Earl G. Hammond

Use of branched-chain esters to reduce the crystallization temperature of biodiesel

To reduce the tendency of biodiesel to crystallize at low temperatures, branched-chain alcohols were used to esterify various fats and oils, and the crystallization properties of the branched esters were compared with those of methyl esters by using differential scanning calorimetry (DSC), cloud point, and pour point. Compared with the methyl esters that are commonly used in biodiesel, branched-chain esters greatly reduced the crystallization onset temperature (TCO) of neat esters and their corresponding ester diesel fuel blends. Isopropyl and 2-butyl esters of normal (∼10 wt% palmitate) soybean oil (SBO) crystallized 7–11 and 12–14°C lower, respectively, than the corresponding methyl esters. The benefit of the branched-chain esters in lowering TCO increased when the esters were blended with diesel fuel. Esters made from a low-palmitate (3.8%) SBO crystallized 5–6°C lower than those of normal SBO. Isopropyl esters of lard and tallow had TCO values similar to that of methyl esters of SBO. DSC provided an accurate means of monitoring crystallization, and the DSC results correlated with cloud and pour point measurements.

Fuel properties and emissions of soybean oil esters as diesel fuel

The effects of using blends of methyl and isopropyl esters of soybean oil with No. 2 diesel fuel were studied at several steady-state operating conditions in a four-cylinder turbocharged diesel engine. Fuel blends that contained 20, 50, and 70% methyl soyate and 20 and 50% isopropyl soyate were tested. Fuel properties, such as cetane number, also were investigated. Both methyl and isopropyl esters provided significant reductions in particulate emissions compared with No. 2 diesel fuel. A blend of 50% methyl ester and 50% No. 2 diesel fuel provided a reduction of 37% in the carbon portion of the particulates and 25% in the total particulates. The 50% blend of isopropyl ester and 50% No. 2 diesel fuel gave a 55% reduction in carbon and a 28% reduction in total particulate emissions. Emissions of carbon monoxide and unburned hydrocarbons also were reduced significantly. Oxides of nitrogen increased by 12%.

Analysis of oleate, linoleate and linolenate hydroperoxides in oxidized ester mixtures

The hydroperoxides in oxidized mixtures of methyl oleate, linoleate and linolenate were analyzed by reducing the hydroperoxides to the corresponding hydroxyesters and separating the hydroxyesters from the unoxidized esters by thin layer chromatography (TLC). The hydroxyesters from linolenate were separated from the other hydroxyesters by TLC on silver ion plates. The hydroxyesters were converted to TMS-hydroxy derivatives. The TMS-hydroxyoleate and TMS-hydroxylinoleate were separated by gas chromatography (GC), and all the TMS-derivatives were quantified by GC. The relative rates of oxidation of methyl oleate, linoleate and linolenate in mixtures were ca. 1∶10.3∶21.6. The hydroperoxides formed in the oxidation of soybean and olive oils were similar before and after randomization and similar to corresponding methyl ester mixtures.

Reducing the Crystallization Temperature of Biodiesel by Winterizing Methyl Soyate

Methyl soyate, made from typical soybean varieties, has a crystallization onset temperature (Tco) of 3.7°C and, as a biodiesel fuel, is prone to crystallization of its high-melting saturated methyl esters at cold operating temperatures. Removal of saturated esters by winterization was assessed as a means of reducing theTco of methyl soyate. Winterizing neat methyl esters of typical soybean oil produced aTco of −7.1°C, but this was not an efficient way of removing saturated methyl esters because of the low yield (26%) of the separated liquid fraction. However, aTco of −6.5°C with 86% yield was obtained by winterizing the neat methyl esters of a low-palmitate soybean oil; aTco of −5.8°C with 77% yield was obtained by winterizing methyl esters of normal soybean oil diluted with hexane.

Organization of Rapid Analysis of Lipids in Many Individual Plants

There is considerable interest in changing the composition of oilseed plants through plant breeding and genetic engineering (Greiner 1990). This may involve increasing or decreasing the total lipid in the seed or the composition of the lipid. Modern plant breeding is largely empirical and produces large numbers of plants whose oilseed composition must be evaluated. For example, two plants may be crossed and give rise to many offspring that are a genetic mixture of the two parents (Graef et al. 1988). Each of the offspring may differ genetically, and those with interesting oilseed compositions must be identified. Or, a batch of seed may be treated with a chemical or physical agent to induce mutations (Hammond and Fehr 1985). The surviving seed will give rise to plants that may have random mutations and must be evaluated to identify those with interesting compositions. In these situations plant breeders turn to those skilled in oilseed analysis, and close cooperation between breeder and analyst is needed for success.

Effect of altered fatty acid composition on soybean oil stability

During the last 15 years, hybridization and induced mutation breeding of soybeans have been successful in producing an altered fatty acid composition in the extracted oil. The objective of those investigations was to produce a low-linolenic acid soybena oil. Crude oils extracted from the seeds of three such genotypes were processed in laboratory simulations of commercial procedures to finished deodorized oils. Analysis of the fatty acid composition of the three oils showed the linolenic acid content to be 3.3%, 4.2% and 4.8%. The stability of these finished oils was compared to that of oil from a soybean variety having a linolenic acid content of 7.7% and of a commercial hydrogenated-winterized soybean oil (3.0% linolenic acid). Test and control oils were evaluated by a trained sensory panel initially, after accelerated storage at 60 C and during use at 190 C in room tests. Peroxide values were determined at the time of sensory evaluation. Results indicated there was no significant difference in flavor stability during storage between test and control oils. There was no significant difference, between the oils, in peroxide development during accelerated storage. Compared to control oils, the test oils had improved overall room odor intensity scores and lacked the fishy odors of non-hydrogenated soybean oil and the hydrogenated odors of commercial cooking oil.

Genetics, characteristics, and utilization of oil in caryopses of oat species

For oats to be an economically feasible oilseed crop in Iowa, the oil percentage would have to be increased to ca. 16%. A survey of the oil percentage in 445 oat cultivars and collections gave a range of 2.0–11.0%. The oil percentage was only slightly affected by growing oats in 5 different locations in Iowa. Inheritance studies indicated that oil percentage was inherited polygenically, and there was a tendency for high oil percentage to be partially dominant. Analysis of 64 cultivars and collections showed a wide variation of fatty acid composition: palmitic, 14–23%; stearic, <1–4%; oleic, 29–53%; linoleic, 24–48%; linolenic, < 1–5%. The oil percentage was positively correlated with oleic acid and negatively correlated with linoleic and linolenic acids. Oats contained a lipase that made extraction of oil with low acid values difficult. The lipase was strongly affected by moisture and was most active in oat doughs containing 25–50% moisture. There was at least a 20-fold variation in lipase activity in oat cultivars and collections. Whole oats may be kept in dry storage for several years without significant lipolysis, but in broken or crushed caryopses, lipolysis occurs even at low moisture levels. The lipase may be inactivated by heat or 95% ethanol treatments.

Biomodification of fats and oils: Trials withCandida lipolytica

Various oil-accumulating yeasts were tested for their ability to produce lipase and live on fats and oils as carbon sources. Of these,Candida lipolytica seemed most promising, and the possibility was explored of modifying fats and oils by fermenting them withC. lipolytica and extracting the modified oil deposited in the yeast cells. Oxygen was required for the growth of yeast on fats and oils, but unless the oxygen level was controlled at a low value after cell populations peaked, most of the substrate oil was converted to citrates rather than accumulating as oil. Oil accumulation byC. lipolytica from a corn oil substrate was slightly depressed by excess nitrogen in the medium. The yeasts were able to use about 18 g/l of oil in 72 hr. At substrate oil levels greater than 18 g/l, the dry yeasts were 60% oil, and about 45–57% of the substrate oil was recovered as yeast oil. The fatty acid composition of the yeast oil was quite similar to that of the substrate oil under optimum conditions of deposition. Sterols, but not tocopherols, were transferred from the substrate to the yeast oil.Candida lipolytica oil was high in free fatty acids. The greatest potential for biomodification by fermentation withC. lipolytica seems to be in altering glyceride structure.

Properties of fibers produced from soy protein isolate by extrusion and wet-spinning

Fibers were produced from soy protein isolate by both wet-spinning and extrusion. In the wet-spinning process, aged, alkaline protein solution was forced through a spinnerette into an acid coagulating bath. In the extrusion process, a twinscrew extruder forced a protein isolate-water mixture through a die. The physical properties of the fibers were measured at various water activities. The fibers produced by both methods were brittle and lacked tensile strength (tenacity). The addition of glycerol reduced brittleness in extruded fibers. Zinc and calcium ions decreased the brittleness of wet-spun fibers. The tenacity of soy fibers was significantly improved by post-spinning treatments, including acetic anhydride, acetaldehyde, glyoxal, glutaraldehyde, a combination of glutaraldehyde and acetic anhydride, and stretching. The best extruded fibers were produced with a mixture of 45% soy protein, 15% glycerol, and 40% water, finished with a combination of glutaraldehyde and acetic anhydride and then stretched to 150% their original lengths. The best wet-spun fibers were produced with a 19.61% soy protein suspension at pH 12.1; coagulated in a 4% hydrochloric acid solution that contained 3.3% sodium chloride, 3.3% zinc chloride, and 3.3% calcium chloride; and followed by treatment with 25% glutaraldehyde and stretching to 170% their original lengths.

Analysis of particle-borne swine house odors☆

Abstract Dust from the air of a swine confinement building was collected with an electrostatic precipitator made of glass. The odorous compounds were extracted from the dust with wet diethyl ether. Acids were removed from the ether with sodium carbonate solution, converted to decyl esters, and analyzed by capillary gas chromatography. Phenols were next removed from the ether by passage through a column containing sodium hydroxide. The phenols were quantified by gas chromatography of their trimethylsilyl esters. Carbonyls were converted to trichlorophenylhydrazones and quantified by gas chromatography. Results of typical analyses are presented, and the mechanism by which dust amplifies the odor of swine house air is discussed.