:麦麸多糖浓度为40～60 mg/mL时,其对地衣芽胞杆菌、大肠杆菌、金黄色葡糖球菌及沙门氏菌等常见致病菌已达到较好的抑菌效果;麦麸多糖的最低抑菌浓度为地衣芽孢杆菌8.0 mg/mL,大肠杆菌10.0 mg/mL,金黄色葡萄球菌和沙门氏菌均为6.0 mg/mL。     

葛根固体饮料的配方优化及体外模拟消化研究

目的 研制葛根固体饮料, 并探究其香气成分和体外消化抗氧化活性。方法 在单因素的基础上, 通过响应面法结合模糊数学感官评价法对葛根固体饮料工艺进行优化, 气相色谱-质谱法分析固体饮料的香气成分, 体外模拟消化过程中的抗氧化活性变化。结果 葛根固体饮料的最佳工艺配方为: 葛根提取物、蔗糖、DL-苹果酸和β-环状糊精的添加量各为3.00、6.50、0.20、3.00 g; 在此条件下, 模糊数学感官得分为(91.85±0.35)分, 与理论误差值为2.69%; 酯类化合物是葛根固体饮料主要风味物质; 胃肠消化后的1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl, DPPH)、2,2-联氨-二(3-乙基-苯并噻唑啉-6-磺酸)二胺盐[2-2’-azino- bis(3-ethylbenzothiazoline-6-sulfonicacid), ABTS]、?OH清除率和总还原能力高达92.59%±0.85%、81.26%±3.43%、93.89%±0.20%和0.564 Abs±0.01 Abs。结论 最佳配方下的葛根固体饮料(2 g/袋), 色泽呈浅棕色、口感绵密、稳定均匀, 其理化指标符合GB/T 29602—2013《固体饮料》标准要求, 且具有较强的抗氧化能力和风味特征, 抗消化稳定性较好, 该固体饮料具有很高的应用价值, 可作为一种新型的健康饮品。