A modification of the AOCS Official Method Ca 5a-40 for determination of free fatty acids (FFA) in 0.3 to 6.0-g samples of refined and crude soybean oil is described. The modified method uses only about 10% of the weight of oil sample, alcohol volume, and alkali strength recommended in the Official Method. Standard solutions of refined and crude soybean oil with FFA concentrations between 0.01 and 75% were prepared by adding known weights of oleic acid. The FFA concentrations, determined from small sample sizes with the modified method, were compared with FFA percentages determined from larger sample sizes with the Official Method. Relationships among determinations obtained by the modified and official methods, for both refined and crude oils, were described by linear functions. The relationship for refined soybean oil had an R 2 value of 0.997 and a slope of 0.99 ± 0.031. The values for crude soybean oil are defined by a line with R 2 = 0.9996 and a slope of 1.01 ± 0.013. JAOCS 75, 563-568 (1998). KEY WORDS:Crude soybean oil, free fatty acid, Official Method, refined soybean oil, titration.In the soybean industry, the presence and development of any amount of free fatty acid (FFA) in soybean oil is undesirable. The FFA content of oil in soybeans indicates how well the beans have been treated during the period between harvest and processing. The eventual consequence of high FFA content is monetary loss because processing soybeans with high FFA content results in more refining loss. Specifically, refining loss is the sum of oil weight lost during removal of FFA and other impurities plus the weight of entrained neutral oil in soapstock during the normal alkali-refining process. The percentage of oil lost during refining can be estimated as a multiple of the FFA percentage. Norris (1) estimates the potential loss at about three times the FFA content. Because of the economic impact of high FFA, it is important to determine the initial level of FFA in soybean oil and also to monitor its concentration during processing.The standard method for FFA determination in extracted crude and refined soybean oil samples is based on an acidbase titration technique in a nonaqueous system. The method commonly used is AOCS Official Method Ca 5a-40 (2). The procedure prescribes an oil sample of maximum 56.4 g and minimum 3.53 g for the titration, depending on the level of FFA in the oil sample. When oil quantities are limited, as in some storage studies or when experimental use of oilseed crops is evaluated, sample sizes of this magnitude are not possible. A simple and inexpensive method is needed that accurately quantifies FFA content from a smaller sample size.The use of smaller amounts of chemicals will have an impact, especially in developing countries, where chemicals are scarce and expensive. Also, it is prudent to limit the use of resources, particularly those hazardous to the environment. For example, hexane, a solvent used in the titration, is a hazardous, highly flammable compound, and its disposal can be harmful to the en...

Corn masa by-product streams are high in fiber and are amenable for utilization in livestock feed rations. This approach is a potentially viable alternative to landfilling, the traditional disposal method for these processing residues. Suspended solids were separated from a masa processing waste stream, blended with soybean meal at four levels (0, 10, 20, and 30% wb), and extruded in a laboratory-scale extruder at speeds of 50 rpm (5.24 rad/ sec) and 100 rpm (10.47 rad/sec) with temperature profiles of 80-90-100°C and 100-110-120°C. Processing conditions, including dough and die temperatures, drive torque, specific mechanical energy consumption, product and feed material throughput rates, dough apparent viscosity, and dough density, were monitored during extrusion. The resulting products were subjected to physical and nutritional characterization to determine the effects of processing conditions for these blends. Extrudate analysis included moisture content, water activity, crude protein, in vitro protein digestibility, crude fat, ash, product diameter, expansion ratios, unit and true density, color, water absorption and solubility, and durability. All blends were suitable for extrusion at the processing conditions used. Blend ratio had little effect on either processing parameters or extrudate properties; extrusion temperature and screw speed, on the other hand, significantly affected both processing and product properties. Corn masa by-product streams are high in fiber and are amenable for utilization in livestock feed rations. This approach is a potentially viable alternative to landfilling, the traditional disposal method for these processing residues. Suspended solids were separated from a masa processing waste stream, blended with soybean meal at four levels (0, 10, 20, and 30% wb), and extruded in a laboratory-scale extruder at speeds of 50 rpm (5.24 rad/sec) and 100 rpm (10.47 rad/sec) with temperature profiles of 80-90-100°C and 100-110-120°C. Processing conditions, including dough and die temperatures, drive torque, specific mechanical energy consumption, product and feed material throughput rates, dough apparent vis- Disciplines Agriculture | Bioresource and Agricultural Engineering

No abstract

No abstract

No abstract

Production of corn masa-based products is flourishing in the United States, as is the generation of masa processing waste. Masa by-products have potential for value-added utilization, an option which could produce less pollution in the environment and economic benefits for masa processors. Physical and nutritional properties of these byproducts are needed for the proper design of processing operations and by-product applications, but information concerning masa byproducts is not currently available. Thus the objective of this study was to fully characterize typical masa by-product streams. The masa by-products studied had moisture contents between 88.15% and 89.29% (w.b.), water activity values between 0.999 and 1.000, densities between 1030.85 and 1047.32 kg/m3 , yield stress values between 1440.04 and 1618.08 N/m2 , pH values between 6.17 and 6.30, Hunter L values between 35.15 and 49.13, a values between 0.27 and 0.98, and b values between 6.85 and 9.38. Drying curves were developed to predict drying behavior. The dried byproducts had protein contents between 4.76% and 4.90% (d.b.), crude fat contents from 0.74% to 5.76% (d.b.), ash contents between 17.41% and 19.09% (d.b.), and carbohydrate contents from 71.93% to 75.41% (d.b.), which was due primarily to fiber, with hemicellulose levels of 20.82% to 24.06% (d.b.) and cellulose between 30.55% and 31.83% (d.b.). Dry masa by-products also consisted of 4.68% (d.b.) calcium. Therefore, dehydrated masa by-products seem very suitable for use as livestock feed additives.

No abstract

No abstract