The effect of different salt concentrations on corn storage stability

Corn is one of the most produced cereal in the world and has great importance in the nutrition of society. However, it is highly sensitive to various forms of deterioration in the storage process because of its high respiratory capacity and grain water content at the time of harvest especially when harvested as a second crop. The mycotoxins and insect's body parts and secretion found in corn which are indicators of deterioration can cause some health problems such as cancer and asthma. Therefore, it is a very important issue conducting studies related to the storage of corn as well as all grains and prevented deterioration in the corn grains causing material losses and health problems. In this thesis, it was aimed at the protective effect of different salt concentrations and dipping time in these salt solutions on microbiological spoilage, grain germination, and insects. For this aim; the salt solutions were prepared at 4 different concentrations (0% control, 10, 18, 26%) and corn grains were dipped into these solutions with 4 different durations (10, 20, 40, 60 seconds). After preparation of samples, the grains were stored for 8 months and some chemical, physical, microbiological and biological analyses were performed at 0., 1., 2., 3., 4., 6., and 8. month for determining the quality characteristics of samples. The unprocessed sample was used as dry control and the samples that dipped to distilled water without salt for 10, 20, 40 and 60 seconds were also used as wet controls. As a result of the analyses and evaluations, it was detected that the average increases in water content and activity of the grains were 1.86% and 0.110 units, respectively. The increasing rate of water content and activity levels decreased with increasing salt concentration but increased with extended dipping time. It was found that increasing salt concentration had an inhibiting effect on the yeast mold growth in corn, and the 26% salt concentration caused 3 log unit decrease compared to the control samples. However, it was determined that the increasing dipping time contributed to an increase in mold growth as 1.78 log units in 60 seconds which is the longest dipping time. It was determined that the germination rate was not affected by the concentration of salts, but it was negatively affected by the dipping time and storage period. The germination rate decreased as 32% at 60 seconds dipping time and the grain germination lost was 63% at the end of the storage period. It was detected that the high concentrations of the salt application did not affect the number of insects, but the dipping time and storage period caused the increase. The number of insects rose from 5 to 340 per kilogram in the longest dipping time application and it reached 813 at the end of 8 months storage. That may have resulted from the increasing of the water content of the corn husks (comparing to the whole kernel) with dipping to the solution, which causes the softening of grain and thus making it easier for insects to damage the grains and/or the high resistance of insects against the salt. As a result, it was found that the application of salt as a reasonable amount could prevent mold growth especially in high salt concentration with short dipping time without any decreasing in the germination rate of grains, but it could not affect insect activity. Additionally, it was evaluated that the spraying of salt to the corn grains together with the drying process instead of dipping to the salt solution can be more effective against both mold growth and insect activities. KEYWORDS: Corn, Germination, Infestation, Mold, Salt, Storage