The effect of temperature, water activity and sorbic acid on ketone rancidity produced byPenicillium crustosumThom in coconut and palm kernel oils

The growth of ochratoxigenic fungus and the presence of ochratoxin A (OTA) in grapes and their derivatives can be caused by a wide range of physical, chemical, and biological factors. The determination of interactions between these factors and fungal species from different climatic regions is important in designing models for minimizing the risk of OTA in wine and grape juice. This study evaluated the influence of temperature, water activity (aw), and pH on the development and production of OTA in a semisynthetic grape culture medium by Aspergillus carbonarius and Aspergillus niger strains. To analyze the growth conditions and production of OTA, an experimental design was conducted using response surface methodology as a tool to assess the effects of these abiotic variables on fungal behavior. A. carbonarius showed the highest growth at temperatures from 20 to 33°C, aw between 0.95 and 0.98, and pH levels between 5 and 6.5. Similarly, for A. niger, temperatures between 24 and 37°C, aw greater than 0.95, and pH levels between 4 and 6.5 were optimal. The greatest toxin concentrations for A. carbonarius and A. niger (10 μg/g and 7.0 μg/g, respectively) were found at 15°C, aw 0.99, and pH 5.35. The lowest pH was found to contribute to greater OTA production. These results show that the evaluated fungi are able to grow and produce OTA in a wide range of temperature, aw, and pH. However, the optimal conditions for toxin production are generally different from those optimal for fungal growth. The knowledge of optimal conditions for fungal growth and production of OTA, and of the stages of cultivation in which these conditions are optimal, allows a more precise assessment of the potential risk to health from consumption of products derived from grapes.

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Development of a model describing the effect of temperature, water activity and (gel) structure on growth and ochratoxin A production by Aspergillus carbonarius in vitro and evaluation in food matrices of different viscosity

Food Microbiology ◽

10.1016/j.fm.2010.06.001 ◽

2011 ◽

Vol 28 (4) ◽

pp. 727-735 ◽

Cited By ~ 18

Author(s):

Anastasia E. Kapetanakou ◽

Anna Ampavi ◽

Stavrianos Yanniotis ◽

Eleftherios H. Drosinos ◽

Panagiotis N. Skandamis

Keyword(s):

Ochratoxin A ◽

Water Activity ◽

Effect Of Temperature ◽

Aspergillus Carbonarius ◽

Gel Structure ◽

Food Matrices ◽

Temperature Water

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EFFECT OF TEMPERATURE, WATER ACTIVITY AND CINNAMON ESSENTIAL OIL ON THE GROWTH OF ASPERGILLUS FLAVUS LA01 AND ASPERGILLUS NIGER LA04

Vietnam Journal of Science and Technology ◽

10.15625/2525-2518/55/5a/12177 ◽

2018 ◽

Vol 55 (5A) ◽

pp. 42

Author(s):

Phan Thi Kim Lien

Keyword(s):

Aspergillus Niger ◽

Essential Oil ◽

Water Activity ◽

Aspergillus Flavus ◽

Effect Of Temperature ◽

Diffusion Method ◽

Potato Dextrose Agar Medium ◽

Sequencing Method ◽

Cinnamon Essential Oil ◽

Temperature Water

The aim of the study was to evaluate the influence of temperature, water activity and cinnamon essential oil on the growth of Aspergillus flavus LA01 and Aspergillus niger LA04 and these factors were further optimized to inhibit their growth. Both strains were isolated by Potato Dextrose Agar medium (PDA) and identified by sequencing method from rice collected in Long An province. Evaluating these factors’ inhibition on the fungi growth was based on growth rate at the various points of water activity (aw) (v/v) such as 0.85, 0.90, 0.95, 0.99 and at 25 oC, 30 oC, 37 oC, 42 oC; at various concentrations of the oils 0 %, 1 %, 3 %, 5 %, 7.5 %, 10 % and 15 % at 30 oC incubated for 5 days - the disc diffusion method. The results showed that 30 oC and aw = 0.95 - 0.99 were optimum conditions for Aspergillus flavus LA01 and Aspergillus niger LA04 growth. However, at 42 oC, 37 oC and aw = 0.85 - 0.9 could control Aspergillus flavus LA01 and Aspergillus niger LA04 growth. At concentration of 10 - 15% cinnamon essential oils (EOs), 30 oC and aw = 0.9 - 0.95 could also inhibit them.

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