Search

This work focuses on the evaluation of commercially available rapid methods for determining frying oil quality. Five rapid methods differing in principle were selected: FOM320 (Ebro), PCT120 (3M), LRSM (3M), Fritest (Merck) and Viscofrit (Viscofrit). The performance of the methods was examined by use of 184 oil samples produced by controlled frying experiments. Twelve series of frying experiments (45 batches each) were performed in which the oil type (palm, sunflower and olive) and the food type (potatoes, zucchini and minced beef meat) varied. Control thermal oxidation experiments with the same oil types were also performed. Results of the rapid methods were compared to results of analytical methods determining legislation criteria. Namely, the total polar compounds and total polymer compounds were determined using High Pressure Size Exclusion Chromatography with and without prior separation of the polar fraction. Furthermore, determination of the free fatty acid concentration, acidity, viscosity and level of oxidation of the oils using UV spectroscopy were carried out. Principal component analysis and linear regression analysis were used in order to assess the obtained results. Comparison of the results of the rapid methods with the analytical ones showed differences in most examined cases. For many of the examined rapid methods the agreement of the results versus those of analytical methods depended on the food-oil combination used in the frying experiments.

Summary Lipophilic bioactive compounds such as lipids, vitamins and phytochemicals serve important antioxidant, functional, nutritional and structural roles in the human body. Colloidal systems such as emulsions are particularly suitable matrices for the protection and delivery of these compounds. This article summarises the principal lipophilic bioactives important for human health and challenges associated with their delivery. It discusses the compositional and physical characteristics of emulsions in relation to bioactive delivery, and chemical stability aspects to consider when engineering efficient emulsion delivery systems. The literature shows that aspects such as oil type, droplet size, interfacial composition and solubilisation capacity impact bioactive availability and that their effects are bioactive specific. Therefore, emulsions must be tailored to the bioactives delivered. Much of the present knowledge is based on in vitro studies, and more data from animal and human models are required to better understand the relationship between emulsion characteristics and bioavailability of lipophilic bioactives.

The effects of endpoint cooking temperature (40, 50, 60, 70, 80, and 90 °C) on emulsion stability, texture, color, and microstructure of meat batters prepared with different fats/oils were studied. Canola oil treatments showed the highest cooking loss whereas hydrogenated palm oil provided the most stable meat batters. Rendered beef fat was less stable than regular beef fat. Increasing endpoint cooking temperatures resulted in a progressive reduction of water holding capacity in all treatments. As temperature was raised, meat batters showed higher hardness and cohesiveness values, but no appreciable changes in cohesiveness above 60 °C. Canola and hydrogenated palm oil treatments showed the highest hardness and chewiness values. Lightness (L(*) ) values of all meat batters increased significantly with increasing temperature from 40 to 60 or 70 °C; no major changes observed above 70 °C. Light microscopy revealed no substantial changes in the microstructure of all the stable meat batters cooked to between 50 and 70 °C. Heating to 90 °C changed the microstructure in all meat batters except the hydrogenated palm oil treatments, which still showed nonround fat particles and a less aggregated protein matrix.

There is considerable interest in the production of emulsions and nanoemulsions using low-energy methods due to the fact they are simple to implement and no expensive equipment is required. In this review, the principles of isothermal (spontaneous emulsification and emulsion phase inversion) and thermal (phase inversion temperature) low-energy methods for nanoemulsion production are presented. The major factors influencing nanoemulsion formation using low-energy methods and food-grade components are reviewed: preparation conditions, oil type, surfactant type, surfactant-to-oil ratio, and cosolvent or cosurfactant addition. The advantages and disadvantages of different low-energy and high-energy methods for fabricating nanoemulsions are highlighted, and potential applications for these techniques are discussed.

Samples of edible oils of different degrees of unsaturation were studied by Raman spectroscopy. We demonstrate the potential of this technique for discriminating these oils. In addition, the Raman spectra for the macadamia, pecan, and Brazil nut oils are for the first time reported here. The fatty acid profile of each type of oil was established by GC. The analytical results obtained from the spectra were highly correlated with those provided by GC as regards the contents in monounsaturated and PUFA of each oil type. Spectra were examined separately in the wavenumber zones 2800–3100 and 800–1800 cm−1, which were those exhibiting the greater differences between oils. Also, as shown in this work, Raman spectroscopy is an effective tool for assessing oxidation in various grades of olive oils. Based on the results, extra virgin olive oil efficiently resists oxidation in the short term by virtue of its increased antioxidant contents. Practical applications: In this paper we show the usefulness of Raman spectroscopy to distinguish between edible oils. Similarly, the technique also allows us to discriminate between different heat-treated olive oils. At the industrial level Raman spectroscopy can be a useful tool to detect adulteration related to the oxidation of fat. Its ease of use and the absence of sample handling make it very effective for use in production systems on-line. Raman spectroscopy allows to distinguish oils with different unsaturation level and also allows us to discriminate between different heat-treated oils.

We evaluated the effects of oil type, oil to water ratio, emulsifier concentration, acidity, and temperature on the distribution of caffeic acid, CA, in emulsions composed of stripped olive and corn oils, acidic water, and Tween 20. CA mainly distributes between the water and interfacial regions because it is sparingly soluble in oils, as demonstrated by auxiliary partitioning experiments in the absence of an emulsifier. The distributions of CA were determined in the intact emulsions from values of the partition constant between the water-interfacial region, P W I , determined under different experimental conditions. At any given pH, CA is mostly located in the interfacial region of the emulsion, %CAI > 50 % at the lowest emulsifier volume fraction, ΦI = 0.005, and its percentage increasing upon increasing ΦI with %CAI > 90 % at ΦI = 0.04. At any given ΦI, %CAI decreases substantially with increasing pH because of the ionization of the CA. Our results indicate that the main parameters affecting the distribution of CA are ΦI and the acidity, while the nature of the oil, the oil to water ratio and temperature have only minor effects. Results should aid the understanding of how environmental conditions affect the distribution of phenolic acids in emulsions.

Microemulsion electrokinetic chromatography (MEEKC) is a CE separation technique, which utilizes buffered microemulsions as the separation media. In the past two decades, MEEKC has blossomed into a powerful separation technique for the analysis of a wide range of compounds. Pseudostationary phase composition is so critical to successful resolution in EKC, and several variables could be optimized including surfactant/co-surfactant/oil type and concentration, buffer content, and pH value. Additionally, MEEKC coupled with online sample preconcentration approaches could significantly improve the detection sensitivity. This review comprehensively describes the development of MEEKC from the period 1991 to 2012. Areas covered include basic theory, microemulsion composition, improving resolution and enhancing sensitivity methods, detection techniques, and applications of MEEKC.

Summary This work focuses on the effect of frying variables (repeated frying, potato-to-oil ratio, potato distribution in the fryer, oil type and potato variety) on French fry properties (water content, oil content, crust thickness and shrinkage). Furthermore, the rate of change in French fry properties during a frying batch is investigated. The temperature was acquired in several positions within the oil and the potato. It was found that when repeated frying was conducted up to regulation limits for frying oil use, the examined French fry properties were not significantly affected. On the contrary, the potato-to-oil ratio, potato distribution and potato variety significantly affected the water content of French fries. The most significant changes occurred during the first 1–2 min of a frying batch. According to the temperature measurements, the crust-core front continued to advance after this first frying period. However, there was no observable crust thickness increase; this was attributed to crust shrinkage.

The present work aims at tracing the essential-oil diversity of wild growing Origanum majorana plants in Cyprus. The study of six populations scattered over the western part of the island has shown that the essential oils were rich either in trans-sabinene hydrate/terpinen-4-ol or in α-terpineol/trans-sabinene hydrate. The former oil type is more common and responsible for the typical marjoram odor of the plants. The comparison of our results with published data concerning wild and cultivated O. majorana showed that the oil composition of the Cypriot populations had not been reported from wild plants from other parts of the Mediterranean region, while it is very common among the cultivated plants. Thus, it seems probable that the nowadays cultivated marjoram may originate from Cypriot wild populations.

Partly in connection with an intended revision of the ring analysis ), partly on account of difficulties encountered in practice to obtain reproducible results with the cryoscopic molecular weight determination with naphthalene as solvent, the sources of error inherent to the latter method were subjected to systematic study. As a result of this investigation a method was developed guaranteeing better reproducibility of results. The large number of precautions which are necessary for obtaining good check values with this modified method, induced us, however, to look out for other methods to determine the molecular weight of oils, the results of which can be reproduced better and in a shorter time, with less trouble. An ebullioscopic method, the apparatus and details of which are described in the second part of this publication, proved to answer the purpose quite satisfactorily. This last-named method was tested by measuring the molecular weight of some pure hydrocarbons of different type, while also some experimental material was collected for oils of different chemical composition and molecular weight. Finally, the results of both methods, obtained with seven oil fractions, were compared.

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

The purpose of the present study was to determine the effects of the frying medium and temperatures on fat content and texture of French fries. The material taken for the study consisted of seven types of vegetable oil: refined sunflower, rape, soy, olive oil, palm, partially hydrogenated rape oil (modified oil I) and a blend of vegetable oils (modified oil II). The French fries prepared from Asterix potato variety were fried at oils heated to 150, 160, 170, 180 and 190 °C. The length of frying (12, 10, 8, 6.5 and 4.5 min, respectively) depended on oil temperature. Fat content and the texture of French fries were determined. The type of frying medium significantly affects the texture of French fries. Temperature influenced both the fat content and texture of product. The increase of frying temperature decreased fat uptake and hardness of French fries. French fries fried in rape oil exhibited the most delicate texture and the lowest oil absorption when compared with French fries fried in other types of oil under investigation. Copyright © 2005 Society of Chemical Industry

Fifty-one oils from ten fields in the Western Niger Delta were analyzed for their C7 hydrocarbon contents. Hierarchical Cluster Analysis and Principal Component Analysis were used to discriminate the oils into four sets which were distinct in all the seven variables used in the cluster analysis. Methylcyclohexane and toluene were the most important discriminating variables. In spite of this separation into four sets, all the oils were found to exhibit a high six-ring preference (6RP). The distribution of C7 hydrocarbons in the oils indicated that two of the eleven fields are homogenous in terms of oil type, whereas the rest are not.

The influence of deep-frying using different oils and temperatures on carotenoid content and physico-chemical and sensory characteristics of carrot chips was investigated. Sliced carrots were steam-blanched, cooled, soaked in 0.2% sodium metabisulfite, and deep-fried in canola, palm, or partially hydrogenated soybean oil (PHSO) at 165, 175, or 185 degrees C. Frying temperature, but not oil, significantly (P < 0.05) affected the alpha-carotene, beta-carotene, and total carotenoid contents. Oil type significantly (P < 0.05) influenced all color values. Increasing temperature lowered the redness value, which correlated with decreased carotenoid content, color darkening, and decreased hardness value. Trained panelists detected no differences among oil types in crispness, sweetness, odor, and acceptability. The best carrot-chip product was that fried in PHSO at 165 degrees C.

The purpose of this study was to compare three oils for extraction of cholesterol when used to cook ground beef and to determine the effect of oil type on fatty acid composition of the ground beef. Ground beef (30 % fat) was cooked in 1 L of corn, canola or palm oil at 100–110C and then rinsed with 500 ml of boiling water, which significantly decreased ether-extractable fat. Control hamburger was skillet-fried without any added oil. Total lipids were extracted and analyzed for fatty acid composition and cholesterol content. Changes in fatty acid composition of residual fat on the meat after cooking reflected those of the oils used for cooking. Cholesterol was significantly lower in all oil-cooked hamburger than in the control. In conclusion, cooking ground beef in any of the three vegetable oils will extract cholesterol, and the lipid remaining after a boiling water rinse will contain fatty acids characteristic of the cooking oil.

The titration of cholesterol is a difficult matter due to the large number of stages involved in the standardized method: extraction of the fat, then the unsaponifiable fraction, and sterol separation using TLC and gas chromatography analysis. The diversity of the products to be analyzed (milks, creams, butter and margarines, powders, etc.) also complicates fat extraction. Titration is however necessary due to the considerable role attributed to cholesterol. The rapid method developed is based on placing the sample in solution or direct suspension in DMF, without prior fat extraction. The protocol then includes extraction of the unsaponifiable fraction, sterol silylation using a micromethod and gas chromatography analysis. The method was successfully applied to cholesterol titration in dairy products and in the routine analysis of oil/water as well as water/oil type emulsions, irrespectively of product consistency. Eine Schnellmethode zur Cholesterin-Titration in komplexen Medien Die Cholesterin-Titration ist schwierig aufgrund der grosen Anzahl von Stufen, die die Standardmethode umfast: Fettextraktion, Extraktion der unverseifbaren Fraktion, Sterin-Trennung unter Anwendung von TLC und Gaschromatographie. Die Verschiedenheit der zu analysierenden Produkte (Milch, Creme, Butter und Margarine, Mehle usw.) erschwert auserdem die Fettextraktion. Die Titration ist aufgrund der beachtenswerten Rolle, die dem Cholesterin zugeschrieben wird, notwendig. Die entwickelte Schnellmethode basiert auf der Einbringung der Probe in Losung oder direkte Suspension in DMF, ohne vorherige Fettextraktion. Die Vorgehensweise umfast dann die Extraktion der unverseifbaren Fraktion, die Sterinsilylierung unter Verwendung einer Mikromethode und die gaschromatographische Analysen. Die Methode wurde bei der Titration von Milchprodukten und bei Routineanalysen von Ol/Wasser- sowie von Wasser/Ol-Emulsionen, unabhangig von der Produktkonsistenz, erfolgreich angewandt.

Lipids used in food products have been conventionally divided into two classes based on their consistency at about 25°C (72°F): (1) liquid oils and (2) solid and semisolid fats. Edible oils can be further divided by their general usage in food, as cooking oil or as salad oil. These types of oils can be characterized by a wide variety of measures that assess attributes such as quality, stability, and nutritional value. Cooking oils are in considerable demand for use in applications such as deep-fat frying of many food products or in other uses where exposure to higher temperature is desired. However, salad oils are not generally used in applications where the oil is exposed to heat; rather this oil type finds application in foods that are shelf stable or refrigerated. One large food use of salad oils is for dressings. Oil-based dressings are divided into two broad categories by their texture: spoonable dressings (salad dressings, mayonnaise) and pourable dressings. Keywords: oil; dressings; salad

本研究ではポリグリセリン脂肪酸エステルを用いて手が濡れた状態でも利用できるクレンジングオイルの開発を行った。自己乳化性に優れるポリグリセリン脂肪酸エステルは, 脂肪酸とポリグリセリンの反応モル比を調整することにより合成することができた。クレンジングの機構を確認するため, 溶存状態の変化という観点から相平衡図を作成した。水/界面活性剤/油系の相図において, 活性剤-油軸付近に少量の水を可溶化したW/O型マイクロエマルションを形成する。相図中で水頂点に向かって洗浄が進むと考えると, 水の可溶化量の少なさが濡れた状態で使えない原因であると予想された。補助界面活性剤としてポリグリセリン中鎖脂肪酸エステルを添加したところ, 無添加系で最大10wt%程度であった水の可溶化量が, 80wt%と急激に増大することがわかった。その結果, これらポリグリセリン脂肪酸エステルを用いて調製したクレンジングオイルは, 濡れた状態でも機能を損なうことなく利用できることが明らかとなった。

Oil-type hybrid sunflowerseed held at 63%, 83% and 93% relative humidities (RH) at 20 C attained equilibrium moisture contents (mc) of 6.7 ± 0.1%, 9.8 ± 0.1% and 13.4 ± 0.3%, respectively, and were stored under these conditions for up to 60 weeks (wk). Germinability was inversely related to both storage duration and RH. Initially, the seed contained only field fungi (mainlyAlternaria spp. andPhoma macdonaldii) and 0.5% free fatty acids (FFA). At 6.7% mc, the amount ofAlternaria spp. andP. macdonaldii isolated declined slowly with time, storage fungi did not invade the seed, and FFA in extracted oil did not change significantly during 60 wk storage. No significant correlation was found between FFA, germination, mold count (cfu/g) or fungi recovered. At 9.8% mc, field fungi declined more rapidly than at 6.7% mc, storage fungi (mainlyEurotium rubrum andE. repens) were isolated from the seed after 4 wk, and FFA increased to 2.5% after 40 wk. FFA content was negatively correlated with germination (r=−0.91) and withAlternaria alternata (r=−0.90) but was positively correlated withE. rubrum (r=0.78). At 13.4% mc, field fungi vanished and storage fungi invaded the seed more rapidly than at 9.8% mc, and FFA increased to 6.3% after 24 wk storage. FFA content was positively correlated with storage fungi such asAspergillus versicolor (r=0.74) and negatively correlated with germination (r=−0.88) andA. alternata (r=−0.82). After 14 wk storage the fungus recovered most frequently wasA. versicolor, followed byEurotium rubrum, E. repens, A. alternata, E. amstelodami, Penicillium spp. andMalbranchea sulphurea.

The gravity-viscous spreading of crude oil on artificially prepared ice surfaces was investigated. Five different types of crudes were studied with three surface roughnesses at -14°C. Crude oil No. 1 was also studied at -8 and -3°C. All spreading experiments were made with an oil volume of 45 and 20 ml. Regardless of temperature, surface roughness, oil type and oil volume, all data may be correlated by: where ρ, V and μ are the density, volume and viscosity of the oil, respectively, R is the radius of the oil slick, t is time, C is a constant and g is the acceleration of gravity. On a etudie, sur des surfaces de glace preparees artificiellement, le deploiement d'huiles brutes par rapport a la viscosite et a la gravite. On a employe cinq types differents d'huiles brutes a -14°C, en presence de trois rugosites distinctes de surface. On a aussi etudie l'huile brute no. 1 a -8°C et -3°C. On a fait toutes les experiences de deploiement avec des volumes d'huile de 45 et 20 millilitres. Quels que soient le type et le volume d'huile, la temperature et la rugosite des surfaces, on peut etablir la correlation suivante entre les donnees:ou ρ, V et μ sont respectivement la densite, le volume et la viscosite de l'huile, R est le rayon de la flaque d'huile, t est le temps, c'est une constante et g est l'acceleration de la gravite.

An account is given of the effect on the development of tomato plants of a chemical soil sterilizer containing orthodichlorbenzene and an emulsifying agent of the sulphonated oil type. The symptoms are described and an account is given of an experimental study of the effect of the treatment on growth and yield: the latter showed a considerable decrease. The injurious ingredient was shown to be orthodichlorbenzene.