Synthesis of active packaging films from Lepidium sativum gum/polyvinyl alcohol composites and their application in preserving cheddar cheese
HPLC analysis of LSE
Aqueous LSE was extracted from the whole seed by distilled water at room temperature. The simple extraction procedure yielded natural compounds of antimicrobial activity and low cytotoxicity28. The composition of the obtained extract was analyzed using HPLC. Twelve phenolic compounds were detected in the seed extract (Table 2). Rutin, sinapic acid, and p-hydroxybenzoic acid were the most abundant phenolic compounds in the water extracts of cress seed, in agreement with29 Abdel-Aty et al. and Kaiyrkulova et al.30.
Table 2 Composition, thermal and mechanical characteristics of prepared films.
Preparation of active packaging films
Free-standing films from LSE/PVA blends were prepared according to Scheme 1. Although PVA acted as a suitable holding matrix for the extract, the optimal concentration of PVA needed to be identified to obtain a high-quality film. The first trials for film preparation were unsuccessful due to the high stiffness of the formed films. The concentrations of the PVA solutions and their ratio to the extract are shown in Table 2. The film F1 contained 10% PVA solution, and this amount was reduced to 5% in F2. The first film was much better than the second one. However, film F3 contained the same amount of PVA as F2 but double the amount of the extract, which worsened its appearance and mechanical properties. Hyperbranched polymers are a class of macromolecules characterized by their low solution and melt viscosity and the presence of many functional terminals31. Thus, hyperbranched PAMAM was added in small amounts to the film formulations for several reasons. It can act as a plasticizer and hence improve the mechanical properties of the film, it is not toxic32, and its amine end groups might have biological activity (its structure is shown in Scheme 1).
Scheme 1
Preparation steps for achieving free-standing films suitable for food packaging.
Chemical structure of PAMAM is investigated using FTIR and the spectrum shown in Fig. 1A…
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