Rheology of liquid foods under shear flow conditions: Recently used models

Study on authenticity identification and quality evaluation of Styrax by combining multiple detection methods with scientific characterization of description

Styrax is a rare and expensive natural spice for food, known for its unique and rich aroma and sticky texture, and has a long history of consumption worldwide. There are many counterfeits in the market, but it is challenging to distinguish them with existing standards. Therefore, identifying the authenticity of styrax and evaluating its quality are challenges. A total of 34 samples of styrax were collected in this study, including 4 samples collected from the origin of Guatemala and 30 samples collected from markets in various regions of China. Gas chromatography-mass spectrometry (GC-MS) and headspace gas chromatography-mass spectrometry (HS-GC-MS) were used to analyze the chemical components of styrax qualitatively, and ultra performance liquid chromatography (UPLC) was used to quantitatively analyze cinnamic acid, cinnamyl cinnamate, and 3-phenylpropyl cinnamate in styrax. The texture, odor, and color of styrax were characterized by three modern sensory evaluation technologies: flash gas chromatography electronic nose (flash GC E-nose), rotational rheometer, and spectrophotometer. Thus, a method for identifying the authenticity of styrax was established. The results showed that a total of 73 components were identified in styrax, and qualitative analysis using GC-MS, HS-GC-MS, and PCA model, OPLS-DA model can effectively identify styrax and its counterfeits. The main adulterated ingredients in counterfeit are benzoic acid, Benzyl benzoate, and Benzyl alcohol. These compounds are toxic and can cause food safety problems. The shear viscosity and odor of styrax and its counterfeits are significantly different(p < 0.001), but the color is not significantly different(p > 0.05). Various analytical methods can be used to identify styrax and its counterfeits effectively. This study provides a more comprehensive method for authenticity identification and quality evaluation of styrax, which is conducive to ensuring the edible safety of styrax.

Cell wall polysaccharides from macauba pulp (Acrocomia aculeata L.): Fractionation and characterization of their chemical and rheological properties

Macauba fruit pulp (Acrocomia aculeata) is an emerging oil source. After de-oiling, the macauba pulp meal (MPM) offers a dietary fiber content of 40-50 %, which mainly comprises cell wall polysaccharides (CWP). The present work aimed to assess the potential of MPM as an innovative source of sustainable food polysaccharides. To this end, the macauba CWP were fractionated into water-soluble galactoglucomannans (21.7 %), calcium- and ester-bound pectins (3.4 %), loosely-bound xyloglucans (27.6 %), strongly-bound xylans (6.5 %), and a cellulose-rich fraction (39.3 %). The galactoglucomannans produced shear-thinning aqueous dispersions with an increase in consistency index from 3.03·10-2 to 3.58·101 Pa·sn by increasing the concentration from 1.0 to 5.0 %. The galactoglucomannans dispersions showed semi-dilute behavior, evidenced by relaxation times ranging from 1.24·10-2 to 1.17 s for concentrations from 2.5 to 10.0 %. Macauba pectins and xyloglucans showed weak gel behavior, with an increase in yield stress from 3.20·10-1 to 1.04·102 Pa and from 7.01·10-2 to 1.35·102 Pa for dispersions at 2.5 to 10.0 %, respectively. 2.5 to 5 times higher concentration of macauba polysaccharides is needed to obtain rheological behavior similar to guar and xanthan gum. The thickening and gelling properties of macauba CWP highlight their potential as thickeners and stabilizers for the food industry.

An Injectable Chitosan Hydrochloride-Sodium Alginate Hydrogel Adjuvant Capable of Eliciting Potent Humoral and Cellular Immunity

Adjuvants can enhance the immune effects of vaccines. Currently, the most commonly used and validated are aluminum and oil-emulsion adjuvants. However, these adjuvants are not without flaws; for instance, aluminum adjuvants can cause adverse reactions and irritation at the injection site. Consequently, the development of new, safe, and effective adjuvants remains a prominent topic in vaccine research. In this study, we synthesized a composite hydrogel by combining sodium alginate (SA) and the chitosan derivative chitosan hydrochloride (CHCL) to explore the feasibility of this polymer composite hydrogel as a novel immunoadjuvant. Our results indicate that this hydrogel material possesses good biocompatibility and antibacterial properties, is easily injectable, and locally initiates vaccine responses by stimulating the phagocytosis of protein antigens by dendritic cells (DCs). Additionally, they offer sustained exposure to vaccine antigens. After administration, a transient inflammatory niche is created to prolong immune system activation. Importantly, our study demonstrated that the CHCL-SA hydrogel loaded with antigens effectively stimulated the body to produce a humoral immune response and enhance the maturation of the CD8+ T lymphocyte subset. In murine tumor challenge experiments, the CHCL-SA supplemented antigen group significantly inhibited tumor cell growth and improved mouse survival rates. In summary, we developed an injectable CHCL-SA hydrogel adjuvant with great potential for enhancing the efficacy of vaccines.

Emulsifiers: Their Influence on the Rheological and Texture Properties in an Industrial Chocolate

The complexity of the chocolate matrix leads to it having characteristic rheological properties that may pose difficulties for its industrial manufacture. Many factors influence the flow behaviour of chocolates, such as raw materials, the amount of fat, the moisture content, particle-size distribution, the concentration of emulsifiers, or manufacturing conditions, among others. This study focusses on the rheological properties of an industrially manufactured chocolate with a 48% cocoa content, and the effect caused by the addition of two emulsifiers (soya lecithin and polyglycerol polyricinoleate (PGPR)) on the rheological properties. In the case of lecithin, a clear effect has been observed on the plastic viscosity and the yield stress. Plastic viscosity decreases until a concentration of 0.6% lecithin is reached, and thereafter remains relatively constant, while yield stress increases over the studied range. This effect is not observed when PGPR is used as the emulsifying agent. In this case, a small concentration of PGPR decreases the yield stress. Thixotropy was determined using the Casson model, and its behaviour was found to be similar to that of plastic viscosity with respect to changes in the PGPR and lecithin concentrations. Textural determinations were also carried out, relating the rheology characteristics to the texturometry.

Stability in Aqueous Solution of a New Spray-Dried Hydrocolloid of High Andean Algae Nostoc sphaericum

There is a growing emphasis on seeking stabilizing agents with minimal transformation, prioritizing environmentally friendly alternatives, and actively contributing to the principles of the circular economy. This research aimed to assess the stability of a novel spray-dried hydrocolloid from high Andean algae when introduced into an aqueous solution. Nostoc sphaericum freshwater algae were subject to atomization, resulting in the production of spray-dried hydrocolloid (SDH). Subsequently, suspension solutions of SDH were meticulously prepared at varying pH levels and gelling temperatures. These solutions were then stored for 20 days to facilitate a comprehensive evaluation of their stability in suspension. The assessment involved a multifaceted approach, encompassing rheological analysis, scrutiny of turbidity, sedimentation assessment, ζ-potential, and measurement of particle size. The findings from these observations revealed that SDH exhibits a dilatant behavior when in solution, signifying an increase in with higher shear rate. Furthermore, it demonstrates commendable stability when stored under ambient conditions. SDH is emerging as a potential alternative stabilizer for use in aqueous solutions due to its easy extraction and application.