Use of smart packaging technologies for monitoring and extending the shelf-life quality of modified atmosphere packaged (MAP) bread: application of intelligent oxygen sensors and active ethanol emitters

Following commercial assessment of the packaging materials and systems used for modified atmosphere packaged (MAP) speciality breads, a study was carried out to assess the bread quality and shelf life following the implementation of an improved MAP (10 % CO2, 90 % N-2) process and compared to controls (held in air). O-2 sensors permitted the continuous and non-destructive monitoring of in-pack O-2 levels over time. Ethanol emitters (EE) or product surface sprays (ES) were used for MAP and control treatments to establish their effects on product shelf life. MAP samples had a continuous O-2 level of < 0.1 % throughout storage. Samples packed in air showed contrasting O-2 profiles, where control samples showed that O-2 levels were depleted by day 6, whereas controls utilising EE and ES demonstrated a reduced O-2 decline over time. ES in control packs slowed O-2 decline over time, with complete O-2 depletion occurring by day 14, whereas the use of EE in control packs showed an even slower decline with complete O-2 depletion occurring by day 35 of storage. The use of ES, but particularly EE, reduced mycological counts in bread samples, reflecting the reduced O-2 utilisation in control packs. This was mirrored, but not to the same extent, for bread held under MAP conditions. Sensory evaluation of breads demonstrated that the use of ethanol in packs produced no negative organoleptic issues. In conclusion, O-2 sensors clearly demonstrate their ability to assess pack containment and O-2 utilisation within packs over time by yeasts/moulds while the use of EE controlled mycological growth, thereby extending product shelf life.