Phenomenological study of the synthesis of pure anhydrous ß-lactose in alcoholic solution.

Lactose is an important additive because of its food, pharmaceutical, and cosmetic applications. Among lactose polymorphs, anhydrous ß-lactose stands out due to its thermodynamic stability. Thus, a simple method to produce the inter-conversion from monohydrate α-lactose to anhydrous ß-lactose was investigated employing a methanolic solution and different reaction variables (catalyst type, temperature, and stirring). Pure ß-lactose powders were synthesized in short reaction time (2-16 h), with a moderate temperature (reflux: 65 °C), and low concentration (0.014 M) of catalysts (NaOH and KOH). The SEM analysis revealed a change in the morphology from fine needles to tomahawk shape, which is dependent on the content of ß-lactose. The products were appropriately characterized using common analytic procedures (XRD, FTIR, and MDSC). In addition, an exhaustive discussion of the obtained results is provided. Finally, it seems to be the first work, where the inter-conversion to pure ß-lactose is reported successfully.

Comparison of Polysaccharides as Coatings for Quercetin-Loaded Liposomes (QLL) and Their Effect as Antioxidants on Radical Scavenging Activity.

Liposomes are microstructures containing lipid and aqueous phases employed in the encapsulation and delivery of bioactive agents. Quercetin-loaded liposomes (QLLs) were coated with three different polysaccharides and then tested as radical scavengers. Lactose (LCQLL), chitosan (CCQLL), and inulin (ICQLL) were employed as coating materials. Particle size determined by light scattering, showed primary size of 200 nm for all samples, while a secondary particle size of 600 nm was observed for CCQLL. Scanning electron microscopy (SEM) evidenced particle aggregation with the addition of the polysaccharide coating. Transmission electron microscopy (TEM) revealed the layered microstructure of liposomes composed of at least two layers, and primary particle size below 100 nm. QLL showed higher antioxidant activity than the coated liposomes. This behavior was attributed to the chemical interaction between quercetin and the corresponding coating polysaccharide in the layered structure, which traps the quercetin and keeps it unavailable for radical scavenging. From the three polysaccharides, lactose showed a better performance as coating material in the antioxidant activity, which suggested that the smaller size of the disaccharide molecule resulted in a faster releasing of the quercetin in the solution. Thus, LCQLL is an advantageous way to deliver quercetin for antioxidant purposes, where the low stability in delivered media of quercetin loaded liposomes is commonly compromised.

Application of Differential Scanning Calorimetry (DSC) and Modulated Differential Scanning Calorimetry (MDSC) in Food and Drug Industries.

Phase transition issues in the field of foods and drugs have significantly influenced these industries and consequently attracted the attention of scientists and engineers. The study of thermodynamic parameters such as the glass transition temperature (Tg), melting temperature (Tm), crystallization temperature (Tc), enthalpy (H), and heat capacity (Cp) may provide important information that can be used in the development of new products and improvement of those already in the market. The techniques most commonly employed for characterizing phase transitions are thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), thermomechanical analysis (TMA), and differential scanning calorimetry (DSC). Among these techniques, DSC is preferred because it allows the detection of transitions in a wide range of temperatures (-90 to 550 °C) and ease in the quantitative and qualitative analysis of the transitions. However, the standard DSC still presents some limitations that may reduce the accuracy and precision of measurements. The modulated differential scanning calorimetry (MDSC) has overcome some of these issues by employing sinusoidally modulated heating rates, which are used to determine the heat capacity. Another variant of the MDSC is the supercooling MDSC (SMDSC). SMDSC allows the detection of more complex thermal events such as solid-solid (Ts-s) transitions, liquid-liquid (Tl-l) transitions, and vitrification and devitrification temperatures (Tv and Tdv, respectively), which are typically found at the supercooling temperatures (Tco). The main advantage of MDSC relies on the accurate detection of complex transitions and the possibility of distinguishing reversible events (dependent on the heat capacity) from non-reversible events (dependent on kinetics).

Thermal Study of Polyols for the Technological Application as Plasticizers in Food Industry.

In this work is presented the complete thermal analysis of polyols by direct methods such as simultaneous thermogravimetric and differential thermal analyzer (TGA-DTA), differential scanning calorimetry (DSC), modulated DSC (MDSC), and supercooling MDSC. The different thermal events in the temperature range of 113⁻553 K were identified for glycerol (GL), ethylene glycol (EG), and propylene glycol (PG). Boiling temperature (TB) decreased as GL > EG > PG, but increased with the heating rate. GL showed a complex thermal event at 191⁻199 K, identified as the glass transition temperature (Tg) and devitrification temperature (Tdv), and a liquid⁻liquid transition (TL-L) at 215⁻221 K was identified as the supercooling temperature. EG showed several thermal events such as Tg and Tdv at 154 K, crystallization temperature (Tc) at 175 K, and melting temperature (Tm) at 255 K. PG also showed a complex thermal event (Tg and Tdv) at 167 K, a second devitrification at 193 K, and TL-L at 245 K. For PG, crystallization was not observed, indicating that, during the cooling, the liquid remained as an amorphous solid.