**1. Introduction**

Maize (*Zea mays* L.) is the most extensively produced and consumed cereal, accounting for over half of Ghana's entire grain harvest [1]. It is principally cultivated by small-scale farmers in most of the agro-ecological zones of Ghana, who depend predominantly on rainfall. Obaatanpa, Mamaba, Dadaba and Aburohoma are the common maize varieties grown by most farmers in Ghana [2]. Ghana's maize production capacity currently stands at 2.76 million MT with an annual growth rate of 8.06% [3]. Maize is used in many Ghanaian staples: poultry feed formulation, maize-grit production, alcohol brewing, baby food and breakfast cereal production [1,3]. There are basically two maize growing seasons (major and minor) along the transitional areas of Ghana, and usually one harvest season coincides

**Citation:** Nyarko, S.K.; Akyereko, Y.G.; Akowuah, J.O.; Wireko-Manu, F.D. Comparative Studies on Grain Quality and Pesticide Residues in Maize Stored in Hermetic and Polypropylene Storage Bags. *Agriculture* **2021**, *11*, 772. https://doi.org/10.3390/ agriculture11080772

Academic Editor: John M. Fielke

Received: 25 June 2021 Accepted: 5 August 2021 Published: 13 August 2021

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**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

with the rainy period, which threatens grain quality, particularly with respect to mold growth and insect pest infestation since most farmers rely on the sun for drying [4].

Maize storage is a major issue in maize production and a key contributing factor to post-harvest losses of maize across the globe. According to a report by FAOSTAT (Rome, Italy) [5], post-harvest losses of maize stand at 30%, with major causes being drying inefficiencies, poor post-harvest management, overdue harvesting and poor storage systems. Studies by Opit et al. [2] and Likhayo et al. [4] discovered that storage of maize in warehouses in Ghana is being affected by insects such as weevils (*Sitophilus zeamais* Motschulsky) and larger grain borer (*Prostephanus truncatus* Horn) owing to inappropriate moisture content, temperature and storage material and high gaseous exchange. Efforts by researchers in reducing post-harvest losses of maize have resulted in formulation of pesticides and invention of storage bags, silos, warehouses and others. However, studies have revealed that due to the high-cost nature and inefficiencies of some of these methods, farmers still use pesticides which are less expensive but have other deleterious effects on consumers' health. In late 2010, 15 farmers living in the Upper East region of Ghana died from consuming cereals suspected to have been treated with pesticides [6]. As a result, some of these pesticides have been banned in Ghana, yet some farmers use them secretly.

Efforts to mitigate the use of pesticides in cereal or maize storage led to discovery of hermetic storage bags, which provide a pesticide-free and cost-effective storage system [7,8]. Hermetic storage technology operates on the principle of depleting O2 and accumulating CO2 concentrations in the interior of the bags by virtue of grain and pest metabolism [4]. Walker et al. [9] emphasized that the hermetic phenomenon thwarts evaporation and gaseous exchange, thereby adjusting the interior composition (O2 and CO2) of the container to eliminate insect pests. Nevertheless, the concept of hermetic storage has not been fully accepted by many stakeholders along the maize value chain because little information has been published on the relative advantages of hermetic bags over traditional (polypropylene) bags with respect to grain quality and pesticide residues.

A national approach in Ghana to attain food security via the introduction of the "Planting for Food and Jobs" initiative may increase maize production to meet domestic consumption as well as international market demands. Nonetheless, the full prospects of the initiative may be unattainable unless stakeholders along the maize supply chain are provided with the capacity to preserve maize and market excesses for profit [8]. The current overreliance of smallholder maize farmers on the storage of maize in polypropylene bags with pesticide application is overwhelming and has the tendency to increase the effect of pesticides on the health of the Ghanaian consumers and the international market. It is therefore vital to provide information on the concentrations of pesticide residues and the quality of maize stored in hermetic and traditional (polypropylene) storage bags in Ghana to offer farmers and other stakeholders the opportunity to make informed storage choices for maize and promulgate laws with respect to eliminating pesticide use for maize preservation, for the safety of consumers.

This research work seeks to determine and compare the quality characteristics and the pesticide residue concentrations of maize stored in hermetic and traditional (polypropylene) bags in the leading maize producing areas in the Ashanti region of Ghana.

#### **2. Materials and Methods**

#### *2.1. Study Area*

This research work was conducted in three leading localities (Ejura, Abofour and Asante-Akyem Agogo) in the Ashanti region of Ghana notable for their high volumes of maize production. The three municipalities were chosen as study areas because of their significant production, active trade and involvement in the maize supply chain.

#### *2.2. Sampling*

Maize samples stored for a period of one year were collected from traditional polypropylene bags and hermetic bags in two different warehouses in each locality. A random sampling was done by taking a minimum of the square root of the number of bags in the warehouse, to get a fair representative sample of the total consignment. Samples were collected from bags by inserting a sampler from the top to the bottom of the bag at multiple random points. They were then sealed separately in zip-lock bags and labelled.
