Effect of water activity, temperature, and incubation period on fungal growth and ochratoxin A production on Nyjer seeds

AbstractPhomopsins are mycotoxins mainly infesting lupines, with phomopsin A (PHOA) being the main mycotoxin. PHOA is produced by Diaporthe toxica, formerly assigned as toxigenic Phomopsis leptostromiformis, causing infections in lupine plants and harvested seeds. However, Diaporthe species may also grow on other grain legumes, similar to Aspergillus westerdijkiae as an especially potent ochratoxin A (OTA) producer. Formation of PHOA and OTA was investigated on whole field peas as model system to assess fungal growth and toxin production at adverse storage conditions. Field pea samples were inoculated with the two fungal strains at two water activity (aw) values of 0.94 and 0.98 and three different levels of 30, 50, and 80% relative air humidity.After 14 days at an aw value of 0.98, the fungi produced 4.49 to 34.3 mg/kg PHOA and 1.44 to 3.35 g/kg OTA, respectively. Strains of D. toxica also tested showed higher PHOA concentrations of 28.3 to 32.4 mg/kg.D. toxica strains did not grow or produce PHOA at an aw values of 0.94, while A. westerdijkiae still showed growth and OTA production.Elevated water activity has a major impact both on OTA and, even more pronouncedly, on PHOA formation and thus, proper drying and storage of lupins as well as other grain legumes is crucial for product safety.

Download Full-text

Prediction of fungal growth and ochratoxin A production by Aspergillus ochraceus on irradiated barley grain as influenced by temperature and water activity

International Journal of Food Microbiology ◽

10.1016/j.ijfoodmicro.2004.02.003 ◽

2004 ◽

Vol 95 (1) ◽

pp. 79-88 ◽

Cited By ~ 73

Author(s):

E Pardo ◽

S Marı́n ◽

V Sanchis ◽

A.J Ramos

Keyword(s):

Ochratoxin A ◽

Water Activity ◽

Fungal Growth ◽

Barley Grain ◽

Aspergillus Ochraceus

Download Full-text

Influence of water activity on physical properties, fungal growth, and Ochratoxin A production in dry cherries and green‐coffee beans

Journal of Food Processing and Preservation ◽

10.1111/jfpp.16226 ◽

2021 ◽

Author(s):

Erick Baruch Estrada‐Bahena ◽

Ricardo Salazar ◽

Mónica Ramírez ◽

Ma. Elena Moreno‐Godínez ◽

Javier Jiménez‐Hernández ◽

...

Keyword(s):

Physical Properties ◽

Ochratoxin A ◽

Water Activity ◽

Fungal Growth ◽

Green Coffee ◽

Green Coffee Beans ◽

Coffee Beans ◽

Influence Of Water

Download Full-text

Effect of water activity, temperature and pH on solid state lactosylation of β-lactoglobulin

International Dairy Journal ◽

10.1016/j.idairyj.2011.10.008 ◽

2012 ◽

Vol 23 (1) ◽

pp. 1-8 ◽

Cited By ~ 26

Author(s):

Marianne K. Thomsen ◽

Karsten Olsen ◽

Jeanette Otte ◽

Kirsten Sjøstrøm ◽

Birgit B. Werner ◽

...

Keyword(s):

Solid State ◽

Water Activity ◽

Effect Of Water ◽

Activity Temperature ◽

Β Lactoglobulin

Download Full-text

Impact of Water Activity and Temperature on Growth and Ochratoxin A Production of Two Aspergillus carbonarius Isolates from Wine Grapes in Greece

Journal of Food Protection ◽

10.4315/0362-028x-70.12.2884 ◽

2007 ◽

Vol 70 (12) ◽

pp. 2884-2888 ◽

Cited By ~ 16

Author(s):

CHRYSOULA C. TASSOU ◽

PANTELIS I. NATSKOULIS ◽

EFSTATHIOS Z. PANAGOU ◽

APOSTOLOS E. SPIROPOULOS ◽

NARESH MAGAN

Keyword(s):

Ochratoxin A ◽

Water Activity ◽

Color Change ◽

Fungal Growth ◽

Grape Juice ◽

Lag Phase ◽

Aspergillus Carbonarius ◽

Wine Grapes ◽

Wine Production

The aim of this study was to determine the effects of water activity (aw; 0.85 to 0.98) and temperature (10 to 40°C) on the radial growth rate and ochratoxin A (OA) production of two Aspergillus carbonarius isolates in vitro. The isolates were obtained from wine grapes cultivated in Greece, and the trial was conducted with a synthetic grape juice medium similar in composition to grapes between veraison (beginning of color change) and ripeness. Fungal growth and OA production data were collected for 55 days. Response surface curves and cardinal values for aw and temperature were obtained using multiple regression analysis. The lag phase lasted from less than 1 to 10 days. Both isolates grew optimally at 30 to 35°C and 0.96 aw, but maximum OA production occurred under suboptimal growth conditions (15 to 20°C and 0.93 to 0.96 aw). Growth also was observed at 0.85 aw and 25°C, however at this same aw the fungus failed to produce mycelium at any other temperatures tested. The isolates produced OA at 15 to 30°C and 0.90 to 0.98 aw. Maximum OA production was detected after 25 days of incubation at 20°C and 0.96 aw and was 3.14 and 2.67 μgg−1, respectively, for the two strains. The isolated strains used in this study were more xerotolerant than others from the Mediterranean basin. These data will allow producers to identify and thus monitor critical environmental conditions effectively in wine grapes. These data also increase the knowledge base concerning the ability of A. carbonarius to grow and produce toxin under different ecological conditions and can contribute to the development of secondary models for the prediction and risk assessment of OA in wine production.

Download Full-text