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Cereal Chem. 85(2):218-223The purpose of this study was to determine the effectiveness of dry heat, steam, and microwave treatments in decreasing lipase activity, while retaining antioxidant activity, to stabilize whole wheat flour against lipid degradation during storage. Bran was heat-treated in 230-g batches using four levels (exposure times) for each of the three treatment methods. Lipase activity and antioxidant activity were quantified for all treatment combinations. None of the treatments significantly decreased antioxidant activity; the levels determined to be optimal, inasmuch as further heating did not significantly decrease lipase activity, were 25 min of dry heat, 60 sec of microwave (1000W), and 60 sec of steam. These treatments effectively decreased lipase activity by 74, 93, and 96%, respectively. Optimum treatments were evaluated for acceptance using a consumer sensory panel during a 12-month storage period. No significant differences in acceptance were found between the control and any of the samples either at baseline or after storage. This suggests that whole wheat flour can be stabilized against lipolysis by utilizing the treatments described in this study without decreasing antioxidant activity, and that manufacturers may utilize these treatments without risking decreased consumer acceptance.

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Nixtamalization is the process of steeping dried corn in hot water with calcium hydroxide (lime) with subsequent removal of all or most of the pericarp through washing. The resulting product is called nixtamal. Approximately 60% of corn tortillas in Mexico are produced from nixtamal, with the remainder prepared from nixtamalized corn flour. Nixtamal was fortified with micronutrient premix containing iron, zinc, folic acid, niacin, riboflavin, and thiamin. Premix composition followed a proposed Mexican regulation for corn flour fortification, adjusted for moisture. Effects of premix on masa adhesiveness, hardness, and pH, as well as tortilla sensory properties, stretchability, rollability, and color were measured. Micronutrient levels were tested in the dry corn, nixtamal, masa, and tortillas. There were no significant differences in masa texture or pH, tortilla rollability, or consumer acceptance of tortillas when comparing unfortified control and fortified treatments. Added thiamin was almost entirely degraded during processing. Folic acid and riboflavin decreased 26 and 45%, respectively, through the masa‐tortilla manufacturing process. Niacin showed no significant loss. Despite processing losses, fortification resulted in significant nutrient increases compared with control tortillas. Folic acid increased 974%, riboflavin increased 300%, niacin increased 141%, iron increased 156%, and zinc increased 153% in fortified tortillas.

Fortified blended foods (FBFs) were introduced into the Food for Peace program (also known as US Public Law 480) in the 1960s. Minimal changes have since been made to their formulations. A Food Aid Quality Enhancement Project to assess the nutritional adequacy of FBFs for vulnerable populations was conducted, and the findings indicate that FBFs do not meet the nutritional needs of infants and young children between the ages of 6 and 24 months. Improvements are also needed for FBFs intended for school-aged children and adults. Two separate products would better meet the varying nutritional needs of diverse groups of beneficiaries. Proposed here is a two-step strategy for better addressing the needs of today's food aid beneficiaries: 1) improving FBFs for general distribution to households, schools, and emergency settings, with potential efficiencies gained in manufacturing and formulation to reduce costs; 2) developing new products for infants and young children, which would deliver the nutrient density required for growth and development.

Cereal Chem. 87(5):434-438Degradation of added folic acid and native folates in micronutrientfortified corn masa and tortillas was evaluated using masa prepared from either nixtamalized corn flour or fresh nixtamal. Variations in masa pH, masa holding time at an elevated temperature, and iron source failed to show significant differences in folate loss in corn flour masa prepared in the laboratory. Masa was subsequently prepared from fresh nixtamal in a commercial mill in Mexico, and fortified with one of two different micronutrient premixes containing iron, zinc, B-vitamins, and either unencapsulated or lipid-encapsulated folic acid. Folate loss in commercial masa increased significantly with prebake masa holding time for both premixes. Unencapsulated folic acid showed a 73% loss after 4 hr of holding, compared to 60% loss for encapsulated. The difference was statistically significant, indicating a protective effect from the lipid coating. No significant differences in folate levels were found between prebake masa and baked tortillas. Holding baked tortillas for up to 12 hr also had no effect on folate levels. Native folate showed no significant losses throughout the process. Results from the commercial tortilla mill indicate that most of the loss in added folic acid occurs during prebake holding of masa, possibly from microbial degradation.

The low incidence of intraspecific combat in territorial systems has traditionally been accounted for by theories that emphasize the bio-energetic advantages or the diminished risk of injury of threat display posture when compared with combat. Recently, however, it has been suggested that territory-holding passerines engaging in highly aggressive defensive behaviour are likely to pay a cost in terms of reduced vigilance for avian predators. To examine this further, two defensive options (combat and threat display) were evoked and observed in territorial European Robins Erithacus rubecula , in both winter and summer. It was found that Robins that engaged in combat during simulated territorial intrusion were significantly slower to react to a stuffed Sparrowhawk Accipiter nisus , than those eliciting threat display. Therefore, the decreased vigilance in escalated fighting may result in higher vulnerability to predation, and this might help, in part, to explain why threat display is favoured over direct combat. Moreover, the mean time to evade the predator was significantly longer in summer than in winter in threat-displaying Robins. In addition to this finding, a clear difference in the type of behaviour adopted between the seasons was observed, with lower incidence of combatative response during the winter months. This difference in response to the appearance of a predator is discussed in relation to reduced levels of safe cover, a reduction in the availability of alternative prey during the winter months and to seasonal fluctuations in plasma androgen levels.

Cereal Chem. 85(6):746-752The corn tortilla plays an integral role in the Mexican diet and is an ideal vehicle for micronutrient fortification. Approximately 60% of corn tortillas in Mexico are produced from nixtamal, with the remainder prepared from masa flour. A process for continuous fortification of nixtamal tortillas was evaluated in two commercial mills in Mexico. A commercial powder dosifier was used to add micronutrient premix containing iron, zinc, folic acid, niacin, riboflavin, and thiamin to nixtamal (1 g/kg) as it was milled. After training and preliminary sampling, mills produced fortified tortillas unassisted for four weeks. Masa flow rates over a four-day period were 10-12 kg/min in both plants. Premix flow from the dosifier showed good stability, with an average coefficient of variation of 1.6%. Initial results indicated consistency in the fortification process, with significantly increased variation during the four-week production period. Fortified tortillas had significantly higher levels of all nutrients tested. Micronutrient losses were <11% in all cases except folic acid, which showed an 80% loss. Despite processing losses, fortification resulted in a nearly fivefold increase in folic acid compared with control tortillas. The new fortification process is technically viable and was well received by millers.