title: Effects of temperature, water activity and incubation time on fungal growth and aflatoxin B1 production by toxinogenic Aspergillus flavus isolates on sorghum seeds.
abstract: Sorghum, which is consumed in Tunisia as human food, suffers from severe colonization by several toxigenic fungi and contamination by mycotoxins. The Tunisian climate is characterized by high temperature and humidity that stimulates mold proliferation and mycotoxin accumulation in foodstuffs. This study investigated the effects of temperature (15, 25 and 37°C), water activity (aw, between 0.85 and 0.99) and incubation time (7, 14, 21 and 28 d) on fungal growth and aflatoxin B1 (AFB1) production by three Aspergillus flavus isolates (8, 10 and 14) inoculated on sorghum grains. The Baranyi model was applied to identify the limits of growth and mycotoxin production. Maximum diameter growth rates were observed at 0.99 a(w) at 37°C for two of the isolates. The minimum aw needed for mycelial growth was 0.91 at 25 and 37°C. At 15°C, only isolate 8 grew at 0.99 a(w). Aflatoxin B1 accumulation could be avoided by storing sorghum at low water activity levels (≤0.91 a(w)). Aflatoxin production was not observed at 15°C. This is the first work on the effects of water activity and temperature on A. flavus growth and AFB1 production by A. flavus isolates on sorghum grains.
authors.affiliation: Laboratory of Biochemistry, Unity of Mycotoxicology, Faculty of Medicine of Sousse, University of Sousse, Sousse, Tunisia; Food Technology Department, University of Lleida, XaRTA-UTPV, Agrotecnico center, Lleida, Spain.
authors.forename: Amani
authors.initials: A
authors.lastname: Lahouar
authors.affiliation: Food Technology Department, University of Lleida, XaRTA-UTPV, Agrotecnico center, Lleida, Spain.
authors.forename: Sonia
authors.initials: S
authors.lastname: Marin
authors.affiliation: Food Technology Department, University of Lleida, XaRTA-UTPV, Agrotecnico center, Lleida, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Crespo-Sempere
authors.affiliation: Laboratory of Biochemistry, Unity of Mycotoxicology, Faculty of Medicine of Sousse, University of Sousse, Sousse, Tunisia.
authors.forename: Salem
authors.initials: S
authors.lastname: Saïd
authors.affiliation: Food Technology Department, University of Lleida, XaRTA-UTPV, Agrotecnico center, Lleida, Spain. Electronic address: vsanchis@tecal.udl.cat.
authors.forename: Vicente
authors.initials: V
authors.lastname: Sanchis
mesh_terms: D016604:Aflatoxin B1 / Q000096:biosynthesis*; D001231:Aspergillus flavus / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism*; D002523:Edible Grain / Q000382:microbiology*; D009172:Mycology / Q000379:methods; D012639:Seeds / Q000382:microbiology*; D045868:Sorghum / Q000382:microbiology*; D013696:Temperature; D013997:Time Factors; D014867:Water
chemical_list: D014867:Water; D016604:Aflatoxin B1
keywords: Actividad de agua; Aflatoxin B1; Aflatoxina B1; Aspergillus flavus; Crecimiento fúngico; Fungal growth; Incubation time; Temperatura; Temperature; Tiempo de incubación; Water activity