Effectiveness of Purdue Improved Crop Storage (PICS) bags for preserving the quality and safety of whole and degermed maize flour

Abstract

The aim of this study was to examine the effectiveness of PICS and interwoven polypropylene bags in preserving the physicochemical, biochemical, safety and sensory characteristics of whole and degermed maize flour. Knowledge, attitudes, and practices of key stakeholders involved in handling and storing of maize flour were assessed in order to know the practices and effect on quality. A semi-structured questionnaire was used to survey 85 respondents selected using purposive sampling of units and simple random sampling. The results indicate that ‘super’ maize flour (50-55% extraction) was the most produced and traded. The most common package used for the storage of maize flour is interwoven polypropylene (PP) bags (96.5% of respondents). To prevent spoilage, maize flour bags were placed on wooden pallets during storage. To determine the effect of packaging on maize flour characteristics, whole (W) and degermed (E) maize flours were stored in Purdue Improved Crop Storage (PICS) and PP bags for six months at room temperature (25±5 oC). The nutrient composition, sensory and physicochemical characteristics and, aflatoxin contamination of the maize flour were determined at two months’ intervals during storage. The gas composition, relative humidity (RH) and temperature of the flour in PICS and PP bags was monitored for a month. A significant increase (p<0.05) in moisture content (MC), free fatty acids (FFA), peroxide value (PV) and titratable acidity (TTA) of W and E maize flour stored in PP bags was observed compared to PICS bags. The protein, fat, carbohydrate and water absorption capacity (WAC) of flour stored in PP bags decreased (p<0.05) with the storage period compared to PICS bags. Crude fibre of whole maize flour stored in PICS bags decreased (p<0.05) from 4.0 to 2.7%. Sensory scores of porridge from W maize flour stored in PP bags decreased (p<0.05) after 4 months of storage to an overall acceptability score of 5.1 on a 9 -point hedonic scale compared to PICS bags. The PICS bags did not significantly affect the overall acceptability of porridge, the overall acceptability score of porridge prepared from W maize flour and E maize flour was 6.00 and 6.95 respectively. Yeast and moulds in W maize flour stored in PICS bags significantly reduced (p<0.05) from 3.8 to 2.6 log cfu/g. A significant difference (p<0.05) in aflatoxins level was observed in whole (7.00 to 7.95μg/kg), and degermed (0.09 to 0.30μg/kg) maize flour stored in PP bags after six-month storage. Relative humidity significantly decreased (p<0.05) with an increase in storage period irrespective of packaging material. Oxygen and carbon dioxide content remained constant in PP and PICS bags during one-month storage period. Both maize flour types stored in PICS bags were found more acceptable sensorial than those in PP bags due to the considerable maintenance of quality characteristics of maize flour by PICS bags during the six-month storage period.