Ultraviolet treatment (UV-C) is well known for its antimicrobial effects and current research shows that it has the potential to inactivate microorganisms in milk at much lower temperatures than conventional thermal treatment. However, Ultraviolet irradiation may result in adverse effects on milk quality, which arises due to photo oxidation in the presence of oxygen. Limiting the dissolved oxygen content in milk can minimize oxidative damage and thus, result in a better product quality. Nitrogen purging could be an effective method for reducing dissolved oxygen from liquids. The present study evaluates effects of nitrogen purging (prior to UV treatment) on milk quality. It was found that nitrogen purged UV treated milk causes minimal changes to physicochemical properties of milk.
As one of the most famous traditional Chinese vinegars, the grains physicochemical content of Zhenjiang aromatic vinegar during solid-state fermentation (SSF) reflects the growth status of microorganisms and the quality of fermentation products. In addition, the time for grain-turning has a significant effect on the quality of fermentation products. In this study, a new evaluation method combined near-infrared (NIR) spectroscopy with partial least squares regression (PLSR) was proposed to predict the physicochemical content of grains and the fermentation stage. The performance of the PLSR models for the total acid and the nonvolatile acid were RMSEP = 0.0371, Rp2 = 0.9760, and RMSEP = 0.0216, Rp2 = 0.9646, respectively. The accuracy ratio of SSF stage judgment was 100%. Experimental results indicate that the proposed method can be used to guide on-site grain-turning and improve the quality of fermentation products.
The β-glucosidase properties from one yeast isolate identified as Wickerhamomyces anomalus C4 were characterised. The β-glucosidase activity of W. anomalus C4 was 41.83 ± 0.25 mU/mL, and the optimum temperature and pH were 40 °C and 5.0, respectively. The glucose, 10% v/v of ethanol and 10 mmol/L of Cu2+ inhibited the β-glycosidases activities. The isolate W. anomalus C4 had a stronger alcohol metabolism capacity than commercial Saccharomyces cerevisiae X16. Besides, fermentation with W. anomalus C4 alone and co-fermentations with S. cerevisiae X16 and W. anomalus C4 reduced the volatile acids content and the sourness value compared to S. cerevisiae X16 control. Moreover, inoculation with W. anomalus C4 could enhance volatile aroma richness and complexity of Rosa roxburghii wines, regardless of type or amount thereof. Therefore, the R. roxburghii native yeast isolate W. anomalus C4 may have some application potentials for R. roxburghii wine-making.
In this study, we reported a facile and economical strategy for producing a functional protein-based composite film that was based on soybean protein isolate (SPI), eggshell membrane (ESM) and eugenol (Eu). The composite films were also characterized by mechanical, water vapor permeability (WVP), UV barrier, water resistance, hydrophobicity, antioxidant and antimicrobial activity. The results suggested the appropriate content of ESM could significantly enhance the mechanical, barrier, water resistance and hydrophobicity performances of the film. The addition of Eu into the SPI/ESM film could improve not only these properties, but also antimicrobial and antioxidant properties. The intermolecular interaction between SPI, ESM and Eu was mainly hydrogen bond confirmed by the Fourier-transform infrared spectroscopy (FTIR). The scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicated a good compatibility existed between SPI and ESM, and the Eu could be well emulsified and dispersed into the SPI/ESM film matrices network. Such edible films carried potentially developed in active packaging applications.
Osmotic dehydration (OD) is a drying process that consists in placing the food in contact with concentrated solutions of soluble solids to reduce its water activity. The use of moderate electric field (MEF) may promote increase of the mass transfer rates due to the non-thermal effects of electroporation and permeabilization of the cells. In this context, the objective of this study was to investigate the mass transfer process kinetics during apples OD assisted by MEF, evaluating the non-thermal effects of this emerging technology. The experiments were conducted with sucrose solutions (40, 50 and 60%, m/m) at 40 °C. Samples were submitted to electrical field strength (0, 5.5 and 11.0 Vcm−1), according to an experimental design. Results indicated that the application of MEF favoured water loss and solid gain. The effective mass diffusivities of water and solids increased as voltage applied increases. Moreover, MEF negatively influenced color and reducing capacity of the samples.