啤酒废酵母酶解液作为有机氮源厌氧发酵制备丁二酸的研究

确定了以啤酒废酵母为原料,酵母酶解液中α-氨基氮含量为考察指标的蜗牛酶酶解破壁条件;并以啤酒废酵母酶解液为有机氮源,厌氧发酵制备丁二酸。结果表明蜗牛酶破壁效果最好,其最佳反应条件为蜗牛酶用量10mg/g干物质,pH6.5,40℃水浴,反应16h,酵母酶解液中α-氨基氮含量为0.504g/100mL;当发酵培养基中葡萄糖浓度为50g/L,啤酒废酵母酶解液作为有机氮源时,菌株Actinobacillus succinogenes NJ113可以产34.6g/L丁二酸,收率69%,和以酵母膏为有机氮源厌氧发酵制备丁二酸(丁二酸浓度为35.1g/L,收率70.2%)比较,产量相近,成本较低。     

山西老陈醋中有机酸的HPLC测定分析

本实验建立了采用离子排斥色谱法快速测定山西老陈醋中的8种主要有机酸的方法。选用PRP-X300离子排斥色谱柱,确定最佳色谱分离条件为:0.05mmol/LH2SO4为流动相,流速1ml/min,柱温为室温,紫外检测器,检测波长为210nm,进样量5μl。各有机酸的相对标准偏差为0.72%～5.47%,回收率达到95.1%～105%。该方法具有简便快速、选择性好、准确度高的特点。     

Effect of starter culture, spice mix and storage time and temperature on biogenic amine content of dry fermented sausages

Two types of dry fermented sausage differing in spicing mixture and the diameter (low content of red pepper + diameter 80 mm, H-sausage; high content of red pepper + diameter 55 mm, P-sausage, respectively) were produced in parallel with two different starter cultures (Pediococcus pentosaceus + Staphylococcus carnosus, B-samples and S. carnosus + Staphylococcus xylosus + Lactobacillus farciminis, F-samples, respectively). The sausages were ripened 21 days and subsequently stored 91 days at the room temperature. Concentration of both most abundant amines, putrescine and tyramine (y; mg/kg DM) increased significantly (P<0.01) in HB-sausage during ripening (x; days): y=2.5+18.13x−0.3144x² (R²=0.99) and y=0.7+8.17x−0.1130x² (R²=0.99), and also during storage: y=127.3+5.123x (R²=0.79) and y=26.0+3.211x (R²=0.74), respectively. At the end of ripening, putrescine (247 mg/kg DM) and tyramine (123 mg/kg DM) content in the HB-sausage was higher (P<0.05) than in the PB-sausage (12 and 9 mg/kg DM, respectively), concentration of either of these amines was negligible (1 mg/kg DM) in either type of F-inoculated sausage. Both starter culture and sausage type influenced significantly (P<0.001) both putrescine and tyramine content in the sausage; starter accounted for 57% and 55% of total variability in putrescine and tyramine content, respectively. Due to the significant (P<0.05) increase of total aerobic counts in the HB-sausage between the end of ripening and the 7th day of storage, followed by the significant (P<0.01) increase of the sum of total biogenic amines between the end of ripening (425 mg/kg DM) and the end of storage (1029 mg/kg DM), the storage of the dry fermented sausages at the room temperature should not be recommended.     

Comparison between conjugated linoleic acid and essential fatty acids in preventing oxidative stress in bovine mammary epithelial cells

Some in vitro and in vivo studies have demonstrated protective effects of conjugated linoleic acid (CLA) isomers against oxidative stress and lipid peroxidation. However, only a few and conflicting studies have been conducted showing the antioxidant potential of essential fatty acids. The objectives of the study were to compare the effects of CLA to other essential fatty acids on the thiol redox status of bovine mammary epithelia cells (BME-UV1) and their protective role against oxidative damage on the mammary gland by an in vitro study. The BME-UV1 cells were treated with complete medium containing 50 μM of cis-9,trans-11 CLA, trans-10,cis-12 CLA, α-linolenic acid, γ-linolenic acid, and linoleic acid. To assess the cellular antioxidant response, glutathione, NADPH, and γ-glutamyl-cysteine ligase activity were measured 48 h after addition of fatty acids (FA). Intracellular reactive oxygen species and malondialdehyde production were also assessed in cells supplemented with FA. Reactive oxygen species production after 3 h of H₂O₂ exposure was assessed to evaluate and to compare the potential protection of different FA against H₂O₂-induced oxidative stress. All FA treatments induced an intracellular GSH increase, matched by high concentrations of NADPH and an increase of γ-glutamyl-cysteine ligase activity. Cells supplemented with FA showed a reduction in intracellular malondialdehyde levels. In particular, CLA isomers and linoleic acid supplementation showed a better antioxidant cellular response against oxidative damage induced by H₂O₂ compared with other FA.     

植物原料乳酸菌发酵剂增菌培养的研究

对筛自泡菜的嗜酸乳杆菌S1的生长条件和增殖培养基进行了研究,优化确定了乳酸菌的培养条件和增殖培养基:起始pH值为5.5、培养温度为35℃、培养时间为12h,培养基主要组成为麦芽糖2%、牛肉膏1%、缓冲盐(NaAc∶CaCO3)0.5∶0.3。控制培养条件,结合优化培养基,可使培养液活菌数提高一个数量级达到5×109cfu/mL。     

食用植物油快速检测方法灵敏度研究

目的:研究快速检测方法对食用植物油的检测精确度,为其推广应用提供科学依据。方法:采用快速检测方法、国标法进行食用植物油检测的对照研究。结果:快速检测法对食用植物油的检测合格率为97.9%,与国标组无统计学差异,并且快速检测法与国标组符合率为97.9%,灵敏度为97.9%。结论:快速检测法与国标组的符合率较高,重复性较好,灵敏度较高,能够满足现场监督检测的需要,具有在现场监督和重大活动保障中推广的潜力。     

利用乙醇胁迫作用提高花生四烯酸产量

利用乙醇胁迫作用提高花生四烯酸(AA)产量。探讨了乙醇加入时间及加入量,并通过发酵后期降低转速延长了乙醇胁迫作用时间,确定了降低转速的时间点。结果表明,发酵5d后添加4%的乙醇,并在5.5d后降低转速减少机械力所带来的对发酵后期菌丝体的破坏作用,最终将AA产量从10.6g/L提高到17.6g/L。     

Comparative amino acid and fatty acid compositions of edible gums kondagogu (Cochlospermum gossypium) and karaya (Sterculia urens)

Gum karaya and gum kondagogu are the two important commercial tree gums of India. The amino acids and fatty acid profiles of gum kondagogu and gum karaya were investigated by preparing their corresponding N-O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) derivatives for amino acids and direct trans-esterification of methyl esters for fatty acids and their subsequent analysis by a GC–MS method. The amino acids, such as, alanine, valine, methionine, tyrosine and tryptophan, were not detected in gum karaya as they were in gum kondagogu. Interestingly, the aspartic acid content (72.8 ± 3.45 μg/g) of gum kondagogu was higher than that of gum karaya (64.2 ± 2.44 μg/g). The ratios of saturated to unsaturated fatty acid in gum kondagogu and gum karaya were found to be 5:1, and 6.6:1, respectively. Among the unsaturated fatty acids, linoleic acid (1.8 ± 0.12 μg/g) and γ-linolenic acid (0.8 ± 0.05 μg/g) were detected only in gum kondagogu. Arachidic acid was not detected in gum karaya. Additionally, the presence of linoleic acid and γ-linolenic acid in gum kondagogu reinforces its nutritional value.     

不同品种彩色马铃薯总花色苷含量与总抗氧化活性

以10 个彩色马铃薯品种为实验材料,采用pH示差法测量其总花色苷含量、1,1-二苯基-2-三硝基苯肼（2, 2-diphenyl-1-picrylhydrazyl,DPPH）法分析其总抗氧化活性,比较不同品种的彩色马铃薯的总花色苷含量和总抗氧化活性。结果表明：不同品种的彩色马铃薯的表皮、薯肉、整薯总花色苷含量的变化范围分别为59.67～293.57 mg/100 g、0～56.11 mg/100 g、1.34～63.32 mg/100 g;表皮、薯肉、整薯抗坏血酸当量（ascorbic acidequivalent antioxidant capacity,AEAC）的变化范围分别为2.74～6.43 mg/g、0.50～1.39 mg/g、0.65～1.50 mg/g。其中,紫云1号的总花色苷含量和总抗氧化活性均为最高;S05-603的总花色苷含量最低;S03-2677的总抗氧化活性最低。此外,整薯总花色苷含量与总抗氧化活性的正相关性极显著（P＜0.01）。     

聚乳酸非织造材料的后牵伸辅助熔喷成形工艺及其力学性能

为改善聚乳酸(PLA)熔喷非织造材料的力学性能,在PLA热力学性能实验分析的基础上,采用后牵伸辅助熔喷成形工艺一步法制备了高结晶度的PLA熔喷非织造材料,并对材料的外观形态、拉伸断裂性能和顶破性能进行分析。结果表明:PLA聚合物的玻璃化转变温度为60.69 ℃,熔点为162.6 ℃,可以很好地用于高牵伸倍率的后牵伸辅助熔喷成形;随着牵伸倍率从1.0增大到3.0,高取向纤维(取向角度≤20°)的数量占比从28%增大至100%,超细纤维(纤维直径≤3 μm)的数量占比从23%增大到67%;同时,材料的结晶度从1.22%增大到37.43%,纵向拉伸断裂强度增大到4.33 N/mm²,顶破强力增大到36.8 N,力学性能有所提升。