Comparison of the processing and quality of tortillas produced from larger grain borer Prostephanus truncatus (Horn.) resistant and susceptible maize genotypes Silverio García-Lara * , Cristina Chuck-Hernández, Sergio O. Serna-Saldivar Centro de Biotecnología-FEMSA, Escuela de Biotecnología y Alimentos, Tecnológico de Monterrey, ITESM-Campus Monterrey, Eugenio Garza Sada 2501, Monterrey, NL C.P. 64849, Mexico article info Article history: Accepted 10 September 2013 Keywords: Larger grain borer Insect-resistant maize Lime-cooking Postharvest losses Tortilla abstract The aim of this research was to compare the processing and quality of tortillas produced from two kinds of larger grain borer (LGB) Prostephanus truncatus (Horn.) damaged kernels: resistant (IRM) and sus- ceptible (ISM) genotypes. The damaged LGB kernels had significant lower test weight, 1000 kernel weigh and density. The ISM kernels were more negatively affected by insects compared with the IRM coun- terpart. A significant reduction of 5% in starch was observed in IRM kernels but not in ISM counterparts. Flour acidity and protein increased 8-fold and 5%, respectively parallel to an augmentation of weight grain losses whereas the crude fat content significantly reduced by 29%. Insect damage enhanced the penetration of the hot lime solution into the starchy endosperm. Insect infested kernels which lost 10% and 20% of their weight required 34% and 42% less lime-cooking time compared to sound kernels. The 10% and 20% insect-damaged kernels lost 15 and 23% of their solids during storage and tortilla pro- cessing, respectively. Finally, LGB damaged kernels reduced substantially the tortilla quality in terms of color. Ó 2013 Published by Elsevier Ltd. 1. Introduction Maize tortillas are considered the most important staple food for the Mexican population. In Mexico, tortillas are consumed by 94% of the population and represent 47% of the average caloric intake and the industrial processing 1% of the gross national product (SAGARPA, 2002). Tortillas and related products, such as tortilla and corn chips, gruels, tamales, among others, are obtained from three different manufacturing processes: traditional, com- mercial fresh-masa and dry-masa flour. Tortilla production efficiency and yield is affected by dry matter losses (DML) incurred during nixtamalization. The most relevant processing parameters that affect DML are lime-concentration and cooking time, steeping time, degree of agitation, and extent of nixtamal washing (Pflugfelder et al., 1988; Sahai et al., 2000). These losses also are affected by major grain properties. It is well known that endosperm texture or hardness, kernel size and ease of peri- carp removal are important traits that affect cooking and DML (Serna-Saldivar et al., 1993). In fact, the use of grain lots with high incidence of stress cracks, broken and damaged kernels increase up to 12% the DML (Jackson et al., 1988). A significant proportion of the damage kernel categories are due to insect pests. This is a major constraint in grain lots because their presence is normed by regu- latory agencies. The Mexican official normativity for white and yellow maize specifies that no more than 3% and 10% of total damage kernels are allowed in order to categorize premium (Mexico-1) and low quality corns (Mexico-4), respectively (SAGARPA, 2002). Furthermore, the maximum allowable amount of insect fragments used as a sanitary indicator is 1 fragment/g of tortilla (SAGARPA, 2002). There are not enough food quality control measurements for the use of damage kernels in small tortilla fac- tories that manufacture more than 60% of the Mexican domestic production (Mery et al., 2010). Recent investigations have documented that grain damage and postharvest losses of maize due to storage insect pests such as the larger grain borer (LGB), Prostephanus truncatus (Horn.) (Coleop- tera: Bostrichidae), are an increasingly important constraint of food security worldwide (Borgemeister et al., 2003; FAO, 2009). Prostephanus truncatus is a woodborer and an invasive post- Abbreviations: DML, dry matter losses; IRM, insect resistance maize; ISM, insect susceptible maize; GWL, grain weight losses; LGB, larger grain borer; RH, relative humidity. * Corresponding author. Tel.: þ52 81 8358 1400; fax: þ52 81 8328 4262. E-mail addresses: sgarcialara@itesm.mx, sgarcialara@gmail.com (S. García-Lara). Contents lists available at ScienceDirect Journal of Stored Products Research journal homepage: www.elsevier.com/locate/jspr 0022-474X/$ e see front matter Ó 2013 Published by Elsevier Ltd. http://dx.doi.org/10.1016/j.jspr.2013.09.002 Journal of Stored Products Research 55 (2013) 99e105