Stephen H. Feairheller

Enzymatic interesterification of tallow-sunflower oil mixtures

In an effort to improve the physical and/or thermal characteristics of solid fats, the enzymatic interesterification of tallow and butterfat with high-oleic sunflower oil and soybean oil was investigated. The two simultaneously occurring reactions, interesterification and hydrolysis, were followed by high-performance liquid chromatography of altered glycerides and by gas-liquid chromatography of liberated free fatty acids. The enzymes used in these studies were immobilized lipases that included either a 1,3-acyl-selective lipase or acis-9-C18-selective lipase. The degree of hydrolysis of the fat/oil mixtures was dependent upon the initial water content of the reaction medium. The extent of the interesterification reaction was dependent on the amount of enzyme employed but not on the reaction temperature over the range of 50–70°C. Changes in melting characteristics of the interesterified glyceride mixtures were followed by differential scanning calorimetry of the residual mixed glycerides after removal of free fatty acids. Interesterification of the glyceride mixes with the two types of enzymes allowed for either a decrease or increase in the solid fat content of the initial glyceride mix.

An energetic evaluation of a “Smith” collagen microfibril model

An energy minimized three-dimensional structure of a collagen microfibril template was constructed based on the five-stranded model of Smith (1968), using molecular modeling methods and Kollman force fields (Weiner and Kollman, 1981). For this model, individual molecules were constructed with three identical polypeptide chains ((Gly-Pro-Pro)n, (Gly-Prop-Hyp)n, or (Gly-Ala-Ala)n, wheren=4, 12, and 16) coiled into a right-handed triple-helical structure. The axial distance between adjacent amino acid residues is about 0.29 nm per polypeptide chain, and the pitch of each chain is approximately 3.3 residues. The microfibril model consists of five parallel triple helices packed so that a left-handed superhelical twist exists. The structural characteristics of the computed microfibril are consistent with those obtained for collagen by X-ray diffraction and electron microscopy. The energy minimized Smith microfibril model for (Gly-Pro-Pro)12 has an axial length of about 10.2 nm (for a 36 amino acid residue chain), which gives an estimated D-spacing (234 amino acids per chain) of approximately 66.2 nm. Studies of the microfibril models (Gly-Pro-Pro)12, (Gly-Pro-Hyp)12, and (Gly-Ala-Ala)12 show that nonbonded van der Waals interactions are important for microfibril formation, while electrostatic interactions contribute to the stability of the microfibril structure and determine the specificity by which collagen molecules pack within the microfibril.

A novel technique for the preparation of secondary fatty amides

A low-temperature synthesis of fatty alkanolamides, fatty diamides and fatty aralkylamides directly from triglycerides and primary amines provides essentially quantitative yields of the various products. The reactions run to completion in 3–12 h at temperatures of 50–60°C, approximately 100°C lower than employed in present conventional practice. The amines are used in excess and serve as solvent, reagent and, perhaps, as catalyst. The amides were characterized by melting point and spectroscopic (infrared and nuclear magnetic resonance) methods. If the mixed amides produced from the various natural triglyceride mixtures of fats and oils are acceptable products, this synthetic method provides these products in satisfactory quality while conserving energy and avoiding the intermediate production of free fatty acids or their esters.

Lipase-catalyzed triglyceride hydrolysis in organic solvent

An investigation of lipases fromRhizomucor miehei,Candida rug osa and porcine pancreas revealed that these enzymes hydrolyzed triglycerides in an organic solvent system. The presence of secondary amines,i.e., diethylamine,N-methylbutylamine, or the tertiary amine, Methylamine, greatly increased the extent of hydrolysis. The lipolysis of tallow took place under mild conditions,e.g., room temperature, moderate shaking and within 20 hr. At 45°C, complete hydrolysis of tallow was obtained in 6 hr. Vegetable oils and a fish oil (cod liver oil) were also hydrolyzed at 20°C byR. miehei lipase in the presence of iV-methylbutylamine for 20 hr. The lipases were recovered for reuse with some loss of activity. Optimum yields of free fatty acids were obtained by usingR. miehei lipase as catalyst.

Lipase catalyzed formation of fatty amides

Certain lipase preparations were found to facilitate the preparation of fatty amides at 20°C in hexane. Lipase preparations investigated were from the fungiCandida rugosa, Rhizomucor miehei and porcine pancreas. Reactants were various primary alkylamines and fatty acid methyl esters or triglycerides. Moderate yields of fatty amides were obtained using aR. miehei lipase preparation which is immobilized on a solid support as catalyst, although all three lipase preparations showed some catalytic activity under these conditions and, in addition, showed different kinds of selectivity for fatty acid and alkylamine chain lengths. No reaction was observed in similar experiments using one fatty acid as the substrate or one secondary amine.

Fatty acid selectivity of lipases: Erucic acid from rapeseed oil

The fatty acid selectivity of several commercial lipases was evaluated in the hydrolysis of high-erucic acid rapeseed oil (HEARO). The lipase ofPseudomonas cepacia catalyzed virtually complete hydrolysis of the oil (94–97%), while that ofGeotrichum candidum discriminated strongly against erucic acid, especially in esterification. A two-step process is suggested for obtaining a highly enriched erucic acid in which theG. candidum lipase is employed to selectively esterify the fatty acid residues of unsaturated C-18, and shorter chain acids, from a mixture of HEARO fatty acids obtained from total hydrolysis of the oil withP. cepacia lipase.

Polymer-Leather Composites V. Preparative Methods, Kinetics, Morphology, and Mechanical Properties of Selected Acrylate Polymer-Leather Composite Materials

This paper reviews an extensive study of largely reported work on polymer-leather composite materials (1–4). In this work two methods were utilized, for depositing selected acrylic polymers into the leather matrix by free radical polymerization (1). In one method polymer was introduced by emulsion polymerization into expanded hydrated panels. In the other, polymer was formed by bulk or solution polymerization in unexpanded acetone-dried panels. The widest feasible range of composite compositions was investigated for both methods. The kinetics of the emulsion process (2), together with the morphology (3) and mechanical properties (4) of both types of composites, were also investigated. In the present paper we attempt to combine the more important aspects of these detailed works into a comprehensive whole and to integrate this peripheral area of composite material science into the main body of work in the field.