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|Title:||Lipid Properties and Stability of Partially Defatted Peanuts|
|Department / Program:||Food Science|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Subject(s):||Agriculture, Food Science and Technology|
|Abstract:||Properties and stability of lipids were studied in partially defatted Spanish peanuts of the comet type produced by pressing at 3,000 psi for 30 minutes. Oil content after pressing was 23 percent, a 67 percent reduction.
Mechanical oil extraction with pressures from 1,000 to 6,000 psi did not affect the distribution of tocopherol in the pressed and retained oil. The retained oil, however, contained a significantly higher tocopherol content than the pressed oil, 378 and 347 (mu)g/g of oil, respectively. Both the pressed and retained oils contained only (alpha) and (gamma) tocopherol in the same ratio of 36:64. Non-tocopherol reducing substances were found in both oils.
Dry heating at 100 C was not effective for lipoxygenase inactivation. Heating for 10 minutes at 100 C, which is sufficient to facilitate blanching, destroyed 2-4 percent of the tocopherol.
Reconstitution was found to inactivate lipoxygenase effectively. Reconstitution at 100 C for 4 minutes completely eliminated lipoxygenase activity on trilinolein, while retaining only 3 percent of the activity on linoleic acid. About 19 percent of the tocopherol was destroyed during reconstitution for 4 minutes at 100 C.
A method was developed for the separation of neutral and polar lipids of the partially defatted peanuts using a Celite 545 column. The column was also very effective for the extraction of total lipids.
During mechanical oil extraction, more than 99 percent of the phospholipids were retained in the partially defatted peanuts. Retained oil contained about 2.7 percent phospholipids, calculated from phosphorus analysis, and 3.8 percent polar fraction by weight.
Peanut phospholipids were found to contain phosphatidylethanolamine, phosphatidylinositol, lysophosphatidylethanolamine, lysophosphatidylcholine, phosphatidylserine, and phosphatidic acid. Phosphatidylinositol appeared to be the largest component. The absence of phosphatidylcholine was probably due to decomposition. The presence of phosphatidic acid may be due to the hydrolysis of phosphatidylcholine or other phospholipids by phospholipase D during cold storage. The polar lipid fraction was observed to have an antioxidant property.
Main differences in the fatty acid composition of polar and neutral lipid fractions were in the higher palmitic acid content, lower linoleic acid content, and the absence of arachidonic, behemic, and lignoceric acids in the polar fraction.
In the development of a modified method for peroxide value (PV), determination by the ferric thiocyanate method, isooctane-ethanol 1:1 was found to be a suitable solvent system to replace benzene-methanol 7:3. Benzene-methanol always gave higher PV's than the isooctane-ethanol system by ratios of from 1.12 to 1.34. This may be due to the lesser ability of benzene to act as a hydrogen donor. The peroxide values obtained by the isooctane-ethanol system was about 1.44 that of the iodometric AOCS method.
Lipoxygenase inactivation in the production of partially defatted peanuts is not required as demonstrated by a low PV during storage at 50 C. The reconstitution process, which proved to be effective for lipoxygenase inactivation, was found to destroy tocopherol substantially, especially (alpha) tocopherol. About 35 percent of (alpha) tycopherol and 4 percent of (gamma) tocopherol were destroyed in the reconstitution and drying process. After 40 days of storage, more than 95 percent of (alpha) tocopherol and 27 percent of (gamma) tocopherol in the reconstituted peanuts were destroyed. In whole and partially defatted peanuts, about 28 percent of (alpha) tocopherol was destroyed during storage, while the destruction was 3 percent and 8 percent, respectively, for (gamma) tocopherol.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.
|Date Available in IDEALS:||2014-12-13|
This item appears in the following Collection(s)
Dissertations and Theses - Food Science and Human Nutrition
Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois