Colored Food Emulsions—Implications of Pigment Addition on the Rheological Behavior and Microstructure

Coloring foods with natural pigments enables the development of attractive products with nutritional advantages. The overall objective of this work was to study the consequences of adding the pigments lutein (lipophylic) and phycocyanin (hydrophilic) on the rheological behavior of oil-in-water food emulsions stabilized by pea protein isolate. The emulsions were characterized in terms of their linear viscoelasticity, and of their steady and transient flow behaviors. The rheological tests were monitored by using a microscope (optical analysis system) coupled to a controlled stress rheometer. Upon lutein incorporation, the emulsions became less stable, presenting lower rheological function values than the control emulsion (without pigment addition). On the other hand, phycocianin addition resulted in a significant reinforcement of emulsion structure, a higher resistance to structural breakdown becoming evident. An emulsion containing both pigments, in the same proportion, presented an intermediate rheological behavior resulting from a combination of the effects observed for the emulsions containing each of them.     

Emulsion PCR-based method to detect Y chromosome microdeletions

Deletions in Y chromosome are thought to be pathologically involved in some cases of male infertility associated with azoospermia or oligozoospermia. An emulsion-based multiplex PCR method was developed for detecting Y chromosome microdeletions in infertile men and a plasma sample of pregnant women carrying a male fetus. The sensitivity of multiplex PCR in emulsion was evaluated. Conventional PCR was also carried out for comparison. A total of 13 sequence-tagged sites (STSs) distributed in the AZF region were analyzed simultaneously with this method. The SRY gene was also detected as the inner control. Results showed that Y chromosome microdeletions were found in 4 of 19 infertile patients. Also, in 1 of 63 samples collected from pregnant women, microdeletions were found in some of the detected sites. It is suggested that the emulsion PCR assay was proven to be a promising diagnostic tool and could be widely used in further clinical and academic research.     

Applications of Microfluidic Devices in Food Engineering

The design of novel food micro-structures aimed at the quality, health and pleasure markets will probably require unit operations where the scale of the forming device is closer to the size of the structural elements (i.e., 1–100 μm). One emerging possibility is microfluidics or devices that employ small amounts of fluids (10⁻⁶ to 10⁻⁹ l) flowing in channels where at least one dimension is less than 1 mm. However, under these conditions, the predominant effects are not necessarily those present in conventional macroscopic unit operations. Dominant physical effects at the microfluidic scale are introduced through the use of dimensionless numbers. Different types of geometries to generate multi-phase flows in micro-channels, techniques and materials to construct the micro-devices, principally soft lithography and laser ablation, as well as methods used to modify surface properties of channels, are reviewed. The operation of micro-devices, the role of flow regimes, rheological behaviour of fluids in micro-channels and of transient time is discussed. Finally, systems developed to generate emulsions and foams, fluid mixing and dispersion, and future applications of these devices in food processing and food analysis are presented.     

Product Design in Food Industry Using the Example of Emulsification

Designing a product according to the consumers’ needs is one of the key targets in food industry. Having once defined the target product properties, it is of imperative importance to know which microstructure of the product is required (property function) and how the target microstructure can then be determined by process parameters (process function). Many food products are emulsions, either during production and/or in the moment of distribution and consumption. This review intends to depict the design of emulsions according to target needs. Even if we concentrate on typical food emulsions as an example, the concept can be widely applied, since emulsification in other branches of industry is governed by the same principles.     

Use of a bacterial cellulose filter for the removal of oil from wastewater

The present study describes the development of a bacterial cellulose (BC) filter for the treatment of oily waters. BC membranes were produced using an alternative medium containing 2.5 % corn steep liquor. Samples of previously purified membranes were characterized and tested as filters for the separation of oil from water (oil concentrations of 10, 150 and 230 ppm). Flow rate, filter diameter and membrane thickness after 6 and 10 days of cultivation were evaluated in a filtration system constructed in polyvinyl chloride. The BC membranes presented satisfactory flexibility, thermal stability and mechanical strength. However, the membrane obtained after 10 days supported 100 % more force than the membrane obtained after 6 days. The experiments revealed 100 % removal of the oil from all emulsions. The filtration flow rate increased proportionally to the filter diameter and decreased from the 6-day membrane to the 10-day membrane. The results of the present study are promising and demonstrate the efficiency, durability and strength of this novel biodegradable, non-toxic material for the treatment of oily waters generated during industrial activities.