Shelf life extension of pre-baked buns by an ACTIVE PACKAGING ethanol emitter

Abstract

The paper reports the influence of an ethanol emitter (Ethicap) on the microbiological condition and the shelf life extension of a bakery product. Pre-baked buns, with a water activity of 0.95, were packaged with different amounts of Ethicap and stored at room temperature. Yeasts and moulds remained largely absent from the core of the pre-baked bun (< 10(2) cfu g(-1)) during storage, independent of the presence of ethanol. The total mesophilic count was low at the beginning of the storage experiment (< 10(2) cfu g(-1)), but increased without ethanol within 1 week to an unacceptable level. In the presence of ethanol, the total mesophilic count stabilizes at a consumable level of 10(5)-10(6) cfu g(-1). The increase of total mesophilic count was caused by growth of a Bacillus spp., probably B. subtilis. Mould growth on the outer surface is limiting for shelf life extension. On the pre-baked buns, the following moulds were present: Penicillium solitum, P. commune, P. corylophilum, Cladosporium sphaerospermum and C. herbarum. These started to grow within 4-6 days. Mould growth can be delayed for 13 days by adding Ethicap. The ethanol probably has to be absorbed by the pre-baked bun to be effective in growth suppression of the Bacillus spp. the moulds. The pre-baked buns absorb most of the ethanol from the package headspace, and the ethanol content of the products is approximately 0.8 weight% after 21 days. This largely exceeds the overall migration limit of 60 mg kg(-1) food (0.006 weight%).