Use of Triple Bagging System and Biopesticides for the Optimization of Storage Methods of Corn Grains for an Application in Oil Industry
Abstract
Corn is the second most cultivated cereal in Ivory Coast after rice. The grain germ represents an important source of quality fat, which could fill the deficit in fat both in populations and in industries. Unfortunately, grain production and the quality of fat are affected by storage methods that are often harmful to health. It is in this context that in the present study carried out in Ivory Coast. Surface response methodology (3- factor Central Composite Design) was conducted to monitor the effectiveness of triple bagging system and biopesticide (leaves of Lippia multiflora and Hyptis suaveolens) on the stability of some alteration parameters of the grains intended for use in oil mills. Thus, humidity, peroxide index and acidity were assessed during storage. The independent variables considered were the storage duration (1 to 18 months), the biopesticide / corn ratio (0 to 5%) and the combination of biopesticides (0 to 100% Lippia). Predictive regression equations were constructed for the estimation of each parameter studied (R2 > 0.70). An increase in grain moisture, peroxide index and acidity (P <0.01) was observed with the storage time. However, a threshold concentration of biopesticides has been shown to be effective for the stability of spoilage parameters. The optimization of the results made it possible to determine the ideal conditions for the conservation of the corn kernels. Thus, the addition of 2.5% of biopesticides (20% of Lippia multiflora and 80% Hyptis suaveolens) in a triple bagging system is effective for the stability of the alteration parameters for 18 months. Under these ideal conditions, the experimental values are respectively of the order of 12.30 ± 0.17%; 3.96 ± 0.14 meq O2 / kg and 3.18± 0.08% respectively for humidity, peroxide index and acidity. These values considered to guarantee quality stability are statistically (P> 0.05) equal to those predicted by the mathematical model.
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Introduction
In Ivory Coast, maize is the second most cultivated cereal after rice (Akanvou et al., 2006). Currently, annual national production is around one million tonnes (FAO, 2017). Used in the preparation of several dishes (boiled, roasts, ''tô'' or even as a local beer ''Tchapalo''), corn constitutes a staple food of a good part of the Ivorian populations in rural areas (Yao et al., 2013).
Corn kernels are an important source of fat, the oil extracted from the seed germ is considered one of the best edible vegetable oils because of its richness in essential nutrients (unsaturated fatty acids, tocopherols and phytosterol) (Shende and Sidhu, 2014). Therefore, its consumption would represent an advantage for human health (Dubois et al., 2007). In addition, the production of corn oil in quality and quantity could fill the shortage of fat that has existed for years in populations and industries. Thus, the mastery of good post-harvest practices and especially that of the conservation of corn kernels becomes very important insofar as the quality of the oil depends on the quality of grain storage.
Conclusion
This study made it possible to determine the ideal conditions for efficient storage from a central composite design in order to guarantee better lipid quality of the grains for industrial purposes. Our results confirm the importance of triple bagging for the conservation of grain corn. This technique prolongs the storage time while keeping the alteration parameters of lipid quality stable. This study also shows that the addition of the leaves of Lippia multiflora and Hyptis suaveolens, as a biopesticide, further extends the shelf life of grains in Côte d'Ivoire. It effectively preserves the lipid quality of the grains against oxidative and hydrolytic rancidity. The ideal storage conditions obtained are 2.5% as the minimum effective concentration of biopesticides (20% of leaves of Lippia multiflora and 80% of leaves of Hyptis suaveolens) for a period of eighteen months. Thus, the triple bagging methodology using the leaves of Lippia multiflora and Hyptis suaveolens as biopesticides in this study is accessible to the various players in the corn sector in Côte d'Ivoire. However, the study deserves to be deepened to follow the evolution of the physico-chemical parameters of the oil from the grains during the conservation in these storage systems.