Background and objectives: While alkaline nixtamalization has historically been used for corn, this process may have application in other cereals. Drawbacks to wider use include the lengthy steep time, as well as the volume of alkaline wastewater produced. This study evaluated a novel, waste-effluent-free nixtamalization process for oat (Avena sativa) masa, and compared properties of oat masa and tortillas prepared with 1, 1.5 and 2% lime, with and without steeping. Findings: A minimal water-addition, 45-min, simmering process, without steeping, was effluent-free, and produced oat tortillas comparable to those produced using a traditional overnight steep. The pH increased significantly with increasing lime content (r=0.982). Consumer overall-liking scores did not significantly differ across treatments, though appearance scores were significantly higher for 2% lime samples (p<0.05), which were significantly darker and more yellow, based on L* and b* values. Masa adhesiveness means ranged from 1.49-1.52 N, with no significant differences between the no-steep treatments. Higher lime addition (1.5-2%) in the no-steep process significantly improved tortilla flexibility, based on extensibility and rollability scores, though tortilla rupture force did not vary significantly across treatments. Tortilla rollability scores at 3-days were lowest (x=1.1 + 0.31, indicating less cracking) for the 1.5-2% lime no-steep treatments, which were significantly better than the steeped treatment (x=3.7 + 0.48). Consumers rated the steeped sample as significantly less flexible. B-vitamins were negatively impacted by increasing lime, while calcium increased significantly with lime addition. Conclusions: The no-steep, effluent-free nixtamalization process produced oat tortillas with good masa and tortilla texture, which were not significantly different in consumer liking to tortillas produced via a traditional process. Significance and novelty: This research suggests nixtamalization can be applied to other grains in a shorter, environmentally-friendly process, with broader commercial applicability.

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Oats are considered to be a highly nutritious breakfast food available to consumers. Heightened consumer interest in functional food products and advances in human nutrition have led to increased levels of interest in the development of new oat based products (Webster and Wood 2011). Developments in technology have led to manufacturing of instant oatmeal, making the product more convenient to consumers. Low moisture extrusion processing is one of the most widely used methods to produce ready to eat breakfast cereals; however, there has been little research carried out to determine if high moisture extrusion methods would be viable. This study evaluated the economic and technical feasibility to utilize high moisture extrusion processing to produce ready to eat oatmeal. A process economics evaluation included measuring the capital requirements to implement the system, process costing to estimate the weighted average unit cost, and net present value of high moisture extrusion production. The capital expense was significantly high. However, the unit cost is comparable to similar products in the market. The net present value of implementing the technology revealed a significant profit over the course of 20 years. Six different technical experiments were performed using a twin screw extruder, each experiment testing for the effect of different extrusion variables on finished product texture. Reference texture data was measured using a control product currently made in the industry using an alternative batch process. The processing parameters which seemed to have the biggest influence on product quality were high rates of water injection, low feed rate, high reaction zone temperature, reduction of particle size, and the use of functional ingredients in the formula. Technical hurdles such as low dwell times, steam plugging, and inconsistent feeding prevented complete starch gelatinization and the steady state of extrusion. Overall, the high moisture methodology did not yield product quality that was consistent and cannot be recommended for use.

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The procedure currently recommended by the University of Arizona for predicting the nitrogen (N) requirements of durum wheat has proven to be quite accurate at sites where grain yields exceeded 5,400 lbs/acre. However, the method slightly overestimated N needs when the yield possibility was below that level. Additional information on the relationships between N rates, stem NO₃⁻N levels and grain yields are needed for the wide range of agronomic conditions found in Arizona. Three N fertility trials were conducted at the Maricopa Agricultural Center to: 1) document the accuracy of the currently recommended soil + stem NO₃⁻N testing procedure in predicting the N needs of durum wheat on soils of varying residual N content and grain yield potentials; and 2) to evaluate the use of the current stem testing procedure on two durum varieties 'Aldura' and 'Westbred -881. The University of Arizona procedure was found to accurately predict the minimum amount of N required for optimum production of durum wheat on two sites where yield potentials were 5,400 and 4300 lbs. grain /A, but it slightly overpredicted N rates on two sites with maximum yield levels of 5,400 lbs /a. 'Aldura' consistently out yielded 'Westbred -881' by about 12 % but 'Aldura' also averaged 0.78 %lower in grain protein content. Little statistical or practical differences were observed in the quantities of NO₃⁻N contained in the stem tissue of these two varieties, which should simplify the interpretation of stem NO₃⁻N values for various wheat cultivars. The currently recommended procedure for predicting optimum N rates in durum wheat production has proven to be accurate when yield levels exceed 5,400 lbs. grain /A. A slight modification of the procedure may be needed to more closely predict N requirements on lower yielding sites.

The relative efficiencies of residual soil NO₃⁻N and fertilizer Nin basin - irrigated wheat production are not well defined. A two-year field study was conducted at the Safford Agricultural Center to investigate what these N efficiencies are under optimum yielding conditions. 'Aldura' durum wheat was grown on the same field site two years in succession. In 1987 a wide range of fertilizer N (0 to 419 lbs /A) applications resulted in residual NO₃⁻N accumulations of 36 to 140 lbs /A in the surface four feet of soil. Residual N plots were split in 1988 with one subplot receiving no additional N while the other was treated with 145 lbs of fertilizer N /A. Grain yield response curves for the –N and +N subplots were used to estimate the marginal rate of substitution (MRS) of soil NO₃⁻N for fertilizer N. The marginal efficiency of residual NO₃⁻N was a constant 16.7 lbs. grain produced /lb. of N across the range of profile N values in this study, while the marginal efficiency of fertilizer N varied from over 17 to below 6 lbs. grain /lb. N. When basin- irrigated wheat is supplied with adequate, but not excessive N, the MRS of soil vs. fertilizer N is about 1:1 although absolute N efficiencies under basin irrigation are considerably lower than those achieved in other grain production systems.

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Wheat irrigations were scheduled using two computer models and an infrared thermometer using two critical threshold values. Yields from these plots were compared with plots scheduled by the farm manager. The highest yield was obtained by the computer model using evapotranspiration data taken from the local AZMET station; the plots scheduled by the infrared thermometer (using the low threshold value) ranked a close second.