Aurelio Dominguez-Lopez

Oaxaca cheese: flavour, texture and their interaction in a Mexican traditional pasta filata type cheese

Oaxaca cheese is classified as a pasta filatacheese and it is considered as an unavoidable ingredient in broad varieties of Mexican recipes. It is produced in many regions by industrial companies but mainly by handmade procedures. It is thought that its flavour and texture profiles could be recognized by consumers even if traditional production processes are not standardized, so this study is intended to define its flavour and texture profiles and the relationship between them considering the variability given by its handmade character. The origin of the milk has a major contribution to define the flavour explaining about 51.9% of the variance. Sensory hardness, cohesiveness, chewiness and springiness were highly correlated (0.6–0.83). Texture and flavour, as multivariate variables, are linearly dependent with a high canonical correlation (0.966) as well.

Electron paramagnetic resonance study of hydrogen peroxide/ascorbic acid ratio as initiator redox pair in the inulin-gallic acid molecular grafting reaction

Gallic acid (GA) was grafted onto inulin using the free radicals method, generated by the hydrogen peroxide/ascorbic acid (H2O2/AA) redox pair. Molar ratios of H2O2/AA at 9, 20, 39 and 49 were evaluated by Electron Paramagnetic Resonance in order to find the effect of the oxidation of the inulin and the efficiency in the inulin-gallic acid grafting (IGA). The highest concentration of the inulin macro-radical was obtained with H2O2/AA molar ratios of 20 and 49 with the removal of a hydrogen atom from a methyl group of the inulin fructose monomers. The highest grafting ratio (30.4 mg GA eq/g IGA) was obtained at 9 M of H2O2/AA. UV-Vis, FT-IR-ATR and XDR results confirmed a successful IGA grafting. The efficiency of the grafting reaction depends on the concentration of the macro-radical, it depends on the molar ratio of H2O2/AA, being affected by simultaneous reactions between components of the mixture (H2O2, AA, inulin, GA and eventually atmospheric oxygen) as well.

Effect of lactic acid bacteria on the textural properties of an edible film based on whey, inulin and gelatin

This study was aimed to evaluate the effects of different components and the addition of probiotic bacteria of lactic acid bacteria (LAB, Lactobacillus casei) on the physicochemical and textural characteristics of edible films using a response surface Box-Behnken design. The edible films were made of the following components: Whey (8%), glycerol (6%), inulin (0 to 4%), gelatin (2 to 5%) and probiotics (0 to 2%). The addition of LAB significantly affected the pH, viscosity, luminosity, hardness and Youngs modulus of the films. However, all formulations presented physicochemical and textural characteristics suitable for the survival of lactic acid bacteria during storage. Formulas 10 and 3 with a composition of 2% inulin, 3.5% gelatin and 1% probiotic, demonstrated higher responses to pH, viscosity, luminosity, hardness and Youngs modulus, whereas formulas 14 and 12 exhibited lower responses to the above-mentioned features but proved the most resilient. Therefore, edible films with added probiotic bacteria could be applied to a variety of foods and to increase consumer choice.

Evaluation of physicochemical, functional and textural properties of rainbow trout (Oncorhynchus mykiss) stored at low temperatures

The physicochemical and functional behaviour of rainbow trout stored at 4 and -20°C for nine days and six months, respectively, were investigated. The combined effect of proteolytic activity and physicochemical changes in the muscle (pH, solubility and proteolytic activity) altered the molecular structure of the proteins. SDS-PAGE showed the degradation of myosin and the formation of peptides of low molecular weight, causing an increase in solubility, which is correlated with changes in the functional properties of meat (water retention, capacity of emulsification and ability of gelling). In a gel obtained from the stored samples, the solubility had an effect on the distribution of the water gel, and significant differences (P<0.05) in colour and texture parameters were observed during storage. Regarding correlation analysis, during cooling, all variables studied were dependent on each other, however, in freezing, the correlation diminished in variables such as hardness, solubility and CRA. Surplus meat of trout according to the time of cold storage, can be incorporated into technological processes up to two days at a storage temperature of 4°C and three months at - 20°C, thus could contribute to the functional and textural properties of commercial meat products, generating a value liked trout producers. After this time of storage, the trout flesh can be consumed in the conventional way. Keywords: Rainbow trout, refrigeration, freezing, texture. African Journal of Biotechnology Vol. 12(32), pp. 5087-5096

Effect of Edible Coating Based on Whey, Inulin and Gelatine with Lactobacillus casei on the Textural and Sensorial Properties of a Cracker Cookie

The objective of this work is to demonstrate the feasibility of the application of an edible coating based on inulin (IN), gelatine (GE), whey (WH) and glycerol (GLY) with added with Lactobacillus casei Shirota (LBC) and its effect on the characteristics of texture, moisture and colour of cracker cookies. A randomised design with two factors (applied volume and period of storage) with seven different formulations and a control derived from a previous experimental study were applied. The components of the formulations were IN, GE, WH, GLY and LBC. The blend of these ingredients was applied by spraying in 1 and 2 mL proportions on cracker cookies stored at 25°C for 20 days. The three-point break method was used. The percentage of moisture and colour change was measured. To verify the survival of LBC, the standard plate count method and scanning microscopy (SEM) were used. In addition, affective sensory tests were performed. Determinations were performed in triplicate at 3, 10, 15 and 20 days of storage. The application of an edible coating with LBC to cracker cookies significantly increased (p<0.05) moisture 1.5% compared with the control, whereas the maximum strength to breaking decreased significantly (p<0.05) by 1-2 N on average. There was no significant colour change, and the observed survival of LBC by SEM and growth in CFU/g in t15, OFZ and OMY formulations during 20 days of storage. In acceptance testing, the cookie was moderately liked by 49% of tasters, whereas only 4% of tasters referred to the cookie as disgusting him. These findings suggest that the use of IN 4%, GE 3.5% and LBC 2% coatings will maintain the cracker cookie’s quality and lead to better acceptance by consumers, providing an alternative for the consumption of LBC.

Color, phenolic composition and antioxidant activity of blue tortillas from Mexican maize races

ABSTRACT Cereal products made from pigmented grains are attractive to consumers. We determined the variability in color, phenolic composition and antioxidant activity (AA) of blue tortillas made from 18 landraces belonging to three blue/purple grained Mexican maize races – Chalqueño (Chal), Elotes Cónicos (Ec) and Bolita (Bol). The color of the tortillas produced ranged from yellow-green to blue-green. Ec tortillas were the only true blue type. Total anthocyanin content (TAC) varied between 3.67 and 1.11 mg equivalents of cyanidin 3-glucoside/kg dry weight (DW). Total soluble phenolics (TSP) were between 9.42 and 5.16 mg equivalents of gallic acid/kg DW. AA was highly correlated (p < 0.01) with TAC, but not with TSP. Blue Ec tortillas had the highest AA, and Bol tortillas had the lowest AA. Color parameters, TSP and TAC allowed the appropriate grouping of blue tortillas according to the maize race they belong to and were made from.