Physicochemical and Antimicrobial Properties of Biopolymer-Candelilla Wax Emulsion Films Containing Potassium Sorbate – A Comparative Study

Abstract

The comparative studies were performed in order to assess the most suitable matrix polymer for potassium sorbate (KS). The preservative (1.0, 2.0, 3.0, 4.0 % w/w) was included into edible films made from different biopolymers: carboxymethyl cellulose (CMC), oxidized potato starch (OPS), soy protein isolate (SPI), gelatin (GEL), sorbitol, candelilla wax, and emulsifier. The incorporation of KS dramatically reduced the toughness of all tested films. The plasticizing action of KS was the weakest in CMC-based films, which exhibited the highest initial stiffness and the lowest stretchability. With the exception of GEL films, KS addition caused an increase in water vapor permeability of the films. Moreover, except for CMC films, increased KS content in the films led to increase in the stickiness, moisture content, and solubility. CMC-based films, regardless of the concentration of KS, had unchanged hygroscopicity and were completely water-soluble. In most cases, KS reduced transmission of light through the films. OPS, SPI, and GEL films, in contrast to CMC-based ones, exhibited sorbitol crystallization; however, the addition of KS successfully overcame this disadvantage.The antimicrobial effectiveness of all tested films increased by increasing the KS concentration. The kind of carrier used affected antimicrobial effectiveness of KS, and SPI films tended to have the weakest antibacterial and antifungal activity, especially at low KS content. The data given here may provide a useful guide in establishing the best compromise between conflicting film property demands. Taken together, our findings suggest that the CMC films could be the best carrier for KS.

Mechanical and Physical Properties of Pea Starch Edible Films in the Presence of Glycerol

“…Since the total solid levels in the cast pea starch film remained constant, the addition of glycerol increased the soluble matter present in the films, leading to the formation of structures more sensitive to water (Kowalczyk et al . ). Increasing of water solubility might be because of an increase of the amorphous regions (Flores et al .…”

Water Sorption Isotherm of Pea Starch Edible Films and Prediction Models

“…By incorporation of glycerol, the crystallization development may be partially prevented, because it can disturb the configuration of polymeric chains by interfering with amylose packing through the formation of glycerol–starch and glycerol–water interactions [38]. The increase of glycerol content resulted in weakening the cohesiveness of the polymer structure, creating the polymer network with greater interchain distances [39], thus facilitating more water molecules immobilizing into the pea starch film matrix [40]. The strong tendency of glycerol to water was associated with its high polarity [41].…”

Biopolymer/candelilla wax emulsion films as carriers of ascorbic acid – A comparative study

“…This result may be attributed to more dissolved state of sorbitol, as a result of increased water content in the AA-added films (Table 1). AA did not prevent sorbitol crystallization in OPS films, most likely due to insufficient moisturizing effect (MC ¼ 8.07e8.74%); previous study (Kowalczyk, Kordowska-Wiater, et al, 2014b) showed that sorbitol did not crystalize from OPS films with MC greater than 10%. It is also possible that inhibition of the plasticizer crystallization in OPS films is difficult, since starch crystals, formed during the retrogradation process, serve as sorbitol-crystal nuclei (Kowalczyk & Baraniak, 2014).…”

“…The plasticizing effect of sorbitol, however, may not be stable during long-term storage. The reason for this is its tendency to recrystallize over time, which could be observed visually from white spots appearing on the film surface (Kowalczyk, Gustaw, et al, 2014a;Kowalczyk, Kordowska-Wiater, Sołowiej, & Baraniak, 2014b). Previous studies have shown that possibility of sorbitol recrystallization depends on both the type of film-forming agent (i.e.…”

“…Previous studies have shown that possibility of sorbitol recrystallization depends on both the type of film-forming agent (i.e. crystallization did not occur in CMC films, while OPS films crystalize within a few days) and the type of additive incorporated into polymeric matrix (CnW accelerates, while potassium sorbate and chitosan lactate inhibit sorbitol crystal growth) (Kowalczyk & Baraniak, 2014;Kowalczyk, Gustaw, et al, 2014a;Kowalczyk, Kordowska-Wiater, et al, 2014b, Kowalczyk, Kordowska-Wiater, Nowak, & Baraniak, 2015. This study demonstrates that AA inhibits the crystal growth process in SPI and GEL films stored up to 1 month (Table 2).…”