Hermetic Bags: A Short-Term Solution to Preserve High-Moisture Maize during Grain Drying.

Maintaining maize quality while drying during a rainy season is a major challenge for smallholder farmers in developing countries. We conducted a study to evaluate the impact of temporarily storing wet maize of 18, 21, and 24% moisture content (m.c.) in hermetic Purdue Improved Crop Storage (PICS) and polypropylene (PP) woven (control) bags for 21 days. Oxygen and carbon dioxide concentrations were monitored, and m.c., germination, and visual mold were assessed. In PICS bags, oxygen dropped below 1% within 7, 11.5, and 21 days for maize at 24, 21, and 18% m.c., respectively. After 21 days, the m.c. of maize stored in PICS bags remained constant, but decreased in PP bags. Germination of maize in PICS bags decreased by 0.5, 6.2, and 95.5 percentage points for 18, 21, and 24% m.c., respectively. In PP bags, germination decreased by 17.5, 15.2, and 39.5 percentage points for the respective moisture levels. After 21 days of storage, visible mold was present on maize stored in PP bags at both 21 and 24% m.c. No mold was observed on maize stored in PICS bags, but a fermentation smell was released from maize at 21 and 24% m.c. The results indicate that maize can be effectively stored in PICS bags at 21% m.c. or below for 21 days with minimal germination loss or mold growth. These findings highlight the potential of using hermetic bags for short-term grain quality preservation just before and during drying. This new utility adds to the current use of hermetic bags for protection against pests during long-term storage. Hermetic bags' dual functionality could significantly improve postharvest management on smallholder farms, thereby enhancing food and nutritional security and safety. Field testing is required in order to integrate this approach under smallholder farmers' conditions (e.g., temperature, m.c., drying practices, etc.).

Short-Term Hermetic Storage of Wet Maize and Its Effect on Quality.

Maize is a major crop grown in many regions of the world for human consumption, starch production, and animal feed. After harvest, maize is dried to avoid spoilage caused by fungal growth. However, in the humid tropics, drying maize harvested during the rainy season poses challenges. In such instances, temporary storing maize under hermetic conditions may preserve grain quality while waiting for conditions suitable for drying. Wet maize at the moisture contents (m.c.) of 18, 21, and 24% was stored for up to 21 days in both hermetic and non-hermetic jars. The stored maize was assessed, every 7 days, for germination and related parameters, presence of visible mold, and pH. After 21 days of storage at 18, 21, and 24% m.c., maize germination decreased by 28.5, 25.2, and 95.5 percentage points, respectively, in hermetic jars; and by 28.5, 25.2, and 94.5 percentage points in non-hermetic jars (control). There was visible mold on maize stored in non-hermetic jars after 21 days regardless of m.c. Maize at 21 and 24% m.c. stored in hermetic conditions underwent lactic acid fermentation that reduced the pH. The findings suggest that maize at 18 and 21% m.c. can be stored for 14 and 7 days, respectively, under hermetic conditions without significant loss of quality. Further research is needed to thoroughly assess the application of these findings for temporarily storing and subsequently drying maize on farms and along the grain value chain.

Finite Element Analysis of Extrinsic Parameters on the Onset of Tensile Strength in Powders.

Most food, pharmaceutical, and chemical industries rely heavily on the supply of free-flowing powders that finds their application in raw materials, additives, and manufactured products. Improper storage conditions combined with environmental factors affect the free-flowing ability of powders. An undesirable transformation of these free-flowing powders into a coherent mass that resists flow is called caking. An important metric that can be used to measure the caking propensity of a material is the tensile strength, which is essentially the resistant stress needed to separate two layers of materials using an isostatic tensile strain. Even though several models have quantified the propensity of caking, the complex nature of interactions between the powder and its micro-environment makes the prediction of caking a challenging task. In the present work, the onset of tensile strength in isomalt with changes in temperature, relative humidity, and consolidation pressures using a shear cell was modeled using a finite element approach. The study found that at a consolidation pressure of 3 kPa and relative humidity of 85±0.1%, an increase in temperature by 5˚C increased the tensile strength of isomalt by a factor of 2. On the other hand, at a constant temperature of 25˚C, an increase in relative humidity from 85±0.1% to 86±0.1% registered an increase in tensile strength by 42.7%. This study also found that an increase in consolidation pressure from 3 kPa to 6 and 9 kPa increased the tensile strength by a factor of 1.79 and 2.54, respectively. The model had good agreement with the measurements and had an overall MAPE of 12.13%. This model can be applied to study the influence of extrinsic parameters on the propensity of caking during storage of bulk solids.

Influence of protein content and storage temperature on the particle morphology and flowability characteristics of milk protein concentrate powders.

Milk protein concentrate (MPC) powders are widely used as ingredients for food product formulations due to their nutritional profile and sensory attributes. Processing parameters, storage conditions, and composition influences the flow properties of MPC powders. This study investigated the bulk and shear flow properties of 70.3, 81.5, and 88.1% (wt/wt, protein content) MPC after storage for 12 wk at 25 and 40°C. Additionally, the morphological and functional changes of the MPC powders were investigated and correlated with flowability. After 12 wk of storage at 25°C, the basic flow energy values significantly increased from 510 to 930 mJ as the protein content increased from 70 to 90% (wt/wt). Flow rate index was significantly higher for samples with high protein content. Dynamic flow tests indicated that MPC powders with high protein content displayed higher permeability. Shear tests confirmed that the samples stored at 25°C were more flowable than samples stored at 40°C. Likewise, the higher-protein content samples showed poor shear flow behavior. The results indicated that MPC powders stored at 25°C had less cohesiveness and better flow characteristics than MPC powders stored at 40°C. Overall, the MPC powders had markedly different flow properties due to their difference in composition and morphology. This study delivers insights on the particle morphology and flow behavior of MPC powders.

Consumer knowledge, preference, and perceived quality of dried tomato products in Ghana.

Postharvest losses (PHL) are incurred in the tomato value chain in Ghana and solar drying of tomato is a promising technology for reducing the loss. However, there are concerns on the usage, functionality and sensory appeal of the dried products to consumers, compounded with the lack of information and research on dried tomato processing in Ghana. A survey was carried out by administering semistructured questionnaires to 395 randomly selected and willing respondents in the Accra Metropolis. Information was obtained on the socioeconomic profile, consumption pattern, knowledge, and acceptance of tomato processing technologies and assessment of quality attributes important to consumers. Most consumers (74%) preferred tomato powder that is conveniently packaged to retain the characteristic intense taste and the flavor using Friedman's rank mean procedure. The study indicated that consumers were more concerned about good manufacturing practices during the production of solar-dried tomato (48.8%) rather than the quality attributes (8.6%). These findings indicate the need for safe solar drying procedures in order to increase consumer acceptability of solar-dried tomato products in Ghana.

A review on flow characterization methods for cereal grain-based powders.

Flow difficulties during handling, storage, and processing are common in cereal grain-based powder industries. The many studies that focus on the flow properties of powders can be classified as flow indicators, shear properties, and dynamic flow properties. The non-uniformity of physical and chemical characteristics of the individual particles that make up the bulk solid of cereal grain-based powders adds complexity to the characterization of flow behavior. Even so, knowledge of flow behavior is critical to the design of productive and cost-effective equipment for handling and processing of these powders. Because many factors influence flow, a single property/index value may not satisfactorily quantify the flow or no-flow of powders. For powders of biological origin, chemical composition and environmental factors such as temperature and relative humidity complicate flow characterization. This review focuses on the specific flow characteristics that directly affect powder flow during handling, processing, and storage.

Analysis of the Effect of Prevailing Weather Conditions on the Occurrence of Grain Dust Explosions.

Grain dust explosions have been occurring in the U.S. for the past twenty years. In the past ten years, there have been an average of ten explosions a year, resulting in nine fatalities and 93 injuries. In more than half of these cases, the ignition source remains unidentified. The effect of ambient humidity on the likelihood of a dust explosion has been discussed for many years. However, no investigation into a possible link between the two has been carried out. In this study, we analyzed local weather data and grain dust explosions during the period 2006 to 2014 to measure potential relationships between the two events. The 84 analyzed explosions do not show any trend with regard to prevailing temperatures, or relative or absolute humidity. In addition, the ignition source could not be identified in 54 of the incidents. The majority of grain dust explosion incidents occurred at grain elevator facilities, where the dust generation potential was high compared with grain processing industries.