Gels of carrageenan-caprine whey protein concentrate: A physicochemical study.

Mixed gels of carrageenan (Car) and caprine whey protein concentrate (WPCc) (pH 7) were studied and compared with those prepared with Car and commercial bovine whey protein concentrate (WPCb). Dynamic rheology studies indicate that gels with WPCc were weaker (lower G') than those made with WPCb. However, textural parameters such as, hardness, springiness and cohesiveness were similar in both type of gels. The addition of CaCl2 incremented the elastic modulus (G'), hardness and adhesiveness of gels. The samples with caprine whey showed higher water holding capacity than samples with bovine whey. Confocal laser scanning microscope images of the gels, showed very different aspects according to the type of WPC used: WPCc-Car gels exhibited aggregates of proteins that interrupt the carrageenan network, while WPCb-Car gels showed a homogeneous appearance with proteins distributed throughout all the matrix.

Rheological and Structural Study of Salmon Gelatin with Controlled Molecular Weight.

This study explores the molecular structuring of salmon gelatin (SG) with controlled molecular weight produced from salmon skin, and its relationship with its thermal and rheological properties. SG was produced under different pH conditions to produce samples with well-defined high (SGH), medium (SGM), and low (SGL) molecular weight. These samples were characterized in terms of their molecular weight (MW, capillary viscometry), molecular weight distribution (electrophoresis), amino acid profile, and Raman spectroscopy. These results were correlated with thermal (gelation energy) and rheological properties. SGH presented the higher MW (173 kDa) whereas SGL showed shorter gelatin polymer chains (MW < 65 kDa). Raman spectra and gelation energy suggest that amount of helical structures in gelatin is dependent on the molecular weight, which was well reflected by the higher viscosity and G' values for SGH. Interestingly, for all the molecular weight and molecular configuration tested, SG behaved as a strong gel (tan δ < 1), despite its low viscosity and low gelation temperature (3-10 °C). Hence, the molecular structuring of SG reflected directly on the thermal and viscosity properties, but not in terms of the viscoelastic strength of gelatin produced. These results give new insights about the relationship among structural features and macromolecular properties (thermal and rheological), which is relevant to design a low viscosity biomaterial with tailored properties for specific applications.

Formulation and attributes of gluten-free cakes of Andean corn improved with green banana flour.

The aim of this work was obtaining layer and sponge cakes formulated with corn flour replaced by green banana flour and to determine the best substitution proportions to achieve nutritionally improved products and with texture and sensory characteristics acceptable. The replacement of corn flour by GB flour increased the density in layer cake batters, while in sponge cake batters the density decreased. The batters were influenced by the increase in the flow properties, the viscoelastic behaviour, and the decrease in the thixotropic properties. The thermal analysis of batters determined a partial gelatinization of the starch, which together with its rheological properties influenced the cakes' texture parameters. The substitution of 30% corn flour by GB flour in sponge and layer cakes produced a decrease in cohesiveness and an increase in hardness. In sponge cakes, incorporation of up to 30% of GB flour improved the sensory attributes and the textural properties, while in layer cakes a 30% substitution did not significantly deteriorate the quality of cakes.

Lactic Acid Fermentation Improved Textural Behaviour, Phenolic Compounds and Antioxidant Activity of Chia (Salvia hispanica L.) Dough.

In this work, autochthonous lactic acid bacteria (LAB) were isolated from chia (Salvia hispanica L.) dough and selected on the basis of the kinetics of acidification and proteolytic activity. Strain no. C8, identified as Lactobacillus plantarum C8, was selected and used as starter to obtain chia sourdough. Lactic acid fermentation increased the organic acid mass fractions (lactic, acetic and phenyl lactic acids to 12.3 g, 1.0 g and 23.8 µg per kg of dough respectively), and antioxidant activities, which increased by approx. 33-40% compared to unfermented chia flour dough. In addition, total phenolic content increased 25% and its composition was strongly modified after 24 h of fermentation by L. plantarum C8. Chlorogenic acid was only found in the fermented dough (2.5 mg/g), while ferulic acid was detected from the beginning of fermentation, being 32% higher in chia sourdough (5.6 mg/g). The use of fermented chia sourdough improved the overall characteristics of white bread, including physical (e.g. reduced hardness and chewiness of the crumb) and antioxidant properties (25% on average), compared to the white bread. These results indicate that the use of chia sourdough could be a promising alternative to improve the technological and antioxidant properties of wheat bread. In addition, this work has shown, for the first time, that lactic acid bacterium is able to ferment chia dough, improving its overall characteristics.

Encapsulating betalains from Opuntia ficus-indica fruits by ionic gelation: Pigment chemical stability during storage of beads.

Betalain encapsulation was performed by ionic gelation as a stabilization strategy for these natural pigments. Betalains were extracted from purple cactus fruits and encapsulated in calcium-alginate and in combination of calcium alginate and bovine serum albumin. Beads were characterised by scanning electron microscopy and thermal analysis using differential scanning calorimetry and thermogravimetry. Moisture sorption isotherms were determined. Bead morphology was affected by matrix composition. Pigments storage stability was evaluated at different equilibrium relative humidity and temperatures. Pigment composition of beads was determined by HPLC-MS-MS and degradation products were also analysed after storage; betalamic acid being the major one. Both types of matrices protected the encapsulated pigments, being their storage stability better at low relative humidity than that of the non-encapsulated control material. Antiradical activities of beads were proportional to remaining betalain contents. At high relative humidity, there was no protection and low storage stability was observed in the samples.

Microencapsulation of betalains obtained from cactus fruit (Opuntia ficus-indica) by spray drying using cactus cladode mucilage and maltodextrin as encapsulating agents.

The microencapsulation of betalains from cactus fruit by spray drying was evaluated as a stabilization strategy for these pigments. The betalains used as active agent were extracted from purple fruits of Opuntia ficus-indica (BE) and encapsulated with maltodextrin and cladode mucilage MD-CM and only with MD. The microcapsulates were characterized by scanning electron microscopy (SEM), thermal analysis (TGA-DSC), tristimulus colorimetry, as well as, their humidity, water activity and dietary fiber content were also determined. The active agent content was measured by UV-Vis spectrophotometry and its composition confirmed by HPLC-ESIMS. A pigment storage stability test was performed at 18 °C and different relative humidities. The addition of CM in the formulation increased the encapsulation efficiency, diminished the moisture content, and allowed to obtain more uniform size and spherical particles, with high dietary fiber content. These microencapsulates are promising functional additive to be used as natural colorant in the food industry.