Water content quantification of raw polysaccharide materials for food processing is generally performed by gravimetric analysis or titrimetric methods, which are time- and energy-consuming, non-eco-friendly and sample destructive. The present study develops and validates a new approach, based on the use of Fourier transform infrared (FTIR) spectroscopy, resulting in a model of the water content of carboxymethyl cellulose (CMC) polysaccharides. Samples of CMC were exposed to different relative humidity conditions. Water content was determined by standard gravimetric methods (OIV-Oeno 404–2010) and compared with the area of FTIR absorption in the range 3675–2980 cm⁻¹, attributed to the stretching of OH groups. The strong correlation between gravimetric results and FTIR area (R² = 0.88) showed no signs of bias across the water content range. A cross-validation technique to predict the water content by band area was assessed obtaining a general equation: y = 2.12 x + 2.80 with a high repetitively and good prediction of the tested models.

Compatibility of CNF with three polysaccharides having different surface charges and backbones (chitosan, methyl cellulose, and carboxymethyl cellulose) was investigated. Chitosan (CH) incorporation reduced water absorption (WA) of CNF films (P < 0.05). CH molecular weight (Mw) (68, 181, 287 kDa) and amount (10 and 20 g/100 g CNF in dry basis) impacted moisture barrier, mechanical, antibacterial, thermal, and structural properties of CNF films. Regardless of Mw, CH incorporation (20 g/100 g CNF) decreased (P < 0.05) WA of CNF films, and high Mw (287 kDa) CH (20 g/100 g CNF) incorporation resulted in lower film water solubility while increasing film water vapor permeability compared with low Mw CH (68 kDa) incorporation (P < 0.05). CNF film with low Mw CH (20 g/100 g CNF) exhibited antibacterial activity against L. innocua and E. coli. Interaction mechanisms between CH and CNF were investigated through thermal, structural, and morphology analyses using DSC, FTIR, and SEM, respectively. CNF films with low or high Mw CH incorporation (20 g/100 g CNF) were further validated as surface contact films for fresh beef patties, showing effectiveness to prevent moisture transfer between the layered patties. This study demonstrated the potential of using CNF-CH composite films as water resistant and antibacterial packaging for foods with high moisture surfaces.

The addition of dietary fibers can alleviate the deteriorated textural properties and water binding capacity (WBC) that may occur when the fat content is lowered directly in the formulas of comminuted meat products. This study investigated the effects of the addition of chitosan or carboxymethyl cellulose (CMC) (2% w/w) to a model meat product. Both dietary fibers improved the water-binding capacity (WBC), while chitosan addition resulted in a firmer texture, CMC lowered the hardness. Chitosan addition resulted in a 2-fold reduction of lipid oxidation products, whereas CMC had no significant effect on oxidation. The effect of chitosan addition on lipid oxidation was evident both in the meat system and after simulated in vitro gastrointestinal digestion. Low-field nuclear magnetic resonance (NMR) relaxometry revealed that the fibers impacted the intrinsic water differently; the addition of chitosan resulted in a faster T₂ relaxation time corresponding to water entrapped in a more dense pore network. Coherent anti-Stokes Raman scattering (CARS) microscopy was for the first time applied in a meat product to study the microstructure, which revealed that the two fibers exerted different effects on the size and entrapment of fat droplets in the protein network, which probably explain the mechanisms by which chitosan reduced lipid oxidation in the system.