A MODEL FOR VISCOSITY REDUCTION IN POLYSACCHARIDES SUBJECTED TO HIGH-PRESSURE HOMOGENIZATION

β-Glucan fragmentation by microfluidization and TNF-α-immunostimulating activity of fragmented β-glucans

Fragmentation of β-glucans secreted by the fungus Ophiocordyceps dipterigena BCC 2073 achieved by microfluidization was investigated. The degree of β-glucan fragmentation was evaluated based on the average number of chain scissions (α). The effects on the α value of experimental variables like solid concentration of the β-glucan suspension, interaction chamber pressure, and number of passes through the microfluidizer were examined. Kinetic studies were conducted using the relationships of the α and suspension viscosity values with the number of passes. Evidence indicated that α increases with the interaction chamber pressure and the number of passes, whereas the solid concentration shows the inverted effect. Kinetic data indicated that the fragmentation rate increases with β-glucan solid concentration and interaction chamber pressure. Furthermore, since β-glucan molecular weight is a key factor determining its biological activity, the effect of β-glucans of different molecular weights produced by fragmentation on tumor necrosis factor (TNF)-α-stimulating activity in THP-1 human macrophage cells was investigated. Evidence suggested that β-glucans have an immunostimulating effect on macrophage function, in the absence of cytotoxic effects. Indeed, β-glucans characterized by a range of molecular weights produced via microfluidization exhibited promise as immunostimulatory agents.

Role of continuous phase and particle properties on the sensory perception of root vegetable purées evaluated by an expert panel and naïve consumers

Textural properties play an essential role in the development of food products. The complexity of textural attributes has been traditionally overcome with extensive panelist training and the use of generic descriptive analysis. A better understanding on the use of rapid methods with naïve consumers to evaluate texture attributes in complex food products is still needed. The present study aimed to investigate the (i) role of different continuous phases and particle properties (i.e., size and hardness) on the mouthfeel perception of root vegetable purées and (ii) the effect of panel expertise (sensory experts vs. naïve consumers) using Rate-All-That-Apply (RATA). The study included six purées made of two different continuous phase (based on Jerusalem artichoke which is rich in inulin and, parsnip which is rich in starch) and three types of beetroot particles (raw, cooked, and comminuted beetroot). Results showed that both panels were able to discriminate and profile in a similar manner. However, sensory experts showed higher ability to discriminate between samples regarding the particle's attributes whereas consumer's sample discrimination was influenced by attributes such as "ease of swallow" and "creaminess." For the expert panel, the presence of hard particles was a clear factor driving the differences between samples. Our results highlighted the contribution of both continuous and dispersed phases to design the texture profile of particulate semisolid plant-based foods.

Effect of the homogenization process on the sensory and rheological properties in model system

High pressure homogenization has been used for preparation and stabilization of emulsions and suspensions, promoting physical changes in products, such as viscosity change. However, its use in model systems for fruit nectar is innovative. This study aimed to evaluate the effect of the processing in high pressure homogenizer on the rheological behavior and the sensory attributes in model system of gellan gum. Gellan gum (0.05%), organic acids (0.3%), and sucrose (10%) were used to prepare the solutions, which were subsequently homogenized (0-control, 25 and 50 MPa) at 25°C. Rheological and sensory analyses were performed. The samples presented pseudoplastic behavior without residual stress and were characterized by the Ostwald-de-Waele model. The homogenization pressure (P_H ) altered the viscosity of the model systems, reduced the consistency index and apparent viscosity, and increased the flow behavior index. The stimuli sour taste and viscosity differed among the parameters evaluated in the time-intensity analysis. No differences were observed for the maximum intensity of viscosity between the treated samples (25 and 50 MPa), which exhibited a similar temporal profile. Therefore, studies on the rheological and sensory behavior are fundamental to product development and process optimization. The present study shows new trends on the use of the high pressure homogenizer and the sensory profile in model systems that can be used for fruit nectar. This study evaluated the sensory attributes through the time-intensity analysis. The sensory data indicate that the homogenization pressure altered the viscosity perception, but did not alter the perception of the acid taste for the same organic acid used. Sensory as well as rheological data present new alternatives for product development. These findings are interesting for future research, equipment design, and process optimization.

Application of time–intensity analysis in model system submitted to homogenization

The use of the high pressure homogenizer has been studied in fruit juices, but researches in model system for application in fruit nectar are scarce. Therefore, it is necessary to evaluate the application of these technologies and how the homogenization pressure (PH) can interfere in the sensorial profile of the samples. To prepare the solutions we used guar gum (0.1%), organic acids (0.3%), and sucrose (10%), which were later homogenized (0—control, 25 and 50 MPa) at 25 ℃. The rheological behavior and the temporal profile of the samples were evaluated. The model systems presented pseudoplastic behavior without residual tension and were fitted to the Ostwald–de Waele model. The consistency index reduced and the flow behavior index increased with processing. Apparent viscosity also decreased due to homogenization. In the time–intensity sensorial analysis, it was observed that the samples differed among the evaluated parameters, demonstrating that the samples with tartaric acid presented higher intensity for the sour taste. However, for sweetness, no change was observed. In the viscosity attribute, the model systems presented similar temporal profiles. Therefore, it was noted that the homogenization process favored a greater temporal profile of sour taste, making sensory perception more lasting in a model system for fruit nectar.

Development of a Gulfweed-Based Edible Coating Using High-Pressure Homogenization and Its Application to Smoked Salmon

Gulfweed-based edible materials were developed in forms of food film and coating. Gulfweed suspension was subjected to high-pressure homogenization (HPH) at 103, 138, and 193 MPa with 1, 2, and 3 passes, and mixed with 14, 30, 50, and 70% (w/w gulfweed) glycerol and 1% (w/w gulfweed) polysorbate 20 to produce a film-forming suspension. The particle size of the suspension decreased with increasing pressure from 103 to 193 MPa and pass number from 1 to 3. The HPH-treated gulfweed suspension behaved like a pseudo-plastic non-Newtonian fluid. High pressure and pass number generally decreased the suspension viscosity. Uniformity and compactness of the films increased with increasing pressure. The optimal conditions for forming a film with high stretchability, low water vapor permeability, low and water solubility, as well as for preparing bright-colored coated smoked salmon, were found to be 193 MPa, three passes of HPH, and a glycerol concentration of 70%. Coating smoked salmon with gulfweed suspension enhanced the redness without altering its texture and volatile properties. The method reported in this study may be useful for seaweed-based edible film production, increasing their potential application to various food products like red meats. PRACTICAL APPLICATION: Seaweeds have high nutritional and functional values, but they are not commonly used as food materials owing to their appearance and size. Therefore, it is important to develop methods to utilize seaweeds by overcoming appearance and size limitations. A self-standing film/coating using gulfweed was developed in this study, making use of commercially available high-pressure homogenization technology. The method developed herein might enable increased applications of gulfweed and possibly other seaweeds to food products such as films, rolls, or coatings.

Application of high-pressure homogenization on gums

High-pressure homogenization (HPH) is an emerging process during which a fluid product is pumped by pressure intensifiers, forcing it to flow through a narrow gap, usually measured in the order of micrometers. Gums are polysaccharides from vegetal, animal or microbial origin and are widely employed in food and chemical industries as thickeners, stabilizers, gelling agents and emulsifiers. The choice of a specific gum depends on its application and purpose because each form of gum has particular values with respect to viscosity, intrinsic viscosity, stability, and emulsifying and gelling properties, with these parameters being determined by its structure. HPH is able to alter those properties positively by inducing changes in the original polymer, allowing for new applications and improvements with respect to the technical properties of gums. This review highlights the most important advances when this process is applied to change polysaccharides from distinct sources and molecular structures, as well as the future challenges that remain. © 2017 Society of Chemical Industry.

Effect of dynamic high pressure on emulsifying and encapsulant properties of cashew tree gum

Dynamic high pressure (DHP) has been applied in the physical modification of biopolymers as polysaccharides, proteins and gums. It is known that DHP is able to promote degradation of polysaccharides (e.g. molecular weight reduction). However, few studies have assessed the effect of DHP on the emulsifying and encapsulating properties of polysaccharides. Thus, this study aimed to investigate the effect of DHP on the emulsifying (average droplet size and particle size distribution, optical and confocal scanning laser microscopy, rheology, zeta potential and electric conductivity, creaming index, and turbidity) and encapsulating (scanning electronic microscopy, flavor retention, average droplet size, and particle size distribution) properties of cashew tree gum (CG). The application of DHP process improved the emulsifying capacity of cashew tree gum (CG) by reducing the medium droplet size (D3,2 and D4,3), increasing the turbidity and improving the emulsion stability. However, no effect of DHP was observed on the encapsulating capacity of CG.

Enhancement of Gleditsia sinensis gum rheological properties with pressure cell treatment in semi-solid state

The apparent viscosity, molecular weight, and molecular weight distribution are important physical properties that determine the functional properties of galactomannan gum. Gleditsia sinensis gum (GSG) in semi-solid state was pressure cell treated over a range of temperature (30-110 °C) under nitrogen maintained at a pressure of 1.0-4.0 MPa. Physicochemical properties of GSG samples both before and after the pressure cell treatment were characterized. These include measurements of rheological properties by LVDV-III Ultra Rheometer, molecular weight and radius of gyration by light scattering, and changes in surface morphology by scanning electron microscopy. GSG had the highest apparent viscosity at a treatment temperature of 30 °C; further increase in temperature led to decrease in apparent viscosity. The apparent viscosity of GSG can be efficiently improved at room temperature and low pressure. The process of pressure cell treatment of GSG in semi-solid state could be industrialized for enhancement of rheological properties of galactomannan gum.

Rapid processes for purification of capsular polysaccharides from Neisseria meningitidis serogroups A and C

The glycoconjugate vaccines against Neisseria meningitidis are highly effective, however most of these vaccines are expensive and still out of reach in the developing world as well as the technical know-how and the set-up required for the consistent production of pure polysaccharide is limited. Our laboratory has developed rapid, efficient and scalable processes for the downstream purification of N. meningitidis serogroup A (MenA) and serogroup C (MenC) capsular polysaccharides (PS). The MenC-PS was purified with a novel 2-step procedure including de-O-acetylation and hydrophobic interaction chromatography whereas, MenA-PS was purified using a rapid method as compared to the prior art. The purified PSs were analyzed by various analytical tests including nuclear magnetic resonance, molecular weight, composition and purity analyses to meet desired specifications. Our results provide a proof of principle for the purification of MenA-PS and MenC-PS with reduced timelines.

High pressure homogenization to improve the stability of casein - hydroxypropyl cellulose aqueous systems

The effect of high pressure homogenization on the improvement of the stability hydroxypropyl cellulose (HPC) and micellar casein was investigated. HPC with two molecular weights (80 and 1150 kDa) and micellar casein were mixed in water to a concentration leading to phase separation (0.45% w/v HPC and 3% w/v casein) and immediately subjected to high pressure homogenization ranging from 0 to 300 MPa, in 100 MPa increments. The various dispersions were evaluated for stability, particle size, turbidity, protein content, and viscosity over a period of two weeks and Scanning Transmission Electron Microscopy (STEM) at the end of the storage period. The stability of casein-HPC complexes was enhanced with the increasing homogenization pressure, especially for the complex containing high molecular weight HPC. The apparent particle size of complexes was reduced from ~200nm to ~130nm when using 300 MPa, corresponding to the sharp decrease of absorbance when compared to the non-homogenized controls. High pressure homogenization reduced the viscosity of HPC-casein complexes regardless of the molecular weight of HPC and STEM imagines revealed aggregates consistent with nano-scale protein polysaccharide interactions.