不同储藏方式对北方优质稻米食味值的影响

[目的]为保证大米的口感,研究不同储藏方式对稻米食味值的影响.[方法]选取3种辽宁地区优质稻米品种为材料,用不同储藏方式对每个品种分别进行处理,为期11个月,利用日本进口SATAKE食味计进行食味值测定.[结果]不同储藏方式下,3个品种在食味上的差异很大,越光介于65 ～ 85,盐粳48介于61 ～ 80,而辽星1号介于50 ～69.除辽星1号的冷库精米的食味值变异系数大于冷库真空米的食味值变异系数外,不同储藏方式下食味值的波动情况均为冷库稻谷＜冷库真空米＜冷库精米＜大库精米＜大库稻谷＜大库真空米,即低温储藏下大米食味值的波动较小,并且以稻谷方式储藏的大米食味值波动也较小.[结论]研究可为稻米粮食的储藏提供参考.     

中华槭花粉活力探究

以中华槭为研究对象,研究了中华槭花粉离体培养萌发最佳测定时间,中华槭花粉活力快速测定的方法,蔗糖、硼酸、氯化钙浓度以及不同贮藏温度(室温、4℃、-20℃)对中华槭花粉活力的影响。试验结果表明:中华槭花粉离体培养16h后,再进行其花粉活力的测定较为适宜;用离体培养萌发法测定的花粉活力,最接近于中华槭花粉的真实活力。适于中华槭花粉萌发的蔗糖、硼酸、氯化钙浓度分别为:100g/L、50mg/L、50mg/L。中华槭花粉在4℃下可以存活60d,在-20℃下可以保存120d,在室温下仅可以存活7d。     

贮藏温度和种子含水量对大豆种子活力的影响

以菏豆13号和辽豆11号为试材,研究不同贮藏温度和种子含水量对大豆种子活力的影响。结果表明:贮藏温度和种子含水量均能影响大豆种子活力;随贮藏时期的延长,大豆种子活力呈下降趋势;25℃贮藏各水分处理与4℃贮藏高水分(12%)处理影响大豆种子活力;-20℃贮藏时,水分条件对种子活力的影响反应敏感度较低,中水(8%)和低水(4%)处理可以减缓大豆种子老化速率,较好地保持大豆种子活力。     

基于生命周期理论的发动机再制造过程研究

为降低发动机再制造成本,并提升发动机的性能,以再制造发动机为研究对象,运用生命周期理论,建立生命周期模型,并对其工艺过程与评估准则进行研究.同时,以斯太尔WD615发动机和康明斯B型发动机为例,通过数据计算,得到再制造零部件的经济效益.研究表明：再制造发动机能够有效地节约成本;通过对修复后的零部件与新技术结合,其性能能够接近于新成品.证明发动机再制造相对于新机制造拥有巨大的环境、能源和经济优势.     

纳米银对华南毛蕨切叶的保鲜效应研究

试验探讨了新型抗菌剂纳米银(nano-silver,NS)预处理对华南毛蕨(Cyclosorus parasiticus)切叶采后的保鲜效应。结果表明,用0.5、1.0、2.0 mg/L NS溶液预处理华南毛蕨切叶24 h后再瓶插于去离子水中,可显著延长该切叶的瓶插寿命。进一步研究发现,NS预处理可显著改善华南毛蕨切叶的水分代谢,并有效延缓其鲜重下降和叶片萎蔫。     

杀虫剂西维因对萼花臂尾轮虫急性毒性和生活史参数的影响

采用生态毒理学方法,研究了(25±1)℃下,杀虫剂西维因对萼花臂尾轮虫的急性毒性影响以及慢性染毒对轮虫生命史参数的影响。结果表明:西维因对轮虫24 h急性毒性半致死浓度为4.868 mg·L-1,95%置信区间为4.538~5.229 mg·L-1;慢性毒性实验结果显示,除产卵量外,西维因对轮虫的主要发育阶段历时、平均寿命、净生殖率、生命期望、内禀增长率以及世代时间均有显著影响(P0.05)。与对照组相比,西维因显著降低(缩短)轮虫平均寿命、净生殖率和内禀增长率,且高浓度的西维因对平均寿命和内禀增长率的影响更为显著;幼体阶段历时和胚胎发育时间均随西维因浓度的升高而延长;除2.2 mg·L-1的西维因对轮虫世代时间无显著影响外,其他各浓度均显著缩短轮虫世代时间(P0.05)。     

中国板栗栽培史考述

板栗原产于中国,是中国最早栽培的果树之一,栽培历史至少有6000年以上。中国板栗品种丰富,分布广泛,无论南方北方,大部分省份均有栽培。本文参考已有研究成果,通过相关考古资料和历史文献资料的考证,对中国板栗的起源、古代栽培技术、古代分布以及利用价值和储藏技术作了略约阐释。     

水产食品特定腐败菌与货架期的预测和延长

Fresh fish and lightly preserved fish products are welcome by the global market, however, they are also among the most perishable food products. The research on specific spoilage organisms (SSO) reveals the spoilage process of aquatic product. This paper reviews the current knowledge (past ten years) on SSO of fresh fish and lightly preserved fish products with particular emphasis on characteristics of SSO and how to apply this concept to determine, predict and extend the shelf life of aquatic product. During storage, the microflora changes owing to different abilities of the microorganisms to tolerate the preservation conditions. SSO is defined as special microorganisms which can increase rapidly during preservation and has the ability to produce off- odours and off- flavours associated with spoilage, and spoilage metabolites. Identification of an SSO relies on comparison of the sensory and chemical characteristics of spoiled product with those of isolates from the spoilage microflora. Generally, the SSO of fresh fish may be a single species or genus, but the ones of lightly preserved fish products will be more complex. One exciting area for use of SSO aims to obtain quantitative knowledge about probable behavior of SSO and their function during the progression of spoilage. Thus mathematical models on the growth of SSO are established to evaluate the quality lost degree of product, which provide a sound information for the rational development of devices to monitor loss of products shelf life. Models for the growth of Pseudomonas spp, S. putrefaciens, P. phosphoreum have been established, and validated for shelf life prediction of seafood successfully. Another application field of SSO intends to develop the techniques to prolong the shelf life of food products by inhibiting SSO targetedly. Targeted inhibition of spoilage bacteria during preservation reduces their growth and results in a significant extension of shelf life in despite of the activity of non - spoilage organisms has not been influenced. Such techniques have been applied in perversion field of fresh fish and lightly preserved fish.     

Bio-based Coating from Fish Gelatin,K-Carrageenan and Extract of Pomegranate Peels for Maintaining the Overall Qualities of Fish Fillet

ABSTRACT

To maintain the overall quality of fisheries products, functional edible coatings from natural ingredients including fish gelatin (Gf), k-carrageenan (Cr), and extract of pomegranate peels (PPE) were composed. The Gf was extracted from blue tilapia (Oreochromis aureus), microencapsulated with Cr, and then loaded with PPE (at concentrations of 0.5%, 1.0%, 1.5% and 2.0%). The Fourier transform infrared (FTIR) spectra of Gf/Cr composites verified their cross-linkage and functionality; the Gf/Cr microcapsules had a mean particle size of 36.2 µm with good distribution and homogeneity. The coating of Nile tilapia (Oreochromis niloticus) fillets, with constructed solutions from Gf/Cr/PPE, revealed their positive effects on fillet quality attributes; the effectiveness was dependent on the supplemented PPE concentration. The Gf/Cr/PPE solutions could effectively reduce the microbial counts of total aerobics, psychrotrophs, yeast and molds, and enterobacteriaceae groups throughout 30 days of refrigerated storage. Additionally, the analysis of spoilage chemical parameters (total volatile basic nitrogen, peroxide value, and thiobarbituric acid reactive substances) in coated samples indicated that formulated solutions could hinder the increase of their values during storage. The sensorial evaluation indicated the acceptability and validity of coated samples for up to 30 days of storage. Gf/Cr/PPE coating is recommended for overall quality maintenance of fish fillets and prolongation of storage using safe and healthy biopreservatives.     

Life-history variation in perch (Perca fluviatilis L.) in five neighbouring Norwegian lakes

Abstract – We have studied the population dynamics and reproductive biology of perch ( Perca fluviatilis L.) from five neighbouring lakes in Norway. The lakes vary in water quality, varying from strongly acidified (pH≤5.0) to not acidified (pH≥6.0). Estimated annual survival rates did not differ among populations. There was no strong relationship between age at maturity in female perch and acidification. However, age at maturity was lower for female perch from the most acidic lake ( c . 2 years) compared with perch in the four other lakes (2.5–3.5 years). There was no relationship between acidification level and size-adjusted egg size, fecundity or reproductive investment (Gonadosomatic index – GSI). Perch in the most acidified lake showed large variation in egg size, the lowest length-specific fecundity, the highest GSI, and the lowest age at maturity. Environmental stress, such as acidification, induces a number of changes to a lake community. It is therefore difficult to predict how acidification will influence the population dynamics and reproductive biology of a perch population.