Oil‐Fat Mixtures with Low Solid Fat Concentration: Influence of Fat Concentration and Cooling Conditions

Uniform suspension of particulates (salt or spices) in oil‐based marinades requires a gel behavior of the matrix. This can be achieved by adding a solid fat to the liquid oil. Besides rheology, appearance and thermal stability are important for the utilization as marinades. The influence of solid fat concentration (c_fat = 2.5–5.5 wt%) and average cooling speed (1.4, 2.6, and 4.7 °C/min) on the functional properties of oil‐fat gels from palm fat and canola oil was investigated. Oil‐fat mixtures showed complex physiochemical behavior depending on the solid fat concentration and cooling rate. All samples had a shear‐thinning behavior. Yield stresses and apparent viscosities increased at a constant cooling rate with increasing solid fat concentration. Frequency dependence of storage and loss modulus showed a transition from a viscous solution to a weak gel at c_fat > 3.5 wt%. Samples at increasing cooling rates transitioned to weak gels at lower fat concentration (2.5 wt%). Mixtures became turbid and increasingly whiter as both solid fat concentration and cooling rates increased, which was explained by increased light‐scattering by fat crystal aggregates. Results show the critical importance of proper formulation and preparation conditions on the functionality of oil‐based marinades.     

Effect of Milk Fat Concentration on Fat Crystallization of Palm Oil-Based Shortenings

The effect of different dosages of anhydrous milk fat (AMF) (25%, 50% and 75%, w/w) on shear-crystallization of fat blends made of refined palm oil, refined palm stearin, and rapeseed oil was studied. Classical techniques as differential scanning calorimetry (DSC), pulsed field gradient nuclear magnetic resonance (pfg-NMR), rheometer, and X-ray diffraction (XRD) were applied to evaluate the crystallization kinetics of fat blends as well as the fat compatibility between components in rapid cooling (15 °C min⁻¹), isothermal crystallization (at 15 °C), and storage (5 °C). Obtained results revealed that the mixtures of palm oils and milk fat had a low compatibility. The co-crystallization between triacylglycerols (TAG) of milk fat and of palm oil occurred during isothermal crystallization and storage resulting in slower crystallization kinetics and the formation of some eutectic mixtures.     

Detection of Fat Concentration in Milk Using Ternary Photonic Crystal

Silicon - Rapid and sensitive detection of fat concentration in milk is a necessary part for citizens in each country. Bio-photonic sensing techniques are an accurate best way to detect biosensing...     

Influence of Dietary Fat and Vitamin E on the Lipids in Pork Meat

48 pigs (gilts and barrows) were divided into four groups and fed for three months on diets containing either 3% soya oil or 3% beef tallow, together with α-dl-tocopheryl acetate at either a basal (20 mg/kg feed) or a supplemented (200 mg/kg feed) level. The fatty acid compositions of the longissimus dorsi muscle (m.l.d.) and adipose (backfat) tissue were found to vary with dietary fats and sex. Gilts showed higher contents of polyene fatty acids (PFA) than barrows. The PFAs C20:4ω6, C22:4ω6, C22:5ω3 and C22:6ω3 were not affected by the diet. Levels of α-tocopherol in muscle and adipose tissue were 2.5 to 4.0 times higher in pigs on the supplemented diet compared to pigs on the basal diet. After storage at – 18°C for nine months the muscle tissues were subjected to iron-induced lipid peroxidation. Supplementation of the feed with α-tocopheryl acetate improved the oxidative stability of the muscle. The influences of dietary fat and sex on lipid peroxidation were reduced by supplemental α-tocopheryl acetate. Muscle tissue from the basal-diet/soya-oil group was more susceptible to lipid oxidation than muscle tissue from the basal-diet/beef-tallow group.     

发酵过程酵母浓度的软测量

针时发酵过程酵母浓度的测量,提出一种基于支持向量机的软测量建模方法。仿真证明,该方法比典型的RBF神经网络软测量有着明显的优势,时于实现发酵过程自动控制和优化运行有着重大的意义。     

Effect of Water Concentration on the Properties of Commercial Soda-Lime-Silica Glasses

The effect of water concentration on the properties of three commercial soda-lime-silica glasses has been measured. Water (H₂O) concentration varied from 50 to 550 ppm-wt. Properties measured include glass transformation temperature, transformation range viscosity, thermal expansion coefficient, electrical conductivity, and refractive index. The viscosity, T _g, and electrical conductivity decreased with increasing water content, while the thermal expansion coefficient and refractive index were unaffected by changes in water concentration.     

Production of Human Milk Fat Substitutes Catalyzed by a Heterologous Rhizopus oryzae Lipase and Commercial Lipases

This study aims to produce human milk fat substitutes by an acidolysis reaction between lard and the free fatty acids (FFA) from a fish oil concentrate rich in docosahexaenoic acid, in solvent-free media. The immobilized commercial lipases from (1) Rhizomucor miehei (Lipozyme RM IM), (2) Thermomyces lanuginosa (Lipozyme TL IM) and (3) Candida antarctica (Novozym 435) were tested as biocatalyst. Also, the heterologous Rhizopus oryzae lipase (rROL), immobilized in Accurel^® MP 1000, was tested as a feasible alternative to the commercial lipases. After 24 h of reaction at 50 °C, similar incorporations of polyunsaturated fatty acids (c.a. 17 mol%) were attained with Novozym 435, Lipozyme RM IM and rROL. The lowest incorporation was achieved with Lipozyme TL IM (7.2 mol%). Modeling acidolysis catalyzed by rROL and optimization of reaction conditions were performed by response surface methodology, as a function of the molar ratio FFA/lard and the temperature. The highest acidolysis activity was achieved at 40 °C at a molar ratio of 3:1, decreasing with both temperature and molar ratio. Operational stability studies for rROL in seven consecutive 24-h batches were carried out. After the fourth batch, the biocatalyst retained about 55 % of the original activity (half-life of 112 h).     

Gas Phase Ozone Concentration Comparisons From a Commercial UV Meter and KI Wet-Chemistry Tests

Formal ozone system power-production tests conducted at ten (10) different ozone installations have resulted in over 100 comparative UV meter versus KI wet-chemistry ozone concentration tests for fifteen (15) individual UV meters. The wet-chemistry tests were conducted by different individuals, including the ozone generator manufacturer's technician and owner's staff. In all cases, the tests were either conducted or witnessed by one of the authors. This paper presents results focused on: 1) precision of UV meter readings, 2) accuracy of the wet-test meter or the UV meter, and 3) expected range in percent difference between UV meter readings and KI wet-chemistry test ozone concentration results for the particular type of UV meter and wet-test meter used in the tests.     

Factors Impacting the Formation of 3-MCPD Esters and Glycidyl Esters During Deep Fat Frying of Chicken Breast Meat

The effect of the frying temperature, frying duration and the addition of NaCl on the formation of 3‐monochloropropane‐1,2‐diol (3‐MCPD) esters and glycidyl esters (GE) in palm olein after deep frying was examined in this study. The eight frying systems were deep‐fat frying (at 160 and 180 °C) of chicken breast meat (CBM) (with 0, 1, 3 and 5% sodium chloride, NaCl) for 100 min/day for five consecutive days. All oil samples collected after each day were analyzed for 3‐MCPD ester, GE, and free fatty acid (FFA) contents, specific extinctions at 232 and 268 nm (K₂₃₂ and K₂₆₈), p‐anisidine value (pA), and fatty acid composition. There was a significant (p < 0.05) decrease in the 3‐MCPD esters and a significant (p < 0.05) decrease in the GE with the increasing of the frying duration. There were significant (p < 0.05) increases in the 3‐MCPD esters formed when the concentration of NaCl increased from 0 to 5%. The addition of NaCl to the CBM during deep frying had no significant effect on the GE generation. The FFA contents, K₂₃₂ and K₂₆₈ and pA showed that all the frying oils were within the safety limit.     

Synthesis of Wax Esters from Crude Fish Fat by Lipase of Burkholderia sp. EQ3 and Commercial Lipases

The lipase from Burkholderia sp. EQ3 was used to synthesize wax esters in comparison with commercial lipases. The supernatant of Burkholderia sp. EQ3 was collected from a liquid basal medium with 1 % fish oil after 12 h cultivation (1.90 U/ml of lipase activity). The crude lipase was prepared by acetone precipitation of the culture supernatant (4.70 U/mg and 9.40 purification folds). The crude fish fat obtained by hexane extraction of waste fat from the wastewater pond of a canned tuna factory and cetyl alcohol were used for wax esters synthesis. Five commercial lipases were screened in comparison with crude lipase from Burkholderia sp. EQ3 in wax esters synthesis. The optimum conditions for wax esters synthesis from crude fish fat using Novozyme 435 were enzyme 1 U, substrate molar ratio of crude fish fat to cetyl alcohol 1:2 (115.30 mg of crude fish fat and 66.67 mg of cetyl alcohol) in hexane at 37 °C and 200 rpm with 90.81 % (TLC–FID peak area) after one h of reaction. The optimum conditions for the synthesis by crude lipase from Burkholderia sp. EQ3 were crude lipase 40 U, substrate molar ratio of crude fish fat and cetyl alcohol 1:2 in isooctane at 30 °C and 200 rpm with 95.07 % (TLC–FID peak area) after 6 h of reaction. The synthesized wax esters were mainly composed of cetyl palmitate and cetyl oleate.     

Fat splitting

Fat splitting, particularly the continuous, high pressure, countercurrent hydrolysis of fats and oils, typified by the Colgate-Emery or modified processes, represents the technological cornerstone for today’s American fatty acid industry. Internationally, other methods such as Twitchell or batch autoclave “medium-pressure” catalyzed or uncatalyzed splitting are still important. All industrial fat splitting methods have as their objectives the attainment of a high rate of hydrolysis together with a high degree of completeness. This objective is achieved, more or less, by the proper optimum balance of: (a) use of excess water; (b) selection of appropriate combination of temperature and pressure to optimize the solubility of liquid water in the fat phases with or without use of suitable “water-in-oil” emulsifiers; (c) use or nonuse of acidic catalyst (rarely basic catalysts); and (d) removal of byproduct glycerol. Significant conditions and details in fat splitting by the important commercial processes are described.     

Fat levels in layer feeds

Supplemental fat, at levels up to 4–6% of the diet, has been shown to produce an “extra-caloric effect” beyond explanation, on the basis of metabolizable energy (ME) contribution to the diet. In addition, during periods of high-temperature stress (above 27 C mean daily temperature), consumption of ME above maintenance requirements decreases to an extent incompatible with economic production of eggs. The feeding of supplemental fat under these conditions to hens less than 50 weeks of age resulted in increased ME intakes and significant increases in egg production, egg weight, or both. This improved performance has been found to be associated with both the reduced heat increment of most diets when fat is added, and the effect on ME consumption. Fatty acid composition was not found to be related to improved performance.     

Changes in the Fatty Acid Content of Used Frying Fat Compared with Fresh Fat

In 21 samples of used frying fat and the corresponding samples of fresh fat the fatty acid content was determined by capillary GLC on a CP Sil 88 column. The content of both saturated and unsaturated fatty acids as well as the content of total fatty acids are decreased by frying. Both the decrease in linoleic acid and the decrease in total fatty acids correlate well with % polar compounds as fat quality evaluation criteria. No isomers of cis,cis-linoleic acid are formed during the frying process. The content of C18: 1 is increased during the frying process from about 0 to 8g/100g in average to 2.3g/100g, which means that also the frying process must be considered as a source to the human intake of trans fatty acids.     

Fat transport mechanism

Summary The body uses several different mechanisms for the transport of fat in the aqueous medium of the blood. Fat is absorbed from the intestine in the form of chylomicrons, which are discrete particles, visible under the microscope. They consist primarily of triglycerides of the longer fatty acids. The chylomicrons are absorbedvia the lymphatic system, which ultimately empties into the blood stream. They are rapidly removed from the blood by several tissues, which either oxidize the fatty acids, store them, or return them to the circulation incorporated in liproproteins or bound to serum albumin. This latter mechanism of transporting fatty acids by binding them to albumin has recently been shown to be of great physiologic significance. Although the quantity of lipide so bound represents only a small percentage of the total serum lipides, it has a rapid turnover. The bulk of the serum lipides are carried as large lipoprotein molecules, of which there is a wide spectrum. Although several methods are now available for characterizing and quantitating these lipoproteins, little is known of their physiologic significance.     

Meat fat formulation

Edible usage of meat fats has somewhat declined over the past years. This can be attributed to several factors. First, the advancement of hydrogenation technology has led to the development of highly functional vegetable oil products. Second, there has been an increased emphasis on Kosher products. Third, various questions relating cholesterol to risks of heart disease have generated some marketing concerns over meat fat usage. Meat fats are still a factor in the edible oils market. U.S. consumption of meat fats in 1976 was 4.1 billion pounds, approximately one billion pounds for edible usage. Because of their trigly ceride profiles, they are excellent sources of highly functional products for bakery applications. They have tended to be the “Cadillac” around which hydrogenated vegetable oil products have been developed. In addition, the economics of these products have generated significant savings for end users. Flavor attributes of meat fats have, in other cases, been the reason for their sole usage in certain specific products. In shortening formulation, meat fats are merely one of many triglyceride sources. They can be blended with any vegetable oil source. They can be subjected to the same processing as other oils in order to modify physical chemical properties such as SFI, melting point, consistency and oxidative stability. This paper will discuss specific applications where lard and tallow contribute unique functionality. It will then discuss various modifications which can be employed to insure more consistent performance or to customize products to specific applications.     

Determination of the Solid Fat Content in Milk Fat by Gas Chromatographic Triglyceride Analysis

Milk fat from 440 butter samples obtained from more than 20 Northern German milk collection areas was extracted and the solid fat content (SFC) determined at 7 temperatures between 0 and 30°C using nuclear magnetic resonance spectrometry. Further, all milk fats were analyzed gas chromatographically for their triglyceride composition. Using a multiple regression analysis triglyceride formulae have been computed which enable the SFC-values to be theoretically calculated at all 7 measuring temperatures. The standard deviations between experimental and theoretical SFC-values at temperatures between 0, 5…, 30°C ranged between 0.88 and 0.38% (r = 0.99990 and 0.99682). Also between the fatty acids C18:1 (oleic acid with isomers), C16 (palmitic acid) resp. C16/C18:1 and the SFC-values measured at 0°C relationships have been established (r = -0.95, 0.93 and 0.93, respectively). Since the expenditure in time necessary for gas chromatographic triglyceride analysis by using simultaneously 2 columns can be reduced to 4 - 5 min and, in addition, extrelut columns allow a very fast isolation of fat from milk for gas chromatographic analyses, rapid characterization of milk fat regarding solid fat contents or also milk fat hardness is feasible by means of triglyceride analysis. Besides the SFC-values a number of other milk fat parameters, such as iodine number, melting point, refraction index etc. can be determined using the same triglyceride analysis.     

Fat encapsulation in spray-dried food powders

The surface composition of spray-dried sodium caseinate/lactose emulsions having different oil phases were estimated using electron spectroscopy for chemical analysis (ESCA), and the particle structure was studied using scanning electron microscopy (SEM) both before and after storage under humid conditions. After spray-drying, powders in which the oil phases consisting of fats with intermediate melting points, such as hardened coconut oil and butter fat, had the highest surface coverage of fat, approximately 34%. The powder with soybean oil as the oil phase had a surface coverage of fat of approximately 15%. The high-melting hardened rapeseed oil was almost completely encapsulated after spray-drying. After storage in a humid atmosphere, fat was released onto all the powder surfaces (surface fat after storage, between 50–65%) except for those with hardened rapeseed oil in which the fat remained encapsulated. These observations are consistent with the powder structure observed by SEM. The surface composition estimated by ESCA for spray-dried sodium caseinate/lactose-containing emulsions with different amounts of soybean oil and a constant lactose/sodium caseinate ratio showed an almost completely encapsulated oil-phase after drying. Storage of these powders in a humid atmosphere leads to a release of fat onto the powder surface even if the soybean oil content is low (1% of the dry weight). Powders made from soybean oil emulsions with sodium caseinate alone exhibit a much lower degree of encapsulation than in the system where lactose is present.