Corn Characterization and Development of a Convenient Laboratory Scale Alkaline Cooking Process

Nixtamalized (alkaline cooked) corn (Zea mays L.) products are increasing in popularity due to their affordable cost, ease of production, and the diversity of products that can be made using similar unit operations. The nixtamal produced after alkaline cooking depends on the processing parameters used during cooking and steeping, as well as the physicochemical properties of the corn hybrids used. Processors incur high costs in narrowing down hybrids suitable for a given process, or they must be able to adjust cooking conditions to obtain the desired end-product characteristics. Improper processing generates large quantities of waste. Researchers have developed small scale cooking procedures that can mimic industrial nixtamalization process. Many of these methods, however, still require significant quantities of grain, such that the screening processes are expensive. The primary aim of this study was to develop a small scale bench top method with 100 g corn, using simple apparatus that can be used to analyze multiple samples at a time. The method was compared to a previously established 500 g method using a range of commercially used cook times, steep times and cook temperatures. Previous studies on relating physico-chemical parameters and nixtamal characteristics have concluded that it is essential to cook corn, at least in small quantities, to understand how corn will process when nixtamalized. The results indicate that the 100 g method can replicate industrial cooking process at a range of processing conditions as the intercept and slopes for response surface models were not significantly different (p \u3c 0.05). The second aim of this study was to understand the effect of physicochemical properties of nine different hybrids, grown in the same season on nixtamal characteristics using the 100 g cooking method. The study found regressions for dry matter loss with thousand kernel weight and kernel calcium content (r2 = 0.98) and for nixtamal moisture with test weight (r2 = 0.52) when corn was cooked for 25 min and steeped for 12 h. Consistent with previous studies, this study found that no one grain parameter can predict all nixtamalized corn properties, confirming the need to cook corn to best understand its potential alkaline cooking performance. Advisor: David S. Jackso