International journal of food microbiology最新文献

As global warming and the energy crisis receive increasing attention, the development of ecofriendly functional food packaging materials has also garnered significant interest. In this study, curdlan was combined with foaming agents (Cremodan and xanthan) and a crosslinking agent (sodium trimetaphosphate) to form a porous curdlan hydrogel. The material properties of the curdlan hydrogels were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and a thermogravimetric analysis (TGA). Results showed that the 2 % curdlan hydrogel exhibited a high water content (96.2 %), and swelling (89.2 %) and reswelling abilities (89.5 %), with a distinctly porous structure and excellent thermostability. These properties make it suitable for loading carvacrol, resulting in the formation of a carvacrol/curdlan hydrogel. In the results of antimicrobial testing, the carvacrol/curdlan hydrogel showed greater antimicrobial properties against Shewanella putrefaciens (32.3 mm) and Vibrio harveyi (33.1 mm) compared to V. parahaemolyticus (24.5 mm) in inhibition zone test. Noteworthy was the certain degree of antimicrobial ability of the carvacrol/curdlan hydrogel, which continuously exhibited microbial inhibition of the total viable count (TVC) of the no-inoculated and V. parahaemolyticus-inoculated group on sea bass fillets during 6 days of storage. In addition, the carvacrol/curdlan hydrogel inhibited the S. putrefaciens-caused microbial spoilage of fish. However, the continuous antibacterial ability of carvacrol/curdlan hydrogel needs to be improved. In future work, changing the porous size of curdlan hydrogel to control the carvacrol release for elongating the durability and long-term usage will be accomplished to fit the need in functional packaging applications.

UV-C light is an alternative for preserving clear fruit-based drinks, replacing existing thermal treatments that degrade product quality and are ineffective against some microorganisms, including Alicyclobacillus acidoterrestris, a spoiling agent of concern in the juice sector. Texturizing agents are essential since consumers' preferences for these products strongly depend on the mouthfeel. However, the complexity of the treated texturized system may have an essential influence on UV-C effectiveness. The main goal of this study was to evaluate the effect of texturization on the UV-C inactivation of A. acidoterrestris spores (AA) and separate cocktails of Escherichia coli (ECC), yeast (YC), and Salmonella (SC) in orange juice. Binary combinations (0.0 to 0.3 % w/v) of carboxymethyl cellulose (CMC) and guar gum (GG) were added to orange juice (OJ). A multiple regression analysis identified suitable CMC and GG combinations with optimal viscosity (~ 20 mPa.s) and maximum suspended particles (%S), leading to two formulations: TOJ₁ (0.075 % w/v CMC + 0.15 % w/v GG at five °C) and TOJ₂ (0.045 % w/v CMC + 0.165 % w/v GG). A consumer field test confirmed the advantages of sweetness, bitterness, flavor, color, and body/viscosity, establishing it as the best formulation. UV-C assisted by mild heat (UV-C/H) inactivation in OJ and TOJ₁ was determined (1651 mJ/cm², 50 °C, 1.8 L/min). Single treatments (UV-C and H) were also performed to evaluate synergy. The UV-C/H induced damage on AA spores was measured by flow cytometry (FC) labeling with fluorescein diacetate (FDA) and propidium iodide (PI) for monitoring membrane integrity. The bacterial cocktails were the most sensitive to the UV-C treatments, followed by YC and AA. UV-C achieved moderate inactivation (1.6-4.6 log reductions) in non-texturized OJ, while UV-C/H significantly enhanced microbial sensitivity (3.4-7.5 log reductions). Texturization slightly reduced UV-C effectiveness, achieving 2.9-5.2 log reductions in TOJ₁. The Weibull model provided the best fit characterizing UV-C inactivation with evidence of subpopulations of different resistances. In TOJ₁ treated by UV-C/H, the flow cytometry study revealed membrane-compromised AA spores with a gradual increase of PI+ cells with treatment time. The scanning electron micrographs showed structural damage, less evident in the texturized system. The results suggest that UV-C can be used to process texturized orange juice and could be a promising alternative for controlling Alicyclobacillus spp. spores and other microbial strains in industrialized orange juice.