Quality of corn germ oil obtained by aqueous enzymatic extraction

Molecular Distillation-Induced Deacidification of Soybean Oil Isolated by Enzyme-Assisted Aqueous Extraction: Effect of Distillation Parameters

Soybean oil isolated by enzyme-assisted aqueous extraction (EAE) was subjected to molecular distillation-induced deacidification, and the effects of evaporator temperature, scraper speed, and feed flow rate on oil quality (acid value, color, peroxide value, p-anisidine value, tocopherol content, and fatty acid content) were evaluated to determine the suitable deacidification conditions. Fatty acid content was largely unaffected by evaporator temperature and scraper speed, while an increase of these parameters decreased tocopherol content as well as acid, peroxide, and p-anisidine values and resulted in Lovibond color deepening. The increase of feed flow rate had an opposite effect on the above quality indices. As a result, molecular distillation of EAE-produced soybean oil under suitable conditions (evaporator temperature = 180 °C, scraper speed = 220 rpm, feed flow rate = 4 mL/min) was found to afford a high-quality deacidified product in an environmentally friendly way.

Response surface methodology to optimize enzyme-assisted aqueous extraction of maize germ oil

The present study was aimed at optimizing the enzyme assisted aqueous extraction (EAAE) process for extraction of maize germ oil. The different EAAE process parameter viz., pH of the slurry, seed to water ratio, the temperature of incubation and time of hydrolysis were optimized for improving oil recovery and oil quality. The combined effect of independent variables on recovery of oil, time taken for oil extraction and various quality parameters were studied using response surface methodology. The designed experimental runs were conducted to obtain the optimal conditions as 5.85 pH of slurry, 1:6.92 seed to water ratio, 45.12 °C temperature of incubation and 1 h time of hydrolysis. Oil extracted under these conditions was light yellowish in color and had a pleasant nutty taste, with maximum oil recovery of 70 %. The extraction variables viz., pH of slurry, seed to water ratio, the temperature of incubation had a significant effect on recovery of oil and various quality characteristics, however the time of hydrolysis had a non significant effect.

Correlation between the release of sugars and uronic acid and free oil recovery following enzymatic digestion of oil seed cell walls

Aqueous extraction of sunflower seeds and rapeseeds with mixtures of hydrolytic enzymes were carried out in 2-L reactor and uronic acid and reducing sugar concentrations were measured during digestion. The goal of the study was to determine if a correlation between those concentrations and free oil exists that would allow predicting free oil release from aqueous solution measurements. Similar concentrations of 4.5 and 4.7 g/L of reducing sugars and 43 and 55 g/L of uronic acid were found for sunflower and rapeseeds, respectively. The corresponding yields of free oil from the two seeds were 83% and 16% of total oil, and this difference was due to the formation of an emulsion in the rapeseed dispersion. Therefore, measurement of reducing sugars or uronic acid concentrations are not sufficient to predict a release of free oil from all oil seeds.

Factors affecting emulsion stability and quality of oil recovered from enzyme-assisted aqueous extraction of soybeans

The objectives of the present study were to assess how the stability of the emulsion recovered from aqueous extraction processing of soybeans was affected by characteristics of the starting material and extraction and demulsification conditions. Adding endopeptidase Protex 6L during enzyme-assisted aqueous extraction processing (EAEP) of extruded soybean flakes was vital to obtaining emulsions that were easily demulsified with enzymes. Adding salt (up to 1.5 mM NaCl or MgCl(2)) during extraction and storing extruded flakes before extraction at 4 and 30 degrees C for up to 3 months did not affect the stabilities of emulsions recovered from EAEP of soy flour, flakes and extruded flakes. After demulsification, highest free oil yield was obtained with EAEP of extruded flakes, followed by flour and then flakes. The same protease used for the extraction step was used to demulsify the EAEP cream emulsion from extruded full-fat soy flakes at concentrations ranging from 0.03% to 2.50% w/w, incubation times ranging from 2 to 90 min, and temperatures of 25, 50 or 65 degrees C. Highest free oil recoveries were achieved at high enzyme concentrations, mild temperatures, and short incubation times. Both the nature of enzyme (i.e., protease and phospholipase), added alone or as a cocktail, concentration of enzymes (0.5% vs. 2.5%) and incubation time (1 vs. 3 h), use during the extraction step, and nature of enzyme added for demulsifying affected free oil yield. The free oil recovered from EAEP of extruded flakes contained less phosphorus compared with conventional hexane-extracted oil. The present study identified conditions rendering the emulsion less stable, which is critical to increasing free oil yield recovered during EAEP of soybeans, an environmentally friendly alternative processing method to hexane extraction.

Ultrasonic pre-irradiation effect upon aqueous enzymatic oil extraction from almond and apricot seeds

The present work evaluates the benefit of using ultrasonic pre-irradiation before extracting oil from almond and apricot seeds by aqueous enzymatic oil extraction (AEOE) process. The use of a commercial preparation which is a mixture of three proteases in AEOE gave 75% w/w oil yield from almonds at pH 4.0 in 18 h at 40 degrees C. The ultrasonic pre-irradiation at 70 W for 2 min increased the yield to 95%, w/w and reduced the extraction time to 6 h. The effect of ultrasonic pre-irradiation on meal morphology could be visually seen by scanning electron micrographs. It indicates development of of microfractures and disruption of cell walls in almond powder. With apricot, also, ultrasonic pre-irradiation also marginally increased the oil yield obtained by AEOE to 77% w/w and reduced the extraction time to 6 h. Thus, ultrasonic pre-irradiation step may reduce time required to extract oil from edible oils from plant sources and hence can improve through put in commercial oil production process.