Carboxymethyl cellulose based bioactive edible films with Lactobacillus casei and fish protein hydrolysates

Abstract

Nowadays, probiotics have been seriously considered for their potential application in healthy food formulations. The most highlighted concern about probiotics is that the number of probiotic bacteria at the time of consumption may be lower than the required value (107 CFU/g). A new approach is the immobilization of probiotic cells in the matrix of edible films. So in this study, edible carboxymethyl cellulose (CMC) probiotic films containing Lactobacillus casei, and the silver carp muscle protein hydrolysates (SCMH) prepared by using limited Alcalase hydrolysis, were analyzed and the viability of bacterial cells was determined at 25, 4, and -18°C for 30 days. An alkaline solubilization/acid precipitation method was used to isolate silver carp white muscle proteins. Protein isolate (3%, W/V) was hydrolyzed with 5% E/S ratio (w/w) Alcalase at 50°C and pH 8.0 for 3 min. Briefly, films were prepared by dissolving SCMH and CMC powder (1.5%, w/v) in a ratio of 1:2 in distilled water and L. casei was added to a final concentration of 108 CFU/mL. Probiotics were counted at intervals of 1, 10, 20, and 30 day. The physical, mechanical [Ultimate tensile strength (UTS) and elongation at break (EB)], thermal and structural properties were determined. XRD patterns of the film samples collected by X-ray diffractometer (XRD) and Fourier transform infrared (FT-IR) spectroscopy of the film samples were recorded. The results indicated that the addition of SCMH significantly (p˂0.05) improved the L. casei viability at all three temperatures. Thickness, moisture absorption, and water vapor permeability (WVP) of the films were not influenced by addition of the probiotic. However, the addition of SCMH negatively affected the film’s mechanical properties. The FT-IR analysis confirmed the formation of hydrogen bonds between L. casei and the CMC matrix, the XRD and differential scanning calorimetry (DSC) analyses confirmed the plasticizing effect of SCMH on the films. Thus, CMC films containing L. casei showed the highest UTS (3.7 MPa) and EB (29.9%). Generally, the results indicated that the SCMH incorporated CMC-based film can be a good carrier for probiotics as bioactive food packaging system with promising potential for shelf life extension of perishable foods.

Keywords

• protein hydrolysates
• l. casei
• carboxymethyl cellulose
• edible films
• probiotic