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.     

金枪鱼酶解液脱色工艺及其对腥味物质和金属元素的影响

为了研究活性炭对金枪鱼酶解液脱色的最佳条件,本文利用活性炭对金枪鱼暗色肉酶解液进行处理,研究活性炭添加量、pH值、温度(T)和脱色时间(t)对脱色率和蛋白质损失率的影响,采用正交试验对脱色工艺进行优化,同时探究了活性炭脱色工艺对酶解液腥味物质和金属元素含量的影响.结果表明,金枪鱼暗色肉酶解液最佳脱色条件为活性炭添加量3％、pH值3.0、温度70℃、时间1h.该条件下脱色率为89.77％±0.77％,蛋白质损失率为13.47％±0.72％;脱色后酶解液挥发性物质含量降低了85.39％,其中三甲胺、己醛、壬醛等特征腥味物质显著降低;活性炭对Pb的吸附作用较明显,其吸附率为93.2％,而对其他金属元素的吸附率不大.研究表明,经过活性炭处理过的酶解液颜色浅,腥味低,具有一定的应用前景,可为酶解液的进一步利用提供依据.     

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．。     

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。     

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。     

即食海带的脱腥与杀菌工艺

探讨了淡干海带加工成即食海带过程中海带脱腥、杀菌温度和杀菌时间的最佳工艺条件,结果表明,醋酸对海带有良好的脱腥效果,海带经体积分数为1.0%醋酸溶液脱腥20 min后,在100℃下杀菌22 min,所得产品无腥臭味、色泽翠绿、口感脆嫩,达到商业无菌要求.     

鱼肉粉脱腥技术研究

[目的]探讨最优的鱼肉粉脱腥技术。[方法]采用掩盖法、β-环状糊精法、活性炭法、蛋白酶水解法和综合处理法对鱼肉粉进行脱腥处理,通过感官评分-岳对除腥效果进行评价。[结果]确定有效的除腥方法为综合处理法,其工艺条件为：用5％活性炭在55oC水浴下吸附鱼肉粉20rain,再用1．5％3-环状糊精在65℃下保温振荡5min,经脱星的鱼肉粉基本无腥味。[结论]该研究可为鱼肉粉在食品行业中的广泛应用奠定基础。     

带鱼鱼丸腥味变化的预测模型

为研究带鱼鱼糜制品冷藏过程中腥味变化的规律,以鱼丸为研究对象,在不同温度0、3、6、9、12℃下监测鱼丸腥味活性值变化,采用零级反应方程拟合腥味活性值变化曲线,拟合系数均大于0.9。根据Arrhenius方程确定了变化速率K与温度T的关系,建立腥味活性值变化预测模型F=2.332×10~(13)e~(-8 190/T)t+5.035。贮藏期间F的实测值与预测值相对误差在15%以内,证明该模型能够较准确地预测鱼丸腥味活性值的变化。