Oxidation stability and fatty acid composition of selected storage and structural lipids: influence of different high fat diet compositions

The oxidation stability of storage lipids from adipose tissue and of structural lipids from liver was compared to the coefficients of oxidizability of the pure fat used: lard (L); lard + sunflower oil 2:1 (LS); butter (B) and partially hydrogenated oil (H). The oxidation stability of the corresponding high-fat dietary regimens (50 energy-%) was also investigated. The experimental groups L, LS, B and H were compared to the control group (C) fed low-fat laboratory pellet-food. The coefficients of oxidizability were calculated from the fatty-acid composition of the used pure fats. The oxidation stability was performed in condition of accelerated oxidation under kinetic regimen, assaying the peroxide concentration in appropriate time intervals. The coefficients of oxidizability of dietary fats and storage lipids were very similar. This is explained by the fact that the fatty-acid composition of storage lipids reflected that of the corresponding high-fat diets. The oxidation stabilities in storage lipids were markedly lower than these in the respective dietary regimens. The highest oxidation stability in lipids from adipose tissue was found in group B, and the lowest in group LS. Contrarywise, the oxidation stability in liver lipid showed the following declining sequence: C greater than H greater than L greater than LS greater than B. The discrepancies in oxidation stability of the various specimens (pure fats, dietary fats, storage and structural lipids) may be explicated by an intervention of factors with pro- and anti-oxidative action. The large deviations in fatty acid composition in the examined tissues in comparison to the composition of the respective high-fat diets may also play an important role in this respect. These parallel studies on oxidation stability at different levels could improve our possibilities for evaluation of the stability and biological value of fats.     

Physical properties of biopolymers containing natamycin and rosemary extract

Antifungal biopolymers were prepared by incorporating natamycin (NA) and NA + rosemary extract (RE) into wheat gluten (WG) and methyl cellulose (MC) films. Interaction between antimicrobial agents and biopolymers was determined with mid-infrared spectroscopy and scanning electron microscopy (SEM). Water vapour permeability and mechanical properties of these films were also measured. Mid-infrared spectroscopy did not indicate any interaction. SEM observations showed that NA crystallises at high concentrations in biopolymers. There were no significant changes in water vapour permeabilities of biopolymers containing active agents at P  < 0.05. While NA incorporation did not result in any changes in mechanical properties of WG films a reduction in tensile strength was observed for MC films containing high concentration of NA. In general, active agent incorporation into WG and MC films did not result in any considerable changes in their physical properties that could affect their application.     

Functional and sensory properties of hen eggs with modified fatty acid compositions

Foaming, emulsifying, gelling, and sensory properties of fresh and stored hen eggs fed with a diet supplemented with flax oil (FO), rapeseed oil (RO), fish oil (FISH), and by-product from black currant processing (BC) were investigated. With these diets, the ω6/ω3 fatty acid ratio of eggs varied from 1.5 to 5.8, while the ratio for eggs in the control group was 6.2. Compared to eggs in the control group, FO supplementation in the feed had statistically significant influences on the foaming properties of the fresh eggs. Eggs stored for 21 days lost part of their foaming properties in FISH oil supplemented group, but the foaming properties in all test groups were technically acceptable. The emulsifying properties of eggs in FO and FISH supplemented feeding groups were statistically different compared to control group. In boiled eggs, flax oil and fish oil supplementation induced off flavours in eggs, but no changes between the control group and test groups were found in the sensory properties of mayonnaise preparations. These results suggest that the egg processing industry may produce egg-based products using oil-supplemented eggs without major problems in functional or sensory properties.     

Effects of cooking and reheating methods on the fatty acid profile of sea bream treated with rosemary extract

BACKGROUND: The effects of rosemary extract on the fatty acid profile of sea bream fillets cooked by different methods (oven baking, grilling and pan frying) as well as the effects of different reheating methods (microwave and conventional oven) on the fatty acid composition of fish after frozen storage for 4 months were investigated. RESULTS: The proportion of saturated fatty acids increased only slightly in fried samples but significantly in oven‐baked and grilled samples, while the proportion of polyunsaturated fatty acids (PUFAs) increased significantly in fried samples but only slightly in oven‐baked and grilled samples. The proportion of monounsaturated fatty acids remained relatively constant after cooking. Of the fatty acids analysed, the most significant increases (P < 0.05) were observed in C18:1n‐9 and C18:2n‐6 and the most significant decreases (P < 0.05) in C14:0, C16:1, C20:5n‐3 and C22:6n‐3. Although sea bream fillets fried in sunflower oil showed an increase in PUFAs, the lowest eicosapentaenoic and docosahexaenoic acid contents were found in fried samples. CONCLUSION: Sea bream fillets treated with rosemary extract showed slower oxidation than untreated fish. Neither conventional nor microwave reheating after frozen storage for 4 months had a detrimental effect on the fatty acid profile and its stability. Copyright © 2009 Society of Chemical Industry     

The effects of consuming docosahexaenoic acid (DHA)-enriched eggs on serum lipids and fatty acid compositions in statin-treated hypercholesterolemic male patients

The purpose of this study was to investigate the effects of consuming a novel docosahexaenoic acid (DHA)-enriched shell egg on the serum lipid levels and ω − 3 polyunsaturated fatty acids (n − 3 PUFA) of serum phospholipid in statin-treated hypercholesterolemic patients. Fifteen subjects were randomly divided into two treatment groups and consumed either two control or two novel DHA-enriched eggs during two organized breakfast periods of 21 consecutive days each using a double-blinded, cross-over design. The novel enriched eggs from feeding the specialty ration provided 217 mg of DHA and 629 mg of total n − 3 PUFA per day. Total serum cholesterol levels were unchanged with either egg consumption and no significant alterations in lipid levels were found due to a treatment effect. The novel egg group exhibited a significant rise in eicosapentaenoic acid (EPA) plus DHA levels in serum phospholipid (by 23%) which can be related to a reduced risk for fatal ischemic heart disease. Consumption of this novel egg offers an alternative food option for more than doubling current sub-optimal DHA intakes in North America.     

调和油的配比对人类健康的影响

天然膳食中的脂肪酸分为SFA、MUFA和PUFA,由于它们具有不同的化学结构和物理性状,对健康亦产生不同的影响。三者的构成比与高脂血症、动脉粥样硬化、心血管疾病关系密切,所以调和油中脂肪酸合理的比例对人体生长、发育及疾病防治至关重要。深入探讨不同膳食脂肪酸构成比对人类健康的影响,为合理调配食用调和油提供科学依据。     

Texture of butter from cows with different milk fatty acid compositions

Milk fatty acid composition and textural properties of butter are known to be affected by the cows' diets. We examined the phenotypic variation in milk fatty acid composition among cows fed the same diet to see if the variation was sufficient to produce butter with different textural properties. Ten cows were selected that tested higher (n = 5) or lower (n = 5) in their proportion of milk unsaturated fatty acids. Milk samples were collected a week after testing, and butter was prepared from the individual samples. Milk and butter samples were again analyzed for fatty acid composition. Butter at 5 degrees C was evaluated by a sensory panel for spreadability and by a texture analyzer at both 5 and 23 degrees C for hardness and adhesiveness. Milk and butter samples from cows with a more unsaturated milk fatty acid composition had a lower atherogenic index, and the butter samples were more spreadable, softer, and less adhesive. Thus, phenotypic variation in milk fatty acid composition among cows fed the same diet is sufficient to produce butter with different textural properties.     

Effects of soybean oil and linseed oil on fatty acid compositions of muscle lipids and cooked pork flavour

This study was conducted to investigate the effects of dietary oil on the fatty acid compositions of the longissimus and biceps brachii muscles and its effects on cooked muscles flavour. Seventy-two crossbred barrows (Duroc×Landrace×Large White), were blocked by weight and randomly assigned to one of three treatments. The three dietary treatments were: (a) no oil supplement (CON); (b) 3% soybean oil supplement (SO3); (c) 3% linseed oil supplement (LO3). Dietary linseed oil and soybean oil significantly increased the contents of C18:3 and C18:2 in the neutral lipids and phospholipids in both longissimus muscle and biceps brachii muscle, respectively. Aroma compounds analysis indicated only few aroma compounds were affected significantly by dietary oil in both cooked longissimus muscle and biceps brachii muscle. The flavour attributes of cooked longissimus muscle and biceps brachii muscle were not influenced by feeding 3% soybean oil. Feeding 3% linseed oil did not deleteriously affect the flavour of cooked longissimus muscle but cooked biceps brachii muscle from LO3 had significantly lower pork flavour and higher abnormal flavour than CON and SO3.     

植物油脂水解工艺及不饱和脂肪酸组成研究

研究了碱性水解小桐子油脂制备脂肪酸的较佳工艺条件：油水比（g/g）为2：1,乙醇-水比（v/v）为2：1,皂化时间1.5h、温度70℃,在该条件下脂肪酸得率、酸值和碘值的平均值分别为：98.25%、203.67mgKOH/g和109.89g/100g。采用桐油、光皮油、棕榈油和大豆油等植物油脂考察了该工艺的原料适用程度,该水解工艺条件下各种油脂制备所得的脂肪酸得率和酸值都接近98%和199mgKOH/g。采用GC-MS分析五种植物油脂脂肪酸组成和含量,其不饱和脂肪酸含量依次为：桐油（94.88%）〉大豆油（84.07%）〉光皮油（81.90%）〉小桐子油（77.84%）〉棕榈油（77.19%）;其中多价不饱和脂肪酸含量次序为桐油（85.36%）〉大豆油（58.01%）〉棕榈油（56.81%）〉光皮油（55.31%）〉小桐子油（42.16%）。大豆油、棕榈油、光皮油和小桐子油四种植物油脂脂肪酸成分基本相同,主要是亚油酸、7,10-十八碳二烯酸、油酸。桐油中脂肪酸组成与其他植物油脂有较大区别,含大量三价不饱和脂肪酸,其主要成分有油酸（9-十八烯酸）13.83%、8,11-十八碳二烯酸24.37%、亚麻酸（9,12,15-十八碳三烯酸和6,9,15-十八碳三烯酸）60.01%。     

不同地区茶叶籽油理化指标及脂肪酸组成的比较分析

茶叶籽油是我国新批准的新型可食用植物油,目前人们对其了解和研究还比较有限.为丰富茶叶籽及茶叶籽油的研究数据,选用了我国9个地区的茶叶籽及其所制得的茶叶籽油进行研究.结果表明:不同地区茶叶籽的粗脂肪含量差异较大,范围在22.6％ ～ 33.1％之间,淀粉含量也与地域有关;不同地区茶叶籽油的酸值和过氧化值两个评价植物油品质最为重要的指标差异较大,而相对密度、碘值和皂化值差异不大;茶叶籽油中共检出棕榈酸、油酸、亚油酸、硬脂酸、亚麻酸和花生酸6种脂肪酸,且不同地区含量存在差异,湖北和湖南的茶叶籽油中不合花生酸,福建的不合硬脂酸,茶叶籽油不饱和脂肪酸含量在80％以上,各地区之间差异不大,福建的含量最高,为84.47％,但各地区间茶叶籽油中的多不饱和脂肪酸含量差异较大,四川的最高,为29.92％.     

不同脂肪酸组成磷脂对大鼠消化吸收的影响

首先通过在饲料中添加胆固醇和卵黄磷脂,研究了卵黄磷脂对大鼠血清和肝脏脂质水平的影响;其次通过配制含有不同磷脂的高脂乳剂灌胃大鼠,考察了不同磷脂的高脂乳剂对大鼠血清总胆固醇、甘油三酯的影响.结果表明:大豆磷脂、卵黄磷脂和鱿鱼磷脂对甘油三酯的消化吸收具有一定的抑制作用,且鱿鱼磷脂的抑制作用最明显;大豆磷脂和卵黄磷脂可以显著促进胆固醇的消化吸收,而鱿鱼磷脂显著抑制了胆固醇的消化吸收.     

不同处理糙米储藏期间脂肪酸及总酸的变化

在不同储藏温度下,研究糙米、发芽糙米及富硒发芽糙米储藏期间脂肪酸值和总酸值的变化。结果表明:随着储藏温度的升高,3种样品的脂肪酸值和总酸值均显著升高;不同储藏温度下,随着储藏时间的延长,3种样品的脂肪酸值均基本呈现先增加后减小的趋势,而总酸值则呈现先减小后增加的趋势。在各储藏温度条件下,未发芽糙米的脂肪酸值及总酸值变化最小,但富硒发芽糙米的储藏品质明显优于发芽糙米,提示硒对糙米储藏期脂质氧化具有抑制作用。     

Oxidation and textural characteristics of butter and ice cream with modified fatty acid profiles

The primary objective of this study was to evaluate oxidation and firmness of butter and ice cream made with modified milkfat containing enhanced amounts of linoleic acid or oleic acid. The influence of the fatty acid profile of the HO milkfat relating to product properties as compared with the influence the fatty acid profile of the HL milkfat was the main focus of the research. Altering the degree of unsaturation in milkfat may affect melting characteristics and oxidation rates, leading to quality issues in dairy products. Three milkfat compositions (high-oleic, high-linoleic, and control) were obtained by modifying the diets of Holstein cows. Ice cream and butter were processed from milkfat obtained from cows in each dietary group. Butter and ice cream samples were analyzed to determine fatty acid profile and firmness. High-oleic milkfat resulted in a softer butter. Solid fat index of high-oleic and high-linoleic milkfat was lower than the control. Control ice cream mix had higher viscosity compared with high-oleic and high-linoleic, but firmness of all ice creams was similar when measured between -17 and -13 degrees C. Nutritional and textural properties of butter and ice cream can be improved by modifying the diets of cows.     

不同产地亚麻籽含油率及亚麻籽油脂肪酸组成的研究

采用索氏提取法和GC-MS法测定并分析了6个不同产地亚麻籽含油率及亚麻籽油脂肪酸组成。结果表明:不同产地亚麻籽含油率在36.59%~44.88%之间,含油率与产地的生长季积温呈显著负相关(r=-0.839 5,P=0.036 6);亚麻籽油中相对含量最高的5种脂肪酸分别是亚麻酸(53.36%~65.84%)、亚油酸(10.14%~16.39%)、油酸(10.03%~12.37%)、硬脂酸(3.98%~9.85%)和软脂酸(2.41%~7.97%),不饱和脂肪酸含量高达77.51%~92.39%。综合含油率及不饱和脂肪酸相对含量等因素,最终确定甘肃陇南作为优质亚麻籽油生产地具有一定优势。     

菜籽油和辛酸酶法合成结构脂质氧化稳定性的研究

对菜籽油(RSO)和辛酸(CA)酶法合成结构脂质(SLs)的特性和氧化稳定性进行了研究,比较了α-生育酚(α-TOH,25~1000 mg/kg)、L-抗坏血酸棕榈酸酯(AP,25~200 mg/kg)、特丁基对苯二酚(TBHQ,25~200 mg/kg)、二叔丁基对甲酚(BHT,25~200 mg/kg)、叔丁基羟基茴香醚(BHA,25~200 mg/kg)和没食子酸丙酯(PG,25~200 mg/kg)等抗氧化剂对提高SLs氧化稳定性的效果。结果表明,RSO和SLs在110℃下诱导时间(IT)分别为7 h和6 h,添加α-TOH几乎不能提高SLs的氧化稳定性(r为0.169);而添加TBHQ、PG、BHA、BHT和AP都能显著提高SLs的氧化稳定性(r分别为0.994,0.948,0.975,0.974和0.985)。SLs和RSO在60℃下加热15 d过氧化值(PV)、共轭二烯酸值(CD)和茴香胺值(AV)显著增加,但RSO和SLs的PV、AV增加幅度没有显著差异(P0.05),而它们的CD变化幅度有显著差异(P0.05)。SLs中CA的插入,一方面增加了饱和脂肪酸,提高了氧化稳定性;另一方面稀释了原料油脂中所含的抗氧化剂浓度,降低了氧化稳定性。     

不同产地白萝卜籽油的理化性质及脂肪酸组成分析

研究了安徽、辽宁、江苏、美国俄勒冈州4产地白萝卜籽的粗脂肪含量、白萝卜籽油的理化性质、脂肪酸组成、生育酚和莱菔素含量。结果表明:4产地白萝卜籽的粗脂肪含量及其油的理化性质、脂肪酸组成和生育酚含量无显著差别;白萝卜籽的粗脂肪含量为37.0%~42.6%;白萝卜籽油中不饱和脂肪酸含量在90%左右,以芥酸(C22∶1)(≥33.49%)居多;白萝卜籽油中生育酚总量在600 mg/kg左右,其中γ-生育酚含量(≥514.3 mg/kg)最高;白萝卜籽油中莱菔素含量为40.4~82.8 mg/kg。     

Effects of processing conditions on structural and functional parameters of whipped dairy emulsions containing various fatty acid compositions

An understanding of the effects of processing parameters can be applied to formulate emulsions with higher unsaturated fatty acid content. Emulsions using the typical ice cream formulation were produced by anhydrous milk fat alone or in a mixture with either olein or stearin at a 2:1 weight ratio. Effects of both pasteurization holding time (40 or 120 s at 80°C) and aging time (ranging from 2 to 24 h) on the structural and whipping properties of the emulsions were studied. Effects of these processing conditions on emulsion structural characteristics were determined using laser light-scattering measurements, rheological properties, microscopic observations, and image analyses of the whipped emulsions. Furthermore, foaming properties of these emulsions were compared and discussed with regard to effects of both processing and composition on properties of the emulsions, such as thixotropy and sensitivity to shearing. We observed changes in fat globules when different pasteurization holding times were applied, but no changes in either apparent viscosity values or sensitivity to shearing were traceable. However, enrichment of milk fat with the olein fraction increased the whipping ability of the emulsions, as evaluated in terms of overrun and the homogeneity of air bubbles, whatever the aging time. The lowest monodispersity of air bubbles was observed in the formulation rich in stearin. After 24 h of aging, this formulation showed the same overrun as the emulsion made with anhydrous milk fat. Increasing the aging time decreased the overrun by approximately 30%, and increasing the pasteurization holding times decreased it by approximately 20%. In general, in our conditions, increasing the aging time and unsaturated fatty acid content reduced changes in the dynamic rheological and structural properties observed just after production of the emulsions, whatever the pasteurization holding time or fat composition applied.     

不同部位猪脂的总脂肪酸组成及Sn-2位脂肪酸成分分析

选择11例猪的4个部位(猪尾巴、猪脖、奶腩和猪板),用乙酸甲酯萃取脂肪,采用DIKMA CP-SIL88FS(60 m×0.25 mm id×0.20μm)毛细管柱气相色谱对各部位猪脂总脂肪酸及Sn-2位脂肪酸组成进行了测定,并采用SPSS 13.0软件对数据进行统计分析。结果表明:猪尾巴油、猪脖油和奶腩油的总脂肪酸及Sn-2位脂肪酸组成和分布与猪板油相比均存在显著性差异,且不饱和脂肪酸和单不饱和脂肪酸含量均高于猪板油。     

The effects of industrial pre-frying and domestic cooking methods on the nutritional compositions and fatty acid profiles of two different frozen breaded foods

This study was carried out to determine the effects of manufacturer pre-frying in olive and sunflower oil, as well as domestic cooking methods (deep-frying in olive and sunflower oil and baking) on the proximate compositions and fatty acid profiles of tuna pasties and ham nuggets. The pre-frying processes reduced moisture and carbohydrates and increased ash, fat and protein content in both pre-fried products. During cooking, the frying processes caused a reduction in moisture content and an increase in fat content in relation to pre-fried samples, while baking did not modify the proximate composition. The fatty acid profiles of products during both the pre-frying and frying processes became similar to those of the culinary fat used. Thus, the frying processes reduced the proportion of saturated fatty acids (SFA) and increased the proportion of monounsaturated fatty acids (MUFA) in the foods when olive oil was used, whereas increased the proportion of polyunsaturated fatty acids (PUFA) in products fried in sunflower oil. The fatty acid profiles of fried samples tended to be more similar to the frying fat than to the pre-frying fat, whereas the fatty acid profiles identified during the pre-frying process for baked products were not significantly modified. Thus, samples pre-fried in olive oil and subsequently baked showed the best proportion of fat content and PUFA/SFA, MUFA + PUFA/SFA and n-6/n-3 ratios of the tested products.     

Antifungal activity of biopolymers containing natamycin and rosemary extract against Aspergillus niger and Penicillium roquefortii

Antimicrobial agent‐releasing films have been proposed as an effective way of inhibiting chiefly surface spoilage of food products. Antifungal activities of natamycin (NA), rosemary extract (RE) and NA + RE were tested against Aspergillus niger and Penicillium roquefortii with agar disc diffusion assay. NA, RE and NA + RE were also included into biopolymers made from gluten and methyl cellulose. Minimum inhibitory concentrations (MIC) of NA in both films were 2 and 1 mg NA per 10 g film solution against A. niger and P. roquefortii, respectively. RE did not show any inhibitory antifungal activity alone. Although NA incorporated into both films at a concentration of 1.5 mg NA per 10 g film solution was not effective against A. niger, combination of NA at the same concentration with RE in the films inhibited the growth of this mould. NA in solution or in biopolymers is very effective in inhibiting the growth of selected organisms, and RE acted synergistically with NA to prevent the growth of A. niger when incorporated into both films.