J. Agric. Food Chem. 2008, 56, 6364–6369
New Cinnamon-Based Active Paper Packaging against Rhizopusstolonifer Food Spoilage
A. RODRI´GUEZ, C. NERI´N,*
Department of Analytical Chemistry, Aragon Institute of Engineering Research (I3A), CPS-University ´ of Zaragoza, Marıa de Luna St. 3, E-50018 Zaragoza, Spain ´
A new active paper package based on theincorporation of cinnamon essential oil to solid wax parafﬁn as an active coating is proposed, developed, and evaluated. The antifungal activity of the active paper is tested against Rhizopusstolonifer, and the results demonstrate that 6% (w/w) of the essential oil in the active coating formulation completely inhibits the growth of R. stolonifer, whereas 4% still has strong antimicrobial activity in in vitroconditions. Then, active paper is evaluated with actual food, sliced bread, using different storage times. After 3 days of storage, almost complete inhibition is obtained with 6% cinnamon essential oil. Qualitative analysis by solid-phase microextraction and determination of cinnamaldehyde in the sliced bread were also performed and conﬁrmed the strong correspondence between the inhibition of themold and the amount of cinnamaldehyde in the bread.
KEYWORDS: Bread spoilage; Rhizopusstolonifer; active paper packaging; cinnamon; cinnamaldehyde
Rhizopusstolonifer fungus (black bread mold) constitutes, together with Aspergillus and Penicillium genera, the most prevalent spoiler of white bread and bakery products (1, 2). This fungus is responsible for the production ofmycotoxins, off-ﬂavor formation, and disgusting appearance in white bread (3, 4). Rhizopusstolonifer stolonifer usually grows on bread and fruit and, because its spores are ubiquitous in the air, infests the product within a short time when bread is stored in an enclosed, humid environment. Some strategies have been reported in the literature to preserve bread from R. stolonifer (5) infestation and toincrease the shelf life of bakery goods. Some of them are based on the use of natural essential oils or spices as food preservatives (6–8). Essential oils are rich sources of terpenes and phenols (9), and for this reason, they have strong antimicrobial properties. Another interesting feature is that these natural compounds do not have any signiﬁcant medical or environmental impact, so theyconstitute effective alternatives to conventional antimicrobial agents. Active packaging is deﬁned as a packaging that changes the condition of the packaged foodstuff to extend its shelf life or improve its safety while maintaining its quality (10, 11), and it has become a popular alternative to control undesirable molds in foods (10, 12). In a previous communication, a new tailor-made active paperpackaging using natural essential oils as antimicrobial solutions was introduced (13). In this packaging, some essential oils (clove, cinnamon, and oregano) were used to manufacture an active wax coating using a quality aqueous solution of anionic/nonionic parafﬁn. The
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selectivity ofcinnamaldehyde-fortiﬁed cinnamon essential oil against several fungi (C. albicans, A. ﬂaVus, P. nalgioVense, P. roqueforti, and E. repens) was demonstrated. Nevertheless, a nonaqueous emulsion but solid parafﬁn was mainly used by coating paper manufacturers in many food-related paper packaging because of its better physical properties. To develop a new active paper based on this solid wax parafﬁnthen became decisive. The work reported here has two main aims. The ﬁrst aim is to demonstrate that a new solid active parafﬁn formulation can be used, in a similar way that the emulsion formulation did, as an efﬁcient antimicrobial active coating in paper or board packaging. For this purpose, this new active paper will be evaluated against mold R. stolonifer using a vapor-phase test, as described...