Dennis P. Wiesenborn

Expanded bed adsorption for recovery of patatin from crude potato juice

An expanded bed adsorption process was used to isolate patatin possessing esterase activity, from a crude juice of potato tubers. Patatin is the major storage protein of potato tubers and is released in ample amounts in the processing effluent during starch milling. We employed mixed mode affinity resins, where the binding depends primarily on the pH, and is almost independent of the ionic strength. From a library of mixed mode chemistries involving both charged and hydrophobic functions, we screened for ligands with binding specificity for patatin. The dynamic binding capacity of two high density (1.45–1.5 g ml-1) patatin-binding agarose-glass resins in response to change of linear velocity (85–230 cm h-1) was tested in packed (25 ml) and expanded (250 ml) column modes. The column operation included a loading step at low expansion; H/Ho~1.2. Adsorption from crude juice at pH 7.5, retained patatins up to a breakthrough level of 50%. The eluate fraction at pH 3.5, now effectively stripped from the pigments, provided a 2.5-fold enzyme enrichment and produced 4 g protein per cycle. Column productivity was 122 kAU L-1 h-1. The study, using potato juice as model feedstock, demonstrated the feasibility of expanded bed-recovery of potentially valuable proteins from plant biomass.

Optimizing pectin extraction from sunflower heads by alkaline washing

Abstract De-seeded sunflower heads (Helianthus annuus L. var. Cargill) with 15–25% pectin can be a valuable source of pectin. Most pigments in heads are water soluble and are strongly associated with the pectin extract. Pretreatment with a hot water-washing process was used prior to pectin extraction to improve pectin quality by removing pigments. Unfortunately pretreatment resulted in increased pectin loss. To optimize pectin extraction, various combinations of pH, time, temperature, and solid:solvent ratio were used. The Response Surface Methodology (RSM) was used to analyze the data set. The experiments of washing ground sunflower heads were performed in the washing medium at pH 6·0–8·0 for 15–55 min at 5–25°C at solvent:solid ratios of 35:1 to 15:1 (v/w). The alkaline washing treatment at pH 7·5 for 25 min at a solvent: solid ratio of 28:1 at 16°C removed more than 48% pigment, but had little effect on pectin loss (less than 3·2%). The pectin extracted had good gelling capacity.

Production and characterization of epoxidized canola oil.

Epoxidized canola oil may be well suited to the partial replacement of petroleum products in composite matrices; however, a process is needed to obtain this material from canola oil at sufficient conversion and scale to assess product properties. Therefore, canola oil was epoxidized in a solvent-free process with a heterogeneous catalyst; a fractional factorial design was used to determine the impact of processing conditions and their two-factor interactions on epoxy group content of epoxidized canola oil. The studied parameters were: molar ratio of acetic acid to unsaturation, molar ratio of hydrogen peroxide to unsaturation, concentration of hydrogen peroxide, concentration of catalyst, and temperature. Epoxidized canola oil with up to 98.5% conversion was produced. The parameters molar ratio of acetic acid to unsaturation, concentration of hydrogen peroxide, temperature, and their interactions were found to be significant in the defined design space. Process conditions that achieved the highest conversion were scaled to 300 g to compare the conversion, production yield, and rheological and melting properties of products of the epoxidation of both canola and soybean oil with and without solvent. Epoxidized canola oil crystallized at room temperature; at 40°C it was shear-thinning with an apparent viscosity of 140 to 150 mPa·s. Elimination of solvent in the epoxidation process decreased the yield 10% but did not reduce the conversion to epoxy groups. Therefore, the scaled-up, solvent-free process is proposed as a green alternative for sufficient epoxidized canola oil to test composite applications.

Effects of Protein Separation Conditions on the Functional and Thermal Properties of Canola Protein Isolates

UNLABELLED Canola meal protein isolates were prepared from defatted canola meal flour using alkaline solubilization and acid precipitation. A central composite design was used to model 2nd-order response surfaces for the protein yield and the functional properties of protein isolates. The solubilization pH and precipitation pH were used as design factors. The models showed that the protein yield and functional properties of isolates, such as water absorption and fat absorption, were sensitive to both solubilization pH and precipitation pH, whereas the emulsification was sensitive to only solubilization pH. Gel electrophoresis analysis of protein fractions gave evidence to the compositional changes between proteins isolated under different conditions. Differences in glass transition temperatures suggest that proteins tend to be more denatured when solubilized at highly alkaline conditions. These conformational and compositional changes due to different protein separation conditions have contributed to the changes in functional properties of protein isolates. PRACTICAL APPLICATION   Protein isolation conditions may be determined primarily through optimization of total protein yield. Improvements in protein functional properties may be achieved with a relatively small sacrifice in yield by altering isolation conditions.

Bench-scale processing of amaranth seed for oil

Amaranth seed (Amaranthus hypochondriacus cv. K432) was processed to obtain oil, reported to be a promising source of squalene. The amaranth seed was ground using a stone mill, then separated into oil-rich embryonic tissue (or “bran”) and starchy perisperm. Amaranth bran was much more stable than rice bran when free fatty acid (FFA) content and peroxide value were monitored. Milling at a gap of 0.755 mm did not result in excessive damage to the starch in the perisperm fraction and yielded a bran fraction that contained more than three-fourths of the oil and a starchy fraction consisting of more than two-thirds of the seed weight. The bran particles were too fine for effective bench-scale extraction of the oil. Consequently the bran was extruded into collects prior to extraction. Two extrusion settings were evaluated regarding the rate of moisture injection, while the bran feed rates were constant. There was no significant difference in appearance or size between the two dried collets. Collets were extracted with hexane using an Armfield Extraction/Desolventizing Unit (Model FT 29, Armfield, Ltd., Hampshire, England). Oil recovery averaged 97.7 and 80.0%, respectively. Oil was extracted at high yield from the bran when the bran was extruded into collets. Oil can be obtained as a coproduct of amaranth starch by milling and separating the fractions of amaranth seed. Milling, extrusion, and extraction did not decrease significantly the squalene content in amaranth oil, but increased FFA content and peroxide value and changed tocopherol content of the oil.

Development and Evaluation of an Ozonated Water System for Antimicrobial Treatment of Durum Wheat

Ozonated water is reported to be effective in reducing the microbial load in foods such as fruits, vegetables, and grains. Ozonated water may be an effective alternative to chlorinated water in treating durum wheat before milling. Therefore, durum wheat was washed with ozonated water and analyzed for yeast and mold count (YMC) and aerobic plate count (APC). A system for producing and monitoring ozonated water was developed. The effect of water quality (tap, distilled, and ultra-pure), temperature (7, 15, and 25 degrees C), and pH (2, 4, and 6.5) was evaluated on the following: steady-state dissolved ozone concentration, ozone decay constant, half-life, mass transfer coefficient, equilibrium ozone concentration, and solubility ratio. The study of these parameters was important to attain a stable, high dissolved ozone concentration at the outset of washing and to have information for system improvement and scale-up. A 1% acetic acid solution (pH 2) at 15 degrees C resulted in high dissolved ozone concentration (21.8 mg/L) and long half-life (9.2 min). Subsequently, wheat was washed with 5 wash water types: distilled water, ozonated water (16.5 mg/L), chlorinated water (700 mg/L), acetic acid solution (1%), and acetic acid + ozonated water (1%, 20.5 mg/L). The treated samples were analyzed for YMC and APC. The acetic acid + ozonated water treatment was the most effective, with a reduction of 4.1 and 3.2 log(10) colony forming units/g in YMC and APC, respectively. Though ozonated water was not very effective alone, it was useful in combination with acetic acid.

Development and Evaluation of a Fluidized Bed System for Wheat Grain Disinfection

Durum wheat grain from the field is naturally contaminated with bacteria, yeast, and mold. The reduction in aerobic plate count (APC) and yeast and mold count (YMC) is often necessary before processing wheat. Gaseous ozone, ozonated water, and acetic acid solution are nontraditional antimicrobial agents for grains and are safe for humans and the environment. Better disinfection may be possible by applying antimicrobial agents to grain in a fluidized state. Fluidization increases the exposure of grain surfaces, resulting in uniform and quick contact of grain with antimicrobial agents. Therefore, a fluidized bed was developed with automated spraying system (to spray treatment waters), and a port for gaseous ozone injection. The pressures and velocities within the fluidized bed system were measured to characterize the system. The treatments used on fluidized grain were: distilled water (control), gaseous ozone (6 ppm), ozonated water (23 mg/L), gaseous ozone + ozonated water (6 ppm, 23 mg/L), acetic acid solution (0.5%), acetic acid + ozonated water (0.5%, 26 mg/L), and gaseous ozone + acetic acid + ozonated water (6 ppm, 0.5%, 26 mg/L). The last of these treatments was most effective with 1.7 and 3.3 log reduction in APC and YMC, respectively. This combined treatment can be used to replace the chlorinated water that industry uses during tempering of grain. Ozonated water alone resulted in a 0.3 log reduction in both APC and YMC. Gaseous ozone alone did not cause a significant reduction in APC and YMC.

Effects of impact dehuller rotor speed on dehulling characteristics of diverse oat genotypes grown in different environments.

ABSTRACT Commercial processing of oats for human consumption generally requires impact dehulling to isolate groats from the hull. Impact dehulling involves feeding oat grain into the center of a spinning rotor that expels the grain against the walls of the dehuller. The force of the impact breaks the hull from the groat. We have tested the effect of rotor speed on dehulling efficiency, groat breakage, and unbroken groat yield on 18 oat genotypes from replicated plots in six different environments. Dehulling efficiency and groat breakage increased with rotor speed with all genotypes and environments, but there were significant genotypic and environmental effects as well. In general, genotypes with higher test weight and kernel density dehulled more efficiently at slower rotor speeds. Oat genotypes with higher oil and protein concentrations in their groats tended to break less during dehulling. Oats from hotter, drier environments suffered greater groat breakage. Maximal unbroken groat yield represented a b...

Epoxidized High-Oleic Vegetable Oils Applied to Composites

Vegetable oils are a renewable source for the production of oleochemicals. Oils with high oleic and low saturate content may be an excellent source for producing epoxy resins because of the uniform distribution of cross-linking sites. Bio-based epoxy resins can be used as matrix components for composite materials. Vegetable oils with oleic acid content varying from 22% to 86% were epoxidized in situ with peracetic acid and a heterogeneous catalyst. Contents of 30%, 35%, and 40% (% wt of total matrix) of bio-based epoxy resins were blended with a synthetic epoxy resin and an anhydride curing agent to be applied as the matrix in the preparation of composites using E-glass as the structural fiber. A control was also prepared with a 100% synthetic epoxy resin. Mechanical properties (flexural properties, interlaminar shear strength, and dynamic mechanical analysis) of the produced composite materials were evaluated. More flexible but less resistant composites were obtained as the content of oleic acid in the initial vegetable oil and the content of bio-based resin increased. Toughness increased at lower levels of oleic acid content. Interlaminar shear strength showed low adhesion of the matrix-fiber at a bio-based epoxy resin content of 40%. High homogeneity and slightly reduced glass transition temperatures were shown in composites with high-oleic bio-based resins when compared with the control. The application of bio-based epoxy resins in the production of composites materials helps decrease the dependence on petroleum-based resins and may lead to a high added-value product from vegetable oils. However, future studies are needed to increase the adhesion of matrices containing bio-based resin with synthetic and natural fibers, which will improve the mechanical performance of the composites.

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.