Evandro Martins

Oil core microcapsules by inverse gelation technique

Abstract A promising technique for oil encapsulation in Ca-alginate capsules by inverse gelation was proposed by Abang et al. This method consists of emulsifying calcium chloride solution in oil and then adding it dropwise in an alginate solution to produce Ca-alginate capsules. Spherical capsules with diameters around 3 mm were produced by this technique, however the production of smaller capsules was not demonstrated. The objective of this study is to propose a new method of oil encapsulation in a Ca-alginate membrane by inverse gelation. The optimisation of the method leads to microcapsules with diameters around 500 μm. In a search of microcapsules with improved diffusion characteristics, the size reduction is an essential factor to broaden the applications in food, cosmetics and pharmaceuticals areas. This work contributes to a better understanding of the inverse gelation technique and allows the production of microcapsules with a well-defined shell–core structure.

Oil encapsulation in core–shell alginate capsules by inverse gelation. I: dripping methodology

Abstract The production of capsules by inverse gelation consists of adding dropwise oil containing calcium dispersion into an alginate bath. A dripping technique to produce capsules from oil-in-water (O/W) emulsions was proposed by Abang. However, little is known about the oil encapsulation using water-in-oil (W/O) emulsions. This work aims to develop a new method of W/O emulsions encapsulation by inverse gelation. The success of the W/O emulsion encapsulation is due to three factors: 1) use of an emulsion with moderate stability (50 min); 2) production of an emulsion with at least 90 g/L of CaCl2 and 3) addition of ethanol (20% v/v) into the alginate bath. Both wet and dry capsules were obtained with a spherical shape with diameters of 7 and 3.6 mm, respectively. All volume of oil was encapsulated and the oil loading in the wet and dry capsules was of 23 and 68% v/v, respectively.

Thermodynamic characterization of single-stage spray dryers: Mass and energy balances for milk drying

ABSTRACT Spray drying is an efficient unit operation applied in food drying that demands a high amount of energy compared to vacuum evaporation and membrane filtration. The objective of this work was to present a mathematical model-like basis for the construction of mass and energy balances. For this purpose, two lab-scale single spray dryers in milk drying with different evaporative capacities have been used as example. The values of the absolute humidity, mass and energy losses, energetic specific consumption (ESC), and the efficiency of the process were obtained by calculations developed in this work. The mathematical model was valid for the evaluation of mass and energy losses, and it allowed us to compare the efficiencies of spray dryers with different designs. From this model, it is possible to compare different drying processes and dryers.

Lactose hydrolyzed milk powder: Thermodynamic characterization of the drying process

ABSTRACT Industrial production of lactose hydrolyzed milk powder (LHMP) remains challenging. Due to the presence of the monosaccharides glucose and galactose, lactose-free powders tend to suffer stickiness, caking, and browning during drying and storage. We sought to find ideal conditions spray dryer inlet air temperature (θair,in) and concentrated milk flow rate (mCM) for LHMP production. We tested θair,in settings of 115–160°C and mCM of 0.3–1.5 kg · h−1, and also applied mass and energetic balances. LHMP generally exhibited higher mass and energetic losses than the control (milk powder containing lactose), as a consequence of the relatively low dryability of LHMP. For a lab scale spray dryer, the ideal conditions settings for LHMP production were θair,in = 145 ± 2°C and mCM = 1.0 kg · h−1, taking into account the mass yield and energetic cost (kJ · kg−1 of powder) of the process. These ideal conditions are a potential tool for the industrial development of lactose-free dairy powders.

Oil encapsulation techniques using alginate as encapsulating agent: applications and drawbacks

Abstract Oils are used in agriculture, nutrition, food and cosmetics; however, these substances are oxidisable and may readily lose their properties. To reduce their degradation or to mask certain undesirable aspects, one strategy consists in encapsulating the oil in inert structures (capsules). The capsules are classified according to the morphology, the number of cores and size, can be produced by several techniques: jet-cutting, vibrating jet, spray-drying, dispersion and milli-microfluidic. Among the polymers used as a membrane in the capsules, alginates are used in oil encapsulation because of their high gelling capacity, biocompatibility and low toxicity. In the presence of calcium ions, the alginate macromolecules crosslink to form a three-dimensional network called hydrogel. The oil encapsulation using alginate as encapsulating material can be carried out using technologies based on the external, internal or inverse gelation mechanisms. These capsules can found applications in areas as cosmetics, textile, foods and veterinary, for example.

Oil encapsulation in core–shell alginate capsules by inverse gelation II: comparison between dripping techniques using W/O or O/W emulsions

Abstract In the first part of this article, it was described an innovative method of oil encapsulation from dripping-inverse gelation using water-in-oil (W/O) emulsions. It was noticed that the method of oil encapsulation was quite different depending on the emulsion type (W/O or oil-in-water (O/W)) used and that the emulsion structure (W/O or O/W) had a high impact on the dripping technique and the capsules characteristics. The objective of this article was to elucidate the differences between the dripping techniques using both emulsions and compare the capsule properties (mechanical resistance and release of actives). The oil encapsulation using O/W emulsions was easier to perform and did not require the use of emulsion destabilisers. However, capsules produced from W/O emulsions were more resistant to compression and showed the slower release of actives over time. The findings detailed here widened the knowledge of the inverse gelation and gave opportunities to develop new techniques of oil encapsulation.

Lactose-hydrolyzed milk powder: Physicochemical and technofunctional characterization

ABSTRACT The objective of this work is to demonstrate the effect of operational drying parameters on the physicochemical and techno-functional properties of lactose-hydrolyzed milk powder (LHMP). LHMP showed water content superior to the control regardless of drying conditions, which is a direct result of the difficulties encountered in drying the product. For a lab-scale spray dryer, the LHMP produced at θair,in = 145°C and mCM = 1.0 kg · h−1 was the only sample that met all stipulated quality parameters: water content <5% (w/w), aw < 0.20 and luminosity value >93, particle sizes similar to control, and complete rehydration.

Performance of two alternative methods for Listeria detection throughout Serro Minas cheese ripening

The ability of pathogens to survive cheese ripening is a food-security concern. Therefore, this study aimed to evaluate the performance of two alternative methods of analysis of Listeria during the ripening of artisanal Minas cheese. These methods were tested and compared with the conventional method: Lateral Flow System™, in cheeses produced on laboratory scale using raw milk collected from different farms and inoculated with Listeria innocua; and VIDAS®-LMO, in cheese samples collected from different manufacturers in Serro, Minas Gerais, Brazil. These samples were also characterized in terms of lactic acid bacteria, coliforms and physical–chemical analysis. In the inoculated samples, L. innocua was detected by Lateral Flow System™ method with 33% false-negative and 68% accuracy results. L. innocua was only detected in the inoculated samples by the conventional method at 60-days of cheese ripening. L. monocytogenes was not detected by the conventional and the VIDAS®-LMO methods in cheese samples collected from different manufacturers, which impairs evaluating the performance of this alternative method. We concluded that the conventional method provided a better recovery of L. innocua throughout cheese ripening, being able to detect L. innocua at 60-day, aging period which is required by the current legislation.

Regional Identification of the Deciduous Forests of Brazil Central Using NDVI Seasonal Variations of the Sensor MODIS and Digital Elevation Model

Paranã river basin has one of the biggest fragments of Decidual Seasonal Forest in Brazil. This kind of vegetation is widely fragmented, mostly, due to the selective wood exploitation and the growth of pasture areas. Thus, many researches have been made in order to understand its dynamics and also to maintain its diversity, most of the times endemic. Thus, the present study aimed at defining a method for regional identification of the Deciduous Forest in the Paranã river basin. Due to the characteristics vegetation, a temporal sequence of MODIS images, over a period of one year, was used for its detection. The methodology adopted can be subdivided into the following steps: (a) NDVI temporal variability examination on deciduous forest vegetation, (b) the influence analysis of rainfall parameter by spatial interpolation, (c) elaboration of the geomorphology map using the DEM and terrain attributes, (d) spectral analysis of the relationships between the NDVI time series and precipitation, and (e) comparison between classified image of NDVI series and geomorphology/geology map. NDVI multi-temporal spectra had their noises treated by the MNF method, limited by the pluviometric data. The Deciduous Forest presents spectral behaviour of NDVI multi-temporal considered typical, with higher values in the raining season and lower values in the dry season, what makes this kind of vegetation different from others. So, the methodology has proved effective for regional delimitation of Deciduous Forests considering the MODIS sensor and SRTM data. Keywords-component; deciduous forest; remote sensing; MODIS; NDVI; changing detection; rainfal; DEM.