马铃薯煎炸过程中食用油稳定性的研究

采用马铃薯作为食材,菜籽油、胡麻油和米糠油3种常用食用油作为煎炸用油,测定不同煎炸温度、不同煎炸时间下3种食用油酸值、碘值、过氧化值,评价不同食用油煎炸过程中的稳定性.结果 表明:经过5h的连续加热,3种食用油的酸值、过氧化值含量都随加热温度和加热时间的增大有逐渐上升的趋势,碘值随着加热温度和加热时间的增大逐渐下降,3...     

磷脂含量对煎炸油烟点、耐寒性、氧化稳定性 和煎炸稳定性的影响

通过添加大豆卵磷脂,使大豆油、菜籽油和棕榈油中磷脂含量分别为本底值、10、20、30、40、50 mg/kg,测定不同磷脂含量的3种煎炸油的烟点、耐寒性、氧化诱导时间,同时检测3种煎炸油在170℃下煎炸不同食材过程中的感官品质、酸价、过氧化值和极性组分含量的变化,以评价其煎炸稳定性。结果表明:随着磷脂含量的增加,大豆油、菜籽油、棕榈油烟点呈下降趋势,其中棕榈油烟点下降受磷脂影响最大;耐寒性随着磷脂含量增加整体呈下降趋势;氧化诱导时间随磷脂含量的增加呈波动变化趋势;在本试验范围内,磷脂含量对煎炸油煎炸稳定性影响的规律尚不明显。     

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     

Physicochemical characterisation and oxidative stability of refined hoki oil,unrefined hoki oil and unrefined tuna oil

Physicochemical characterisation and oxidative stability of refined hoki oil, unrefined hoki oil and unrefined tuna oil were carried out in the present study. Tuna oil contains a higher percentage of polyunsaturated fatty acids (42.57%) than the hoki oils (28.79–30.13%), which have higher percentages of monounsaturated fatty acids (45.02–47.16%). All oils showed a good ratio of n‐3 to n‐6 fatty acid (7.01–8.10). Cholesterol contents in the unrefined hoki (5149.40 μg g^?1) and tuna (2045.48 μg g^?1) oils were higher than the refined hoki oil (1411.27 μg g^?1). Tuna has a higher concentration of natural α‐tocopherol (752.49 μg g^?1) but lower concentration of vitamin A (110.99 μg g^?1) than unrefined hoki oil (151.44 μg g^?1 and 997.60 μg g^?1, respectively). Higher percentages of unsaponifiable matter were found in the hoki oils (4.90–7.24%) compared with the tuna oil (0.56%). The hoki oils appear more yellow than the tuna oil, which is darker by comparison. Moisture, p‐anisidine value and free fatty acid contents in the hoki oils were lower than the tuna oil. Other indicators of oxidative stability showed that the hoki oils were more stable than the tuna oil.     

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.     

大豆油煎炸过程极性组分和非极性组分中脂肪酸组成的研究

通过柱层析法分离煎炸油的极性组分和非极性组分,采用GC-MS分析两种组分中的脂肪酸组成及含量。结果表明:煎炸油极性组分和非极性组分具有相似的脂肪酸组成及相对含量,且两种组分间饱和脂肪酸(SFA)、不饱和脂肪酸(UFA)、单不饱和脂肪酸(MUFA)和多不饱和脂肪酸(PUFA)呈极显著相关(r0.90,p0.01)。极性组分中cis C18∶2含量相对较高;非极性组分中cis C18∶2/C16∶0比值减小程度明显大于极性组分,则非极性组分的cis C18∶2在生成极性基团时反应最为剧烈。煎炸油中极性物质含量随煎炸时间延长而增多,其中极性组分中总脂肪酸含量呈梯度增加趋势,并与煎炸油中总极性物质(TPC)含量呈极显著相关(p0.01);非极性组分中总脂肪酸含量显著减少,表明在煎炸过程中各种甘油三酯均参与反应,导致含有极性基团的脂肪酸含量不断增加,其中cis C18∶2组成与极性组分含量变化密切相关。按极性大小将复杂的煎炸油成分进行分类研究,有利于对大豆油煎炸过程中的复杂组分进行全面分析,为得到脂肪酸组成与极性组分含量变化的关系和提出煎炸油寿命的建议提供更为可靠的数据。     

Enrichment of ω‐3 fatty acids in flax seed oil by alkaline lipase of Aspergillus fumigatus MTCC 9657

Flax seed oil obtained from the seeds of flax plant (Linum usitatissimum, L.) is an unexploited source which contains ω‐3 and ω‐6 fatty acids. Flax seed oil is hydrolysed with a novel alkaline lipase from Aspergillus fumigatus MTCC 9657 for the removal of unwanted fatty acids and enrichment of ω‐3 fatty acids. An appropriate balance of ω‐3 and ω‐6 polyunsaturated fatty acids and enzymatic enrichment of polyunsaturated fatty acids in diet promote nutrition and health. Fatty acid composition shows that flax seed oil contains about 26.80%, 13.5% and 25.45% of ω‐3 and ω‐6 fatty acids in triglyceride (TG), diglyceride (DG) and monoglyceride (MG), respectively. After 8 h of hydrolysis, ω‐3 content was increased to 39% in TG, showing that unwanted saturated fatty acids are removed. ω‐6 content of triglycerides in flax seed oil also showed 54.76% increase after 8 h of hydrolysis. An enzymatic method of hydrolysis by fungal lipase was developed by this study and achieved to concentrate the essential fatty acids linoleic acid (LA) and α‐linoleic acids (ALA).     

Hypolipidemic Activity of Peony Seed Oil Rich in α‐Linolenic,is Mediated Through Inhibition of Lipogenesis and Upregulation of Fatty Acid β‐Oxidation

Peony seed oil (PSO) is a new resource food rich in α‐Linolenic Acid(ALA) (38.66%). The objective of this study was to assess the modulatory effect of PSO on lipid metabolism. Lard oil, safflower oil (SFO), and PSO were fed to wistar rats with 1% cholesterol in the diet for 60 d. Serum and liver lipids showed significant decrease in total cholesterol (TC), triglyceride (TG), and low density lipoprotein‐cholesterol (LDL‐C) levels in PSO fed rats compared to lard oil and SFO fed rats. ALA, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), contents were significantly increased, whereas linoleic acid (LA), arachidonic acid (AA) levels decreased in serum and liver of PSO fed rats. Feeding PSO increased ALA level and decreased n‐6 to n‐3 polyunsaturated fatty acid (PUFA) ratio. The hypolipidemic result of PSO indicated that PSO participated in the regulation of plasma lipid concentration and cholesterol metabolism in liver. The decreased expression of sterol regulatory element‐binding proteins 1C (SREBP‐1c), acetyl‐CoA carboxylase (ACC), and fatty acid synthase (FAS)‐reduced lipid synthesis; Activation of peroxisome proliferator–activator receptor (PPARα) accompanied by increase of uncoupling protein2 (UP2) and acyl‐CoA oxidase (AOX) stimulated lipid metabolism and exerted an antiobesity effect via increasing energy expenditure for prevention of obesity.     

Effect of flavonoids on the oxidative stability of corn oil during deep frying

To study the effect of flavonoids on the stability of frying oil, refined corn oil was analysed periodically for its peroxide value (PV), p‐anisidine value (p‐AV) and iodine value (IV) after its use for deep‐frying of French fries at 180 °C for varying periods of time, namely 30, 60 and 90 min. PV and p‐AV values increased with respect to time while a decrease in IV was observed with increase in time (P < 0.001). Deep‐frying of French fries in corn oil was then carried out in the presence of flavonoids, viz. pelargonidin, cyanidin, quercetin, myrecetin and gallic acid as antioxidants. All antioxidants effectively reduced the oxidation rate in the oil, as detected by decrease in PVs and p‐AVs and relatively low reduction rate in IVs (P < 0.001). The order of antioxidative activity was gallic acid > quercetin > myrecetin > cyanidin > pelargonidin.     

油炸对鸡肉中反式脂肪酸含量及棕榈油品质的影响

以棕榈油作油炸油,油炸表面涂抹蜂蜜水的鸡腿,研究棕榈油连续使用时间对鸡肉中反式脂肪酸含量的影响,并测定棕榈油的酸价和羰基值,探究其品质变化规律。结果表明:以棕榈油作油炸用油,油炸后鸡肉中所含的主要反式脂肪酸为C18∶1 9t;棕榈油使用2~10 h,鸡肉中总反式脂肪酸含量显著增加。棕榈油酸价在油炸过程中一直符合食用油煎炸过程中卫生标准;而羰基值在160℃下使用10 h时达到54.66 meq/kg,超过国标规定的最大限量,180℃下使用8 h即将超标,而200℃时已经超标。因此,以棕榈油进行油炸加工鸡肉时,应选择160℃左右的加工温度,并控制棕榈油使用时间不超过10 h。      

Oxidative Stability of ω3-rich Camelina Oil and Camelina Oil-based Spread Compared with Plant and Fish Oils and Sunflower Spread

ABSTRACT: The oxidative stability of ω3‐rich oil from Camelina sativa and the storage stability of a camelina oil‐based spread were evaluated. Camelina oil was more stable than fish oil and linseed oil, but less stable than sunflower, corn, sesame, and olive oils, indicated by measuring peroxide values (PV), ρ‐anisidine values (AV), total oxidation values (Totox), thiobarbituric acid reactive substances (TBARS), conjugated diene levels (CD), and conjugated triene levels (CT) during storage at 65 °C for 16 d. The camelina oil‐based spread had higher PV, AV, Totox, TBARS, CD, and CT than the sunflower spread but maintained adequate sensory quality for 16 wk of storage at 4 °C or 8 °C.     

Quality changes in mixtures of hydrogenated and non‐hydrogenated oils during frying

BACKGROUND: There is a need for frying oils with reduced trans fatty acid content and increased oxidative stability. This study was conducted to measure and compare frying oil quality parameters, namely colour, viscosity, free fatty acid (FFA) content and dielectric property, and to investigate changes in properties of mixtures of fully hydrogenated and non‐hydrogenated canola oils during deep‐fat frying of chicken nuggets. Proportions of hydrogenated oil to non‐hydrogenated oil used in the study were 0, 20, 40, 60, 80 and 100%. Chicken nuggets were fried at 190 °C. The relationships among quality parameters, frying time and oil type were investigated. RESULTS: Frying time and oil type had significant effects on all properties. First‐order kinetic equations were used to represent changes in colour, viscosity and FFA content. The rates of change of viscosity and FFA content were higher in non‐hydrogenated oil, whereas the rates of change of colour were similar in the different oils. Increasing the level of hydrogenated oil in the mixture resulted in only slight changes in quality parameters. CONCLUSION: Quality parameters, namely colour, viscosity, FFA content and dielectric property, of frying oil are significantly affected by frying time and hydrogenation level. Frying oil quality and stability can be adjusted by mixing hydrogenated and non‐hydrogenated oils. Copyright © 2008 Society of Chemical Industry     

DHA油脂在精炼过程中氧化稳定性的变化

分析了DHA毛油依次经历脱胶、碱炼、脱色、脱臭等环节后,油脂的微组成及氧化稳定性变化。结果显示,在整个精炼过程中各微组分的含量整体呈下降趋势。DHA油脂对光稳定性:精油>脱色油>毛油/脱胶>碱炼油;DHA油脂对热稳定性(Rancimat法):脱色油>精油>脱胶油>毛油>碱炼油。DHA油脂在脱色环节之前,氧化稳定性差归因于其中促进氧化的微组分过多。在脱色环节之后油脂对热稳定性变差,归因于内源性的抗氧化组分在脱臭环节中大量损失。      

Salt effects on Origanum majorana fatty acid and essential oil composition

BACKGROUND: The effects of salt on the essential oil yield and fatty acid composition of aerial parts of two marjoram varieties were investigated. Plants with 6 leaves were treated with NaCl (75mM). RESULTS: Salt treatment led to a reduction in aerial part growth. Salinity increased the fatty acid content more significantly in Tunisian variety (TV) than in Canadian variety (CV). CV showed an increase in double‐bond index (DBI) and a decrease in malondialdehyde content under salt stress, while the opposite was observed in TV. The DBI was mainly affected by a strong reduction in oleic and linoleic acids in TV, whereas a strong stimulation of linoleic acid in CV was observed. Salt decreased and increased the essential oil yield in TV and CV respectively. The main constituents of the essential oil of TV were trans‐hydrate sabinene and terpinen‐4‐ol, which showed a significant decrease under salt stress. In contrast, the main constituents of the essential oil of CV were sabinene and trans‐hydrate sabinene, which showed a significant decrease and increase respectively under salt stress. CONCLUSION: Marjoram oil is a rich source of many compounds such as essential oils and fatty acids, but the distribution of these compounds differed significantly between the two varieties studied. Copyright © 2011 Society of Chemical Industry     

Effect of a novel induction food‐processing device in improving frying oil quality

Producing quality fried snacks involves monitoring the chemical processes that occur during frying to control oil degradation. Our objective was to evaluate the effects of a Novel Induction Food‐Processing Device (NIFPD) on the quality indices of frying oil. Under standard frying conditions, vegetable oil samples (corn and canola) were collected during a standardised frying cycle to test oxidative stability. Fourier transform infrared spectroscopy was used to evaluate and classify samples during the frying time, and standard reference methods used to monitor the oil stability included p‐anisidine value, free fatty acid content and CIELAB colour. The induction technology decreased the rate of free fatty acid and aldehyde formation. Tests also showed a marked effect on total colour difference between control and treatment (NIFPD), reducing colour degradation. Overall, our results showed that a patented induction device slows the rate of lipid degradation, resulting 7–20% reduction in formation rate of key quality parameters and significantly longer utilisation of frying oil.     

Oxidative stability,shelf-life and stir-frying application of Torreya grandis seed oil

Torreya grandis seed oil, with a feature of Δ5-sciadonic acid (SA, 20:3 Δ5, 11, 14 ω-6), is an attractive woody oil as its potential health benefits in lowering blood and hepatic lipids and anti-inflammatory properties. In the present study, its oxidative stabilities at both room temperature and heating conditions were investigated by analysing oxidation stability index (OSI), shelf-life, changes of fatty acids, acid value and peroxide value during stir-frying tests. Also, its effects on the sensory qualities of stir-fried shredded potatoes were evaluated. The OSI of T. grandis seed oil was 2.97 h at 120 °C, which was 11.24% higher than that of the control soybean oil, contributing to a longer predicted shelf-life of 135–195 d for T. grandis seed oil than 127–180 d for soybean oil. T. grandis seed oil also exhibited superior thermal stability compared to soybean oil. The feature fatty acid, SA, only lost 2.48–5.73% (decreasing from 14.14 to 13.33–13.79%) under the optimised stir-frying conditions at 140–180 °C for 3–5 min. For the stir-frying shredded potatoes, T. grandis seed oil made it more pleasing in colour, odour and palatability. Due to its desirable oxidative stability at room temperature and stir-frying performance at high temperature, T. grandis seed oil is suitable for use as a domestic cooking oil.