Inactivation of Aspergillus carbonarius and Aspergillus flavus in malting barley by pulsed light and impact on germination capacity and microstructure

Abstract

The impact of pulsed light (PL) fluence on reduction of Aspergillus carbonarius and Aspergillus flavus conidia in barley grains (aw 0.60 and 0.98), germinability and structure was studied. Treatments were done for 5–75 s at 5 and 10 cm distance from the flash lamp (fluence: 11.0–165.8 J/cm2 at 5 cm, and 6.0–89.6 J/cm2 at 10 cm). Maximum reduction in fungal population was 1.2–1.7 log cycles up to 5–15 s (fluence: 6.0–18.0 J/cm2). Acceptable germinability values were obtained up to 25 s treatment at 10 cm distance. Light microscopy study supported changes in germinability. Most of the structure elements of the caryopsis were drastically altered with high fluence values, while embryo viability was maintained with doses up to 29.9 J/cm2. PL up to 18.0 J/cm2 could be a nonchemical option to reduce moulds in barley with minor impact on germinability. Industrial relevance text The reduction of fungal load in malting barley will contribute to improve the production process and the quality of beer. The application of intense light pulses up to 18.0 J/cm2 (15 s, 10 cm from the lamp quartz window) could be a potentially suitable nonchemical (residue-free) option to reduce fungal presence in barley grains with minor impact on structure and germinability.