Margarine analysis

Typical examples that fall in this group would be the determination of the active ingredients in analgesic tablets for pharmaceutical use, such as aspirin or codeine or the analysis of a food product such as margarine. Examples of both these analyses will be described to illustrate the sample preparation procedure. 

Analysis of vitamin content of food materials appears to be a developing field. B vitamins in rice were analyzed using a mobile phase which contained pentanesulfonic acid and heptanesulfonic acid (558). Although the peaks were not sharp, the separation of the vitamins was satisfactory. Vitamin D in fortified milk has b n analyzed after removal Of cholesterol and carotenes in a preliminary cleanup (559, 540). Vitamin A has been analyzed in margarine, infant formula, and fortified milk (541, 542). Reports of the analysis of other vitamins in food are few to te but this mode of analysis can be expected to rapidly expand in the future in light of the variety of vitamin determinations in formulations which have been done (see Section VIII,F,l). 

Margarine -m tall oil [CARBOXYLIC ACIDS - FATTY ACIDS FROM TALL OIL] (Vol 5) -food additives m [FOOD ADDITIVES] (Vol 11) -food packaging for [FOOD PACKAGING] (Vol 11) -lecithin m [LECITHIN] (Vol 15) -nut oils m [NUTS] (Vol 17) -trace analysis of [TRACE AND RESIDUE ANALYSIS] (Vol 24) -useofsorbates [SORBIC ACID] (Vol 22)... 

Free fatty acids are separable by GC by the inclusion of phosphoric acid in the packing so, for HPLC analysis, the phosphoric acid or other equivalent strong acid is included in the mobile phase. On a SUPELCOSIL LC 18 column, a model mixture of free fatty acids was separated with a mobile phase containing tetrahydrofuran, acetonitrile, water, and phosphoric acid (6 64 30 0.1) at pH 2 (Fig. 1) (15). Oleic and elaidic acids, palmitoleic and palmitelaidic acids, and linoleic and linoelaidic acids were well separated, but margarine fatty acids presented a difficult problem. Ultraviolet detection of 220 nm was used to prepare this chromatogram. 

The removal of triglycerides from the food sample by saponification provides the opportunity to utilize reversed-phase chromatography. The unsaponifiable matter is conventionally extracted into a solvent [e.g., diethyl ether/petroleum ether (50 50) or hexane] that is incompatible with a semiaqueous mobile phase. It then becomes necessary to evaporate the unsaponifiable extract to dryness and to dissolve the residue in a small volume of methanol (if methanol is the organic component of the mobile phase). For the analysis of breakfast cereals, margarine, and butter, Egberg et al. (153) avoided the time-consuming extraction of the unsaponifiable matter and the evaporation step by acidifying the unsaponifiable matter with acetic acid in acetonitrile to precipitate the soaps. An aliquot of the filtered extract could then be injected, after dilution with water, onto an ODS column eluted with a compatible mobile phase (65% acetonitrile in water). 

A number of reference materials for vitamins in foods are under development. Extensive analysis and stability testing have been conducted to assess the potential of vitamin-enriched milk powder, wholemeal flour, and margarine as well as lyophilized brussels sprouts, mixed vegetables, and pork liver for use as reference materials (193-196). The certification study for vitamin C in the brussels sprouts reference material has been completed. However, methodology problems continue to have a significant negative effect on the development of reference materials. 

The physical and chemical characters of margarine, after melting and filtering, are naturally related to the fatty substances used in its preparation. For its analysis, use is made of the methods indicated for the various oils and fats (see Fatty Substances, Vol. I), and its distinction from butter is effected by the methods described for butter. Further, the methods there given are used for testing for various extraneous matters (flour, mineral substances), preservatives (salicylic acid, boric acid, etc.) and colouring matters. 

Besides margarine, there are other artificial butters in which the oleomargarine is substituted, partly or wholly, by cacao butter for these, too, the general methods for the analysis of fatty substances [see Vol. I) and especially those given for butter are employed. 

In recent years HPLC procedures have evolved as the methods of choice for the analysis of vitamin Do in bulk drug (32,33,53-61), pharmaceutical preparations (52-73), fortified milk (74-82), animal feed supplements (83-89), margarine (79), infant formulae (79), cod liver oil (90-93), and chicken egg (96). It may be pointed out that these reports represent the latest in the state-of-the-art in the HPLC analyses of vitamins Dg and D3. In spite of the intensive effort by a number of investigators and a few collaborative studies, there is no consensus on widely acceptable HPLC methods for vitamin D analysis in the bulk drug, pharmaceutical preparations, and fortified milk. 

Butter and margarine. Soften the sample in a sampling container by warming in a water bath at as low a temperature as practicable, but not exceeding 39°C. Shake at frequent intervals during softening procedure, remove from bath, shake vigorously until the sample cools to a creamy consistency and promptly remove the sample for analysis. 

In 2000-2001, Argentina produced 1.60 MMT of sunflower oil and exported 1.18 MMT (of that oil), with 0.42 MMT disappearance, 75% of which was destined for direct consumption, whereas the rest was used in the manufacture of margarine and mayonnaise. An analysis of internal demand by oil type in Argentina shows sunflower oil with 70% of the trade, followed by soybean (26%), and low volumes of corn and olive oils. Use of sunflower oil is widespread in this region. 

The properties of food products such as margarine or low-fat spreads are extremely dependent on the droplet size distribution. Water and fat diffusion in cheese have been studied in this context (Callaghan et al., 1983) and the size distribution of water droplets in margarine products has been measured (Van den Enden et al., 1990). The Gaussian phase distribution (GPD) approximation has been used to determine the size distribution of water droplets in margarine and low-fat spreads (Balinov et al., 1994). NMR diffusometry studies have been compared in some cases with results from image analysis (Fourel et al., 1995). However, up to now, most studies assume that the emulsion droplets are more or less spherical. 

Preparative TLC is still very much in use as a preliminary separation technique when there is interference of peaks in mixtures to be analysed by GC or HPLC. An example of this is the characterisation of the double-bond configurations of fatty acid methyl esters derived from hydrogenated soybean oil and margarine which required preparative TLC using silver nitrate/silica gel coated plates to separate the mixture prior to GC analysis [10],... 

Analysis of triacylglycerol composition of margarines by 13C NMR Characterization of hydrogenated fats for margarine manufacturing purposes... 

In addition to the above analysis, it is recommended that any refiner of sunflower oil should also check the following micro components because they indicate the true quality of the oil as salad oil or as other finished products such as margarine and shortening. 

Byrdwell, W.C., Neff, W.E. and List, G.R. (2001) Triacylglycerol analysis of potential margarine base stocks by high-performance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry and flame ionization detection. J. Agric. Food Chem., 49, 446-457. 

Slip point (ISO 6321, 2005) and solid fat index (AOCS method Cd 10-57, 2005) can provide information as to the suitability of an oil for use in manufacturing margarines and shortenings. Triacylglycerol (TAG) composition is an additional compositional analysis that can provide information on the potential functionality of an oil as well as its potential oxidative stability. Reversed-phase HPLC with various detection methods such as flame ionization, refractive index, evaporative light scattering, or atmospheric chemical ionization (coupled with mass spectrometry) can be used to determine TAG composition (Neff et d., 1994 Neff et al., 2001). 

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