Effect of steaming time on the linear expansion of fish crackers (‘keropok’)

The effect of steaming time on ‘keropok’ was studied. The morphology of the starch granules in keropok gel at different steaming times was examined using scanning electron microscopy (SEM). There was an optimum time for the steaming of keropok which gave the best linear expansion and hardest texture of steamed gel. This occurred when the starch granules were expanded to their largest sizes and before fragmentation of the granules. A steaming time of 20–30 min is sufficient to cook the keropok gel. Excessive steaming time will result in a poor-quality product as well as extra production costs. © 1999 Society of Chemical Industry     

Anti-oxidant activity of added tea catechins on lipid oxidation of raw minced red meat, poultry and fish muscle

The comparative anti-oxidative effects of added tea catechins (TC) and α-tocopherol to raw minced red meat (beef and pork), poultry (chicken, duck and ostrich) and fish (whiting and mackerel) muscle on susceptibility to lipid oxidation were investigated during 10 days of refrigerated (4 °C) display. Fresh meats, poultry and fish, purchased from a local market, were trimmed to remove bones, skin and surface fat and minced through a 4 mm plate. The minced muscle of each species was treated with either the addition of 300 mg TC kg^–1 minced muscle (TC300) or 300 mg α-tocopherol kg^–1 minced muscle (VE300). Minced muscle without any additives served as control (C). Oxidative stability (TBARS) was measured at 3-day intervals. Total lipids, fatty acid composition, total iron and haem iron from minced muscle for each species were also analysed. The susceptibility of untreated minced muscle to lipid oxidation was in the decreasing order: mackerel > beef > duck > ostrich > pork ≥ chicken > whiting. This may be because of the different content of total fat, iron and fatty acid composition between species. The TC300 significantly ( P  < 0.05) reduced lipid oxidation compared with controls for all seven species as shown by lower TBARS values. The anti-oxidant potential of TC was two to fourfold greater than that of α-tocopherol at the same concentration and this potential was species dependent. The VE300 showed limited capacity in inhibiting lipid oxidation for pork, chicken, duck and whiting. The results obtained show that TCs are powerful natural antioxidants when used in minced muscle food.     

Effect of caffeic acid on haemoglobin‐mediated lipid and protein oxidation in washed cod mince during ice and frozen storage

BACKGROUND: Little is known about the relation between haemoglobin (Hb)‐mediated lipid and protein oxidation in muscle foods and how these two reactions can be inhibited by naturally occurring antioxidants. This study was aimed at evaluating (1) lipid oxidation and protein oxidation induced by 20 µmol L^?1 Hb during chilled and frozen storage of washed cod mince and (2) the efficiency of 10–1000 ppm (0.063–6.3 mmol L^?1) caffeic acid in preventing these reactions. RESULTS: Addition of 20 µmol L^?1 Hb increased peroxide value (PV), rancid odour, protein carbonylation, protein insolubilisation, redness loss and α‐tocopherol loss in ice‐stored washed cod mince. Since both lipid and protein oxidation developed at the same time, it was not possible to conclude which reaction initiated the other. All studied reactions were efficiently inhibited by ≥ 50 ppm caffeic acid, which could be a result of α‐tocopherol regeneration, general radical scavenging, reduced formation of oxidised Hb forms and/or conformational changes in Hb structure. During frozen storage the only clear effect of Hb was increased PV, and here caffeic acid was less efficient as an antioxidant. CONCLUSION: Hb‐induced lipid and protein oxidation occurred quickly in ice‐stored washed cod mince, and the two reactions could not be separated in time. During frozen storage, Hb caused only limited lipid oxidation. Caffeic acid (≥50 ppm) was an efficient antioxidant during ice storage. Copyright © 2010 Society of Chemical Industry     

Effect of plant extracts on lipid oxidation during frozen storage of minced fish muscle

The aim of the study is to determine the effect of pomegranate seed extract (PSE) and grape seed extract (GSE) addition to chub mackerel minced muscle on lipid oxidation during frozen storage. Each extract was added to minced fish muscle at 2% concentration and then stored at ?18 °C for 3 months. The effect of plant dietary fibres to control lipid oxidation was compared with untreated samples (control). Formation of lipid hydroperoxides and thiobarbituric acid‐reactive substances (TBARS) was significantly inhibited by PSE and GSE addition when compared with control. Both extracts significantly retarded lipid oxidation according to the results of TBARS. A significant reduction of L* (lightness), a* (redness) and b* (yellowness) values was detected during frozen storage. GSE added samples had the highest redness and the lowest lightness and yellowness. However, samples with PSE showed the lowest redness and highest yellowness and h° (hue angle) values. The results from this study suggest GSE is a very effective inhibitor of primary and secondary oxidation products in minced fish muscle and have a potential as a natural antioxidant to control lipid oxidation during frozen storage of fatty fish.     

Effect of lipid oxidation and frozen storage on muscle proteins of Atlantic mackerel (Scomber scombrus)

The effect of storage on the lipids and proteins in Atlantic mackerel stored for up to 24 months at ?20 and ?30 °C was studied. Traditional methods including the peroxide value, thiobarbituric acid‐reactive substances (TBARS) and a reverse phase HPLC method were used to determine the primary and secondary lipid oxidation products. All tests showed an increase in lipid oxidation products with storage time and at a higher storage temperature of ?20 °C compared with samples stored at ?30 °C. Antioxidants had a significant effect (P < 0.01) on the inhibition of lipid oxidation, as shown by the reduction in peroxide value and hydroxides, and malondialdehyde formation. Similarly, deterioration of protein structure and functionality in mackerel stored for 3, 6, 12 and 24 months was greater at ?20 than ?30 °C. ATPase activity in the myosin extract of Atlantic mackerel showed a significant decrease (P < 0.01) with progressive frozen storage. Protein solubility in high salt concentration (0.6 M NaCl) decreased (P < 0.01) during storage at both ?20 and ?30 °C but was greater at ?20 °C. Interestingly, antioxidants BHT, vitamin C and vitamin E protected the proteins against complete loss of ATPase activity and protein solubility to a significant level (P < 0.01) for up to 1 year at ?20 °C compared with samples stored without antioxidants. This study confirms the deleterious effect of lipid oxidation products on protein structure and function in frozen fatty fish. © 2002 Society of Chemical Industry     

浒苔多酚在鲣鱼肉冻融过程中的抗脂质氧化活性研究

目的 探究浒苔多酚及其3种主要单体多酚在鲣鱼肉冻融过程中的抗脂质氧化活性与其单体多酚之间的联系。方法 分别用蒸馏水和质量分数为0.1%的表儿茶素(epicatechin,EC)、表儿茶素没食子酸酯(epicatechin gallate,ECG)、表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)、浒苔多酚溶液对5组鲣鱼肉进行浸泡处理,再分别进行0、1、3、5次冻融循环,测定比较5组鱼肉的1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基、2,2’-联氮-二(3-乙基-苯并噻唑啉-6-磺酸)二铵盐[2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) ammonium salt,ABTS]阳离子自由基清除率、还原力、过氧化值、硫代巴比妥酸反应物、酸价、游离脂肪酸含量、脂质羰基值和双烯值,分析浒苔多酚抗氧化活性与其单体多酚之间的关系。结果 浒苔多酚对鲣鱼肉的脂质氧化具有较强的抑制作用,主要与EC、ECG和EGCG螯合金属离子、清除自由基和捕...     

Effect of heating fatty fish: Baltic herring (Clupea harengus membras), European sprat (Sprattus sprattus) and rainbow trout (Oncorhynchus mykiss) on lipid oxidation and contents of eicosapentaenoic and docosahexaenoic acids

In this study, analyses were carried out to establish the impact of heating three species of fatty fish: trouts, herrings and sprats, on the lipids oxidation and on contents of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. The comminuted fish tissue was heated at restricted access of oxygen at temperature of 60, 100 and 160 °C for 15–120 min. Lipids, extracted with the Bligh‐Dyer method, were determined for peroxide value (PV) and anisidine value (AV). The Fatty acid methyl esters were prepared directly from the tissue, whereas contents of EPA and DHA were determined with the GC/MS method. Depending on the temperature applied, 15‐min heating of fish meat tissue caused 30–80% decrease of PN and 20–40% decrease of AV, on average. Generally, the continued heat treatment caused successive decreases in both PV and AV and the rate of this process was observed to increase along with an increasing temperature. The heating of trout and sprats at temperature of 60, 100 and 160 °C even for 1–2 h did not evoke losses either in EPA or in DHA content. In turn, in the case of herring caught during the pre‐spawning season, ca. 90–120 min of heat treatment contributed to ca. 20–25% decrease in contents of these fatty acids.     

CS/GA鱼油微胶囊辅助降血脂功能研究

以鱼油为芯材,以阿拉伯胶(GA)和壳聚糖(CS)为壁材,采用复凝聚法制备鱼油微胶囊.以昆明小鼠为供试动物,喂食高脂饲料建立高血脂症模型,设置高脂模型组、正常对照组、CS/GA壁材组、鱼油组和鱼油微胶囊组.喂养28 d后测定小鼠血清中甘油三酯(TG)、总胆固醇(TC)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)以及小鼠体重的变化,以考察鱼油微胶囊与液态鱼油在小鼠形成高血脂症过程中对血脂的影响.结果表明:单纯的CS/GA壁材复凝聚物对血脂调节没有效果,喂食鱼油微胶囊和鱼油组小鼠TC、LDL-C均极显著低于高脂模型组(P＜0.01),且HDL-C均极显著高于高脂模型组(P＜0.01).说明鱼油微胶囊和鱼油降低血脂胆固醇作用显著.     

抗氧化剂对早餐肠高压后脂肪氧化的影响

为探究抗氧化剂对早餐肠高压后脂肪氧化的影响,在低温鸡肉早餐肠中添加0.05%的乙二胺四乙酸二钠(Na2EDTA)或维生素E(VE),与无添加抗氧化剂组作对比,然后进行不同强度的超高压处理(HPP,400、600MPa,20min),检测各组样品在4℃下贮藏28d各脂肪氧化指标的变化。结果表明:4℃随着贮藏时间延长,早餐肠的不饱和脂肪酸(UFA)比例逐渐减小,POV和TBA值逐渐增大。贮藏前期,脂肪氧化以一级氧化为主;后期二级氧化占主导作用。抗氧化剂Na2EDTA和VE都能在高压下提高脂肪的稳定性,且前者的抗氧化效果更佳。     

Development of lipid oxidation during manufacturing of horse mackerel surimi

When fatty fish are transformed into surimi, lipid oxidation takes place, decreasing the quality of the product. This study was aimed to identify the critical stages of the process in terms of the development of lipid oxidation. Horse mackerels were transformed into surimi on a pilot line and samples taken (hand‐skinned fillets = minced fillets, mince, washed and refined minces, paste, surimi and washing water). Most of the lipids were removed during the process and neutral lipids were lost in higher proportion than polar lipids. As a consequence, total lipids of surimi contained more polyunsaturated fatty acids (338 ± 19 g kg^?1) than total lipids of the minced fillets (220 ± 8 g kg^?1). Thiobarbituric acid reactive substances (TBARS) was higher in the minced fillets than in the mince because less subcutaneous fat and dark muscle were removed during hand‐mincing, indicating that the settings of the skinning–deboning machine can strongly influence the final quality of the product. Concentrations of lipid oxidation products increased significantly during the next stages of surimi processing. The increase was more pronounced for TBARS than hydroperoxides. Concentrations in hydroperoxides were similar in mince and washed mince (15.3 ± 2.8 and 16.6 ± 2.8 mmoles kg^?1 lipid) and increased in refined mince (29.6 ± 2.8 mmoles kg^?1 lipid). TBARS accounted for 2.7 ± 1.0 mg kg^?1 lipid in mince, 40.4 ± 2.3 mg kg^?1 lipid in washed mince and 237 ± 7 mg kg^?1 lipid in refined mince. Hydroperoxides and TBARS were found in appreciable amounts in washing water (76.9 ± 4.7 mmoles kg^?1 lipid and 479 ± 8 mg kg^?1 lipid respectively), when they decreased in surimi (27.3 ± 3.8 mmoles kg^?1 lipid and 44.2 ± 0.8 mg kg^?1 lipid respectively) compared with refined mince. This shows that the last dewatering stage is crucial to ensure surimi quality. Copyright © 2005 Society of Chemical Industry     

内源性痕量物质及其联合胶体对脂肪氧化的影响

综述自由基链式反应机理,阐述油脂中常见的内源性痕量物质如氧气、水、自由脂肪酸、单甘油酯和甘油二酯等对植物油脂肪氧化的影响,并对具有表面活性功能的痕量物质在植物油中所形成的联合胶体对植物油的氧化影响进行总结。最后提出,在油脂精炼加工过程中应严格控制促氧化痕量物质的含量,并避免内源性抗氧化物质的氧化降解,从而有效防止和延长脂肪氧化的发生。     

影响补铁剂脂质体脂质氧化的因素分析

脂质氧化是补铁剂脂质体稳定性的主要指标之一,为明确内外因素对补铁剂脂质体脂质氧化的影响,以TBA法测定脂质体中丙二醛(MDA)含量,并以此为评价指标,考察了壁材组成、芯壁比、芯材类型、p H、温度、超声等主要因素对补铁剂脂质体脂质氧化的影响。实验结果显示,在壁材组成(蛋黄卵磷脂:胆固醇,EPC∶CHOL)为8∶1(wt./wt.)时脂质氧化程度最低;随着芯壁比的降低脂质氧化程度下降;越短、超声功率越低越能有效降低补铁剂脂质体的脂质氧化程度,提高其稳定性。这为补铁剂脂质体的合理生产,以及提高其贮藏和应用过程中的稳定性提供了科学依据。     

Lipolysis and lipid oxidation caused by Staphylococcus xylosus 135 and Saccharomyces cerevisiae 31 isolated from Suan yu,a traditional Chinese low‐salt fermented fish

The aim of this study was to investigate the lipolysis and lipid oxidation of Staphylococcus xylosus 135 and Saccharomyces cerevisiae 31 in Suan yu. Suan yu were made inoculated with and without two strains at different stages, and model systems of emulsions were also established. Lipolysis and lipid oxidation were evaluated by determining the changes in free fatty acid (FFA) content and composition, conjugated diene (CD) value and thiobarbituric acid reactive substances (TBARS) value. The total FFA of the sample without cultures increased from 476.61 mg/100 g fat to 1413.89 mg/100 g fat after 5 weeks fermentation, while those of samples with cultures declined to 258.98 and 452.89 mg/100 g fat, respectively. On the other hand, CD and TBARS values of samples with inoculation markedly increased. In the model system, higher FFA, CD and TBARS values for the samples added with CFE were observed. This study showed that Staphylococcus xylosus 135 and Saccharomyces cerevisiae 31 made a significant contribution to lipolysis and lipid oxidation during the processing of Suan yu.     

Effect of clove extract pretreatment and drying conditions on lipid oxidation and sensory discrimination of dried omena (Rastrineobola argentea) fish

Sun‐drying is a low‐cost, low‐technology fish preservation method frequently employed in developing areas. However, the process promotes lipid oxidation and its associated undesired flavours and odours. This study investigated low‐technology solutions for impact on lipid oxidation and sensory attributes of oven‐dried omena fish (Rastrineobola argentea). Two oven‐drying conditions and four doses of clove water extract ‘dip’ pretreatments were studied in a complete factorial design. Lipid oxidation in dried fish was assessed by TBARS, peroxide value and fatty acid analysis by GC‐FID. Results showed that soaking in 10 g L^?1 clove water extract for 1 h and oven‐drying at 150 °C × 30 min significantly reduced TBARS and peroxide values in omena fish by 77% and 79%, respectively, and polyene index showed improved retention of long‐chain polyunsaturated fats, compared to original drying condition. Lastly, panellists of a triangle test were able to discriminate between biscuits made with the modified and original dried fish.     

鱼脑磷脂对小鼠脂质代谢的影响

研究鱼脑磷脂对ICR小鼠血脂水平的影响。ICR小鼠随机分成正常对照组、高脂模型组、阳性对照组、鱼脑磷脂低剂量组、鱼脑磷脂高剂量组5组,分别进行灌胃给药。正常对照组喂饲基础饲料,其余各组喂饲高脂饲料,28 d后,测定小鼠的血清胆固醇(TC)、甘油三脂(TG)、高密度脂蛋白(HDL-C)和低密度脂蛋白(LDL-C)含量。结果显示,鱼脑磷脂可以显著降低高脂血症小鼠的血清TC、TG和LDL-C水平。说明鱼脑磷脂具有降血脂作用。     

高压促进猪肉肌内脂肪氧化过程中脂肪氧化酶的作用

为研究高压促进猪肉肌内脂肪氧化过程中脂肪氧化酶(Lipoxygenase,LOX)的作用,以去除LOX的猪背最长肌为原料,在其中加入事先从猪肉中提取的或外源LOX(大豆脂肪氧化酶),经600MPa、50℃或350MPa、20℃处理并经6d冷藏后,测定各样品高压处理和冷藏后LOX活性和TBARS值。结果表明:LOX对高压下肌内脂肪氧化的启动有重要作用,但其不会影响样品冷藏后的最终氧化状态(TBARS值);在高压处理后的冷藏中,LOX的作用不明显,主要以脂肪自动氧化为主,即使加入5倍浓度的外源LOX,也只引起样品最终TBARS值的少量增加。因此,高压促进猪肉肌内脂肪氧化中主要以自动氧化为主,而LOX的作用很小。      

A trout (Oncorhynchus mykiss) perfusion model approach to elucidate the role of blood removal for lipid oxidation and colour changes in ice-stored fish muscle

Whole body saline-perfused rainbow trout (Oncorhynchus mykiss) was ice-stored for 4 weeks and compared with unwashed/washed minces from unbled and bled trout in terms of rancid odour, peroxide value (PV), thiobarbituric acid reactive substances (TBARS) and redness loss. Muscle from saline-perfused fish, which had 72% less total haem, was deficient in rancid odour during the whole storage, while bled (54% less haem) and unbled samples developed rancid odour already after ~4 and 2 days; higher intensity without bleeding. PV/TBARS also developed in the order unbled > bled > perfused samples; however, PV/TBARS were not as completely prevented as rancid odour after perfusion. Saline washing (3 × 3 volumes) of unbled mince removed 84% haem and yielded the second most stable sample while saline washing (1 × 1 volumes) destabilised unbled mince, despite 64% haem removal. Concurrent antioxidant removal during washing of minces obviously counteracted the effect of blood removal and washing fish mince with small volumes of solution should be used with great care.     

天然抗氧化剂抑制油脂氧化的研究进展

油脂氧化是食品工业中经常遇到、严重影响食品品质的主要问题之一.虽然应用各类人工合成抗氧化剂在抑制食品中脂肪氧化的问题上取得了比较好的效果,但是这一类抗氧化剂会带来食品安全问题.深入研究和推广应用天然抗氧化剂是同时解决脂肪氧化和食品安全问题的重要途径.     

肉制品中脂肪氧化与蛋白质氧化及相互影响

近年来,食品中脂肪氧化与蛋白质氧化之间的联系在国内外引起了广泛关注。肉制品中脂肪及蛋白质的氧化能产生特征风味,但更多的是引起风味的劣化和颜色的褪变,且脂肪氧化和蛋白氧化之间是相互关联的,彼此相互促进。针对由脂肪氧化和蛋白质氧化影响肉制品品质的问题,就脂肪氧化与蛋白质氧化机理、肉制品中脂肪与蛋白质氧化的相互影响关系及控制措施进行综述。     

HPLC determination of ethoxyquin and its major oxidation products in fresh and stored fish meals and fish feeds

A new method was developed to determine 1,2‐dihydro‐6‐ethoxy‐2,2,4‐trimethylquinoline (EQ, ethoxyquin), 2,6‐dihydro‐2,2,4‐trimethyl‐6‐quinolone (QI) and 1,8′‐di(1,2‐dihydro‐6‐ethoxy‐2,2,4‐trimethylquinoline) (DM) in fish meals or fish feeds, QI and DM being the oxidation products of EQ. The sample was first extracted with hexane. After the removal of hexane the three analytes were extracted from the resulting oil with acetonitrile and determined by C₁₈ reverse phase high‐performance liquid chromatography with a UV detector set at λ = 280 nm. The mobile phase was acetonitrile–0.01 M ammonium acetate (80:20 v/v). The recoveries for EQ, QI and DM from the samples spiked at different levels varied in the ranges 90–100 per cent, 75–85 per cent and 90–100 per cent respectively. At room temperature, QI and DM were the major oxidation products of EQ in stored fish meals and fish feeds. Loss of EQ from fish meals is faster than that from feeds, resulting in relatively higher accumulations of QI and DM in the fish meals. Both QI and DM, especially the former, were not stable during storage of either and could be further oxidised to unidentified compounds. The residue levels of these two compounds were thus unpredictable during storage intervals. When the storage temperature was increased to 50 °C, EQ disappeared more rapidly, but neither QI nor DM accumulated. © 2000 Society of Chemical Industry