Curcumin is a bioactive molecule with limited industrial application because of its instability and poor solubility in water. Herein, curcumin-loaded Pickering emulsion was produced using purified bacterial cellulose from fermented kombucha (KBC). The morphology, particle size, stability, rheological properties, and antioxidant activities of the curcumin-loaded Pickering emulsion were investigated. The fluorescence microscope and scanning electron microscopy images showed that the curcumin-loaded Pickering emulsion formed circular droplets with good encapsulation. The curcumin-load Pickering emulsion exhibited better stability under a wide range of temperatures, low pH, sunlight, and UV-365 nm than the free curcumin, indicating that the KBC after high-pressure homogenization improved the stability of the CPE. The encapsulated curcumin retained its antioxidant capacity and exhibited higher functional potential than the free curcumin. The study demonstrated that the KBC could be an excellent material for preparing a Pickering emulsion to improve curcumin stability and antioxidant activity.

In this study, a new type of 3D printed living biological hydrogel was developed by integrating lactic acid bacteria (LAB) into biocompatible and non-toxic polymer materials. Interestingly, the living materials loaded with LAB can be freeze-dried and reused for more than 100 times. The bio-hydrogel can be used to co-culture different LAB and keep its fermentation performance stable in long-term use. The release kinetics model and response surface method were used to simulate and optimize the bacteria release mode in the bio-hydrogel. The results show that the release of bacteria from hydrogel is regulated by the coupling of Fickian diffusion and polymer swelling. The stability of LAB hydrogel was evaluated by reuse experiments. The images of confocal microscopy and scanning electron microscope showed that the bacteria with high cell viability were distributed in the hydrogel and intact structure of the living hydrogel was maintained after 100 times of reuse as yoghurt starter. In conclusion, the 3D printed LAB bio-hydrogel developed in this study has the advantage of reuse and sustainability, which is expected to open up a new way for the preparation of food culture starter.

Fungi contamination is an important factor affecting the quality and commercial value of fermented milk. Vanillin is known as a safe and efficient natural antimicrobial additive with great potential value as a food bio-preservative. In this study, the microbiological quality of fermented milk of different brands retailed in China and the antimicrobial activity of vanillin were investigated. A total of 27 fermented milk samples were purchased and evaluated. Fungal isolates obtained were characterized by DNA sequencing of the internal transcribed spacer (ITS) region. The effects of vanillin on the growth of fungi were studied by plate dilution method, radical colony diameter, and mycelium biomass. The result showed that 14.8% of the samples were contaminated with three different species of fungi with Cladosporium spp. being the most predominant fungal contaminant. The study further showed that vanillin had significant inhibitory activity against the growth of the fungi species. The cell number, radical colony diameter, and the mycelium biomass of the fungal contaminant were significantly reduced by the inhibitory action of the vanillin. The study thus provides reliable data evidence that will help relevant stakeholders in the fermented milk industries to improve their quality control strategies and consider vanillin as a bio-preservative with the potential to increase the shelf-life and safety of fermented milk.

The objective of this study was to isolate and identify a yeast strain from the kombucha beverage and evaluate in-vitro its potential as a novel starter in beverage fermentation. Starmerella davenportii Do18 was characterized for its cholesterol reduction; growth at different conditions such as temperatures (25, 30, 37 and 42 ℃), low pH (1.2, 1.5, 2.0 3.0, and 7.0), bile salts (0%, 0.25%, 0.5%, 1% and 2%) high-sucrose stress (2%, 10%, 20%, 40% and 60%); and in-vitro survival in gastric and intestinal environments. Results showed that the yeast strain has a cholesterol-lowering capacity of 45% ± 2%, grew at temperature of 37 ℃ and is resistant to pH 1.5, 2% bile and 40% sucrose solution, could survive in simulated gastric and intestinal environments. The physicochemical characteristics of the fermented beverages were also evaluated, which indicated that the yeast has pH reduction capacity and can produce organic acids and volatile compound such as 2-phenylethanol. Furthermore, the fermented beverage also has high total phenolics and flavonoids content and showed great antioxidant and antimicrobial activities. Therefore, the findings of this research provide strong evidence that S. davenportii Do18 has good fermentation properties, can be a potential starter in food and beverage fermentation.