The effects of fennel essential oil (FEO) and peppermint essential oil (PEO) on chitosan-based films were evaluated in this study. The results showed that the addition of FEO and PEO slightly increased the density and thickness, while significantly decreasing the moisture content, water swelling, and solubility properties. The color values (L, a, b, ΔE and whiteness index (WI)) of the composite films containing FEO and PEO changed obviously with a tendency toward yellowness, which was beneficial in resisting food decomposition caused by ultraviolet light. The differential scanning calorimetry (DSC) and fourier-transform-infrared (FTIR) results indicated that the addition of FEO and PEO affected the structure of the chitosan films, while the interaction between the chitosan and polyphenols in FEO and PEO established new hydrogen bonds and improved the thermal stability. The environmental scanning electron microscopy (ESEM) illustrated that the surfaces of the composite films containing FEO and PEO were smooth, but the cross-section was rougher than in pure chitosan film. Furthermore, the composite films containing FEO and PEO exhibited prominent antioxidant activity. In short, the novel active chitosan-based films with incorporated FEO and PEO present broad application prospects in fresh-cut meat or vegetable packaging.

Background: This study evaluated the influence of intramuscular connective tissue (IMCT) on structural shrinkage and water loss during cooking. Longissimus thoracis (LT), semimembranosus (SM) and semitendinosus (ST) muscles were cut and boiled for 30 min in boiling water, followed by detection of water holding capacity (WHC), tenderness, fiber volume shrinkage and protein denaturation. Results: Compared with LT and SM, ST had the best WHC and lowest WBSF and area shrinkage ratio. The mobility of immobilized water (T22) was key to holding the water of meat. ST contained the highest content of total and heat-soluble collagen. On the contrary, ST showed the lowest content of cross-links and decorin, which indicate the IMCT strength of ST is weaker than the other two. The heat-soluble collagen is positively correlated to T22. Conclusions: The shrinkage of heat-insoluble IMCT on WHC and WBSF may partly depend on the structural strength changes of IMCT components rather than solely caused by quantitative changes of IMCT.