Salted duck egg yolk (SDEY) is one of the traditional pickled egg products in Asian countries, which suffers from the weight loss and deterioration of texture characteristics during storage. To better maintain the texture of SDEY, an edible coating based on whey protein isolate nanofibers (WPNFs) with glycerol (Gly) as a plasticizer and incorporating carvacrol (CA) as an antimicrobial agent was developed. Whey protein isolate (WPI, 5%) was used to self-assemble into WPNFs at 80 °C for 10 h. The particle size, zeta-potential and microstructure of WPNFs–CA emulsion were investigated to evaluate the distribution. Results proved that WPNFs–CA emulsion had smaller particle size and better distribution than WPI–CA emulsion. WPNFs–CA/Gly edible coating was then prepared based on WPNFs–CA emulsion. The WPNFs–CA/Gly edible coating exhibited higher antibacterial activity while the WPNFs–CA/Gly film had smooth and continuous surfaces and better transmittance compared with other samples. Furthermore, weight losses and textural properties changes of SDEYs with WPNFs–CA/Gly coating were evaluated. Results proved that salted duck egg yolks with WPNFs–CA/Gly coating exhibited lower weight losses. Textural properties were significantly improved by the WPNFs–CA/Gly coating on SDEYs than those uncoated samples. It was noted that the egg yolks coated with the WPNFs–CA/Gly coating had the lowest hardness increase rate (18.22%). Hence, WPNF-based coatings may have a good development prospect in the food industry.

The composition and properties of edible coatings (ECs) will significantly influence their effects of food preservation. For the first time, whey protein isolates nanofibers (WPNFs), as a novel material with high hydrophobicity and antioxidant activity, combined with carvacrol (CA) as an antimicrobial agent and glycerol (Gly) as a plasticizer, was used to prepare edible coating (WPNFs-CA/Gly) for preserving fresh-cut Cheddar cheese. The prepared WPNFs and ECs emulsions have been investigated with transmission electron microscopy. Furthermore, the antioxidant activity of ECs emulsions, antimicrobial activity of edible films, and the physical properties of edible films, such as micromorphology, thickness, transparency, and moisture content, have also been evaluated. The weight losses and physical characteristics of both coated and uncoated fresh-cut Cheddar cheese samples have been assessed during storage. The DPPH free radical scavenging rate of WPNFs-CA/Gly emulsion was up to 67.89% and the reducing power was 0.821, which was higher than that of WPI-CA/Gly emulsions. The antimicrobial activity of WPNFs-CA/Gly films was nearly 2.0-fold higher than that of WPNFs/Gly films for the presence of CA. The WPNFs-CA/Gly films had smooth and continuous surfaces, and the transparency reached 49.7% and the moisture content was 26.0%, which was better than that of WPI-CA/Gly films. Furthermore, Cheddar cheese with WPNFs-CA/Gly coatings has shown lower weight losses (15.23%) and better textural properties than those uncoated samples. This in-depth study has provided a valuable and noteworthy approach about the novel edible coating material.

Whey protein isolate nanofibrils (WPNFs) can be used as a novel stabilizer in the Pickering emulsion system to improve the water solubility, stability and bioavailability of lipophilic bioactive ingredients. In this study, conjugated linoleic acid (CLA) and WPNFs were used to prepare a stable Pickering emulsion. We used a transmission electron microscope, low-temperature scanning electron micrographs and other methods to evaluate the micromorphology, surface hydrophobicity and structural units of the obtained WPNFs. Compared with whey protein isolate/CLA Pickering emulsion, the WPNFs/CLA Pickering emulsion has greater ability to remove 2,2-Diphenyl-1-picrylhydrazyl and 2,2′-amino-di(2-ethyl-benzothiazoline sulphonic acid-6) ammonium salt free radicals. Furthermore, the WPNFs/CLA Pickering emulsion has a more stable effect in terms of droplet size and zeta potential over a wider range of ionic strength and temperature conditions. These findings indicate that Pickering emulsion stabilized by WPNFs is more suitable as a carrier of CLA, as it increases the solubility of CLA and has better active applications in biology and food.

从温度、 pH、 空气、 白炽光照和紫外光照五个方面, 研究环境变化对微胶囊贮存稳定性的影响。 首次证实乳清蛋白与半乳糖美拉德反应产物 (WPI-半乳糖MRPs) 有助于提高β-胡萝卜素微胶囊的贮存稳定性。 利用扫描电镜观察β-胡萝卜素微胶囊形态特征; 用激光粒度分析微胶囊颗粒的大小; 以微胶囊的保留率为检测指标, 研究温度、 pH、 空气、 白炽光照及其紫外光照对微胶囊贮存稳定性的影响。 以

Thiocyanate could effectively inhibit bacteria in milk and extend the shelf life of milk. However, excessive addition will lead to health risks. Therefore, the determination of thiocyanate in raw milk has received a lot of attention, but the determination could be interfered with by other components in raw milk and the pre-treatment of raw milk is complex. In this study, a new pretreatment method combined with ion chromatography (IC) for rapid and sensitive determination of thiocyanate is proposed. An acetonitrile/(NH₄)₂SO₄ aqueous two-phase system (ATPS) was developed for the separation and enrichment of thiocyanate in raw milk. Response surface methodology was performed to optimize the extraction conditions and an efficient pretreatment were obtained using ATPS composed of 42% acetonitrile (w/w) and 16% (NH₄)₂SO₄ (w/w), with the pH 4.7, and the recovery of thiocyanate reached 107.24 ± 0.5%, and the enrichment ratio was 10.74 ± 0.03. IC was used to establish a thiocyanate enrichment method. The linear range was from 0.05 to 15 mg/L and R² = 0.998, the limit of detection (LOD) was 0.2 μg/L, the limit of quantification (LQD) was 0.6 μg/L. Hence, it is feasible to combine ATPS with IC for the enrichment and determination of thiocyanate in raw milk.