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Turgut Dunford N.,Robert rr Food And Agricultural Products Center | Goad C.,Oklahoma State University
Transactions of the ASABE | Year: 2015

The objective of this study was to evaluate the efficiency of acid and enzymatic degumming for crude wheat germ oil refining. Both hexane extracted and mechanically pressed oils were examined in the study. The effects of five variables on acid degumming efficiency were examined: temperature, time (mixing type: 60 min stirring versus 2 min homogenization), water:oil ratio, acid type (phosphoric and citric acids), and acid concentration. Phosphoric acid was more effective than citric acid for removing phospholipids from crude wheat germ oil. Phosphoric acid degumming at 70°C, 2 min homogenization, phosphoric acid concentration of 0.05%, and water:oil ratio of 7.5% resulted in the lowest (989 mg kg-1) residual phosphorus content in the oil. The oil yield under these degumming conditions was 93.5%. About 76% of the total tocopherols were lost during phosphoric degumming of hexane extracted oil. Tocopherol loss was much lower (19%) for mechanically pressed oil degummed under the same conditions as hexane extracted oil. A commercial phospholipase (GumZyme) was also evaluated for WGO degumming. The lowest phosphorus level achieved in the enzymatically degummed oil was 573 mg kg-1. Enzymatic degumming was more effective than acid degumming in removing phospholipids from wheat germ oil. © 2015 American Society of Agricultural and Biological Engineers.


Dunford N.T.,Robert rr Food And Agricultural Products Center | Goad C.,Oklahoma State University
Transactions of the ASABE | Year: 2015

Wheat germ oil (WGO) contains significantly higher amounts of phospholipids than commodity oils. The high phospholipid content in WGO adversely affects its appearance and gives it a very dark and cloudy appearance. Previous studies have demonstrated that water and acid degumming, which are commonly used for commodity oils, are not effective for WGO. This study examined the efficiency of enzymatic degumming for removing phospholipids from hexane extracted and mechanically pressed crude WGO. Two enzymes, Lecitase Ultra and Lysomax, were examined. Process variables (water:oil ratio, reaction time, and temperature) were evaluated for high oil yield and low residual phospholipid content in degummed WGO. Degumming with Lecitase Ultra was more effective than Lysomax. Both enzymes, Lecitase Ultra (219 mg kg-1 residual phosphorus in the oil) and Lysomax (294 mg kg-1 residual phosphorus), were more effective than water and acid degumming. The oil yields under the conditions that resulted in the highest phospholipid removal (84% to 88% removal) were about 88.7% and 89.6% for Lecitase Ultra and Lysomax, respectively. Significant amounts of tocopherols were lost during enzymatic degumming. © 2015 American Society of Agricultural and Biological Engineers.


Dunford N.T.,Robert rr Food And Agricultural Products Center | Dunford N.T.,Oklahoma State University | Goad C.,Oklahoma State University
Biological Engineering Transactions | Year: 2013

Algal biomass harvesting from dilute suspensions of a culture is challenging. Although a flocculation process is commonly used to separate suspended solids from water, information on the flocculation characteristics of microalgae cells is limited. In this study, the flocculation characteristics of Nannochloropsis oculata (NO) were examined. Chitosan addition, adjustment of the pH of the growth medium, and electroflocculation techniques were examined. Adjustment of the algae growth medium pH to 11 resulted in over 99% flocculation efficiency. Although chitosan addition facilitated cell flocculation at a lower pH (pH 9), the high flocculant requirement is a disadvantage of this process. In general, the efficiency of electroflocculation improved with increasing current, operation time (OT), and settling time (ST), and 97.1% NO cell flocculation efficiency could be obtained at 0.3 A, 3 min OT, and 30 min ST. This study demonstrated that over 90% NO cell flocculation efficiency is achievable by adjusting the pH of the growth medium, chitosan addition, or electroflocculation. The process selection for commercial operations needs to be based on the characteristics of the harvested biomass required for a given application and the environmental impact and economic feasibility of the process. © 2013 ASABE.


Xie M.,Robert rr Food And Agricultural Products Center | Dunford N.T.,Oklahoma State University | Goad C.,Oklahoma State University
Biological Engineering Transactions | Year: 2012

In this study, the aqueous extraction of wheat germ oil was examined. The effects of three different buffers and pH on oil extraction yields were evaluated. Preliminary tests carried out at a liquid:solid ratio of 12:1 (v/w) and extraction time of 4 h showed that relatively high oil yields could be obtained at alkaline pH (pH = 8.0). Tris- HCl buffer at pH 8.0 produced the highest oil yield, about 49%. Response surface methodology was used to optimize the processing parameters (liquid:solid ratio and extraction time) to maximize oil yield. Quadratic models with R2 values higher than 0.94 were developed for the three buffer systems: Tris-HCl at pH 8.0, sodium borate (boric acid- NaOH) at pH 8.0, and citrate-phosphate buffer at pH 5.0. In general, oil extraction yield improved with increasing liquid:solid ratio and decreased with prolonged extraction time at pH 8.0. The highest predicted oil extraction yields were similar for Tris-HCl and sodium borate buffers at pH 8.0, about 70%. The verification experiments carried out at the optimum conditions predicted by the models, liquid:solid ratio of 20 (v/w) and extraction time of 0.5 h, resulted in oil yields of 65% and 55% for Tris-HCl and sodium borate buffers, respectively. This study demonstrated the potential of aqueous extraction as a viable technique for recovery of oil from wheat germ. Even though the oil recovery rates achieved in this study were not very high, aqueous extraction of wheat germ oil could be economically feasible because of the higher nutritional and commercial value of wheat germ oil as compared to commodity oils such as soybean oil. © 2012 ASABE.


Ramirez-Lopez L.M.,Oklahoma State University | Ramirez-Lopez L.M.,Robert rr Food And Agricultural Products Center | McGlynn W.,Robert rr Food And Agricultural Products Center | McGlynn W.,Oklahoma State University | And 2 more authors.
Food Chemistry | Year: 2014

Phenolic acids, flavanols, flavonols and stilbenes (PAFFS) were isolated from whole grapes, juice, or pomace and purified using enzymatic hydrolysis. Only anthocyanin mono-glucosides and a few of the oligomers from Cynthiana grape (Vitis aestivalis) were analysed. Flavonoid-anthocyanin mono-glucosides (FA) were isolated using methanol/0.1% hydrochloric acid extraction. In addition, crude extractions of phenolic compounds from Cynthiana grape using 50% methanol, 70% methanol, 50% acetone, 0.01% pectinase, or petroleum ether were also evaluated. Reverse phase high performance liquid chromatography (RP-HPLC) with photodiode array (PDA) detector was used to identify phenolic compounds. A method was developed for simultaneous separation, identification and quantification of both PAFFS and FA. Quantification was performed by the internal standard method using a five points regression graph of the UV-visible absorption data collected at the wavelength of maximum absorbance for each analyte. From whole grape samples nine phenolic compounds were tentatively identified and quantified. The individual phenolic compounds content varied from 3 to 875 mg kg-1 dry weight. For juice, twelve phenolic compounds were identified and quantified. The content varied from 0.07 to 910 mg kg -1 dry weight. For pomace, a total of fifteen phenolic compounds were tentatively identified and quantified. The content varied from 2 mg kg -1 to 198 mg kg-1 dry matter. Results from HPLC analysis of the samples showed that gallic acid and (+)-catechin hydrate were the major phenolic compounds in both whole grapes and pomace. Cyanidin and petunidin 3-O-glucoside were the major anthocyanin glucosides in the juice.


Septiano W.,Robert rr Food And Agricultural Products Center | Dunford N.T.,Robert rr Food And Agricultural Products Center | Wilkins M.,Robert rr Food And Agricultural Products Center | Edwards J.,Oklahoma State University
Biological Engineering | Year: 2010

This study examined the potential of two winter hulless barley varieties, Eve and VA125, as feedstock for ethanol production. Starch and β-glucan contents of the barley samples were analyzed using official analytical techniques. Both wholegrain and flour samples were hydrolyzed by enzymes and heat treatment preceding fermentation experiments. A simultaneous saccharification and fermentation method was used to convert starch to ethanol. Eve variety had higher starch content than that of VA125. The β-glucan content of VA125 was higher than that of Eve. The highest ethanol conversion efficiency, 88.6%, was attained with the mash prepared from whole-grain Eve. This study demonstrated that winter hulless barley can be a viable feedstock for bio-ethanol production with similar starch content to corn. Dry milling can be used to obtain high starch content flour fractions from barley grain. It is possible to produce ethanol from winter barley varieties with acceptable conversion yields. Optimization of dry milling and ethanol conversion process parameters could improve the economic feasibility of barley-to-ethanol conversion operations. © 2010 ASABE ISSN 1934-2799.

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