Adhesion of fermented diary products to packaging materials. Effect of material functionality, storage time, and fat content of the product. An empirical study

Legendary fermented herbs: an ethnobotanical study of the traditional fermentation starter of the Chuanqing people in Northwestern Guizhou, China

BACKGROUND

Plants that contain brewing microorganisms are used in traditional fermentation starters, which are an essential part of local diet, nutrition, life, and health. Regionally, the plant species used and the microorganisms included in traditional fermentation starters are diverse, endowing local fermented drinks with different flavors and health benefits. However, related traditional knowledge has been scarcely documented or revealed.

METHODS

An ethnobotanical survey was conducted in five towns of Nayong County in northwestern Guizhou, China. Snowball sampling, semi-structured interviews, free lists, and participatory observation were used to collect information on Jiuqu Plants (JPs) and jiuqu-making techniques. The PacBio platform was used to study the microbial community structure and diversity in the Chuanqing people's jiuqu.

RESULTS

In total, 225 informants were interviewed, including 116 who provided plants and technological processes for making Chinese baijiu jiuqu (CBJ) and 139 who provided information about making fermented glutinous rice jiuqu (FGRJ). This study found that older people have more abundant knowledge about CBJ plants. Poaceae was found to be the dominant family used in making CBJ and FGRJ (7 species each). Compared to individual plant parts, the whole plant is most commonly used in two kinds of jiuqu (19.5% in CBJ and 22.6% in FGRJ). The Chuanqing people's jiuqu is used to treat dietary stagnation and indigestion. The highest relative frequency of citation of the CBJ plant was Ficus tikoua Bureau, and the counterpart of the FGRJ plant was Buddleja macrostachya Benth. The dominant bacterial species in jiuqu were Gluconobacter japonicus (YQ1, YQ4) and Pediococcus pentosaceus (YQ2, YQ3), and the dominant fungal species was Rhizopus oryzae.

CONCLUSION

For the first time, this study documents the unique traditional jiuqu knowledge and reveals the microbial mystery behind the FGRJ of the Chuanqing people. Therefore, this study encourages the use of online social media platforms in order to spread Jiuqu culture, the use of the new media wave in order to create multimedia databases, and also suggests that local communities should develop preservation intervention programs, in addition to nurturing the inheritors in order to prevent the disappearance of traditional Jiuqu knowledge. This research contributes to the conservation and demystification of the traditional jiuqu knowledge of the Chuanqing people and lays the foundation for further research on its microbiology, nutrition, and metabolomics.

Dependence of lactose adsorption on the exposed crystal facets of metals: a comparative study of gold, silver and copper

In this theoretical work, we investigated the adsorption of a lactose molecule on metal-based surfaces, with a focus on the influence of the nature of the metal and of the type of exposed crystal facet on the adsorbed structures and energetics. More precisely, we considered three flat crystallographic facets of three face-centered cubic metals (gold, silver, and copper). For the global exploration of the energy landscape, we employed a multi-stage procedure where high-throughput searches, using a stochastic method that performs global optimization by iterating local searches, are followed by a refinement of the most probable adsorption conformations of the molecule at the ab initio level. We predicted the optimal conformation of lactose on each of the nine metal-surface combinations, classified the many low-energy minima into possible adsorption modes, and analyzed the structural, electronic and energetic aspects of the lactose molecule on the surface, as well as their dependence on the type of metal and exposed crystal facet. We observed structural similarities between the various minimum-energy conformations of lactose in vacuum and on the surface, a rough correlation between adsorption and interaction energies of the molecule, and a small charge transfer between molecule and surface whose direction is metal-dependent. During adsorption, an electronic reorganization occurs at the metal-molecule interface only, without affecting the vacuum-pointing atoms of the lactose molecule. For all types of surfaces, lactose exhibits the weakest adsorption on silver substrates, while for each coinage metal the adsorption is strongest on the (110) crystal facet. This study demonstrates that the control of exposed facets can allow to modulate the interaction between metals and small saccharides.

Preparation and Properties of Fluorinated Acrylate Resin Film with Resisting Fluid for Dairy Packaging

Nowadays there is a widespread phenomenon of dairy residue, which causes a great deal of waste. To solve this problem, the copolymer of fluorinated acrylate resin was synthesized and the resisting fluid film was prepared. The proprieties of the fluorinated acrylate resin coatings were characterized by scanning electron microscope (SEM), measuring the contact angle of the droplet liquid on the surface of the coating, the influence of acidic environment, the adhesion to substrate material, and analyzing thermogravimetry (TG) and Gas Chromatography (GC). It was found that the fluorinated acrylate resin film is a kind of resisting fluid film with excellent property and it is safe, nontoxic and readily biodegradable. So it was said a very potential dairy packaging material.

Adsorption of unstructured protein β-casein to hydrophobic and charged surfaces

In this Monte Carlo simulation study we use mesoscopic modeling to show that β-casein, an unstructured milk protein, adsorbs to surfaces not only due to direct electrostatic and hydrophobic interactions but also due to structural rearrangement and charge regulation due to proton uptake and release. β-casein acts as an amphiphilic chameleon, changing properties according to the chemical environment, and binding is observed to both positively and negatively charged surfaces. The binding mechanisms, however, are fundamentally different. A detailed, per-residue-level analysis shows that the adsorption process is controlled by a few very specific regions of the protein and that these change dramatically with pH. Caseins, being the most abundant proteins in milk, are crucial for the properties of fermented dairy products, such as nutrition, texture, and viscosity, but may also influence adhesion to packaging materials. The latter leads to product losses of about 10%, leading to economical and environmental problems.