全豆油条的加工工艺研究

为提升普通油条的营养价值,制作特浓全豆豆浆加入面粉中制备全豆油条。以感官评分作为评价指标,通过单因素试验和正交试验确定全豆油条的最佳配方:特浓全豆豆浆100.0 g、食盐1.5 g、酵母粉3.0 g、小苏打1.2 g、中筋面粉142.0 g。按此工艺制作的全豆油条,色泽金黄、外观形态整齐、气孔均匀、复原性好、口感咸香,同时大豆与面粉的组合实现了蛋白质互补,大豆中丰富的膳食纤维、维生素和矿物质全面提升了全豆油条的营养价值。该全豆油条兼具营养价值高,加工工艺简单和成本低等优点,具有较好的市场推广价值。     

罗非鱼头长链碱的分离纯化及抗肿瘤活性

目的:探讨罗非鱼头长链碱(tilapia head long chain bases,TH-LCB)的提取纯化方法及其体外抗肿瘤活性。方法:以罗非鱼头为原料,采用有机溶剂提取法,提取纯化得到TH-LCB;采用四甲基偶氮唑盐法、细胞凋亡率和细胞周期的测定和蛋白免疫印迹等方法,探讨了TH-LCB对人白血病K562细胞的增殖抑制作用和凋亡诱导作用。结果:TH-LCB可显著抑制人K562细胞的增殖,TH-LCB作用24、48 h后的半数抑制浓度分别为42.207、39.494μg/m L;随着TH-LCB质量浓度的增加,细胞凋亡率逐渐增加,sub-G0/G1峰(凋亡峰)也随之升高,表明TH-LCB通过诱导细胞凋亡来抑制K562细胞增殖;Western blot结果表明,TH-LCB可提高细胞内Caspase-3的蛋白表达量,呈剂量依赖效应。结论:TH-LCB可通过诱导K562细胞凋亡抑制其增殖,这一过程可能与Caspase-3的激活有关。     

Study on the self‐assembly property of type I collagen prepared from tilapia (Oreochromis niloticus) skin by different extraction methods

Type I collagen was prepared from tilapia (Oreochromis niloticus) skin by acetic acid and pepsin process at 4 °C, respectively (ASC and PSC), and hot‐water method separately at 25, 35 and 45 °C (C‐25, C‐35 and C‐45). Their structure and self‐assembly property were discussed. SDS‐PAGE patterns suggested that pepsin hydrolysis and the 35 and 45 °C extraction produced collagen with much reduced proportions of α‐ and β‐chains. Fourier transform infrared spectroscopy spectra revealed that pepsin hydrolysis did not change the conformation of collagen, but higher extraction temperature did. Self‐assembly curves and atomic force microscopy (AFM) observations showed that only ASC, PSC and C‐25 could self‐assemble into fibrils with D‐periodicity, but the reconstruction rate of C‐25 was lower. Besides, PSC had relatively higher resolution ratio compared with others. Overall, pepsin‐extracted collagen displayed higher solubility and better fibril‐forming capacity, having the potential of applying in biomaterials and food‐packaging materials.     

Cytotoxic effect of sodium arsenite on Nile tilapia (Oreochromis niloticus) in vivo

This study showed the relevance of using chromosomal aberration (CA) as potential indicators of sodium arsenite (SA; NaAsO₂) cytotoxicity. The study investigated cytotoxic potential of SA in Oreochromis niloticus using CA assessment. The fish were exposed to four different concentrations of SA (5, 10, 20 and 40 mg/L) for 24 hours in comparison to a control group. The As concentrations in the samples were analysed by inductively coupled plasma atomic emission spectrometry. The differences in As concentrations in the water and O. niloticus samples between the control and experimental groups were significant (p<0.05), whereas the within experimental group differences were not significant. The cytotoxic assessment of SA in O. niloticus revealed five types of CAs, including single chromatid gaps (SCG), single chromatid break (SCB), centric gap (CG), fragmentation (F) and deletion (D). The most common CA in the O. niloticus samples was SCG. A total of 2.33, 10.67, 18.67, 18.00 and 23.67% of the cells in the control and experimental groups exhibited CAs. The numbers of CAs and cells with CAs from the control and experimental groups of fish were significantly different (p<0.05); additionally, the fish exposed to 5 and 40 mg/L showed significant within experimental group differences (p<0.05).     

预冷温度对冰温罗非鱼片品质的影响

通过设置不同预处理温度(-18,-30,-60℃)对罗非鱼片进行预冷处理,使鱼片中心温度降至-1℃后置于-2℃环境中贮藏。以pH、色泽、质构特性、挥发性盐基氮(TVB-N)、菌落总数、硫代巴比妥酸值(TBA)、钙离子酶活(Ca~(2+)-ATPase)作为考察指标,进行不同时间间隔下的系列跟踪测试与分析。结果表明:预冷温度对鱼片的TVB-N值、菌落总数、TBA、Ca~(2+)-ATPase有较大影响,经过预冷处理鱼片的TVB-N值、菌落总数增长趋势有所减缓,并且预冷温度越低,鱼片细菌生长速率和鱼肉腐败的进程越慢,同时鱼片脂肪氧化和蛋白质变性的程度也相对较小,其中-30,-60℃预冷处理能更好地维持鱼肉的品质;贮藏期间各处理组鱼片的pH值整体表现出先下降后上升的趋势,预冷处理可显著抑制鱼片pH的回升。预冷处理组与对照组鱼片的硬度、咀嚼性和胶黏性均随贮藏时间推移呈下降趋势。-30,-60℃预冷处理鱼片的货架期为17d,比对照组延长了6d。综上可知,预冷处理能够进一步抑制鱼片微生物繁殖和腐败变质,改善冰温罗非鱼片的品质。     

The LBP Gene and Its Association with Resistance to Aeromonas hydrophila in Tilapia

Resistance to pathogens is important for the sustainability and profitability of food fish production. In immune-related genes, the lipopolysaccharide-binding protein (LBP) gene is an important mediator of the inflammatory reaction. We analyzed the cDNA and genomic structure of the LBP gene in tilapia. The full-length cDNA (1901 bp) of the gene contained a 1416 bp open reading frame, encoding 471 amino acid residues. Its genomic sequence was 5577 bp, comprising 15 exons and 14 introns. Under normal conditions, the gene was constitutively expressed in all examined tissues. The highest expression was detected in intestine and kidney. We examined the responses of the gene to challenges with two bacterial pathogens Streptcoccus agalactiae and Aeromonas hydrophila. The gene was significantly upregulated in kidney and spleen post-infection with S. agalactiae and A. hydrophila, respectively. However, the expression profiles of the gene after the challenge with the two pathogens were different. Furthermore, we identified three SNPs in the gene. There were significant associations (p < 0.05) of two of the three SNPs with the resistance to A. hydrophila, but not with the resistance to S. agalactiae or growth performance. These results suggest that the LBP gene is involved in the acute-phase immunologic response to the bacterial infections, and the responses to the two bacterial pathogens are different. The two SNPs associated with the resistance to A. hydrophila may be useful in the selection of tilapia resistant to A. hydrophila.     

几种生物大分子对罗非鱼皮Ⅰ型胶原自聚集性的影响

研究海藻酸钠、硫酸软骨素、透明质酸和壳聚糖对罗非鱼皮Ⅰ型胶原自聚集动力学和聚集后微观结构的影响。结果表明:在海藻酸钠、硫酸软骨素、透明质酸和壳聚糖存在的情况下,胶原自聚集过程仍然包含两个阶段:成核阶段和生长阶段,但是各物质对两阶段的动力学参数影响不同。海藻酸钠、透明质酸和壳聚糖均能够降低生长阶段的速率常数,然而对成核阶段的影响各有差异。海藻酸钠对成核阶段的速率常数没有显著影响,但是随着含量的增加能够延长成核时间;壳聚糖能够提高成核阶段的速率常数,同时缩短成核时间;透明质酸对成核阶段的速率常数和成核时间却没有显著影响。而硫酸软骨素对成核阶段和生长阶段均没有显著影响。扫描电子显微镜结果表明海藻酸钠、硫酸软骨素、透明质酸易使胶原纤维横向聚集形成纤维束,影响其直径大小的顺序为硫酸软骨素海藻酸钠透明质酸,而壳聚糖却未表现类似作用。