Fungicides Films of Low-Density Polyethylene (LDPE)/Inclusion Complexes (Carvacrol and Cinnamaldehyde) Against Botrytis Cinerea

Abstract

Low density polyethylene (LDPE) films were prepared with the incorporation of natural agents (carvacrol and trans-cinnamaldehyde) by the melting process. The co-precipitation method was used successfully to complex the carvacrol or trans-cinnamaldehyde with β-cyclodextrin (β-CD). The active compounds encapsulated in β-CD achieved ca. 90% encapsulation efficiency (E.E.). The inclusion complex studied by scanning electron microscopy (SEM) found particles of different sizes, ca. 4 μm. The active compounds were added directly (1 and 5 wt %) into the polymer matrix, yielding LDPE + carvacrol and LDPE + cinnamaldehyde films. The active compounds encapsulated in β-cyclodextrin (β-CD) were added to LDPE, yielding LDPE + β-CD-carvacrol and LDPE + β-CD-cinnamaldehyde films. The incorporation of carvacrol and trans-cinnamaldehyde, and their corresponding inclusion complexes with β-cyclodextrin, did not affect the thermal properties of LDPE. The microcapsules distributed in all polymer matrices had sizes of 5–20 μm as shown by scanning electron microscopy (SEM). In terms of mechanical properties, the polymers showed a slight decrease of Young’s modulus (12%) and yield stress compared (14%) to neat LDPE. This could be due to the essential oil acting as a plasticizer in the polymer matrix. The LDPE + carvacrol and LDPE + cinnamaldehyde films had the capacity to inhibit fungi by 99% compared to neat LDPE. The effectiveness against fungi of LDPE+β-CD + active agent was slower than by the direct incorporation of the essential oil in the LDPE in the same amount of active agent. The biocidal properties were related to the gradual release of active compound from the polymer. The results confirm the applicability of carvacrol, trans-cinnamaldehyde, and their corresponding inclusion complexes in active packaging, as well as their use in the food delivery industry.

Preparation and Characterization of Carboxymethyl Cellulose-Based Bioactive Composite Films Modified with Fungal Melanin and Carvacrol

“…Those results are higher than reported for WPI/WPC/melanin [ 2 ], as well as flaxseed gum/CV films [ 36 ], but comparable with results reported for whey protein isolate nanofibrils–carvacrol films [ 54 ]. This effect might be attributed to synergistic effect of both antioxidants present in polymer matrix [ 40 , 46 ]. In fact, it is already established that the antioxidant activity of polymer-based films is directly dependent on the content of antioxidant compounds present in composite materials [ 2 , 23 , 40 , 46 ].…”

“…This effect might be attributed to synergistic effect of both antioxidants present in polymer matrix [ 40 , 46 ]. In fact, it is already established that the antioxidant activity of polymer-based films is directly dependent on the content of antioxidant compounds present in composite materials [ 2 , 23 , 40 , 46 ]. A similar synergistic effect of CV with other antioxidants such as pomegranate peel extract [ 40 ], whey protein isolate nanofibrils [ 54 ], as well as in inclusion complexes with cinnamaldehyde [ 46 ] was reported.…”

“…In fact, it is already established that the antioxidant activity of polymer-based films is directly dependent on the content of antioxidant compounds present in composite materials [ 2 , 23 , 40 , 46 ]. A similar synergistic effect of CV with other antioxidants such as pomegranate peel extract [ 40 ], whey protein isolate nanofibrils [ 54 ], as well as in inclusion complexes with cinnamaldehyde [ 46 ] was reported. The hight antioxidant activity of CMC-modified films shown their potential to be used in active antioxidant packaging to prevent oxidation-sensitive food matrices, as well as to increase their shelf life.…”

“…However, the mechanisms of action of CV against Candida have been investigated in several studies and seems to exert its antifungal activity by inducing envelope, disrupting membrane integrity, and blocking ergosterol biosynthesis [33]. Fungicidal activity of starch/CV [43], polyethylene/CV [46], and polypropylene/CV [45] films, as well as polyvinyl alcohol/CV coatings [42] was reported. The literature on melanin applications to develop antimicrobial properties of polymer film is relatively limited.…”

“…This bioactive compound possesses antimicrobial properties, antioxidant, and a particular aroma which makes an attractive ingredient for certain types of foods [37,38]. Moreover, CV has been also reported to be used for modification of biopolymer [5,30,31,36,[39][40][41][42][43][44], and synthethic films [45,46].…”