Deep fat frying of frozen foods in sunflower oil. Fatty acid composition in fryer oil and frozen prefried potatoes

The fatty acid pattern was used to evaluate the alteration of a sunflower oil that had been used 20 times to fry various frozen foods with frequent replenishment (FR) or without replenishment (NR) of the used oil with fresh oil during frying. Furthermore, the fat extracted from potatoes fried in the sunflower oil from fryings 1, 5, 8, 12, 16 and 20 was also analysed by gas–liquid chromatography to compare its fatty acid profile with that of the corresponding fryer oil. The amount of unaltered fatty acids decreased from 96.2 mg per 100 mg oil in the unused sunflower oil to 89.6 mg per 100 mg oil after 20 fryings in the FR oil and to 88.9 mg per 100 mg oil in the NR oil, following a linear adjustment (r > 0.97; p < 0.001). Linoleic acid also decreased while palmitic and oleic acids increased in the bath oil. Fatty acid variations were more pronounced in NR than FR oil for major fatty acids and not only related to the degradation of unsaturated fatty acids but also to the interactions between the bath oil and the fried food fat. Thus the increase in palmitic acid of the fryer oil could be due to migration of this fatty acid from the prefried frozen potatoes as revealed by the composition of the fat extracted from those potatoes. Although the fatty acid variation (eg myristic, palmitic, oleic, trans–cis isomers of linoleic and linoleic acids) was not equivalent in FR or NR fryer oil and in the fat of the potatoes, the changes in total unaltered fatty acids were not significantly different in oil and potatoes. Present data suggest that frequent addition of fresh oil throughout the frying process minimises the fatty acid changes, contributing to the obtainment of fried foods with a healthy fatty acid profile. © 2000 Society of Chemical Industry     

降低大豆油精炼过程反式脂肪酸含量研究

研究精炼过程对大豆油反式脂肪酸含量变化,发现在碱炼、脱色工段反式脂肪酸含量没明显变化,而在脱臭工段反式脂肪酸含量发生显著变化,表明精炼时脱臭是产生反式脂肪酸主要阶段;同时比较脱臭温度,脱臭塔结构,脱臭时间对大豆油反式脂肪酸形成影响,并根据研究结果,提出工业化降低大豆油反式脂肪酸可行性工艺。     

Influence of composition on degradation during repeated deep‐fat frying of binary and ternary blends of palm,sunflower and soybean oils with health‐optimised saturated‐to‐unsaturated fatty acid ratios

The American Heart Association recommended the fatty acid balance contributed by all the fats in our diet, suggesting it would be best at approximately 1:1:1 for saturated (SFA), monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA), respectively. Three individual oils: palm oil (PO), soybean oil (SBO) and sunflower oil (SNF) and their binary and ternary blends were prepared and used for repeated deep‐fat frying of French fries. The acid value, peroxide value, p‐anisidine value and Totox values, as well as oxidative stability, contents of total polar compounds, tocochromanols, triacylglycerol dimers and oligomers, were determined in individual and blended oils. The lowest Totox value and highest stability were found for PO, and the opposite data were obtained for SNF and SBO. The degradation of tocochromanols in blends ranged from 91% to 95% after 4 days of frying, while in individual oils, it was 63% in SBO, 71% in SNF and 100% in PO. The lowest formation of dimers and oligomers was observed for the PO: SNF blend. Obtained results showed that only pure PO was a better frying medium than its blends with SBO and SNF. However, a prepared blend had a better fatty acid composition for human health and was more stable than pure SBO and SNF.     

Lipid,fatty acid and carotenoid content of edible egg yolks from avian species: A comparative study

A comparative study has been conducted of the major lipid classes composition, as well as the fatty acid and carotenoid content in the yolk of conventional eggs from five avian species (ostrich, turkey, quail, duck and goose); the nutritional indices were calculated. The neutral lipids were the major yolk fractions but their proportions varied among species. All yolks and especially ostrich’s yolk were found to be an excellent source of dietary lecithin. Quail yolk displayed the lowest fat and cholesterol content and the lowest values for the cholesterol index (CI) and cholesterol-saturated fat index (CSI). It is therefore more appropriate for a healthier diet. Turkey and goose yolks contained significantly (P < 0.05) higher ω-3 fatty acid proportion and ω-6/ω-3 ratio. The turkey yolk was characterised by the lowest AI and TI values, which are recommended for a healthy diet. Quail yolk lipids contained a favourable PUFA/SFA ratio. All the examined yolks contained highly bioavailable functional nutrients, such as lutein and zeaxanthin.     

日粮添加葵花籽油与豆油对奶牛生产性能及牛奶中共轭亚油酸含量的影响

研究通过日粮添加葵花籽油及葵花籽油与豆油混合油对牛奶中共轭亚油酸(CLA)含量及奶牛生产性能的影响。结果表明:在奶牛精料中添加葵花籽油及葵花籽油与豆油混合油,奶牛的采食量下降,产奶量上升。牛奶中CLA含量提高(P0.05),分别达到21.36与16.92 mg/(g乳脂);牛奶中乳脂率与乳蛋白含量下降显著,干物质含量略有下降(P0.05),对密度、pH值及乳糖的含量没有影响;乳脂中中短链脂肪酸含量下降,长链脂肪酸中的不饱和脂肪酸增加,而硬脂酸含量下降。     

Short communication: Diurnal profiles of conjugated linoleic acids and trans fatty acids in ruminal fluid from cows fed a high concentrate diet supplemented with fish oil, linseed oil, or sunflower oil

Trans-18:1 and 18:2 isomer composition in ruminal fluid during the daily feeding cycle was examined in 3 cows fed a high concentrate diet (35:65) with 5% (DM basis) sunflower oil (SO), 5% linseed oil (LO), or 2.5% fish oil (FO) in a 3 x 3 Latin square with 3 4-wk periods. Grass hay and concentrate mixtures were fed at 0900, 1300, and 1700 h daily. Ruminal fluid was collected at 0900, 1100, 1300, 1500, 1700, 2000, and 0000 h. Feeding SO resulted in the greatest mean concentrations (% of total fatty acids) of trans10,cis12-18:2 and cis9,trans11-18:2. In particular, trans10,cis12-18:2 with SO was greater at 1500 (0.29%), 2000 (0.34%), and 0000 h (0.25%) relative to 0900 h (0.07%). Cis9,trans11-18:2 concentration increased from 0.47% at 0900 h to a peak of 2.06% at 1100 h; it remained greater than the percentage determined at 0900 h at 1300 (1.4%) through 0000 h (1.1%). Concentration of trans11,cis15-18:2 was greatest with LO, ranging from 3.3% (0900 h) to a peak of 11.4% at 2000 h. Mean trans10-18:1 concentration ranked by diet was SO > FO > LO. Peak trans10-18:1 with SO was observed at 1700 h (14.9%) compared with 0900 h (5.1%). Trans11-18:1 did not differ with diet or time. Stearic acid decreased over time with all diets reaching minimum concentrations at 1700 to 2000 h relative to 0900 h. Feeding FO, however, decreased mean 18:0 concentration 4-fold compared with LO or SO. The moderate effect on concentration of trans-18:1 coupled with accumulation of 18:2 intermediates and the decrease of 18:0 over time suggest that oils reduced the biohydrogenation of 18:2 isomers to trans-18:1.     

Effect of dietary soybean oil addition on the odd-numbered and branched-chain fatty acids in rabbit meat

The effect of dietary soybean oil (SO) inclusion (20 g/kg) on the odd-numbered (ONFA) and branched-chain (BCFA) fatty acids (FA) of two muscles, differing in fatness (Longissimus lumborum and Biceps femoris), was studied in 24 New Zealand × Californian rabbits. The increased muscle fatness in Biceps femoris (P < 0.001) was related to higher saturated (P < 0.01) and monounsaturated (P < 0.01) fatty acids. Intramuscular ONFA and BCFA contents were not affected, but their proportions were reduced (P < 0.01 and P < 0.001) by SO addition, suggesting a dilution effect of the dietary polyunsaturates accumulated in both muscles, except for 17:0i which decreased only in Longissimus lumborum due to significant (P < 0.05) soybean oil × muscle interaction. The higher (P < 0.05) BCFA contents and the FA profile in Biceps femoris were not affected by fatness, indicating an association with other muscle properties. The present study supplies new information on ONFA and BCFA in rabbit meat.     

毛细管气相色谱法测定精炼和氢化大豆油中的反式脂肪酸

采用CP—Sil88强极性毛细管柱气相色谱法对精炼和氢化大豆油中的顺、反异构和位置异构的脂肪酸进行定性、定量分析。结果表明，精炼和氢化大豆油中主要顺、反式脂肪酸实现了很好地分离，各种位置异构的反式脂肪酸也实现了较好地分离。采用归一化法对各种脂肪酸进行定量分析，结果表明，精炼大豆油中反式脂肪酸为总脂肪酸含量的3．45％，以△9c，12t—C18：2、△9t，12c—C18：2和△9c，12c，15t—C18：3、△9t，12c，15c—C18：3 4种形式为主；氢化大豆油中反式脂肪酸为总脂肪酸含量的38．73％，以△9t—C18：1、△10t—C18：1、△11t—C18：1 3种形式为主的反式十八碳单烯酸（t—C18：1）占反式脂肪酸总量的90．81％。     

Hypolipidemic activity in sprague-dawley rats and constituents of a novel natural vegetable oil from cornus wilsoniana fruits

Cornus wilsoniana Wanger is a woody oil plant distributed in the south region of the Yellow River, China. Its oil has been taken as edible oil for over 100 y, and consumption of such oil is believed to prevent hyperlipidemia in Chinese folk recipe. This study has investigated the hypolipidemic effect of Cornus wilsoniana oil (CWO) in Sprague-Dawley rats. The results demonstrated that CWO could significantly decrease total cholesterol (TC), total triacylglycerol (TG), and low-density lipoprotein cholesterol (HDL-C) in serum, liver weight, hepatic TC, and TG. After analyzing the chemical constituents of CWO, we found that the content of unsaturated fatty acids (UFA) was very high (69.12%). Specially, the n-6 polyunsaturated fatty acids (PUFA), including linoleic acid, γ-linolenic acid, and 11,14-eicosadienoic acid, accounted very great proportion (38.86%). The high hypolipidemic activity of CWO might be attributed to the lipid-lowering functions of these polyunsaturated fatty acids. Molecular docking was further performed to study the binding model of fatty acids (FA) from CWO to a possible hypolipidemic target, peroxisome proliferator-activated receptor δ (PPARδ). The results showed that linoleic acid and γ-linolenic acid could bind PPARδ very well. Practical Application: Cornus wilsoniana oil could be used as equilibrated dietary oil, not only having hypolipidemic function, but also helping to overcome essential fatty acids deficiency.     

Effect of increasing amounts of a linoleic-rich dietary fat on the fat composition of four pig breeds. Part I: Backfat fatty acid evolution

Four diets prepared, respectively, with 0%, 2%, 4% and 8% of a high-linoleic added fat were administered (76 days of treatment) to a sample of 112 pigs of four breeds (Landrace, Large White, Duroc and a crossbreed Landrace × Duroc). The effects of diet and breed on the evolution of the fatty acid composition of backfat were examined by taking biopsies. Over time, a continuous increase in stearic, palmitic and oleic acids throughout the pig’s life was observed. Oleic acid showed the smallest differences among the four diets at the end of the experiment, while stearic and palmitic acid showed higher differences according to the increase in the percentage of dietary fat. Stearic acid showed the highest rate of increase over time, according to the increasing intake of linoleic acid (diets 1–4). These increases were compensated by a decrease in linoleic acid, although this decrease tended to stabilize according to a higher percentage of added fat and also, for diet 4 (8% fat), an increase in linoleic acid was observed at the end of the experiment. Among the minor fatty acids, arachidonic acid showed a clear decrease over time, although higher levels at the end of the experiment were observed for diets including 4% and 8% of added fat, compared to the other two diets including lower amounts of linoleic acid. Moreover, a significant effect was observed for the factor breed. So, Duroc pigs showed the highest rate of deposit of linoleic acid and the lowest of stearic acid, while the other three breeds showed similar rates.     

精炼工艺对大豆油中微量物质变化的影响研究

植物油的精炼过程在除去不利于油脂稳定性的游离脂肪酸、过氧化物和磷脂及其他影响食用安全和油脂品质的物质同时,也造成油脂中微量营养物质的损失,以及一些新的有害物质的生成。研究了国内5个厂家的大豆油在精炼过程中微量物质的含量变化。结果发现,精炼后大豆油中生育酚及甾醇含量显著降低,分别由26.0~37.4 mg/100 g、402.75~841.92 mg/kg降为15.3~31.3mg/100 g、291.90~372.50 mg/kg,同时反式脂肪酸、聚合甘油三酯、缩水甘油酯含量分别提高到0.23%~1.85%、0.220%~0.738%、0.40%~2.94%。对精炼各工序中微量物质的含量进行显著性分析发现,除甾醇主要是在碱炼工序损失外,生育酚、反式脂肪酸、聚合甘油三酯及缩水甘油酯变化最显著均在脱臭工序。同时还考察了不同厂家各工序段的工艺参数,以期阐明大豆油精炼过程中微量物质的变化规律,为植物油适度精炼工艺的改进提供依据。     

Effect of the feeding system on intramuscular fatty acids and conjugated linoleic acid isomers of beef cattle,with emphasis on their nutritional value and discriminatory ability

Thirty two Alentejano purebred bulls were used to investigate the effect of four feeding systems (pasture only, pasture feeding followed by 2 or 4 months of finishing on concentrate, and concentrate only) on meat fatty acid composition (GC-FID), including conjugated linoleic acid (CLA) isomeric distribution (Ag[+]–HPLC–DAD). In addition, meat fatty acids and CLA isomers were used to elucidate the impact of the different feeding regimens on the nutritional value of intramuscular fat and their usefulness as chemical discriminators of meat origin. The diet had a major impact on the fatty acid composition of beef (affected 27 of 36 fatty acids and 10 of 14 CLA isomers), which was independent of the fatty acid concentration. Beef fat from pasture-fed animals had a higher nutritional quality relative to that from concentrate-fed bulls. Finally, meat fatty acid composition was an effective parameter to discriminate between ruminant feeding systems, including different finishing periods on concentrate.     

Matrix composition effect on the digestibility of carob flour phenols by an in-vitro digestion model

Carob flour (CF) and washed carob flour (WCF) (without the water soluble dietary fraction) were submitted to an in-vitro digestion method to evaluate the dietary soluble fibre (DF) and soluble sugars content on the digestibility and bioaccessibility of polyphenols. In addition, combinations of the raw materials (CF and WCF) with hazelnut oil (HO) were proposed in order to evaluate the protection of a vegetable oil rich in polyunsaturated fatty acids (PUFA) on the phenolic compounds submitted to in-vitro digestion conditions. The results showed that the soluble dietary fraction enhanced the stability of the phenolic compounds during the duodenal digestion phase. Similarly, the lipid fraction (rich in PUFA) showed a protective effect on the recovery of the phenolic compounds during duodenal digestion. Disruption of the natural matrix under digestion conditions led to the release of DF and PUFA, which could establish interactions with certain polyphenol compounds enhancing their recovery and stability during digestion.     

Restoration of EPA and DHA in rainbow trout (Oncorhynchus mykiss) using a finishing fish oil diet at two different water temperatures

Feeding fish a fish oil finishing diet (FOFD) after grow-out on vegetable oil diet is one strategy to restore eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels. We investigated restoration of EPA and DHA in rainbow trout fed a FOFD preceded by a grow-out period on 50% or 75% palm fatty acid distillate (PFAD) diets at optimal (15 °C) or elevated (20 °C) water temperatures. Using the FOFD restored EPA and DHA in fillet and whole carcass of fish previously fed either 50% PFAD diet from 85% to 98% or 75% PFAD from 66% to 93% of values obtained for fish fed FO diet throughout. Water temperature did not influence EPA and DHA restoration. Growing rainbow trout with diets where FO was replaced by either 50% or 75% PFAD followed by a FOFD reduced FO usage by around 30% and 44% at 15 °C, respectively, and 32% and 48% at 20 °C, respectively.     

Effect of cooking methods on fatty acids,conjugated isomers of linoleic acid and nutritional quality of beef intramuscular fat

The effect of boiling, microwaving and grilling on the composition and nutritional quality of beef intramuscular fat from cattle fed with two diets was investigated. Longissimus lumborum muscle from 15 Alentejano young bulls fed on concentrate or pasture was analyzed. Cooking losses and, consequently, total lipids, increased directly with the cooking time and internal temperature reached by meat (microwaving > boiling > grilling). The major changes in fatty acid composition, which implicated 16 out of 34 fatty acids, resulted in higher percentages in cooked beef of SFA and MUFA and lower proportions of PUFA, relative to raw meat, while conjugated linoleic acid (CLA) isomers revealed a great stability to thermal processes. Heating decreased the PUFA/SFA ratio of meat but did not change its n−6/n−3 index. Thermal procedures induced only slight oxidative changes in meat immediately after treatment but hardly affected the true retention values of its individual fatty acids (72–168%), including CLA isomers (81–128%).     

Dietary influence on the m. longissimus dorsi fatty acid composition of lambs in relation to protein source

Dietary lipid effect, as a consequence of protein supplement, on lamb m. longissimus dorsi fatty acid composition was investigated, with emphasis on biohydrogenation intermediates. Crossbred lambs (White Swedish Landrace × Texel) were fed a barley-based diet without (CON) or with protein supplements including peas (PEA), rapeseed cake (RC) or hempseed cake (HC). The HC diet resulted in the highest muscle 22:6n-3 proportion, with the RC diet being similar (P<0.05). Protein supplement did not affect the c9,t11 conjugated linoleic acid (CLA) proportion, however the HC diet increased some minor CLA isomers, including t10,c12 CLA (P<0.05). The t10-18:1 and total trans-18:1 were lowest for the RC diet (P<0.05), likely relating to rumen conditions and precursor availability. The saturated, monounsaturated and branched-chain fatty acids were largely unaffected by protein supplement. In conclusion, feeding the RC diet lowered the t10-18:1 and total trans-18:1 in meat, and modestly increased 22:6n-3 content. The direction of these changes would be beneficial, making the RC diet the preferred protein supplement; however the magnitude of the changes in the present experiment may not be sufficient to have an impact on human health.     

Seasonal changes and muscle type effect on the nutritional quality of intramuscular fat in Mirandesa-PDO veal

The influence of slaughter season and muscle type on the detailed fatty acid composition, including conjugated linoleic acid isomers, and contents of total cholesterol and lipid-soluble antioxidant vitamins (α-tocopherol and β-carotene) in Mirandesa-PDO veal was assessed. Mirandesa purebred calves (n = 29) were raised in a traditional production semi-extensive system, slaughtered in late spring (June) or early autumn (October) and the longissimus lumborum and semitendinosus muscles were sampled for analysis. Although the lipid composition of PDO veal was only slightly affected by the slaughter season, it was markedly changed by the muscle type. However, PDO veal had values of pasture-fed cattle for lipid grass intake indicators, in both seasons and muscles. From a human health standpoint, intramuscular fat in Mirandesa-PDO veal has a high nutritional value throughout the year, with favorable ratios of n− 6/n− 3 and contents of n− 3 PUFA and α-tocopherol, as a result of the beneficial effects of grass feeding.     

Olive oil traceability by means of chemical and sensory analyses: A comparison with SSR biomolecular profiles

The relationship between genetic diversity and phenotype in olive, instrumental to improve the efficacy of olive clonal selection, is still far from being fully understood. This work reports on a comparison made between plant SSR genetic data and quality of monovarietal olive oils. Nine monovarietal oils produced by selected genotypes were characterised under chemical and sensory profiles. Fatty acid compositions were determined to evaluate quantitative differences among oils; some fatty acids are actually highly correlated with the genetic matrix, and PCA of fatty acids composition explains 85.53% variability. Moreover some oils characterised by high levels of oleic acid appeared interesting from a nutritional standpoint. Organoleptic profiles evidenced differences especially for the attributes defined as “pleasant flavours”; oils obtained by different genetic matrices were characterised by different flavour intensities of tomato or artichoke, almond or aromatic herbs, correspondence analysis among sensory pleasant attributes and olive oil samples explaining 91.68% variability.     

Synthesis of monoacylglycerol rich in polyunsaturated fatty acids from tuna oil with immobilized lipase AK

The aim of this study was to produce monoacylglycerols (MAG) rich in polyunsaturated fatty acids (PUFA), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), by glycerolysis of tuna oil with lipase AK from Pseudomonas fluorescence immobilized on Accurel EP-100 (IM-AK). tert-Butyl methyl ether (MTBE) was the most suitable organic solvent after screening a list of different solvents and their mixtures. The optimum conditions for MAG production were: 10% w/v of tuna oil in MTBE; mole ratio of glycerol to tuna oil 3:1, water added 4 wt% in glycerol; the amount of IM-AK 30 wt%, based on tuna oil. The temperature was controlled at 45 °C. Under these conditions, with a 24 h reaction, the yield of MAG was 24.6%, but containing 56.0 wt% PUFA (EPA and DHA). Stability of the IM-AK was also studied. The hydrolytic activity of the enzyme remained at 88% and 80% of initial activity after incubating in MTBE for 24 h at 4 and 45 °C, respectively. The K_m and V_max values of the lipase-catalyzed glycerolysis of tuna oil in MTBE were found to be 19.5 mM and 2.71 mg MAG/min, respectively, for IM-AK.