蒸煮工艺对鲣鱼鱼柳品质的影响

以鲣鱼为原料,考察了两种不同的蒸煮工艺(T1、T2)对蒸煮过程中鱼柳的升温曲线、失水率、失重率、色泽、质构和组胺含量等的变化情况,分析两种蒸煮工艺对鱼柳蒸煮品质影响的差异,找出两种工艺的优缺点。结果表明,蒸煮工艺T1蒸煮损失较低,鱼柳得率比T2高1%~2%,蒸煮时间比T2短6~8 min,蒸煮过程中鱼肉色泽变化稳定,蒸煮完成后具有较好的质构特性,并且T1能有效降低鲣鱼肉中的盐含量。蒸煮工艺T2步骤相对简单,总加工时间比T1短20~30 min,组胺产生量比(T1)少约18 mg/kg,同时所得鱼柳还具有较高的非蛋白氮,气味较浓郁。两种蒸煮工艺各有优势,企业可以根据鲣鱼新鲜度及生产条件选择合适生产工艺。      

Antioxidant effects of flavonoids used as food additives (purple corn color, enzymatically modified isoquercitrin, and isoquercitrin) on liver carcinogenesis in a rat medium-term bioassay

To clarify the effects of purple corn color, enzymatically modified isoquercitrin (EMIQ), and isoquercitrin (IQ), registered as natural food additives in Japan, on liver carcinogenesis in vivo, a medium-term bioassay was employed. A total of 100 male F344 rats were divided into 5 groups; groups 1 to 4 were given a single intraperitoneal injection of diethylnitrosamine (200 mg/kg b.w.) on day 1. From weeks 2 to 8, they were administered basal diet purple corn color, EMIQ, or IQ as containing test chemicals at doses of 1.0% (groups 1 and 5), 0.1% (group 2), 0.01% (group 3), or 0% (group 4) (experiments 1, 4, and 5). All rats were subjected to two-thirds partial hepatectomy at week 3 and were sacrificed at week 8. Purple corn color exerted no significant modifying effects on GST-P positive foci, preneoplastic foci, development in the liver. However, serum of rats treated with purple corn color provided evidence of antioxidant power significantly by potential antioxidant (PAO) test in vivo (experiment 2). And microarray analyses showed purple corn color to induce RNA expression such as P450 (cytochrome) oxidoreductase, phosphatidylinositol 3-kinase, and phospholipase A2 (experiment 3). Higher doses of EMIQ or IQ with strong antioxidant power in vivo by PAO test treated groups were correlated with smaller numbers of GST-P positive foci, with Spearman's rank correlation coefficients of P= 0.002 and P= 0.049, respectively (experiments 4 and 5). Therefore, the tested food additives may be effective as antioxidants in vivo and have chemopreventive potential against liver preneoplastic lesion development.     

Validation of a recombinant cell bioassay for the detection of (gluco)corticosteroids in feed

Use of hormones for fattening purposes is forbidden in the animal production in Europe (European Commission. 1996. Council Directive EC/96/22 (replacement of 88/146/EC). Off J Eur Commun. L125:3–9; European Commission. 1996. Council Directive EC/96/23. Off J Eur Commun. L125:10–32). Moreover, Regulation (EC) 178/2002 (European Commission. 2002. Regulation EC No 178/2002. Off J Eur Commun. L31:1–24) and Regulation (EC) 882/2004 (European Commission. 2004. Regulation EC No 882/2004. Off J Eur Commun. L165:1–135) oblige the member states to identify emerging risks and use validated and accredited methods for control analysis. Only combinations of bioassay activity screening with chemical identification are suited to uphold all laws. No such combination is described for the detection of (gluco)corticoids. In the present study, the GR-CALUX bioassay was validated as a qualitative screening method for the determination of glucocorticoid activity in feed. This validation was performed according to EC Decision 2002/657/EC (European Commission. 2002. Commission Decision 2002/657/EC from Directive 96/23. Off J Eur Commun. L221:8–36). Twenty-two representative blank feed samples were selected and spiked with 50?ng?g^?1 of dexamethasone, 100?ng?g^?1 of betamethasone or 500?ng?g^?1 of triamcinolone. All blank and spiked feed samples fulfilled the CCα and CCβ criteria; the method was specific and robust and glucocorticoids in feed were stable for at least 88 days.     

养殖大黄鱼片碱性脂肪酶脱脂工艺优化

选用碱性脂肪酶对大黄鱼鱼片酶解脱脂工艺进行优化。以脱脂率为考核指标,采用单因素试验与正交试验相结合的方法,对大黄鱼鱼片进行脱脂。结果表明:采用碱性脂肪酶对大黄鱼脱脂的最适工艺条件为温度32℃、反应pH8.5、酶用量60U/mL、酶解时间60min、鱼与酶解液质量比1:4。在最适酶解条件下,大黄鱼鱼片的脱脂率为67.32%。     

The nutritional toxicity of sweet lupin (Lupinus angustifolius) seed proteins

The effects of raw sweet lupin (Lupinus angustifolius) meal on the growth and N utilisation of rats were determined in two ad libitum and two restricted‐feeding net protein utilisation (NPU) and five N balance experiments. Sweet lupin seed grown in Western Australia, obtained as meal, either unsupplemented (LMU) or fully supplemented with required amino acids (360 g kg⁻¹) (LMFS), was tested. Rats fed lactalbumin (130 g kg⁻¹) (LACT) were used as positive controls, while rats fed a non‐protein diet (NPC) were used as negative controls. In addition, seed protein, extracted at pH 7.0 with water and insoluble after dialysis at pH 7.0 (LPADI; 124 g kg⁻¹), was also used. The diets contained the same amounts of energy and protein and were supplemented with essential amino acids, vitamins and minerals to target requirements for rats. Inclusion of LPADI in the diet of growing rats caused urinary losses of N, almost all as urea, hypoproteinaemia and increase in body water that resulted in the lowest NPU values, N balance and growth rate as compared with other diets used. These rats developed atrophy of the spleen (low dry weight) and had a comparatively smaller thymus gland than those given raw meals. Furthermore, the LPADI fraction was shown by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS‐PAGE) to contain three polypeptides with molecular weights between 30 and 36 kDa which are similar to lectins obtained from Phaseolus vulgaris, Abrus precatorius and Ricinus communis. It is possible that the toxic protein component in the sweet lupin, which has negligible in vitro haemagglutination properties and is extremely toxic in vivo, exerts toxicity by interfering with protein synthesis in the liver, while the immune responses are secondary to azotaemia (high level of urea in the blood) or cytotoxicity action on lymphocytes. The unusual depletion of fat from the body, however, was due to the failure of absorbed amino acids to assimilate as proteins, creating dietary protein restriction and leading to lipolysis. It is therefore tentatively suggested that sweet lupin seed contains a lectin‐like protein that is concentrated in this fraction. Further purification and biological evaluation to establish the exact nature of this protein may be important. © 2000 Society of Chemical Industry     

粉红单端孢体外产毒条件的探讨及粗毒素活性测定

培养粉红单端孢(Trichothecium roseum)使其产生毒素,筛选出有利于该菌体外产毒的培养基和培养时间,并初步探讨毒素的活性大小。采用玉金香甜瓜种子发芽抑制实验测定了不同培养条件下粉红单端培养滤液对种子发芽的抑制率,用抑制率的大小表示培养滤液毒性的大小;对粉红单端孢体外产生的毒素用有机溶剂分别从菌丝和培养滤液中提取,经减压旋转蒸发浓缩,获得粗毒素。结果表明,PDA液体培养基,pH4.5时的培养滤液对玉金香甜瓜种子发芽抑制率最大;随着培养时间的延长,培养滤液对种子的抑制率呈现上升→下降→上升的趋势,17d时,培养滤液对玉金香种子的抑制率最大,并且抑制率与毒素浓度的大小也有关。     

The effects of feeding conjugated linoleic acid (CLA) on rat growth performance,serum lipoproteins and subsequent lipid composition of selected rat tissues

Four groups of 12 albino rats (six males and six females), at 4 weeks of age, were fed for 60 days a semi‐synthetic diet containing graded amounts of conjugated linoleic acid (CLA; 0.0, 0.5, 1.0 and 1.5%) to determine its effect on growth performance and serum lipoprotein profiles and its incorporation into abdominal and muscle lipids. Rats fed CLA responded by significantly improved body mass gains; however, this effect was observed only with the 1.0% CLA‐supplemented diet. It was also true for feed conversion efficiency. The changes in serum total cholesterol (TC) and HDL cholesterol concentrations were insignificant and showed an opposite pattern. However, the resulting HDL cholesterol/TC ratio was significantly (P ≤ 0.01) increased. At the same time, serum triacylglycerol (TAG) concentrations were significantly (P ≤ 0.01) elevated, thus counteracting the potential antiatherogenicity of the improved HDL cholesterol/TC ratio. Feeding CLA to rats resulted in its substantial incorporation into both abdominal and muscle lipids. Generally, tissue lipids were enriched with CLA at the expense of long‐chain polyunsaturated fatty acids, eg linoleate and arachidonate. This effect is likely to correspond with reduction of arachidonate‐derived eicosanoid synthesis. These data together suggest that CLA has a potent effect on lipid transport and metabolism in rats. Also, they confirm the potential of nutritional methods to provide CLA‐enriched functional animal products, especially meat, for human consumption. © 2000 Society of Chemical Industry     

Investigation of the in vivo antioxidative activity of Cynara scolymus (artichoke) leaf extract in the streptozotocin‐induced diabetic rat

The in vivo antioxidant activity of a quantified leaf extract of Cynara scolymus (artichoke) was studied. The aqueous artichoke leaf extract (ALE), containing 1.5% caffeoylquinic acid with chlorogenic acid being most abundant (0.30%), and luteolin‐7‐O‐glucoside as major flavonoid (0.15%), was investigated by evaluating the effect on different oxidative stress biomarkers, after 3 wk oral supplementation in the streptozotocin‐induced diabetic rat model. Apart from two test groups (0.2 g ALE/kg BW/day and 1 g ALE/kg BW/day, where BW is body weight), a healthy control group, untreated oxidative stress group, and vitamin E treated group (positive control) were included. A 0.2 g/kg BW/day of ALE decreased oxidative stress: malondialdehyde and 8‐hydroxydeoxyguanosine levels significantly diminished, whereas erythrocyte glutathione levels significantly increased. A 1.0 g/kg BW/day ALE did not show higher antioxidant activity.     

4种烹饪方式对中华绒螯蟹感官及风味品质的影响

为探讨烹饪方式对中华绒螯蟹感官品质的影响,分析冷水蒸制、冷水煮制、热水蒸制、热水煮制4种熟制方式对中华绒螯蟹不同部位游离氨基酸、核苷酸及虾青素含量的影响,同时进行感官评定。结果表明:热水处理组肌肉和性腺中游离氨基酸总量、鲜味氨基酸总量、头胸甲中的虾青素含量均显著高于冷水处理组(P0.05);感官评定结果显示4种烹饪方式对中华绒螯蟹可食部分红度、甜味影响显著(P0.05),其中热水熟制组性腺较甜,冷水蒸制组性腺和肝胰腺较红,总体上热水蒸制组得分最高。热水蒸制是烹饪中华绒螯蟹的优选方式。     

5种生物农药对烟蚜和食蚜瘿蚊的毒力测定及安全性评价

为筛选出对食蚜瘿蚊安全的生物农药,选用5种常用的生物农药对烟蚜及食蚜瘿蚊幼虫（喷雾法）和食蚜瘿蚊成虫（药膜法）进行了毒力测定和安全性评估。结果表明,无论处理24 h还是48 h,对烟蚜毒力较高的是甲维盐和苦参碱,LC₅₀分别为2.166和3.695 mg/L（24 h）,1.567和2.874 mg/L（48 h）;对食蚜瘿蚊幼虫的毒力较高的是鱼藤酮,LC₅₀为18.137 mg/L（24 h）、13.771 mg/L（48 h）,对成虫的毒力较高的是多杀菌素,LC₅₀为7.249 mg/L（24 h）、4.125 mg/L（48 h）。因此5种生物农药中苦参碱、甲维盐、苏云金杆菌对烟蚜和食蚜瘿蚊的选择性较高,适宜在田间与食蚜瘿蚊联合应用防控烟蚜。     

Effect of some habitual cooking processes on the domoic acid concentration in the cockle (Cerastoderma edule) and Manila clam (Ruditapes philippinarum)

The effect of cooking on the concentration and burden of domoic acid in two bivalve molluscs was studied. The Manila clam (Ruditapes philippinarum) and cockle (Cerastoderma edule) were subjected to steaming and boiling, respectively. In both cases, factorial plans were used to evaluate the effects of common cooking methods and the variations likely to take place during the cooking procedure (cooking time and salt concentration in both species, in addition to ethanol percentage in Manila clam). The domoic acid concentration and toxin content were affected by cooking in very different ways in the two species studied. The cockle lost a significant part of its domoic acid content, while the clam did not. Since the weight of the soft tissues in cooked bivalves was lower than in the raw samples in both species, the toxin concentration decreased less than the toxin burden in the cockle, while it increased in the clam, where the toxin burden did not change significantly. Among the cooking variables tested, only cooking time had a noticeable effect on the domoic acid content in the clam and cockle, with the bivalves that were cooked for a longer time having smaller amounts of toxin. It is clear that cooking affects the toxin concentration in bivalves in a way that is species specific. This characteristic must be taken into account when evaluating epidemiological information, establishing allowable toxin levels and in cases where pre-processing treatments such as cooking or similar methods are used in monitoring systems.     

Determination of dioxins (PCDDs/PCDFs) and PCBs in food and feed using the DR CALUX® bioassay: Results of an international validation study

Maximum levels for dioxins in food and feedstuffs have been recently established by the European Commission through two regulations. Dioxin-monitoring programmes of food and feedstuffs will therefore be undertaken by the European Member States to implement these regulations, which would be facilitated by fast and low-cost screening methods. Commission Directives 2002/70/EC and 2002/69/EC describe specific characteristics for such screening methods. In the present study, the performance characteristics of the DR CALUX® method from BioDetection Systems were established in a validation study with 14 participants. The study was based on two materials (fish oil and feed), each containing four different levels of dioxins and dioxin-like PCBs around the current limits. The results demonstrate that the test is very promising but that in particular the clean-up procedure was a source of variation and requires further optimization and standardization. In addition the quantification is improved by the use of control samples to correct for background contamination, recovery and differences between the TEF values and REP (relative potency) factors in the test.     

Mycotoxin contamination of home-grown maize in rural northern South Africa (Limpopo and Mpumalanga Provinces)

The aim of this study was to assess mycotoxin contamination of crops grown by rural subsistence farmers over two seasons (2011 and 2012) in two districts, Vhembe District Municipality (VDM, Limpopo Province) and Gert Sibande District Municiality (GSDM, Mpumalanga Province), in northern South Africa and to evaluate its impact on farmers’ productivity and human and animal health. A total of 114 maize samples were collected from 39 households over the two seasons and were analysed using a validated liquid chromatography-tandem mass spectrometry mycotoxins method. Aflatoxin B₁ (AFB₁) occurrence ranged from 1 to 133 µg kg^?1 in VDM while AFB₁ levels in GSDM were less than 1.0 µg kg^?1 in all maize samples. Fumonisin B₁ levels ranged from 12 to 8514 µg kg^?1 (VDM) and 11–18924 µg kg^?1 (GSDM) in 92% and 47% positive samples, respectively, over both seasons. Natural occurrence and contamination with both fumonisins and aflatoxins in stored home-grown maize from VDM was significantly (p < 0.0001) higher than from GSDM over both seasons.     

烹制时间对狮子头营养品质和挥发性风味物质的影响

为探究烹制时间对狮子头营养品质和挥发性风味物质的影响,该文对不同烹制时间条件下狮子头的基础营养成分、色泽、卡路里、质构、嫩度和挥发性风味物质指标进行研究.结果 表明,不同烹制时间对狮子头的营养品质和挥发性风味物质含量影响显著(P<0.05).烹制过程使狮子头中水分含量增加显著(P<0.05).与原料肉相比,烹至120 ...     

NNK和B[a]P在卷烟烟气复杂基质中的联合遗传毒性

为对卷烟进行安全性评价,以肯塔基参比卷烟3R4F为研究对象,以B[a]P、NNK为目标化合物,采用检测哺乳动物细胞致突变性的微核试验,结合三者对人体支气管上皮细胞的毒性作用,分析了B[a]P、NNK在卷烟烟气复杂基质中的联合作用.结果表明:(1)B[a]P、NNK与CSC均具有体外细胞遗传毒性;(2)两两联合作用诱发细胞微核存在一定的拮抗效应;(3)三者联合作用呈现一定的协同作用.     

Dietary exposure and risk assessment of polychlorinated dibenzo-p-dioxins,polychlorinated dibenzofurans and dioxin-like polychlorinated biphenyls of the population in the Region of Valencia (Spain)

Dietary exposure of the Valencia Region population to polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and PCBs was assessed in the Region of Valencia in 2010–2011. A total of 7700 food samples were collected. Occurrence data were combined with consumption data to estimate dietary exposure in adults (>15 years of age) and young people (6–15 years of age). The estimated intake was calculated by a probabilistic approach. Average intake levels (upper-bound scenario) were 1.58 and 2.76 pg toxic equivalent (TEQ) kg^?1 body weight (bw) day^?1 for adults and young people, respectively. These average intakes are within range of the tolerable daily intake of 1–4 pg WHO-TEQ kg^?1 bw day^?1 recommended by WHO, and slightly above the tolerable weekly intake (TWI) of 14 pg TEQ kg^?1 bw week^?1 and the Provisional tolerable monthly intake of 70 pg TEQ kg^?1 bw month^?1 set by the Scientific Committee on Food and the Joint FAO/WHO Expert Committee on Food, respectively. These results show that the contamination levels in food and therefore the exposure of the general population to PCDD/Fs and PCBs have declined in this region and therefore show the efficiency of the European risk-management measures. In terms of risk characterisation, the results showed that, under the upper-bound scenario, 22% of the adult and 58% of the young people population could exceed the TWI.     

The effect of cooking on the location and concentration of oxalate in three cultivars of New Zealand‐grown oca (Oxalis tuberosa Mol)

Oca (Oxalis tuberosa Mol) originates from South America but is now also grown commercially in New Zealand. It contains moderate amounts of oxalate, which is only present in its soluble form. The skin of the oca tuber is thought to contain more oxalate than the flesh. In this study the concentration of soluble oxalate was measured in the skin and outer and inner flesh and in the whole tuber of raw, boiled, baked and steamed oca. The analysis was carried out on the traditionally pinkish‐red New Zealand cultivar and on the newly introduced cultivars ‘Mellow Yellow’ and ‘Apricot Delight’. In the raw oca tuber the oxalate concentration in the skin is significantly higher than in the flesh (mean value 7.3 g kg^?1 fresh weight (FW) compared to 1.7 and 1.4 g kg^?1 FW in the outer and inner flesh respectively). The highest concentration was found in the skin of the pinkish‐red cultivar (10.9 ± 1.0 g kg^?1 FW). All cooking methods seemed to cause a migration of oxalate from the skin to the underlying flesh. On a fresh weight basis, baking significantly increased the oxalate concentration in the whole tuber, whereas boiling decreased the concentration and steaming had no significant effect (p < 0.001). Boiling might therefore be a better way of cooking oca than baking when a low intake of oxalate is desired. © 2001 Society of Chemical Industry