Odor Modification in Salmon Hydrolysates Using the Maillard Reaction

The aim of this work was to study the effect of adding sugar during proteolysis to promote the Maillard reaction and mask the initial fish odor and off-flavors generated. An experimental design, based on the Doehlert plan, was used to study the influence of hydrolysis conditions (time, temperature, sugar, and antioxidant addition) on the odor characteristics of hydrolysates, soluble protein levels, and amino acid content. Results showed that the lowest level of sugar (10 g of D-xylose added to 1 kg of by-products) was enough to develop a grilled odor in hydrolysates. In the hydrolysis conditions used—i.e., enzyme inactivation at 95°C for 30 min—hydrolysis temperature had no effect on grilled odor production but significantly affected the soluble protein fraction, as did hydrolysis time. Soluble protein content and essential amino acid content increased with the enzymatic reaction but were not modified by adding sugar. Hydrolysis conditions that promote Maillard reactions while keeping a nutritional balance have been identified.     

Water quality,waste production,and off-flavor characterization in a depuration system stocked with market-size Atlantic salmon Salmo salar

Land-based Atlantic salmon, Salmo salar, grow-out facilities utilize depuration to remediate off-flavor. Water used in this process is either discharged or repurposed as supply water in recirculating aquaculture systems (RAS). Both approaches require an understanding of water quality and waste production for water treatment decisions and compliance with pollution discharge standards; however, these data were lacking. Therefore, a study was carried out to characterize these parameters. To begin, 311 salmon (5–6 kg) originally cultured in freshwater RAS were stocked at 100 kg/m³ in an 18 m³ depuration tank. Feed was withheld 1 day before transfer and throughout the 7-day study period. Hours after stocking, total suspended solids (TSS), total phosphorus (TP), and total ammonia nitrogen (TAN) levels spiked, and concentrations declined thereafter. Delta TSS and TP were negligible by the end of the trial; however, TAN plateaued, indicating that salmon began to catabolize somatic tissue in the absence of feeding. Geosmin and 2-methylisoboreol levels in water and fish were low throughout the study. This research indicates that residual waste production occurs while depurating Atlantic salmon. Procedural refinements and recommendations were gleaned including locality for introducing depuration system water within RAS and extension of the feed withholding period before depuration.     

Off-flavors in pond-grown ictalurid catfish: Causes and management options

Ictalurid catfish grown in ponds often acquire undesirable off-flavors prior to harvest. Off-flavors develop when odorous, lipophilic substances in food or water are absorbed across gut or gill epithelium and concentrated in edible tissues. The most common causes of catfish off-flavors are two nontoxic secondary metabolites of planktonic cyanobacteria: geosmin (causing an earthy off-flavor) and 2-methylisoborneol (causing a musty off-flavor). Off-flavored fish are unacceptable for processing, and harvest must be postponed until the source of the odorous compound disappears and the compound purges from edible fish tissue. Harvest delays caused by episodes of off-flavor increase production time, interrupt cash flow, and increase the risk of fish loss. Catfish farmers consider off-flavor to be one of their most important production-related problems. This paper reviews the causes of off-flavor in catfish, pharmacokinetics of uptake and loss of odorous compounds in catfish, seasonality and prevalence of off-flavors, farm- and industry-level impacts, the ecology of cyanobacteria in catfish ponds, and various strategies for preventing or treating cyanobacterial (and other) off-flavors. A decision-making system based on knowledge gained from research is presented as a guide to effective use of the limited tools available to manage off-flavors.     

淡水浮游藻类与鱼体异味关系的初步研究

通过对在北京市通州区、昌平区和海淀区几家渔场采集的浮游藻类进行定量，并结合对相应池塘养殖鱼类口感的品尝，初步筛选出以下10个属的种类与养殖鱼体异味有关：蓝球藻Chroococcus spp．、蓝纤维藻Dactylococcopsis spp．、颤藻Oscillatoria spp．、鱼腥藻Anabaena spp．、席藻Phormidium spp．、颗粒直链藻Melosira granulato、针杆藻Synedra spp．、舟形藻Navicula spp．、菱形藻Nitxschia spp．和栅藻Scenedesmus spp．。     

两种异味藻类的筛选及盐度对针晶蓝纤维藻生长的影响

从2种淡水常见藻类——针晶蓝纤维藻Dactylococcopsis rhaphidloides和斜生栅藻SceMdesmus obliquus中,筛选出能够引起鱼类明显异味的藻类针晶蓝纤维藻,并对其进行盐度耐受性试验。结果表明,当盐度为3．2时,针晶蓝纤维藻的生长受到抑制;当盐度为10时,该藻停止生长。该藻96h的半致死盐度（EC50）为7．8。     

白酒中异杂味产生的原因及防止措施

通过总结白酒中呈味物质的来源,分析白酒中异杂味的种类和产生原因,提出防止白酒中产生异杂味的措施。     

抗坏血酸与金属离子在光照引起的牛奶风味劣化中的作用

为了解决光照引起的牛奶风味劣化,在牛奶中添加天然抗氧化剂如抗坏血酸等来研究其抗劣化作用.通过对光照处理牛奶的感官评价、pH、酸度和硫代巴比妥酸反应物(TBARS)值的测定,研究抗坏血酸和金属离子对牛奶风味劣化的影响.结果显示,与只加入抗坏血酸的牛奶样品相比,添加一定比例的金属离子的抗氧化剂试验组的pH值最低,酸度较高,TBARS值为0.25mg·kg-1,感官评价值最高,这为更深入地研究光照引起的牛奶中的劣化风味物质提供了基础.     

用流水、活性炭和施入光合细菌去除养殖鱼类的异昧

采用土腥味感官检测评分方法，研究了用流水、活性炭和施入光合细菌去除养殖鱼类异味（MIB）的效果。结果表明，用流水处理15h和用活性炭吸附法处理12h，均可有效地去除鲤Cyprinus carpio的异味，施用光合细菌4周后，可降低或消除鲂、草鱼和淡水白鲨的异味。     

3种抗氧化剂对辐照猪肉火腿肠异味的控制技术研究

为探讨即食肉制品辐照过程中异味形成的有效控制措施,本研究选取VE、茶多酚、迷迭香提取物3种抗氧化剂,在火腿肠加工过程中添加到肉糜中,研究其对火腿肠辐照异味强度的影响,并筛选出控制火腿肠辐照异味最好的抗氧化剂,进行响应面优化试验,分析火腿肠的储藏效果和辐照异味的调控工艺。结果表明,3种抗氧化剂中迷迭香提取物对火腿肠辐照异味的控制效果最好。火腿肠异味控制的最优条件为:迷迭香提取物浓度0.55%、辐照剂量5.733 kGy、储藏温度4℃。贮藏7 d后火腿肠中总菌落数为1.253 log(CFU·g^-1),与对照组样品相比,菌落总数降低了83%,辐照异味感官评价值为4.30,几乎无辐照异味。本研究为辐照技术在即食肉制品保鲜方面的应用提供了数据支撑。     

电化水去除淡水鱼土腥味的研究

为改善淡水鱼土腥味严重导致品质下降的现状,实验从淡水鱼终端暂养环节出发,以电化水暂养淡水鱼,探讨去除土腥味效果和实用性。结果显示,电化水通过比常规水体更小的水分子团簇结构以及更低的粘度、更强的渗透性和溶解力等理化性质实现鱼肉土腥味物质的快速脱除,暂养淡水鱼24 h可去除64.66%以上土臭素(Geosmin)和24.45%以上二甲基异莰醇(2-Methylisoborneol),相比井水分别提高136.65%、196.13%以上。