Marcela Gaytán-Martínez

Resistant Starch Formation in Tortillas from an Ecological Nixtamalization Process

The objective of this work was to study the formation of resistant starch (RS) in tortillas from an ecological nixtamalization process compared with the traditional nixtamalization process. The RS increased through all the steps of tortilla production. It was found that the increase of the RS corresponds mainly to the formation of RS5 (V-amylose-lipid complex), but in tortillas two major types of RS coexist: RS5 and RS3 (retrograded starch). In general, tortillas from the ecological nixtamalization process gave higher values of protein, lipids, total dietary fiber, insoluble fiber, soluble fiber, and RS compared with tortillas from the traditional nixtamalization process and commercial flour. The highest glycemic index (GI) occurred in the tortillas from commercial flour, whereas tortillas from 0.4% CaCO3 and 0.6% CaSO4 were classified as medium-GI (GI 50–70). Tortillas from 0.6% CaCl2 had the lowest value of GI. The ecological nixtamalization processes caused significant differences in quality and nutrit...

Physico-chemical properties and quality assessment of corn flour processed by a continuous ohmic heating system and traditional nixtamalization

Traditional nixtamalization is performed to produce corn flour and tortillas. This process has undergone several modifications for industrialization purposes. Extrusion is an industrially used process for nixtamalization and ohmic heating may be considered an alternative. For this study, a continuous ohmic heater was used to produce nixtamalized corn flour and the effects of the process parameters – process temperature, feed moisture, and screw speed – on the physicochemical and textural properties of dough and tortilla were reviewed. Data showed that the process temperature had a greater effect than the feed moisture on the resulting product, while screw speed did not appear to have any significant influence on this. Tortillas showed good quality characteristics because of good water absorption and retention during the process. The products obtained by continuous ohmic heating process show quality characteristics similar to those present in traditional corn flour products.

Bioaccessibility and antioxidant activity of free phenolic compounds and oligosaccharides from corn (Zea mays L.) and common bean (Phaseolus vulgaris L.) chips during in vitro gastrointestinal digestion and simulated colonic fermentation

Corn (Zea mays L.) and common beans (Phaseolus vulgaris L.) are alternative suitable ingredients for snacks, because of their content of bioactive compounds such as phenolic compounds (PC) and oligosaccharides (OS). However, there is no information about the transformation of these compounds associated with food matrix during gastrointestinal digestion. Therefore, the objective of this work was to simulate the whole digestion process (mouth to colon) to estimate bioaccessibility and small intestine permeability of free PC and OS, and the antioxidant capacity of free PC. Digested nixtamalized corn-cooked common bean chips exhibited significant different quantities of free PC and OS, and higher antioxidant activity compared to methanolic extract. The free PC showed high values of apparent permeability coefficients (0.023-0.729×10-3), related with their absorption in the small intestine. Both free PC and OS were retained in the non-digestible fraction of chips (10.24-64.4%) and were able to reach the colon. Our results suggest the digestion potential to increase chip bioactive compounds and antioxidant activity. Additional studies are required to evaluate their in vivo effects.

2-Furoylmethyl amino acids as indicators of Maillard reaction during the elaboration of black garlic

This study reports the formation of 2-furomethyl-amino acids (2-FM-AA) as indicators of Maillard reaction (MR) in black garlic elaboration, followed by the determination of furosine by ion-pair RP-HPLC-UV. The method was assessed for accuracy, repeatability and detection and quantitation limits indicating its adequacy. Traditional procedure of black garlic obtainment and the inclusion of convective drying (CDP) and ohmic heating (OHP) were assayed. For comparison purposes, three commercial black garlic samples were used. Together with furosine (2-FM-lysine), 2-furoylmethyl-γ-aminobutyric acid and 2-FM-arginine were detected. Levels of furosine were higher in CDP (46.6-110.1mg/100g protein) than in OHP (13.7-42.0mg/100g protein) samples, probably due to the most severe processing conditions used in the former. These results highlight the suitability of 2-FM-AA as chemical indicators to monitor the process of black garlic elaboration in order to obtain high quality products.

Propiedades funcionales de harinas de maíz nixtamalizado obtenidas por extrusión a baja temperatura

The aim of this work was to study the effect of temperature on the functional properties of extruded corn flours compared to a flour produced by means of a traditional nixtamalization process. The extrusion treatments were as follows: temperature of 70°C, 75°C, and 80°C; moisture content of 45%, 55%, and 65% w/w; and particle size of 500, 800, and 1300 µm. According to the ANOVA, the temperature significantly affected the functional properties: the water solubility index (WSI), the water absorption index (WAI), adhesion, and relative viscosity. A temperature lower than 80°C favors high viscosity and suitable texture. The principal component analysis revealed that flours with a particle size of 1300 µm have pasting properties that are similar to those of nixtamalized flour, but with a high degree of retrogradation. The flour extruded at 75°C, with 800 µm particle size, and 45% moisture content showed WSI, WAI, and texture similar to those of nixtamalized corn flour, but with a lower viscosity.

Relationship Between Electrical Conductivity and Water Activity of Starch-Water Composites

When electrical conductivity (EC) is studied in food hydrocolloids, such as starch, molecular structure is important because conductivity depends on the interaction of water with charged carboxyl group or hydroxyl groups (Marcotte et al. 1998). Several authors have found that EC of starch-water composites increases with temperature and decreases during starch gelatinization (Wang and Sastry 1997; Karapantsios et al. 2000; Li et al. 2004). This behavior is explained considering granule swelling, increase of viscosity, and reduction of the area for starch particle movement. Decreasing water content in the material decreases EC (Lewicki Piotr 2004).

In vitro health promoting properties of antioxidant dietary fiber extracted from spent coffee ( Coffee arabica L.) grounds

Antioxidant dietary fiber extracted from spent coffee grounds (FSCG) was evaluated as a potential functional food ingredient when incorporated in a food model (biscuits), and digested in vitro under simulated human gastrointestinal conditions. FSCG added to biscuits increased its total dietary fiber, antioxidant capacity after in vitro digestion, bioaccessibility of phenolic compounds (gallic acid and catechin) and amino acids. Furthermore, advanced glycation end products (AGEs), involved in chronic diseases, decreased up to 6-folds in the biscuits containing FSCG when compared with the traditional biscuit. The digestible fraction of biscuits containing the highest amount of FSCG (5 g) displayed the higher inhibiting α-glucosidase activity, correlating with the bioaccessibility of ascorbic acid and catechin. Our study seems to indicate that anti-diabetic compounds may be released in the small intestine during FSCG digestion, where biscuits containing FSCG may be able to beneficially regulate sugar metabolism thereby helping in producing foods friendly for diabetes.