Predicting suitable storage conditions for spray-dried microcapsules formed with different biopolymer matrices

Effect of Mixed Particulate Emulsifiers on Spray-Dried Avocado Oil-in-Water Pickering Emulsions

Avocado oil is a very valuable agro-industrial product which can be perishable in a short time if it is not stored in the right conditions. The encapsulation of the oils through the spray drying technique protects them from oxidation and facilitates their incorporation into different pharmaceutical products and food matrices; however, the selection of environmentally friendly emulsifiers is a great challenge. Four formulations of the following solid particles: Gum Arabic, HI-CAP^®100 starch, and phosphorylated waxy maize starch, were selected to prepare avocado oil Pickering emulsions. Two of the formulations have the same composition, but one of them was emulsified by rotor-stator homogenization. The rest of the emulsions were emulsified by combining rotor-stator plus ultrasound methods. The protective effect of mixed particle emulsifiers in avocado oil encapsulated by spray drying was based on the efficiency of encapsulation. The best results were achieved when avocado oil was emulsified with a mixture of phosphorylated starch/HI-CAP^®100, where it presented the highest encapsulation efficiency.

Accurate Determination of Moisture Content in Flavor Microcapsules Using Headspace Gas Chromatography

This study demonstrates an accurate method for determining the moisture content in flavor microcapsules using headspace gas chromatography. The method involves measuring the gas chromatography signals of water from vapor in a headspace vial containing flavor microcapsules at a temperature of 125 °C. The measurements were recorded over four headspace extractions, from which the moisture content in the microcapsule samples was extrapolated via simple vapor-phase calibration. The results revealed that the proposed method demonstrated good precision (a relative standard deviation of <3.11%) and accuracy. The proposed method is accurate, highly sensitive, automated, and suitable for testing the moisture content of flavor microcapsules and related products.

Thermodynamic Properties and State Diagram of Gum Ghatti-Based Edible Films: Effects of Glycerol and Nisin

In this present study, the thermodynamic and thermal properties of glycerol and nisin-incorporated gum ghatti (GG, Anogeissus latifolia)-based films were determined. The films exhibited type III isotherm behaviors. Moisture content (MC) of films was increased with increasing water activity (aw) and decreased with higher temperature. The incorporation of glycerol and nisin increased the sorption ability of GG films. The net isosteric heat of adsorption (qst) and differential entropy (Sd) were decreased with increasing MC, showing an exponential negative correlation between them. Spreading pressure (φ) was increased with increasing aw, but decreased with higher temperature. This incorporation of glycerol and nisin increased the qst, Sd and φ of the GG films. The sorption behaviors were enthalpy-driven and non-spontaneous processes. The glass transition temperature (Tg), critical MC and aw of the films were decreased, and increased respectively with the incorporation of glycerol and nisin. This work provides a theoretical basis for the application of edible films in fresh food preservation.

Moisture sorption properties and glass transition temperature of a non-conventional exudate gum (Prosopis alba) from northeast Argentine

Water-solid interactions were explored in purified and freeze-dried Prosopis alba exudate gum as approach to get a deeper insight of structural and functional aspects of this novel biomaterial. Particularly, the study of water-binding properties combined with glass transition temperatures allowed obtaining interesting theoretical data for practical applications. The Guggenheim-Anderson-de Boer (GAB) and Generalized D'Arcy and Watt (GDW) models were applied to describe the sorption behavior and thermodynamic properties of the studied gum. The study of the relationship between relative humidity, water content and thermal transitions allowed to characterize the material in terms of water plasticizing susceptibility as well as define the suitable storage conditions that guarantee the quality, safety and physical stability of P. alba gum. Obtained results contribute to the characterization of a non-conventional exudate gum with great potential for its use in different food industry applications.

Thermodynamic criteria analysis for the use of taro starch spherical aggregates as microencapsulant matrix

Spherical aggregates can be obtained from taro starch by spray-drying without using bonding agents. Accurate information about thermal issues of spherical aggregates can provide valuable information for assessing the application as encapsulant. Spherical aggregates of taro starch were obtained by spray-drying and analyzed using dynamic vapour sorption. The use of the Guggenheim, Anderson and de Boer (GAB) model indicated a Type II isotherm pattern with weaker interactions in the multilayer region. Differential enthalpy and entropy estimates reflected a mesoporous microstructure, implying that energetic mechanisms dominate over transport mechanisms in the sorption process. The limitation by energetic mechanisms was corroborated with enthalpy-entropy compensation estimates. The diffusivity coefficient was of the order of 10^-8 m²·s^-1, which is in line with results obtained for common materials used for encapsulation purposes. The thermodynamic properties and the lack of a bonding agent indicated the viability of spherical aggregates of taro starch for encapsulation of biocompounds.

Thermodynamic sorption analysis and glass transition temperature of faba bean (Vicia faba L.) protein

Freeze-dried faba bean (Vicia faba L.) protein adsorption isotherms were determined at 25, 35 and 40 °C and fitted with the Guggenheim-Anderson-de Boer model. The pore radius of protein was in the range of 0.87-6.44 nm, so that they were considered as micropores and mesopores. The minimum integral entropy ranged between 4.33 and 4.44 kg H₂O/100 kg d.s., was regarded as the point of maximum of stability. The glass transition temperature of the protein equilibrated at the different conditions of storage was determined, showing that the protein remained in glassy state for all cases. The protein showed compact and rigid structures, evidenced by microscopy analysis.

Predicting Storage Conditions for Rice Seed with Thermodynamic Analysis

The desorption isotherms ofjaponicaandindicarice seeds were determined at 15, 25, 35, 45 °C within the water activity range from 0.12 to 0.92 and it was observed that GAB model could accurately describe the desorption behaviors with low values of mean relative error (MRE). The thermodynamic properties of rice seeds were obtained by water desorption isotherms. The moisture content with the minimum integral entropy was considered as the best storage condition where the strongest energetic interaction between water molecular and solid occurred and the optimum seed moisture for storage at 35 °C occurred at 6.02 g water per 100 g of dry matter (ɑwof 0.12) forjaponicarice seed and 5.28 g water per 100 g of dry matter (ɑwof 0.08) forindicarice seed, respectively. The mechanisms of desorption process were determined with integral enthalpy–entropy compensation theory and it was observed that the at low moisture content the desorption process of rice seed was controlled by changes of entropy, whereas the desorption process was considered to be controlled by enthalpy mechanism at high moisture content. It was found that theindicarice seed exhibited a wider water activity range in the minimum integral entropy zone, indicating thatindicarice seed was more stable to withstand the different storage conditions compared withjaponicarice seed.

Water adsorption isotherms of carboxymethyl cellulose, guar, locust bean, tragacanth and xanthan gums

Water adsorption isotherms of carboxymethyl cellulose (CMC), guar gum (GG), locust bean gum (LBG), tragacanth gum (TG) and xanthan gum (XG) were determined at different temperatures (20, 35, 50, and 65°C) using a gravimetric method. Several saturated salt solutions were selected to obtain different water activities in the range from 0.09 to 0.91. Water adsorption isotherms of tested hydrocolloids were classified like type II isotherms. In all cases, equilibrium moisture content decreased with increasing temperature at each water activity value. Three-parameter Guggenheim-Anderson-de Boer (GAB) model was employed to fit the experimental data in the water activity range and statistical analysis indicated that this model gave satisfactory results. CMC and GG were the most and the least hygroscopic gums, respectively. Sorption heats decreased with increasing moisture content. Monolayer moisture content evaluated with GAB model was consistent with equilibrium conditions of maximum stability calculated from thermodynamic analysis of net integral entropy. Values of equilibrium relative humidity at 20°C are proposed to storage adequately the tested gums.