大黄鱼鱼卵脂质含量及脂肪酸组成分析

用氯仿-甲醇法提取大黄鱼鱼卵的粗脂肪,经甲酯化处理,用气相色谱法对其脂肪酸的组成进行分析。结果显示大黄鱼鱼卵湿基总脂肪含量达19.6%,干基总脂肪含量达44%,磷脂占总脂肪比例为61.2%,胆固醇占总脂肪比例为3.2%,而且大黄鱼鱼卵还含有丰富的ω-3PUFA多不饱和脂肪酸,其EPA和DHA之和达到了25.5%。     

Chemical characterisation and histamine-forming bacteria in salted mullet roe products

Sixteen salted mullet roe products sold in the retail markets in Taiwan were purchased and tested to determine the occurrence of histamine and histamine-forming bacteria. The levels of pH, salt content, water content, total volatile basic nitrogen (TVBN) and aerobic plate count (APC) in all samples ranged from 5.4 to 5.8, 5.1% to 7.2%, 15.4% to 27.3%, 32.0 to 69.6 mg/100 g and <1.0 to 7.1 log CFU/g, respectively. None of these samples contained total coliform and Escherichia coli. The average content of each of the nine biogenic amines in all samples was less than 4 mg/100 g, and only one mullet roe sample had the histamine content (8.18 mg/100 g) greater than the 5.0 mg/100 g allowable limit suggested by the US Food and Drug Administration. Two histamine-producing bacterial strains capable of producing 10.7 ppm and 9.6 ppm of histamine in trypticase soy broth (TSB) supplemented with 1.0% l-histidine (TSBH) were identified as Staphylococcus carnosus by 16S rDNA sequencing with PCR amplification, and they were isolated from the sample with higher histamine content (8.18 mg/100 g).     

Cholesterol oxide, cholesterol, total lipid and fatty acid contents in processed meat products during storage

The effects of storage time on the formation of cholesterol oxides and on alterations in the fatty acid composition of processed meat products manufactured by Brazilian industries were investigated in this study. Cholesterol oxides and cholesterol were determined by HPLC using photodiode array and refractive index detectors. Samples of jerked beef, Italian-type salami, chicken mortadella and Chester mortadella were analysed at 30 day intervals starting at zero time, for 90 days for the mortadella and 120 days for the jerked beef and salami. The mortadellas were stored under refrigeration at 6 °C and the jerked beef and salami at room temperature, but protected from the light. No cholesterol oxides were formed during the storage time in any of the samples. The cholesterol content, the fatty acid composition and total lipid contents showed no significant differences during storage with the exception of the total lipid content of the jerked beef, which varied from 3.5 at zero time to 2.4 g/100 g after 120 days storage.     

The effect of heat treatment on the cholesterol oxides,cholesterol, total lipid and fatty acid contents of processed meat products

The effects of heat treatment on the formation of cholesterol oxides and on alterations of fatty acid composition were investigated in processed meat products. Meatballs (beef), hamburger (beef and Chester), sausage (pork, chicken and Chester) and frankfurter (mixed meat, chicken and Chester) were analysed. There was no cholesterol oxide formation caused by heat treatment of the samples analysed. The fatty acid compositions, calculated as g/100 g sample, showed alterations only between the raw and grilled beef hamburger. Only the cholesterol levels were significantly changed when comparing the raw and grilled pork sausages and the raw and grilled Chester hamburger, the values being lower in the grilled samples. Also, the total lipid contents of grilled beef hamburgers were lower than the values.     

Total lipid content and fatty acid composition of commercially important fish species from the Mediterranean, Mar Grande Sea

The fatty acid (FA) profiles of 11 commercially important fish species from the sea of Southern Italy (Mar Grande Sea) were investigated.The results showed significant differences among the fatty acid profiles of the examined fish (p < 0.05). A relatively high proportion of n − 3 polyunsaturated fatty acids (PUFAs), of which more than 70% were accounted by docoesahexaenoic acid (DHA) and eicoesapentaenoic acid (EPA) in salema, bogue, common two-banded seabream and sand smelt, and lower proportions of oleic acid (C18:1n − 9) and palmitic acid (C16:0) also dominating. The percentages of EPA and DHA were between 5.03-8.61% and 9.85-17.39% of total lipid, respectively.The results showed that the fish examined are a good source of n − 3 PUFAs, resulting in a very favourable n3 - n6 ratio, especially in salema, sand smelt, common two-banded seabream and picarel.     

Feeding feedlot steers fish oil alters the fatty acid composition of adipose and muscle tissue

Sixteen steers (441±31.7kg initial body weight) consumed two high concentrate diets with either 0 or 3% fish oil to determine the impact of fish oil, an omega-3 fatty acid source, on the fatty acid composition of beef carcasses. Collected tissue samples included the Longissimus thoracis from the 6th to 7th rib section, ground 10th to 12th rib, liver, subcutaneous adipose tissue adjacent to the 12th rib, intramuscular adipose tissue in the 6th to 7th rib sections, perirenal adipose tissue, and brisket adipose tissue. Including fish oil in the diet increased most of the saturated fatty acids (P<0.01) and proportions of polyunsaturated fatty acids (P<0.06), and decreased (P<0.01) proportions of monounsaturated fatty acids. Dietary fish oil increased (P<0.01) levels of omega-3 fatty acids in sampled tissues, resulting in lower (P<0.01) omega-6:omega-3 ratios. The weight percentages of C20:5 and C22:6 in tissue may provide the recommended daily allowance for humans. Fish oil may have a role in beef niche marketing if there are no deleterious effects on consumer satisfaction.     

Liquid chromatographic quantification of synthetic colorants in fish roe and caviar

According to the directive 94/36/EC of the European Union (EU), quantities of synthetic colorants added to foods are restricted by upper limits and, therefore, reliable methods for their quantification have to be established. Approved colorants, defined by so-called E numbers, are permitted for dying fish roe (commonly named caviar). We developed a chromatographic method for the quantitation of colorants in roe. The recovery rates of 14 synthetic food colorants from solid materials (Al₂O₃, XAD-2, anion exchangers, and polyamide-6) were tested, and polyamide powder was selected as adsorbent for quantitative determination of colorants in fish roe. The most effective sample preparation comprises extraction of colorants from roe with 1 M aqueous ammonia, defatting of the solution with n-hexane, adjustment of pH 2 of the extract, adsorption of dyes on the polyamide and desorption with a mixture of aqueous ammonia (25%) and methanol (1:9 v/v). The isolated colorants were analyzed by RP-HPLC with diode-array detection. In several caviars, the maximum of individual colorants regulated by EU were exceeded or colorants declared on food labels were not detected. Presented at 25th International Symposium on Chromatography, Paris, France, October 4–8, 2004.     

Effect of antioxidant on the fatty acid composition and lipid oxidation of intramuscular lipid in pressurized pork

To investigate the effect of antioxidants on lipid oxidation and fatty acid composition in pressurized pork, minced pork with or without 1% Na(2)EDTA was pressurized at 500MPa before 7days storage at 4°C. TBARS value, lipid content and fatty acid composition in untreated and high-pressure (HP) treated samples were analyzed. HP treatment induced marked increases in TBARS values and lipolysis of partial phospholipids causing an increase of free fatty acid content. Preferential hydrolysis for polyunsaturated fatty acids (PUFA) in phospholipids resulted in the percentage of PUFA in phospholipids decreasing markedly and thereby that in free fatty acids increasing significantly. Addition of 1% Na(2)EDTA to minced pork before HP significantly decreased the TBARS values in pressurized samples, but did not inhibit the lipolysis of phospholipids, causing the fatty acid composition of phospholipids and free fatty acids to change similarly to those samples without Na(2)EDTA.     

Influences of potassium ferrocyanide on lipid oxidation of salted cod (Gadus morhua) during processing, storage and rehydration

The effects of added potassium ferrocyanide (CN) in different concentrations (2.5 ppm, 7.5 ppm and 100 ppm), in salt, on lipid oxidation in cod during salting, storage and rehydration were examined in this study. An increase in CN concentration accelerated lipid oxidation of the salted cod, as observed by increases in lipid hydroperoxides (PV) and thiobarbituric acid-reactive substances (TBARS), as well as in the development of fluorescence compounds (δF_or and δF_aq). A yellow discolouration (higher b^∗ value) of salted cod was associated with higher levels of oxidation derivatives. High correlation between PV, TBARS and free fatty acid (FFA), as well as between FFA and δF_or, was found. The results of principal component analysis showed that TBARS, b^∗ value and δF_or were the strongest indicators of lipid oxidation during salting and storage.     

Effect of ascorbic acid and citric acid on the quality of salted Chinese cabbage during storage

Changes in color, browning indices, enzyme activity, and physical and chemical quality during the storage period were investigated to assess the effectiveness of storage period extension along with the addition of ascorbic acid (AA) and citric acid (CA) to salted Chinese cabbage. After 16 days of storage, the change in chromaticity value showed treatment with 0.5% CA showed the lowest change in the brown index during the storage period. The control showed the highest residual activity of polyphenol oxidase among control, AA, and CA-treated salted cabbage. AA and CA treatment effectively inhibited the initial populations of microorganisms including total aerobic bacteria, lactic acid bacteria, and yeast and molds in salted Chinese cabbage during storage. Further, the texture, i.e., hardness, chewability, and elasticity, tended to decrease with increasing storage. These results suggest that treatment with AA could help maintain the quality of salted Chinese cabbage during the storage period.     

Effect of high-pressure treatment on the fatty acid composition of intramuscular lipid in pork

To investigate the effect of high-pressure (HP) treatment on lipid oxidation and fatty acid composition of intramuscular lipid in pork, the longissimus muscles from Rongchang (RC) pig were pressurized at 200, 350 and 500 MPa for 20 min at 20 °C prior to 7 days storage at 4 °C. The changes in TBARS number, lipid content and fatty acid composition of total intramuscular lipids, phospholipids, triglycerides and free fatty acids in untreated and HP treated samples were analyzed. HP treatment had no significant effect on the content and fatty acid composition of total lipids and triglycerides in the samples, but treatment at 350 MPa and above led to marked increases in TBARS values and lipolysis of partial phospholipids causing a correlative increase of free fatty acid content. A preferential hydrolysis for polyunsaturated fatty acids (PUFA) in phospholipids was observed, which resulted in the percentage of PUFA in phospholipids decreasing markedly and thereby that in free fatty acids increasing significantly.     

Cholesterol content and lipid composition of low fat dairy products

The lipid composition of different products obtained from the same raw milk was investigated. The cholesterol content of skim milk (0.05% total fat) and butter milk (0.57% total fat) lipids was 4.20% and 1.31%, respectively, while raw milk lipids and butter fat contained 0.34% or 0.30%, respectively. As the cholesterol content of these low fat milk products increases with decreasing fat content, equations were derived to estimate the fat-related cholesterol content from the value analysed in butter fat. In contrast to the fat-related cholesterol content, the product-related content is still relatively small in skim and butter milk. Their fat-related cholesterol content was found to be influenced by drying. The high content of phospholipids in skim and butter milk led to considerable changes in the fatty acid composition and affected the detection of foreign fat by butyric acid as well as by triglycerides. Skim and butter milk lipids contained only 2.41% or 2.33% butyric acid, respectively, instead of 3.36% found in raw milk lipids. Further, the overlap of phospholipids as well as cholesterol with the gas chromatographic triglyceride pattern resulted in calculated foreign fat contents of more than 20%.     

Changes in lipid composition and fatty acid profile of Nham,a Thai fermented pork sausage,during fermentation

Changes in lipid composition and fatty acid profile of Nham during fermentation were investigated. Total lipids of Nham were in the range 2–3%. The extracted lipid of initial Nham mix consisted mainly of triglycerides (TG), accounting for more than 75% of the total lipid, followed by phospholipids (PL) and a trace amount of diglycerides (DG) and free fatty acid (FFA). During fermentation, TG, DG and PL decreased with a concomitant increase in FFA, indicating lipolysis of Nham lipids during fermentation. Changes in fatty acids of the total lipids, non-polar and polar lipid fractions were observed during fermentation. In both total and non-polar lipid fractions, the major fatty acids found in a descending order were oleic (C18:1), linoleic (C18:2) and palmitic (C16:0) acids, which together accounted for 90% of the total fatty acids. Increases in fatty acid contents in both total and non-polar lipid fractions, were observed with a corresponding decrease in the quantity of fatty acids of phospholipids. As the fermentation proceeded, peroxide value generally increased while TBARS values decreased. Overall, lipid oxidation in Nham occurred during fermentation but did not cause the objectionable odour and taste in any Nham tested.     

Comparison of two different methods for the separation of lipid classes and fatty acid methylation in reindeer and fish muscle

In the present study different methods for the separation of lipid classes and methylation were compared and evaluated for method optimisation in muscle tissue. Fish and reindeer muscle were tested as fish represents a high proportion of polyunsaturated FA (PUFA) and reindeer a moderate amount of PUFA. Lipids were separated either by solid phase extraction (SPE) into neutral (NL) and polar lipids (PL) or by thin layer chromatography into triacylglycerols (TAG) and phospholipids. All fractions were methylated with or without boron trifluoride (BF₃). The two different separation methods showed differences between PL and phospholipids, while TAG and NL were largely similar. Methylation method did not lead to important differences when comparing within the different separation methods, though methylation with BF₃ generally resulted in similar or higher values of methylated FA, indicating a more complete methylation. The content of PUFA in the muscle tissue did not affect these outcomes. Separation of lipids by SPE, followed by methylation with BF₃ was judged to be the best overall method, though not suitable for analysis of samples with labile fatty acids.     

Intramuscular and subcutaneous lipid fatty acid profile composition in male and female foals

This study characterised the lipid classes of Longissimus dorsi (LD) muscle and the fatty acid profiles of the LD intramuscular fat and subcutaneous (SC) adipose tissue of male and female foal mixed populations. Two animal groups were studied based on slaughter ages of 16 and 24 months. The sex of the animals had no statistical significance in the lipid fractions of the LD muscle or in the intramuscular fatty acids (p ? 0.05). In contrast, there was a significant effect of sex on the fatty acid profile of the SC adipose tissue. Furthermore, the livestock production system showed difference in both lipid class and fatty acid profiles from the LD and SC adipose tissues. The LD of 24-month old foals had lower phospholipids content (p ? 0.001), displayed little difference in saturated fatty acids (SFA) (p ? 0.1), exhibited higher levels of monounsaturated fatty acids (MUFA) (p ? 0.05) and lower levels of polyunsaturated fatty acids (PUFA) (p ? 0.05) compared with that of the 16-month old foals. Furthermore, the fatty acid profile of the SC adipose tissue of the 24-month old foals had higher SFA (p ? 0.05) and PUFA (p ? 0.01) with lower amounts of MUFA (p ? 0.001) relative to the 16-month old foals.     

Enrichment of food products with polyunsaturated fatty acids by fish oil addition

Fish oil remains the main dietary source of long chain polyunsaturated fatty acids omega-3, which desirably impact on human health. Increase of omega-3 fatty acids intake is currently recommended. Results of many studies showed that consumption of food products enriched with fish oil offers the potential health benefits, especially in protection against cardiovascular diseases (CVD), cancer and improvement of brain development and function. Health influence, methods, advantages and disadvantages of food enrichment with fish oil as well as characteristics of market of such products were presented.     

Changes in lipid composition,fatty acid profile and lipid oxidative stability during Cantonese sausage processing

Lipid composition, fatty acid profile and lipid oxidative stability were evaluated during Cantonese sausage processing. Free fatty acids increased with concomitant decrease of phospholipids. Total content of free fatty acids at 72 h in muscle and adipose tissue was 7.341 mg/g and 3.067 mg/g, respectively. Total amount of saturated, monounsaturated and polyunsaturated fatty acids (SFA, MUFA, and PUFA) in neutral lipid exhibited a little change during processing, while the proportion of PUFA significantly decreased in the PL fraction. The main triacylglycerols were POO + SLO + OOO, PSO (P = palmitic acid, O = oleic acid, L = linoleic acid, S = stearic acid), and a preferential hydrolysis of palmitic, oleic and linoleic acid was observed. Phosphatidylcholines (PC) and phosphatidylethanolamines (PE) were the main components of phospholipids and PE exhibited the most significant degradation during processing. Thiobarbituric acid values (TBARS) increased while peroxide values and hexanal contents varied during processing.     

Effect of low dose gamma irradiation on beef quality and fatty acid composition of beef intramuscular lipid

Eight Chinese Yellow Cattle semitendinous muscles were irradiated using a (60)Co irradiation source (with the dose of 1.13, 2.09, or 3.17kGy) and stored (0 day or 10 days at 7°C) to estimate fatty acids change of neutral lipid (NL), polar lipid (PL) and total lipid (TL) fractions, and the beef quality change. Total saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) increased with irradiation, ratios of MUFA to SFA did not change in TL. Whilst, total polyunsaturated fatty acid (PUFA) reduced with irradiation, which resulted in PUFA to SFA ratio decreased in TL (0 day or 10 days). Purge loss and 2-thiobarbituric acid reactive substances values increased with irradiation (from 0 to 3.17kGy) at 0 day, but these values were lower with irradiation at 10 days. Total bacterial counts decreased proportionally with irradiation dose increasing from 0 to 3.17kGy. It can be concluded that fatty acid profiles in beef changed with irradiation; however, fatty acid profiles did not change much at 3.17kGy compared with 1.13 or 2.09kGy, and the beef quality were most acceptable at the dose of 3.17kGy, thus, low dose of about 3kGy gamma irradiation was recommended to apply in fresh beef preparation.     

Phenotypic and genetic evaluations of biogenic amine production by lactic acid bacteria isolated from fish and fish products

In this work, biogenic amine production (histamine, tyramine and putrescine) by a collection of 74 lactic acid bacteria of aquatic origin has been investigated by means of amino acid decarboxylation by growth on decarboxylase differential medium, biogenic amine detection by thin-layer chromatography (TLC) and decarboxylase gene detection by PCR. None of the evaluated strains showed neither production of histamine and putrescine, nor presence of the genetic determinants encoding the corresponding decarboxylase activities. However, the tyrosine decarboxylase gene (tdc) was present in all the enterococcal strains, and tyramine production was detected by TLC in all of them but Enterococcus faecium BCS59 and MV5. Analysis of the tyrosine decarboxylase operon of these strains revealed the presence of an insertion sequence upstream tdc that could be responsible for their lack of tyrosine decarboxylase activity.