This study used Wood-Based Activated Carbon Fibers Paperboard (WACFP) to investigate the water activity (Aw), color difference (sup deltaE*) change, and percent weight with various Aw foods in the environment systems at the relative humidity of (RH) 90 and 40% and temperature of 25degC, which were expected to be references for food moisture-proof material. From the Aw result, WACFPs was 0.47-0.50, which was lower than the habitat for general microorganisms. WACFP with 40% wood-based activated carbon fibers (WACFs) had better stability for high, intermediate, and low Aw foods (HAwF, MAwF, and LAwF) in the RH 90 or 40% environment than the other specimens. In the RH 90% environment, the hygroscopic ability of WACFP was 4.49-6.18%; while that at RH 40% was 1.69-2.20%. According to the simulation results of WACFPs, as food moisture-proof material in HAwF, MAwF, and LAwF in the RH 90% environment, WACFPs had a good stability in MAwF. The Aw change was 0.02-0.03, the sup deltaE* change was 1.24-2.70, and the percent weight was -0.26-0.31%. In terms of RH 40%, better stability occurred in HAwF, where the difference of Aw was 0.02-0.03, the sup deltaE* change was 1.23-2.83, and the percent weight was -1.22 - -1.24%. The developed WACFP; therefore, can be an optional food moisture-proof material for different Aw food systems.

Motivated by the increasing need for new solutions with less environmental impact, in this work we have investigated the benefits of depositing a wheat gluten (WG) coating on paperboard substrates intended for food packaging applications. To overcome the inherent moisture sensitivity of this protein, WG was combined with a silica network obtained by sol-gel chemistry. WG/silica hybrid coatings were characterized in terms of structural, thermal, morphological, surface, and water vapor barrier properties. Spectrometric analysis demonstrated that the organic and inorganic phases interacted primarily through hydrogen bonding. This was also supported by thermal experiments, which revealed a higher Tg measured for the hybrid materials with the higher silica content (114 ± 1 °C and 128 ± 2 °C, respectively) compared to the pure WG material (Tg = 89 ± 1 °C). Scanning electron microscopy showed that the surfaces of the coatings were very smooth, though the presence of pinholes, cracks, fractures, and voids was detected, especially for the silica-rich formulations. Upon deposition of the coatings, the wettability of the bare paperboard increased, as demonstrated by the lower water contact angle values. In addition, hybrid coatings exhibited a higher wettability over the pristine WG coating, which was due to a more intense spreading phenomenon. The deposition of the coatings led to a ∼ 4-fold reduction in water vapor transmission rate (WVTR ∼ 90 g m⁻² 24 h⁻¹ at 23 °C and 65% relative humidity) of the specific cellulosic substrate tested in this work (WVTR ∼ 350 g m⁻² 24⁻¹).

The chloropropanols, monochloropropane-1,2-diol (3-MCPD) and 1,3-dichloro-2-propanol (1,3-DCP) are potential contaminants that may be found in food contact materials (FCM) from paper and paperboard that have been treated with certain wet-strength resins. They can migrate from the paper matrix to aqueous food and beverages and, due to their potentially carcinogenic properties, are of increasing interest in quality assurance or official controls of paper-based FCM. We hereby describe an improved method for the analysis of 3-MCPD and 1,3-DCP in water extracts of FCM making use of 1-chloro-3-methoxy-2-propanol (CMP) as a novel internal standard. The LOD and LOQ were determined to be 0.4 µg/L and 1.2 µg/L for both analytes, making the method appropriate for the quantification of 3-MCPD and 1,3-DCP below the current legal limits. The method was applied to an extensive market survey of food contact articles made from paper and paperboard including 674 samples. The survey revealed that a high percentage of the products available on the market (e.g., up to 55% of the analysed drinking straws) exceed the BfR limits with values of up to 327 µg/L 3-MCPD and 20 µg/L 1,3-DCP detected in the cold water extract. Remarkable differences were observed concerning the release of 3-MCPD and 1,3-DCP from different kinds of paper-based FCM products, with drinking straws, cupcake cases, bagasse bowls and kitchen rolls showing particularly high rates (>10%) of non-conformity with the legal limits. A number of samples with especially high concentrations were additionally analysed by hot water extraction, which surprisingly yielded considerably lower results for the release of 3-MCPD and 1,3-DCP than cold water extraction. The results indicate that cold water extraction is the most sensitive method to detect the migration and control the risk of exposure to 3-MCPD and 1,3-DCP.