Mold spoilage of bread and its biopreservation: A review of current strategies for bread shelf life extension

Abstract

Microbial spoilage of bread and the consequent waste problem causes large economic losses for both the bakery industry and the consumer. Furthermore the presence of mycotoxins due to fungal contamination in cereals and cereal products remains a significant issue. The use of conventional chemical preservatives has several drawbacks, necessitating the development of clean-label alternatives. In this review, we describe current research aiming to extend the shelf life of bread through the use of more consumer friendly and ecologically sustainable preservation techniques as alternatives to chemical additives. Studies on the in situ-production/-expression of antifungal compounds are presented, with special attention given to recent developments over the past decade. Sourdough fermented with antifungal strains of lactic acid bacteria (LAB) is an area of increasing focus and serves as a high-potential biological ingredient to produce gluten-containing and gluten-free breads with improved nutritional value, quality and safety due to shelf-life extension, and is in-line with consumer's demands for more products containing less additives. Other alternative biopreservation techniques include the utilization of antifungal peptides, ethanol and plant extracts. These can be added to bread formulations or incorporated in antimicrobial films for active packaging (AP) of bread. This review outlines recent progress that has been made in the area of bread biopreservation and future perspectives in this important area.

Strategies to Extend Bread and GF Bread Shelf-Life: From Sourdough to Antimicrobial Active Packaging and Nanotechnology

“…amylovorous has been attributed to the synergy among more than ten antifungal compounds, including cyclic dipeptides, fatty acids, phenyllactate and phenolic acids. Interestingly, it has been also observed that production of antifungal compounds in sourdough is species-and substrate-specific [2].…”

“…These compounds are nevertheless present with a relatively high minimal inhibition concentration, which ranges from 0.1 to 10,000 mg/kg [2], despite being produced in low amount in the fermentation substrate. For that reason, it has been hypothesized that the antifungal inhibitory mechanism likely originates from complex mechanisms of synergy among the low molecular mass compounds [2].…”

“…In vitro screening experiments have shown that the addition of propionate to rye sourdough bread is not recommended due to the resistance of P. roqueforti [28], as well as to the fact that propionate has only slight effect in mould inhibition when included in bread at pH 6 [2].…”

“…For that reason, it has been hypothesized that the antifungal inhibitory mechanism likely originates from complex mechanisms of synergy among the low molecular mass compounds [2].…”

“…responsible for rope spoilage [37]. However, the pH drop and the acidification, which is usually associated with the production of lactic and acetic acids, are reportedly parameters which can extend bread shelf-life only to a limited extent and/or do not extensively influence mould inhibition [2].…”