Alberto Tecante

Thermal and physicochemical properties and nutritional value of the protein fraction of Mexican chia seed (Salvia hispanica L.).

Thermal, functional and nutritional properties of the main protein fractions and a protein isolate of chia seed from the state of Jalisco, Mexico, were studied by differential scanning calorimetry, gelling, foaming, water-holding capacity (WHC) and oil-holding capacity, amino acid profile, chemical score and in vitro digestibility tests. The protein isolate showed good WHC (4.06 g/g) and excellent oil-retention capacities (4.04 g/g), making it attractive as an additive in bakery products and food emulsions. It also contained high amounts of glutamic acid (123 g/kg raw protein), arginine (80.6 g/kg raw protein) and aspartic acid (61.3 g/kg raw protein). However, its essential amino acid profile showed deficiencies with respect to the 1985 standard of the FAO/WHO/UNU for pre-school children. Therefore, its use as a sole protein source is not recommended; supplementation with a lysine-rich source would be necessary, as this was the limiting amino acid.

Mixing performance induced by coaxial flat blade-helical ribbon impellers rotating at different speeds

The mixing performance (pumping, dispersion capabilities, power consumption) of a new dual impeller mixer composed of a disc turbine and a helical ribbon impeller mounted on the same axis but rotating at different speeds is investigated. The methodology is based on a blend of experimental measurements and 3D numerical simulations in the case of Newtonian and non-Newtonian shear-thinning fluids. It is shown that the dual impeller mixer outperforms the standard helical ribbon in terms of top-to-bottom pumping when the fluid rheology evolves during the process. The power consumption of this new mixer is also studied which allows to derive a generalized power curve.

Chemical Characterization of the Lipid Fraction of Mexican Chia Seed (Salvia hispanica L.)

The lipid fraction of Jalisco and Sinaloa chia seeds was analyzed for oil content, fatty acids, squalene and phytosterols. The mean oil content of seeds from these two regions was significantly (p ≤ 0.05) different, but with a similar composition of α-linolenic, linoleic, oleic, palmitic and stearic acids. Total phytosterols in the oil ranged from 7 to 17 g/kg. β-sitosterol accounted for up to 74% of the total unsaponified fraction. The seeds contained less than 0.5 g/kg of squalene. The oil is an attractive source of ω-3 linolenic acid and phytosterols but a poor source of squalene.

Mixing Time in Rheologically Evolving Model Fluids by Hybrid Dual Mixing Systems

Mixing time experiments were performed using a hybrid dual mixing system, which included a helical ribbon impeller (HR) and either a Smith (ST) or Rushton turbine (RT). Xanthan gum solutions were used as rheologically evolving fluids to evaluate changes in mixing time under non-aerated and aerated conditions. The helical ribbon agitator and turbine of the hybrid dual mixing system was kept at a constant rotational speed ratio, N T /N HR =10. Experiments showed that performance of the hybrid mixing system was superior to that of the individual impellers. Flow properties and gassing conditions played an important role in mixing time. While mixing time was practically identical under non-gassed conditions for both the ST-HR and RT-HR mixing systems in low-viscosity fluids, differences up to 1000% were observed in high shear-thinning fluids. In these fluids, the RT-HR combination exhibited better performance than the ST-HR. In high-viscosity fluids, gassing enhanced mixing time particularly when the ST-HR hybrid system was used. Both mixing systems showed similar mixing times under the highest gassed condition evaluated in this work.

Power consumption of a dual turbine-helical ribbon impeller mixer in ungassed conditions

Abstract Ungassed power measurements in a dual coaxial mixer composed of a helical ribbon and a Rushton turbine were carried out in laminar mixing conditions for Newtonian and non-Newtonian shear thinning fluids. For the Newtonian case, the power draw constant Kp for the hybrid geometry was not the sum of the individual impellers. This was explained by considering the radial discharge flow in the turbine region as well as the top-to-bottom circulation pattern of the helical ribbon impeller. For the non-Newtonian fluids, the results showed that, at a given Reynolds number, power consumption decreases as the shear thinning behaviour increases. A dimensionless and unique representation of the power draw data was obtained by shifting the non-Newtonian power draw results to the Newtonian curve. This was carried out with a Ks function defined from the Kp(n) data. The predictions for Ks were found to be in good agreement with those obtained using the classical method of A.B. Metzner and R.E. Otto (AIChE J., 3 (1957) 3–10). It was observed that pseudoplasticity tends to shift the upper limit of the laminar region toward Reynolds numbers higher than 10.

Flow patterns in rheologically evolving model fluids produced by hybrid dual mixing systems

The flow patterns produced by two dual mixing systems composed of independently driven impellers were studied. The dual impellers included a turbine rotating at high speed (Rushton or Smith) and a slowly rotating helical ribbon agitator (HR). Visualizations and power input were used to evaluate mixing performance. The influence of the rotational speed ratio on the flow patterns was evaluated. For high shear-thinning fluids, N T /N HR modifies the flow patterns considerably. Three typical behaviors were found with shear thinning fluids: segregation of two principal flow patterns (N T /N HR 10), and a well-distributed flow pattern throughout the tank (N T /N HR =10). For low-viscosity fluids, the motionless HR reduced the vortex length and the T-HR systems eliminated vortex when the impellers rotated in opposite directions at N T /N HR =10. Finally, a relationship between the dimensionless vortex length and the Froude number is proposed for individual turbines as well as for the turbine-motionless HR systems.

Chia (Salvia hispanica): A Review of Native Mexican Seed and its Nutritional and Functional Properties.

In this chapter, a review is made on various aspects of chia seed in order to provide an overall, yet comprehensive view, about this important commodity with the aim of updating the current state of knowledge on its composition, possible nutraceutical properties, and potential benefits for human health. Based on this approach, the discussion includes some comments on the main historical aspects, morphology of the seed, its importance in the diet of humans and stresses the main results issued from investigations on its three main components; lipid, protein, and fiber. The chapter closes with a discussion on the potential benefits for human health, highlighting the contradictions that still exist in this area and the need for continued research in this direction and considerations on the role of chia seed as a functional food.

Lipase-catalyzed synthesis of hyperbranched poly-L-lactide in an ionic liquid

Hyperbranched poly-l-lactides have been synthesized by eROP in [C4MIM][PF6] media. The bis(hydroxymethyl)butyric acid molecule was used as the AB2 core co-monomer and immobilized lipase B from Candida antarctica as biocatalyst. The degree of branching could be controlled by the reaction conditions, with the maximum achieved being 0.21. The successful achievement of the hyperbranched structure is attributed to the high solvent power of substrates and products in the ionic liquid besides sustained lipase activity.

Chia (Salvia hispanica)

In this chapter, a review is made on various aspects of chia seed in order to provide an overall, yet comprehensive view, about this important commodity with the aim of updating the current state of knowledge on its composition, possible nutraceutical properties, and potential benefits for human health. Based on this approach, the discussion includes some comments on the main historical aspects, morphology of the seed, its importance in the diet of humans and stresses the main results issued from investigations on its three main components; lipid, protein, and fiber. The chapter closes with a discussion on the potential benefits for human health, highlighting the contradictions that still exist in this area and the need for continued research in this direction and considerations on the role of chia seed as a functional food.

Solution Properties of κ-Carrageenan and Its Interaction with Other Polysaccharides in Aqueous Media

Carrageenans are an important class of hydrophilic sulfated polysaccharides used as thickening, gelling and stabilizing agents in a great number of foods such as sauces, meats and dairy products. In frozen foods its high stability to freeze-thawing cycles is very important. They are also responsible of the smoothness, creaminess, and body of the products to which they are added. Its combination with starch allows different textures to be obtained and reductions in fat content of up to 50%.The commercially important forms are kappa (κ), iota (ι) and lambda (λ). κ-carrageenan, consists of an alternating linear chain of (1→3)-β-D-galactose-4SO3--(1→4)-3,6, anhydro-α-D-galactose. It is soluble in hot water (> 75 °C) and even low concentrations (0.1 to 0.5%) yield high viscosity solutions. Viscosity is stable over a wide pH range, because the semi-ester sulfates are always ionized even under strongly acidic conditions. κ-carrageenan can adopt different conformations in solution, e.g. random coil and double helix. Therefore, its rheological behavior is strongly affected by the total ionic concentration, temperature and ion content of the system.