attributed to the significant effect of a w, temperature and headspace oxygen
concentration on A. flavus. The extensive growth of A. flavus evident during the
first week of storage is due to the availability of oxygen, thereby enhancing active
metabolism and multiplication. A similar observation was made by Shih and Marth
(1974), who found that maximal growth of A. parasiticus occurred at day 5 of
storage in a static or agitated glucose-salt medium. Karunaratne and Bullerman
(1990) also observed that the maximum growth of A. flavus on sterile rice occurred
within 3-5 days of incubation at higher temperatures (35°C) and within 5-7 days at
28°C, after which the mold entered the stationary phase of growth.
The changes in headspace gas composition for selected packaging conditions
are shown in Fig. 1. In all cases, headspace oxygen decreased to less than 1%
within 1-3 days depending on the initial headspace oxygen concentration and
environmental storage conditions. An initial increase in headspace carbon dioxide
was observed in all treatments as a result of mold metabolism, followed by a
gradual decrease due either to its adsorption into the pores of the peanut (Holaday
et al., 1979), its loss through the packaging film or possibly its incorporation into
the biosynthetic pathway for aflatoxin production (Hsieh and Mateles, 1971).
Generally, the rate of oxygen consumption and carbon dioxide production depends
on the level of a w, storage temperature, the inoculum level and the gas transmis-