Influence of Added Soy Presscake and Soy Flour on Some Physical and Sensory Properties of Corn Tortillas

Reduced in vitro starch hydrolysis and in vivo glycemic effects after addition of soy presscake to corn tortillas

BACKGROUND

Chronically elevated blood glucose leads to development of prediabetes and type 2 diabetes, as well as increased risk for heart and kidney disease and vision loss. For many, elevated blood glucose can be managed through diet and exercise. Consequently, the availability of foods that limit blood glucose elevation would aid in addressing this global problem. This paper investigated the effect of adding soy presscake (SP) to corn tortillas on starch hydrolysis in vitro as well as the glycemic responses elicited in vivo upon consumption of these modified tortillas.

RESULTS

SP in corn tortillas decreased the rate and extent of starch hydrolysis in vitro. The in vivo glycemic index (GI) values decreased from 43 for corn control tortillas to 31 with 40% SP fortification. A high correlation (r = 0.9781) was found between the GI values from in vivo analysis and the area under the curve of starch hydrolysis in vitro. The best correlations (r > 0.96) between GI and degree of hydrolysis were found at 45-90 min of in vitro starch hydrolysis.

CONCLUSIONS

Incorporating SP into corn-based tortillas lowers glycemic responses to them. In addition, in vitro starch hydrolysis could be used to estimate the GI values of food products and, in particular, the comparison of multiple items during food product development. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Quality Parameters of Masa and Tortillas Produced from Blue Maize (Zea mays sp. mays) Landraces

There is increasing interest in the production of landrace blue maize varieties for the production of traditional foods and for specialty (noncommodity) products. Most varieties have soft (floury) endosperm and their suitability for thermo-alkaline processing is not known. We examined the physical and functional properties of eight floury varieties with those of three dent and one flint variety for masa and tortilla production. Results revealed high variability in physical properties of kernels. Significant differences (P < 0.05) were observed in kernel, flour, masa, and tortilla color. The softer kernels of blue maize varieties had lower (P < 0.05) cooking times during nixtamalization than those of denser kernels. The results showed variation among varieties (P < 0.05) in the kernel, masa, tortilla hardness, as well as in extensibility of the tortillas. Nixtamalization affected (P < 0.05) masa color, resulting in reduced yellow and reddish tones. The gelatinization temperature was the same (P > 0.05) in all studied landraces for the flour and the masa. The enthalpy was affected (P < 0.05) by the landrace analyzed for starch gelatinization (P > 0.05). The landraces studied showed similar (P > 0.05) starch gelatinization and denaturation temperatures. The storage modulus (G'), loss modulus (G''), and the temperature (TG') of flour and masa-dough were different (P < 0.05) among different varieties. Southwestern floury varieties can be cooked during nixtamalization for shorter periods than flint and dent varieties to obtain comparable tortilla quality. PRACTICAL APPLICATION: Southwestern blue floury maize varieties are suitable for nixtamalized tortilla production. Variation between varieties was observed for quality parameters. Floury varieties require shorter cooking time but it is recommended that nixtamalization parameters be optimized.

National School Lunch Nutrition and Cost Profile: A Case Study of the Ghana School Feeding Programme

Numerous governments in developing countries institute school lunch programs or school feeding programs as a strategy to address high malnutrition and low education rates among children. In 2005, the Ghanaian government launched the Ghana School Feeding Programme (GSFP). The GSFP policy does not document (1) the actual meal and associated nutrient profile received by the student, (2) the cost of the meal ingredients to the caterer who prepares the food, nor (3) the recipe derivations that may supply an enhanced nutritional profile. We address these 3 information gaps by employing a detailed case study of 4 caterers supplying a traditional tomato stew recipe in northern Ghana within GSFP-supported school lunch programs. Specifically, we explore the following propositions: (1) GSFP caterers can deliver a school lunch for under 100 pesewas (1 GH¢ or $0.21 USD) per student; (2) the meal meets the recommended daily allowance for protein; (3) soy can serve as a cost-effective ingredient to fortify the meal in terms of protein level and protein quality; and (4) significant differences exist in the macro- and micronutrient profile due to caterer discretion. We answer the above 4 propositions, and by doing so show the importance of accurately measuring the nutritional content, costs, and quantities of the actual school lunch under study. Second, among our results, we show the economy of locally produced soy flour as an ingredient that can lower costs and raise nutrition when substituting for other locally produced proteins such as ground beef and mackerel.