Beatriz Herranz

Different additives to enhance the gelation of surimi gel with reduced sodium content.

This study tested the effect of adding tetra-sodium pyrophosphate, cystine and lysine as surimi gelation enhancers (Alaska Pollock) in order to reduce the sodium content of gels up to 0.3%. These gels were compared with others that contained 3% NaCl content (the amount typically used for surimi processing). To induce protein gelation, gels were first heated and then set at 5 °C/24 h. Once the physicochemical and rheological properties of the gels were determined, cystine and lysine were found to be the most effective additives improving the characteristics of low NaCl surimi gels. The action of these additives is mainly based on the induction of myofibrillar protein unfolding thus facilitating the formation of the types of bonds needed to establish an appropriate network. It was found that a setting period was needed for gel processing to maximize the effect of the additives.

Obtaining a Restructured Seafood Product from Non-Functional Fish Muscle by Glucomannan Addition: First Steps

A procedure for fish minced muscle gelation has been created in order to restructure mince muscle that lacks functionality due to processing. This consists of adding glucomannan, dispersed in water in concentrations of 3–6%, to the mince. Then, 0.6 N KOH is added to bring the pH up to 11.8–12, and the sample is kept at 30°C for 1 h and then at 5°C for 4 h, so that the glucomannan gels with the mince incorporated as a “filler.” This gel is subsequently neutralized by placing it in a buffer. The result is a thermostable gel with the same aspects of raw fish muscle and oral sensory properties similar to those of muscle when both are cooked. Therefore, this gel could be used to mimic muscle fibers or myotomes.

New Alternatives in Seafood Restructured Products.

A general overview, focusing on new trends in the different techniques used in restructured seafood product processing has been described in this work. Heat-induced gelation has been more widely studied in scientific literature than cold gelation technology. This latter technology includes the use of hydrocolloids (alginates and glucomannan) or enzymes (microbial transglutaminase) for making both raw and cooked restructured products. In restructuration processes, fortification processing with some functional ingredients is studied, giving as a result extra value to the products as well as increasing the variety of new seafood products. The process of alleviating heavy metals and organic pollutants from the raw material used has also been reviewed in the present paper.

FIRST STEPS IN USING GLUCOMANNAN TO MAKE THERMOSTABLE GELS FOR POTENTIAL USE IN MINCE FISH REESTRUCTURATION

A methodology for making thermostable konjac glucomannan (KGM) gels was examined with a view to eventual use with fish mince to make restructured products. A gelation method was developed with 3 and 6 % (w/v) aqueous dispersions of glucomannan (ADG) by adding alkali v/v (NaOH or KOH) up to pH 11.8- 12 and then allowing it to set (1 hr at 30ºC and 4 hrs at 5ºC). Both 3 and 6 % are suitable concentrations and KOH and NaOH (at 0.6 and 1M) are the most suitable alkalis for deacetylation of the glucomannan at pH 11.8- 12.0.

Corn starch and egg white enriched gluten-free chickpea flour batters: Rheological and structural properties

ABSTRACT Ten batter formulations were made with different chickpea flour:corn starch (CF:CS) ratios (0:0, 100:0, 75:25, 50:50, and 25:75), with or without partial replacement of whole egg with egg white (EW). EW in control gluten batter (0:0 ratio) and batters made with CS resulted in weaker structured systems. CF-based batters had more viscous behaviour than gluten ones. All batters showed time-dependence which was reduced after shearing. Batter with CF alone (100:0 ratio) without EW had the highest d43, d90, and span values. The 100:0 ratio batters were much more complex structured systems than gluten batters because of their higher protein content.

Rheometric Non-Isothermal Gelatinization Kinetics of Chickpea Flour-Based Gluten-Free Muffin Batters with Added Biopolymers

An attempt was made to analyze the elastic modulus (G′) of chickpea flour (CF)-based muffin batters made with CF alone and with added biopolymers (whey protein (WP), xanthan gum (XG), inulin (INL), and their blends) in order to evaluate their suitability to be a wheat flour (WF) substitute in muffins, and to model the heat-induced gelatinization of batters under non-isothermal heating condition from 25 °C to 90 °C. A rheological approach is proposed to determine the kinetic parameters (reaction order (n), frequency factor (k0), and activation energy (Ea)) using linearly-increasing temperature. Zero-order reaction kinetics adequately described batter gelatinization process, therefore assuming a constant rate independent of the initial G′ value. The change of the derivative of G′ with respect to time (dG′/dt) versus temperature is described by one exponential function with activation energies ranging from 118 to 180 kJ·mol−1. Control wheat gluten batter, with higher and lower starch and protein contents, respectively, than CF-based batters, exhibited the highest Ea value. Formulation of CF-based gluten-free batters with starch and protein contents closer to the levels of WF-based batter could be a strategy to decrease differences in kinetic parameters of muffin batters and, therefore, in technological characteristics of baked muffins.

Association of plasma and urine viscosity with cardiometabolic risk factors and oxidative status. A pilot study in subjects with abdominal obesity

There is increasing interest in the search for accurate, repeatable and widely applicable clinical biomarkers for the early detection of cardiometabolic alterations and oxidative status. Viscosity is a promising tool in that sense, although most studies have used simple viscosimeters, providing limited information, and have not considered oxidative status. The aim of this study was to assess whether viscosity determinations were associated with cardiometabolic and oxidative status in subjects at a primary stage of cardiometabolic risk. A pilot study (n = 20) was conducted in subjects with abdominal obesity, determining urine and plasma viscosity with a rotational rheometer at different shear rates (10000–1000 s–1 in plasma and 1000–50 s–1 in urine). Simple regression showed that urine viscosity was significantly (p< 0.05) associated with markers of oxidative status, and plasma viscosity with blood glucose. Categorical Principal Component Analysis plots showed that urine viscosity measurements at different shear rates clustered in three groups (low, intermediate and high shear rates) were selectively associated with uric acid, polyphenols and antioxidant capacity respectively. Plasma viscosity did not seem to be a relevant clinical marker in subjects with abdominal obesity. Therefore, urine viscosity could potentially serve as a complimentary marker in the evaluation of oxidative status.

Influence of interfacial mechanisms on the rheology of creaming emulsions

ABSTRACT A set of protein-stabilised emulsions at pH 7.0, pH 6.0, and pH 5.0, and their counterpart surfactant emulsions, was designed with near-identical droplet size distribution and phase volume to study the specific contribution of hydrodynamic and pair potential interactions to the interfacial mechanisms of these emulsions systems. In this way, further the interfacial layer of these creaming emulsions to enhance perceived fat content could be manipulated. Creaming behaviour, surface shear, and bulk rheological measurements were performed. This work reflects the great importance of local pair potential in the formation of a highly viscoelastic interfacial film, which could be manipulated changing the surface charge of the protein to develop a well-packed cream layer in the protein-stabilised emulsions.

End‐product quality characteristics and consumer response of chickpea flour‐based gluten‐free muffins containing corn starch and egg white

The objective of this work was to study changes in technological characteristics and sensory properties of gluten-free muffins when using chickpea flour (CF) alone and/or with partial CF replacement by corn starch (CS). The effect of partial whole egg replacement by egg white (EW) was also investigated. Four different CF:CS ratios (100:0, 75:25, 50:50, and 25:75) were used in formulations with and without incorporated EW, and compared with wheat flour (WF) muffins (0:0). Muffins prepared from CF alone had lower hardness, springiness, cohesiveness, chewiness, and resilience than control ones. However, reducing protein content by CS addition significantly increased texture profile analysis parameters of muffin crumb. Muffins prepared with 25:75 ratio had a structure with springiness similar to muffins made with WF but were too hard. Reducing whole egg content by partial replacement with EW also significantly increased muffin hardness. Flash profile performed by consumers showed a clear discrimination of muffins according to CF:CS ratio. Muffins containing both CF and CS at 50:50 ratio had the same high overall acceptability and purchase intention as gluten ones. Gluten-free CF-based muffins of satisfactory quality can be manufactured by CS incorporation, either with or without EW. PRACTICAL APPLICATIONS By decreasing and increasing protein and starch contents of chickpea flour (CF) by incorporation of corn starch (CS), muffins formulated from a combination of CF and CS at different CF:CS ratios, either with or without partial replacement of whole egg with egg white, result in high-quality muffins with similar technological and sensory characteristics to those of their gluten counterparts. Sensory overall acceptability and purchase intention of muffins made with a 50:50 ratio did not differ significantly from those of the controls. These findings will benefit celiac population, while promoting the value and utilization of pulses through muffins.

Structural and rheological properties of weakly deacetylated glucomannan gels after high-pressure treatment

ABSTRACT Native glucomannan (Lot A; pH = 5.3) and weakly deacetylated glucomannan (Lot L; pH = 9.1) gels were subjected to high hydrostatic pressure (HHP): 100, 200, 400, and 600 MPa and studied the influence of HHP on the structural and rheological properties of glucomannan gels. HHP improved the conformational stability, reticular deformability and the energy stability of hydrogen bonds in junction zones of the glucomannan matrix for lot A gels. For lot L gels, 600 MPa was needed to increase the energy content of physical bonds enhancing the solid-like character of the glucomannan matrix. Thermal profiles of pressurized lot A gels exhibited thermophobic behaviour and increased the gel-like character up to 90°C as compared with its unpressurized control. For Lot L gels, the rubber-like response was also shown at T > 70°C for the unpressurized sample, and was maintained at 100, 200, and 600 MPa.