Kristi Tostenson

CHARACTERIZATION OF PREPARATION PARAMETERS FOR IMPROVED SCREW PRESSING OF CRAMBE SEED

Screw pressing of niche oilseeds such as crambe may be a viable alternative to solvent extraction of oil. Cooking before pressing is known to improve oil recovery. Use of well–defined cooking conditions of time and temperature was expected to aid characterization of the relationship between cooking and press performance, and to reduce soluble seed protein according to a fundamental kinetic model. A pressure cooker modified to permit both steam injection and vacuum permitted the cooking of crambe seed at well–defined conditions of 90³C to 120³C for 5 to 20 min. Oil recovery increased with increasing cooking temperature and time to a maximum of 75.9% at 100³C and 12 min, versus 70.9% for uncooked seed, and a low of 70.6% at 120³C and 20 min. Oil recovery and press rate were nonlinear functions of cooking temperature and time. A cooking index based on soluble protein decreased according to a modified thermal processing model with D0 and z values of 3.3 min and 28³C, respectively. The index was also useful for identifying optimally cooked seed. Oil recovery increased with decreasing seed moisture content to a high of 82.5% recovery at 3.5% m.c. The approach described here may be extended to the tuning of other screw presses for crambe and other oilseeds.

SCREW PRESSING CHARACTERISTICS OF DEHULLED CRAMBE SEED

Screw press performance with a given oilseed depends on the method of preparation before pressing. Oil recovery and press rate of two screw configurations, R-8 and R-11, that differed in flight pitch, height, and width, were compared at dehulling levels from 0% to 100%. The oil recovery with the R-11 screw was better than that of the R-8 at dehulling levels >40%, and the press rate was similar. Thus, the R-11 was selected for a subsequent experiment involving four preparation parameters (dehulling level, cooking time, cooking temperature, and moisture content), each at five levels, using a central composite rotatable design. Multiple regression analysis of the experimental results revealed that linear, quadratic, and interaction terms of the parameters cooking time, cooking temperature, and dehulling level were non-significant even at P > 0.10; however, the linear term for moisture content was significant at P < 0.001. A comparison of oil recovery for cooked seed/kernel versus uncooked at different dehulling levels (30% to 70%) indicated a significant difference at P < 0.01, but the improvement in oil recovery due to cooking was small. A steady rise in oil recovery with decrease in moisture content from 9% to 3% was observed. Moisture content was the major factor influencing press rate, followed by dehulling level and cooking temperature, respectively. It was concluded that acceptable screw press performance was achieved with dehulled crambe seed, that proper moisture content adjustment before pressing dehulled seed was important, and that cooking dehulled seed was of negligible benefit.

Kinetic characterization of cooking-induced changes in crambe seed prepared for expelling

Abstract Expellers offer a viable means for extracting oil from crambe seed ( Crambe abyssinica ) and other niche oilseeds. Oilseeds are often cooked before expelling; however, little is known about the effects of cooking on the seed. Crambe seed (9% moisture) was cooked at exactly 80–112 °C for 5–20 min, using a bench-scale steam cooker developed for this purpose. Seed myrosinase activity decreased to below detection under the more intense conditions. Soluble protein content and light absorbance (280 and 420 nm) of aqueous seed extracts decreased with increased cooking time and temperature, in accordance with a first-order kinetic model. The D 0 and z -values for absorbance at 280 nm were 12.7 min and 36.6 °C, respectively. Measurement of absorbance at 280 nm is a simple, rapid analytical method that may be useful to tune the cooking conditions for improved expeller performance.

Oil and Biodiesel from Canola Having a High Content of Green Seed

The price of canola seed is sharply discounted if the content of green seed in the sample is greater than 2%. The main reason for the discount is the higher cost to refine oil from green seed to a food-grade oil. Current practices for swathing and harvesting canola, as recommended by the North Dakota State University Extension Service, are intended to reduce the percentage of green seed in the sample to acceptable levels. Harvest with the swath method is more expensive than the straight cut method. Straight cutting canola would reduce the field operations by farmers and would probably reduce shatter loss by at least 5%. Canola production must be increased greatly to meet the anticipated demand for canola biodiesel. The objective of this study was to determine whether oil from straight-cut canola seed will be acceptable for production of biodiesel.

Canola-based Epoxy Resins Applied to Plastic Composites

Canola-based epoxy resins were obtained by chemical synthesis with peracetic acid derived from the oxidation of acetic acid with hydrogen peroxide in-situ at 50°C. The epoxidation reaction was carried out in different experimental systems (a. Mechanical stirring, 491 rpm at 50 °C; b. Magnetic stirring, 500 rpm at 25 °C, and c. Orbital stirring, 150 rpm at 50 °C.). Under the experimental conditions of the mechanical stirring system, the time of the reaction (1, 3, 5, 7, 9h) and the presence of solvent (at 5h) were evaluated. The highest conversion of double bonds to epoxy ring was 92% with the mechanical stirring system at 5h. The epoxidation at 5h without solvent was difficult to recover, however the conversion was the same as in presence of solvent. The qualitative analysis by Fourier transform infrared spectroscopy confirmed the results of the analytical determinations of the oxirane content of the prepared samples. The content of double bonds decrease with the time at 3007 cm-1, while the formation of the epoxy groups at 823.8 cm-1 increased with the time of reaction until 5h, time after which the oxirane content remained constant. FTIR spectrum of a canola epoxy resin at 5h in absence of solvent showed a lightly lower content of epoxy groups than in presence of solvent, which was not detected by the analytical determination of the oxirane oxygen content.

Preparation and Partial Characterization of Canola-based Epoxy Resins for Bio-based Plastic Composites

Epoxy resins from unsaturated vegetables oils are used in the production of bio-based composites. Such products have a positive economic and environmental impact, because they do not require the addition of volatile reactive diluents. This makes them more desirable from an environmental and workplace safety standpoint. The objectives of the present study were to obtain and partially characterize the epoxides from canola oil and canola methyl ester and evaluate their performance in a fiberglass composite application. Epoxidation was carried out by two methods, using a percarboxylic acid (m-chloroperoxybenzoic acid) and hydrogen peroxide (50%). To evaluate the composite performance, the canola methyl ester epoxy resin and a commercial soybean oil epoxy resin were blended with a synthetic epoxy resin and compared with a 100 % synthetic epoxy resin. The canola-based resin was found to have lower iodine value, lower oxirane oxygen content and lower viscosity compared to the commercial soy-based resin. Flexural modulus and flexural strength of composite samples were decreased with both types of resins in blends with synthetic epoxy, when compared to 100% of synthetic epoxy. Further research is required to improve flexural properties of canola-based epoxy resins to be competitive with soy-based resins.