Contribution of 2-methyl-3-furanthiol to the cooked meat-like aroma of fermented soy sauce

The cooked meat-like aroma compound, 2-methyl-3-furanthiol (2M3F), was detected in fermented soy sauce (FSS) by GC-olfactometry and GC-MS. 2M3F was present in FSS at a concentration considerably greater than the perception threshold, and the 2M3F concentration increased with heating temperature. Sensory analysis indicated that with the addition of only 0.2 μg/L of 2M3F to the soy sauce sample, the cooked meat-like aroma is significantly stronger than that of sample without the addition of 2M3F. Hence, 2M3F contributes to the cooked meat-like aroma of FSS, which constitutes the key aroma component of FSS. In addition, 2M3F was generated from the addition of ribose and cysteine in FSS by heating at 120 °C, but it was not detected in a phosphate buffer under the same condition. Furthermore, 2M3F was not detected in acid-hydrolyzed vegetable-protein-mixed soy sauce (ASS) and heated ASS. These results indicated that fermentation by micro-organisms facilitates the generation of 2M3F in FSS.     

Heat production and retained energy in lactating cows held under hot summer conditions with evaporative cooling and fed two rations differing in roughage content and in vitro digestibility

The objective of this study was to measure the effect of feeding two total mixed rations (TMRs), differing in their roughage content and in vitro dry matter (DM) digestibility, on the physiological response and energy balance of lactating cows. The partitioning of metabolizable energy intake (MEI) between heat production (HP) and retained energy (RE) of cows held under hot weather conditions and external evaporative cooling was measured. In all, 42 lactating cows were divided into two similar sub-groups, each of 21 animals, and were fed either a control (CON) ration containing 18% roughage neutral detergent fiber (NDF) or an experimental (EXP) TMR containing 12% roughage NDF and used soy hulls as partial wheat silage replacer. The in vitro DM digestibility of the CON and EXP TMR was 75.3% and 78.6%, respectively (P < 0.05). All cows were cooled by evaporative cooling for 2 adaptation weeks plus 6 experimental weeks under hot weather conditions. The EXP diet reduced rectal temperature and respiratory rate of the cows while increasing their DM intake (DMI) from 23.1 to 24.7 kg/cow per day, milk yield from 41.9 to 44.2 kg and yield of energy-corrected milk from 38.7 to 39.7 kg, as compared with the CON group. Cows fed the EXP TMR had increased RE in milk and body tissue, as compared with the CON group, but the diets had no effect on the measured HP that was maintained constant (130.4 v. 130.8 MJ/cow per day) in the two groups. The measured MEI (MEI = RE + HP) and the efficiency of MEI utilization for RE production were also similar in the two dietary groups.     

基于包裹染料木黄酮的甘露糖靶向长循环纳米脂质体抗肿瘤效应研究

采用超声薄膜水化法制备包裹大豆异黄酮主要功能成分染料木黄酮(Ge)的甘露糖修饰聚乙二醇化纳米脂质体(man-PEG@LP/Ge)。伴刀豆球蛋白A(Con A)凝集实验证实甘露糖能够成功修饰在纳米脂质体表面。man-PEG@LP/Ge呈规则的球形,大小分布均一,颗粒分散性好。其粒径为(270±15)nm,Zeta电位为+7.5m V。由于聚乙二醇(PEG)长链的空间位阻效应和颗粒所带正电荷的排斥作用实现了较强的结构刚性和较好的稳定性。流式细胞术的结果表明:man-PEG@LP/Ge能够特异性的识别甘露糖受体高表达的人肝癌Huh-7细胞。细胞毒理实验证明:药物载体man-PEG@LP本身没有毒副作用,生物相容性较好。细胞水平和动物水平的肿瘤杀伤实验结果表明:运载药物之后的man-PEG@LP/Ge在甘露糖介导的"主动靶向"作用下高效而特异性的进入肿瘤细胞,对肿瘤组织进行了有效地杀伤。     

Proteins of the penicillin biosynthesis pathway

Two sequential steps are common to the biosynthesis of all penicillin-derived antibiotics: the reaction of three l-amino acids to give lδ-(α-aminoadipoyl)-l-cysteinyl-d-valine, and the oxidation of this tripeptide to give isopenicillin N. Recent studies on the peptide synthetase and oxidase enzymes responsible for these steps have implications for the mechanisms and structures of related enzymes involved in a range of metabolic processes.     

Preparation of Immobilized Protease Inhibitor (S-SI) and Application to Enzyme Purification

Microbial alkaline protease inhibitor, S-SI, was immobilized by covalent binding with Sepharose (agarose spheres) which was previously activated by cyanogen bromide. S-SI-Sepharose, thus obtained, contained 7.2 mg of S-SI in 1 ml of settled volume, and its subtilisin-combining capacity was 16.6 mg per ml. Stability of S-SI did not be lowered by immobilization. Affinity of immobilized S-SI for various proteases was examined, and it was revealed that α-chymotrypsin, as well as microbial alkaline proteases, had affinity for immobilized S-SI. To determine the most effective condition for dissociation of coupled subtilisin BPN’, effects of pH, ionic strength, protein denaturants, and sodium dodecyl sulfate (SDS) were examined. Dissociated subtilisin BPN’ with high specific activity was obtained when SDS was used as dissociating agent and was removed with Dowex 2-X10 column from dissociated enzyme solution. S-SI-Sepharose was applied to purifications of B. subtilis S04 alkaline protease and α-chymotrypsin, and purified enzymes with high specific activity were obtained.     

酶解大豆蛋白替代鱼粉对星斑川鲽幼鱼生长、血液生化和体组成的影响

正近年来,水产品消费需求量的增长促进了水产养殖业的快速发展,相应的也推动了水产饲料工业的发展,使我国水产饲料产量由2001年的627万吨增长到2011年的1855万吨。然而,鱼粉作为海水鱼类配合饲料的主要组成(占干物质的7%—70%)[1],水产饲料工业的壮大也加大了对其需求     

Cryopreservation of three Saprolegnia species (Oomycota): Preliminary evidence for the long-term archiving of water mould species

Saprolegnia spp. water moulds are opportunistic pathogens that can cause economic losses to aquaculture. The diseases caused by them are difficult to control since use of the effective drug, malachite green oxalate, is no longer permitted in several regions (including the European Union and USA). To develop an effective control strategy, Saprolegnia isolates must be maintained in the laboratory. Cryopreservation is a useful solution for long-term maintenance; however, at present, there is no developed protocol for the cryopreservation of Saprolegnia spp. Here, we isolated and identified three Saprolegnia species, S. parasitica, S. australis and S. ferax, and developed a deep-freezing protocol that enables the long-term archiving of these species. The survival and growth rates of isolates kept at −80 °C for 3, 6, 9 and 12 months, were tested and compared among the species examined. Although the growth rates of frozen isolates were significantly lower than those of the control (i.e. non-frozen) isolates, the overall survival rate (>90%) indicated the effectiveness of the technique developed. Thus, the protocol developed appears to be a promising method for the long-term preservation of Saprolegnia isolates and may facilitate the creation of stock collections.     

Soybean β-conglycinin improves carbohydrate and lipid metabolism in Wistar rats

The effects of dietary soybean β-conglycinin on lipid metabolism and energy consumption were studied in Wistar adult rats. Rats were fed, a diet containing casein (control group) or β-conglycinin (β-conglycinin group), for 4 weeks. Carbohydrate consumption was higher and fat consumption was lower in the β-conglycinin group than in the control group, whereas the total energy consumption was the same between the two groups. Serum adiponectin was higher in the β-conglycinin group than in the control group. Serum triacylglycerol levels in the β-conglycinin group were significantly lower than those in the control group. The secretion rate of triacylglycerols from the liver after the administration of tyloxapol, an inhibitor of lipolysis, was significantly lower in the β-conglycinin group than in the control group. These results suggest the possibility that β-conglycinin exerts hypolipidemic effects through an acceleration in carbohydrate consumption associated with an increase in adiponectin in rats.     

Development toward rapid and efficient screening for high performance hydrolysate lots in a recombinant monoclonal antibody manufacturing process

Plant‐derived hydrolysates are widely used in mammalian cell culture media to increase yields of recombinant proteins and monoclonal antibodies (mAbs). However, these chemically varied and undefined raw materials can have negative impact on yield and/or product quality in large‐scale cell culture processes. Traditional methods that rely on fractionation of hydrolysates yielded little success in improving hydrolysate quality. We took a holistic approach to develop an efficient and reliable method to screen intact soy hydrolysate lots for commercial recombinant mAb manufacturing. Combined high‐resolution ¹H nuclear magnetic resonance (NMR) spectroscopy and partial least squares (PLS) analysis led to a prediction model between product titer and NMR fingerprinting of soy hydrolysate with cross‐validated correlation coefficient R² of 0.87 and root‐mean‐squared‐error of cross‐validation RMSECV% of 11.2%. This approach screens for high performance hydrolysate lots, therefore ensuring process consistency and product quality in the mAb manufacturing process. Furthermore, PLS analysis was successful in discerning multiple markers (DL‐lactate, soy saccharides, citrate and succinate) among hydrolysate components that positively and negatively correlate with titer. Interestingly, these markers correlate to the metabolic characteristics of some strains of taxonomically diverse lactic acid bacteria (LAB). Thus our findings indicate that LAB strains may exist during hydrolysate manufacturing steps and their biochemical activities may attribute to the titer enhancement effect of soy hydrolysates. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 1061–1068, 2012     

Soy protein recovery in a solvent-free process using continuous liquid-solid circulating fluidized bed ion exchanger

Soy protein concentrates and soy protein isolates act as ingredients in bakery, meat and dairy products, baby formulas, starting materials for spun textured vegetable products, and other nutritional supplements. In this study, the effectiveness of a liquid-solid circulating fluidized bed (LSCFB) ion exchanger is demonstrated for the recovery of soluble soy proteins from full fat and defatted soy flour. Under steady-state operating conditions, about 50% of the proteins could be recovered from the feed streams entering the ion exchanger. The LSCFB was shown to be a promising system for the recovery of soy protein from both defatted and full fat soy flour solutions. As the ion exchange process captures dissolved proteins, the system may offer a less damaging form of processing compared with the acid precipitation process where soy protein aggregates form and functionality is affected. In addition, the LSCFB allows simultaneous adsorption and desorption of the proteins allowing for a continuous operation. No prefiltration of feed containing suspended particles is required as well, because fluidization is used in place of packed bed technology to improve on current ion exchange processes.