Hydrogenation of low erucic acid rapeseed oil (Zephyr) under selective conditions

Low erucic acid rapeseed oil (Zephyr) was hydrogenated under selective conditions, 200°C, 48 kPa pressure, with 0.2% of five different commercial nickel catalysts and the standard catalyst of the American Oil Chemists' Society. From the change in iodine value, the relative activities of the catalysts were calculated. The trans-isomer levels were determined by infra-red spectroscopy and the specific isomerization index calculated. Catalysts with the lowest activity resulted in the highest level of trans-isomers. From the change in fatty composition, the selectivity ratio was calculated. Physical properties were measured by determination of dropping point and solid fat content. The commercial catalysts differed widely in their action on the hydrogenation of Zephyr oil.     

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     

INFLUENCES OF THE PROPORTION OF SOLID FAT IN A SHORTENING ON LOAF VOLUME AND STALING OF BREAD

Fats and oils are an important component of bread. Fats and oils are added to improve the properties of a loaf of bread, such as increasing loaf volume and increasing the time before staling is initiated. The physical form of the added fat can affect the overall dough behavior. The effect of hydrogenated soybean oil concentration in an emulsion used for the baking of bread was studied. It was observed that increasing concentration of hydrogenated soybean oil (solid fat) while keeping total lipid content constant led to increased loaf volume and decreased loaf weight. Also, increasing solid fat content led to a reduction in the rate of staling.     

Thermal and crystal characteristics of enzymatically interesterified fats of fatty acid-balanced oil and fully hydrogenated soybean oil in supercritical CO2 system

Blends of fatty acid-balanced oil that was prepared by the aqueous enzymatic extraction, and with fully hydrogenated soybean oil in different weight ratios from 30:70 to 80:20 (wt%) were interesterified using Lipozyme RM IM in a supercritical CO₂ system. The optimal immobilized enzyme dosage, pressure, substrate ratio, temperature, and time were 6% (w/w) of initial substrates, 8 MPa, blend ratio with 60:40 (wt%) of fatty acid-balanced oil and fully hydrogenated soybean oil, a temperature of 70°C, and reaction time of 2 h, respectively. It was observed that at the optimal conditions, under supercritical CO₂ conditions, the reaction time of the interesterification was shorter than that of conventional enzymatic interesterification. The slip melting point, solid fat content, fatty acid composition, differential scanning calorimetry, polymorphic form and crystal morphology of the enzymatically interesterified fats were evaluated. The results indicated that the interesterified fats showed desirable physical properties with lower slip melting point and solid fat content, suitable crystal form (β′ polymorph), and without trans-fatty acid for possible use as a shortening and margarine stock.     

Evaluation of shortenings based on various palm oil products

Several formulations based on blends of hydrogenated palm oil (MP 41·5°C) and palm stearin (IV 44) with other liquid oils, on direct blends of palm stearin with other liquid oils, and on 100% inter-esterified palm olein, were used as feedstocks in shortening production. The shortenings were stored at 20°C over a period of one month. Physicochemical characteristics, creaming properties and baking performance of the shortenings were evaluated and compared with the best shortening on the market. Slip melting point of the shortenings ranged from 41·5 to 46·4°C. Palm-cottonseed oil shortenings had higher solid fat contents at all temperatures than palm-soya bean or palm-low erucic acid rapeseed oil shortenings. The shortenings were rich in C₅₀, C₅₂and C₅₄ glycerides. Creaming power after 12 min of beating ranged from 1·55 to 1·77 cm³ g^?1. Palm stearin-cottonseed (3:2) oil shortening showed the best creaming performance. The specific volume of cakes ranged, for the experimental shortening, from 90% to 101% from the control, with low erucic acid-palm blends showing the best performance. In applications for both aerated cream and cakes, inter-esterified palm olein was excellent.     

Effect of Gradual Heating and Fat/Oil Type on Fat Stability,Texture, Color,and Microstructure of Meat Batters

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.     

Influence of temperature and pressure on hydrogenation of low erucic acid rapeseed oil (Zephyr)

Low erucic acid rapeseed oil (Zephyr) was hydrogenated at 200, 170 and 140°C and pressure of 48 and 303 kPa. The hydrogenated oils were characterized by determination of the iodine value, trans-isomer content, fatty acid composition, dropping point and solid fat content. From the change in iodine value and trans-isomer content, the specific isomerization index (SII) was determined. The SII was generally lower at high pressure and low temperature. The hydrogenation reaction rate increased with temperature as well as pressure. Selectivity ratios for the hydrogenation reaction were more influenced by pressure than by temperature, the highest selectivity ratios were observed at the lower pressure.     

Release kinetics and encapsulation efficiency of embedded active ingredients in fat-based matrices using cold extrusion

Cold extrusion offers great potential as a continuous and gentle encapsulation technique. Due to their melting and crystallization properties, lipids are ideal matrix materials as they can be influenced by extrusion process parameters, such as temperature and shear. This offers the possibility to develop various lipid-based matrix materials with specific release properties, ensuring a delayed release during gastrointestinal digestion. The objective of the present work was a methodical physicochemical characterization of cold extruded fat matrices serving as matrix material for the embedding of 10% beetroot powder, which was used as model active agent due to its detectability by photometric measurement. The matrices were composed of a high-melting fully hydrogenated rapeseed oil as the base fat and one of four low-melting fats/oils. By performing a semi-dynamic in vitro digestion test, physicochemical characteristics of fat-based matrices were investigated. The influence of release properties and encapsulation efficiency of encapsulated beetroot powder were identified. The results showed that the matrix composition influences, particle size distribution, melting behavior and microstructural fat distribution. Melting behavior and solid fat content proved to be determinant properties influencing the release behavior – especially, the deviation of solid fat contents in the temperature range from room (20.0 °C) to body temperature (36.5 °C) during in vitro digestion. Generally, a higher content of low-melting fat led to an increased release of beetroot powder during the intestinal phase of up to 48%, whereas only 3.3% on average were released during oral and gastric phase each. Microstructural analysis showed that melting properties are also influenced by the time factor as a temporal delayed release of beetroot powder was determined.     

The influence of oil type and frying temperatures on the texture and oil content of French fries

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     

Influence of SFC, microstructure and polymorphism on texture (hardness) of binary blends of fats involved in the preparation of industrial shortenings

Several binary blends of vegetable oils commonly used in industrial shortenings (i.e., palm oil (PO), hydrogenated palm oil (HPO), soybean oil (SO), hydrogenated soybean oil (HSO), low-erucic acid rapeseed oil (LERO), hydrogenated low-erucic acid rapeseed oil (HLERO)) were studied for their physical properties such as solid fat content (SFC) by nuclear magnetic resonance (NMR) and textural properties (hardness). Microstructure was also observed by microscopy in order to explain the variability in hardness for samples having the same SFC values. The blends studied by microscopy were the following: HSO, HPO and HLERO diluted in LERO. For these three blends which had the same SFC, the level of network structure was different. HSO diluted in LERO had more crystals, closer to each other and overlapped. This can explain that HSO has a higher hardness than HPO or HLERO, for a same SFC value, when diluted in LERO. Polymorphism was also observed by powder X-ray diffraction. The variability in hardness for samples having the same SFC is due to various crystal types and/or network structures that are formed upon crystallization of hard fats. This work demonstrates that for binary blends of studied oils, changes in the hardness are controlled mostly by the SFC, polymorphism and also by the material’s microstructure.     

Evaluation of Heated Frying Oils Containing Added Fatty Acids

Frying oils (corn, lightly and highly hydrogenated soybean and tallow) were heated 24 hr at 200°C and acid value and percentage polar compounds measured. Fatty acids (stearic, oleic and linoleic) were added to the oils at 1 and 5% levels to determine their effect on oil quality. Corn oil formed acidic and polar compounds at faster rates than the other oils. With 5% fatty acids added, acid value decreased because acidic compounds evaporated faster than they were formed. Polar compound formation generally increased with fatty acid addition in corn oil and lightly hydrogenated soybean oil and decreased in highly hydrogenated soybean oil and tallow.     

Effect of heating oils and fats in containers of different materials on their trans fatty acid content

BACKGROUND: The nature of the container material and temperature employed for deep‐frying can have an influence on the development of trans fatty acids (TFAs) in the fat used. The present study was undertaken to determine the effect of heating vegetable oils and partially hydrogenated vegetable fats with different initial TFA content in stainless steel, Hindalium (an aluminium alloy), cast iron and glass containers. Ground nut oil (oil 1), refined, bleached and deodorised (RBD) palmolein (oil 2) and two partially hydrogenated vegetable oils with low (fat 1) and high (fat 2) TFA content were uniformly heated at 175–185 °C over a period of 12 h. RESULTS: An increase in TFA content to 20 g kg^?1 was observed in oil 2 in the cast iron container, while a decrease in TFA content of 20–30 g kg^?1 was observed in fat 2 in all containers. The heating process of fats and oils also led to an increase in Butyro refractometer reading and colour values. CONCLUSION: This study showed that the TFA 18:1t content of oil 1, oil 2 and fat 1 increased with repeated or prolonged heating. The cast iron container showed the highest increase in TFA 18:1t for RBD palmolein (oil 2). The amount of linoleic acid trans isomers formed in the heating process was negligible. Fat 2 with high initial TFA content showed a decrease in TFA 18:1 and 18:2 on heating in all containers. Oils heated in glass and stainless steel containers showed less TFA 18:1t formation. Copyright © 2012 Society of Chemical Industry     

The influence of frying medium degradation on fat uptake and texture of French fries

The purpose of the present investigation was to study the influence of the degree of degradation of different kinds of oils used as a frying medium on fat uptake and texture of frozen pre‐fried French fries. As has been found, the degradation degree of the frying medium depends on the kind of oil and processing time. Liquid hydrogenated rapeseed oil exhibited the best thermo‐oxidative stability among the oils under investigation. The kind of oil influenced fat uptake and the texture of French fries. The lowest fat uptake was observed with French fries fried in solid oil. Some correlations between fat uptake and changes in fatty acid content were found in the frying medium during frying. Fat absorption increased with increasing unsaturated fatty acids and decreasing saturated fatty acid content. The texture of French fries fried in hydrogenated oils was harder than that exhibited by French fries fried in liquid rapeseed oil. The hardness of French fries fried in liquid oils decreased during frying while the hardness of French fries fried in solid oil increased. Some correlations between the texture of French fries and iodine value and fatty acids content of frying media were found. The hardness of French fries increased with increasing content of saturated fatty acids and decreasing unsaturated fatty acids and trans isomer fatty acid content. Copyright © 2005 Society of Chemical Industry     

Production of trans‐free margarine stock by enzymatic interesterification of rice bran oil,palm stearin and coconut oil

BACKGROUND: Trans‐free interesterified fat was produced for possible usage as a spreadable margarine stock. Rice bran oil, palm stearin and coconut oil were used as substrates for lipase‐catalyzed reaction. RESULTS: After interesterification, 137–150 g kg^?1 medium‐chain fatty acid was incorporated into the triacylglycerol (TAG) of the interesterified fats. Solid fat contents at 25 °C were 15.5–34.2%, and slip melting point ranged from 27.5 to 34.3 °C. POP and PPP (β‐tending TAG) in palm stearin decreased after interesterification. X‐ray diffraction analysis demonstrated that the interesterified fats contained mostly β′ polymorphic forms, which is a desirable property for margarines. CONCLUSIONS: The interesterified fats showed desirable physical properties and suitable crystal form (β′ polymorph) for possible use as a spreadable margarine stock. Therefore, our result suggested that the interesterified fat without trans fatty acid could be used as an alternative to partially hydrogenated fat. Copyright © 2010 Society of Chemical Industry     

Application of hydrogenated palm kernel oil and palm stearin in whipping cream

Non-dairy creams made from hydrogenated palm kernel oil (HPKO) are generally more stable than dairy creams. However, in summer the emulsion tends to separate. This paper outlines some steps that were taken to modify the HPKO with the intention of increasing the stability without affecting whipping performance. This was achieved by blending HPKO with palm stearin (POs). Interesterification was employed to eliminate the increase in solid fat content at 37°C and 40°C. Results of the experiment showed that an interesterified HPKO: POs 66:34 blend proved to have satisfactory whipping performance when compared to creams made with HPKO alone.     

Crystallization and rheology of palm oil in the presence of sugar

Palm oil is an alternative to partially hydrogenated vegetables oils for fat-based confections given its semi-solid consistency and zero trans fat content. However, its slow crystallization behaviour results in hardening during storage and an objectionable texture. While there are numerous studies on palm oil solidification and storage properties in bulk, the impact of sugar in this context has yet to be reported. In this study, the crystallization and rheology of two commercial palm oils in both bulk and mixed 1:1 (wt.%) with confectioner's sugar were explored over four weeks of storage. The palm oil with the higher diacylglycerol and saturated triacylglycerol content experienced significantly higher solid fat contents and viscous/elastic moduli with storage time. The presence of sugar reduced the solid fat content of both palm oils, but increased their solid-like character, an effect we ascribed to the role of the dispersed sugar on oil viscosity. Principal component analysis on lipid composition identified the key species contributing to these properties. These findings establish a foundation for the optimization and improvement of palm-based confections.     

Compression Heating of Selected Fatty Food Materials during High-pressure Processing

ABSTRACT: Compression heating of selected fatty and model food materials during high‐pressure processing was studied using a specially designed experimental system. Commercially available soybean oil, olive oil, beef fat, chicken fat, and salmon fish were studied at different pressures (150 to 600 MPa) and at different initial temperatures (25 to 70 °C). At an initial temperature of 25 °C, fats and oils showed higher compression heating values (up to 8.7 °C per 100 MPa) compared to 2 to 3 °C per 100 MPa for water. Though the compression heating of water depends on its initial temperature, oils have little or no effect of initial temperature.     

Frying Oil Deterioration and Vitamin Loss During Foodservice Operation

Oxidation and vitamin E loss in four frying oils (two partially hydrogenated soybean oils, one with methyl silicone, the other with tertiary butyl hydroquinone, citric acid and dimethyl siloxane added; a semi-solid hydrogenated soybean and palm oil shortening with mono and diglycerides added; and 100% corn oil) were studied under experimental and ‘actual’ operational conditions. Vitamin E loss in the frying oil increased significantly with increasing fatty acid oxidation. Added antioxidants, vitamin E and hydrogenation of fat decreased the rate of vitamin E loss. No significant change in vitamin E of the French fries occurred during 4 days of commercial frying; a significant increase in French fry fat uptake improved the 40% reduction in vitamin E of the frying oil. Vitamin C in the French fries (a major source of the vitamin in fast food meals) decreased significantly as the vitamin E content of the oils was reduced.     

Detection of milk fat adulteration with admixture of foreign oils and fats using a fractionation technique and the apparent solidification time test

A fractionation technique followed by the apparent solidification time (AST) test was adopted for detecting the admixture of foreign oils and fats in milk fat. The AST values of the solid fraction obtained at 20°C, and solid and liquid fractions obtained at 18°C for pure cow milk fat, were 2 min 30 s, and 3 min 21 s and 3 min 31 s, while for buffalo milk fat they were 1 min 58 s, and 2 min 47 s and 3 min 10 s respectively. This new approach can detect some mixtures of foreign oils and fats in cow milk fat but not in buffalo milk fat.