SELECTED RESEARCH TOPICS IN FATS AND OILS AT FOOD PROTEIN R&D CENTER
TEXAS A&M UNIVERSITY
Latest Developments in Refining by Adsorption and Filtration of Specialty Oils with Soluble Silicates. E. Hernandez, Texas A&M University, USA.
Use of sodium silicate as a refining agent was applied to several specialty oils such as sesame, safflower, borage, and grapeseed and some conventional vegetable oils (soybean, sunflower, canola, and cotton). This was done at lab and pilot plant scale and the results in the pilot plant were confirmed in runs done at an industrial scale (30,000 lb batches) using soybean oil. The agglomerating properties of liquid sodium silicates after free fatty acid neutralization allowed to remove soapstock by filtration. Processing requirements of high value, small volume oils for specialty applications such as cosmetic or pharmaceutical, are often different than for conventional oils. For small operations, other factors include the use of smaller scale equipment and simpler processing conditions, such as filter-refining. This new refining process can also be applied to larger scale processing of conventional vegetable oils. Agglomerating characteristics of sodium silicate when neutralizing free fatty acids also allows for the separation of soapstock by filtration in combination with the bleaching step. Soaps in the oil resulting from the refining step were low (less than 100 ppm) and the washing step was avoided. In a specific example, sesame oil was treated with a caustic-silica adsorbent to remove free fatty acids and bleaching with neutral and acids activated clays was used to remove color and peroxides. The resulting oil had a free fatty acids content of less than 0.05 % and 0 peroxide.
Study of Refining Vegetable Oils with Buffered Silicate Solutions to Approach Neutrality. M. Hossen and E. Hernandez, Texas A&M University, USA.
Use of sodium silicate in continuous refining of several vegetable oils has been reported as potential new method over conventional caustic refining. A further research has been carried-out in the lab to approach complete neutralization of free fatty acids of vegetable oils by using soluble sodium silicates. The basic principle followed in this study is that silicate solution is a buffered caustic and thus saponification of neutral oil is minimal.
The experimental procedure is as follows: crude degummed soybean oil was first heated up to a predetermined temperature and then different levels (% excess) of sodium silicate solution are added in to the system under constant stirring and heat for a particular time. Three different temperatures 180oF, 200oF, 210oF, and 3 levels of %excess 0.2%, 0.5%, and 2 % of sodium silicate and three mixing time 10 min, 20 min, and 30 min were used in this experimental. A 33 factorial fixed effect statistical model was used to see the effect of different levels of all three factors and all possible combinations (Interactions) of different levels in approaching complete neutralization of vegetable oil. A response surface model will be used to get the best combination. Results showed that final refined oil with less than 0.02 % final free fatty acids can be obtained with minimal oil loss.
Conjugated Linoleic Acid (CLA), which is naturally present at low concentrations only in some animal fats, has been suggested to have various physiological activities. As result, high interest exists in the synthesis and production of CLA as free fatty acid. However, recent discoveries have shown that the absorption and utilization of CLA by the body, as many other fatty acids, is superior if they are esterified to molecules of triglycerides like structured lipids. Therefore, the addition of CLA to triglyceride molecules for the production of structured lipids is a key step. Three different methods for addition of CLA to triglyceride molecules were evaluated in this study: i) chemical synthesis (CS) of triglycerides by reaction of glycerol with the acid chloride of CLA; ii) enzymatic esterification (EE) of CLA with glycerol using Lipozime IM; and iii) chemical interesterification (CI) of methyl esters of CLA with a vegetable oil using sodium methylate as catalyst. Special care to avoid lost by oxidation of CLA should be taken in each case. The addition efficacy of CLA to triglycerides was in the order CS>CI>EE.
Design of Nutritional Food Blends with Functional Lipids.
Ernesto Hernandez AND Monjur Hossen. Food Protein R&D Center, Texas A&M University, College Station, TX 77843
ABSTRACT.
The development of new emulsifiers, new fat replacers, functional lipids and functional proteins have made it possible to develop foods with high nutritional value and at the same time low in fat. Foods, that otherwise have been traditionally high in fat, can be manufactured wit equivalent rheological properties and .A modified starch, modified protein, a modified hydrocholid and omega 3 oils were used as ingredients to produce functional and nutritionally balanced fat spreads, the ingridients such as flavorings and lipid emulsifiers were same as used in conventional spreads. A model was developed to design foods with a balanced content of nutritional components.Samples of low in fat margarines and salad dressings (10, 20, 30 and 40 % fat) were prepared in a pilot plant margarine making machine and a homogenizer respectively. Modified starch and modified protein were used as fat replacers and modified hydrocolloids were used to improve the functional properties of the emulsions.The resulting samples of fat spreads compared well, rheologically and organoleptically, with control samples prepared with conventional ingredients. The rheological properties, i.e., viscosity and texture of fat replacers were comparable with the fats and oils used.
