Application of active packaging for increasing mould-free shelf life of bread

Abstract

Microbial spoilage of bread and the consequent waste problem causes large economic losses for the bakery industry. Active systems of food packaging have been developed not only to protect food products, but also to inhibit or retard microbiological growth, extending food shelf life. At the same time, the interest in natural and non-synthesized substances, as a potential alternative to extend shelf life has increased regarding consumer’s demand. In this context, the objective of this dissertation is to study an active packaging, based on ethanol, for a traditional recipe of sliced bread without crust, in order to improve its shelf-life. An analysis of the state-of-the-art was performed defining principal factors that affects shelf life of bread, exploring the use of ethanol as food preservative and the potential antioxidant and antimicrobial activities of olive leaf extract. Bread, without chemical preservatives, was produced in the kitchen lab and packaged in active packaging systems based in ethanol. In one case the ethanol was applied directly by spray, and in the other case sachets with ethanol emitter at two concentrations were used. The bread was packaged in these active systems and stored at 23 ºC. The performance of each system was compared by monitoring several physical, chemical, sensorial and microbiological parameters during the storage time. The ethanol was successfully tested, showing a potential alternative to conventional preservatives in bread industry. The ethanol emitters were more efficient, particularly against moulds, than the direct application system. It was concluded that the active emitters allowed for an ethanol concentration in the head-space constant and tending to increase, while the direct system showed a higher concentration in the beginning but decreasing ethanol concertation. In comparison with control samples, the Antimold Mild® grade 20 emitters increased bread’s shelf life by 70 %, whereas Antimold Mild® grade 10 and ethanol directly applied at a concentration of 0.5 % increased it by 57 % (10 and 13 days, respectively).

Date of Award	14 Mar 2017
Original language	English
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Maria de Fátima Poças (Supervisor)