Natural antifungal systems for prevention of mould spoilage in bakery products

摘要

Growth of spoilage fungi in bread and other bakery products is currently controlledwith the addition of weak acid preservatives. Consumers demand more naturalproducts and thus there is a need to reduce the amount of chemical preservativesadded to foods, or to identify alternative, more 'natural' antifungal compounds withstrong biological activity. This thesis reports on several areas of research undertakenin the project: evaluation of sub-optimal concentrations of existing preservatives,under different environmental conditions, on growth and ochratoxin A (OT A)production by six bread spoilage moulds; efficacy of new/natural antifungalcompounds for possible use in bread preservation; evaluation of the impact ofpreservation hurdles on ecophysiology of the spoilage fungi, including niche overlap;and mechanisms of action of preservatives on hydrolytic enzymes.It was found that the use of currently applied levels of the existing preservativespotassium sorbate, calcium propionate and sodium benzoate were effective, under lowpH environments (pH 4.5) at completely controlling growth of spoilage moulds(Aspergillus ochraceus, Eurotium repens, Cladosporium herbarum, Penicilliumcorylophilum and Penicillium verrucosum) on wheat flour-based substrates over aperiod of 30 days. At higher pH levels, the efficacy decreased being almost nil at pH7.5. The use of sub-optimal concentrations of weak acid preservatives led in mostcases to reductions in lag times and/or stimulation of mould growth and ochratoxin Aproduction by P. verrucosum strains. Cont/d.