Relationship of Shelled Corn Fungal Susceptibility to Carbon Dioxide Evolution and Kernel Attributes

Abstract

Fifty‐one samples of shelled corn were rewetted to 21% wb moisture content (MC) and evaluated for susceptibility to fungal invasion using ergosterol measurements and a test kit that measures carbon dioxide (CO2) evolution. The sample attributes measured were percent germination, electrolyte leakage after soaking in deionized water, percent fines, and percent kernel infection. The difference in ergosterol content before and after incubation at 24°C was used as the standard measure of fungal growth. Differences in CO2 evolution among the samples were consistent with expectations for fungal growth based on storage history. The coefficients of determination (r2) for the linear regression of ergosterol difference with CO2 kit readings were 0.46–0.60. All were statistically significant (α = 0.001) and r2 values were slightly greater when four high‐oil corn samples were removed. These results indicate that the CO2 test can be used to assess fungal susceptibility of rewetted shelled corn, which may also be indicative of its susceptibility before rewetting. The linear regressions of kernel attributes with ergosterol difference (48 < n < 51) that were statistically significant included percent germination, r2 = 0.49 (α = 0.001); electrolyte leakage, r2 = 0.27 (α = 0.001); and percent fines determined with a 4.76‐mm sieve, r2 = 0.12 (α = 0.05).

Corn Cob Dry Matter Loss in Storage as Affected by Temperature and Moisture Content

“…4) presented a linear trend for all treatments, as opposed to the equivalent conditions for kernels, in which an exponential curve was observed after a short lag phase (Friday et al, 1989;Wilcke et al, 2001;Moog et al, 2008). Following the regression model observed in this study, important losses would be reached (almost 25% over six months) if the deterioration rate for six months fits the rate observed in this study (table 3), hence the importance of extending the study for prolonged times.…”

“…Many authors (Wilcke et al, 2001;Bern et al, 2002;Chitrakar et al, 2006;White, 2007;Moog et al, 2008) quantified corn kernel deterioration due to fungal growth with different conditions of moisture, temperature, mechanical damage, genetic hybrid resistance, ozone treatment, and fungicide treatment. Nevertheless, little is known about handling and appropriately storing cellulosic biomass for biofuel production.…”

Fungal Susceptibility at Four Temperature‐Moisture Combinations and Carbon Dioxide Kit Color Reader Evaluation

“…Managers of elevators, storage facilities, or processing plants have little or no information about these factors and must assess the likelihood of spoilage by visually examining a sample of shelled corn and measuring its moisture content (MC). As stated previously (Moog et al 2008), we believe that a relatively simple carbon dioxide (CO 2 ) test kit can be used to assess susceptibility of shelled corn to fungal invasion. Fungal susceptibility, as it is used here, is defined as the likelihood that fungi will grow during subsequent storage or shipment if the shelled corn is subjected to conditions conducive to fungal growth.…”

“…In an earlier study (Moog et al 2008), we used a test kit to measure CO 2 evolution from samples rewetted to 21% MC and incubated at 24°C for ≤80 hr. We assumed that fungal growth during the incubation period could be assessed on the basis of difference in ergosterol before and after testing and concluded that CO 2 evolution measured using the test kit was a reasonable measure of fungal susceptibility.…”

“…They found that relatively little deterioration occurred over a period of two months when the samples were stored at highland conditions, while mold biomass doubled and there was a significant increase in percentage of kernels with mold infection when samples from the same bulk grain lot were stored at lowland conditions. In the earlier study of fungal susceptibility (Moog et al 2008), we did not consider the effects of using a higher incubation temperature, similar to that found in tropical climates, or using a lower moisture, closer to typical storage moistures.…”