Assessment of Quality Stability of Composite Flours Produced By Dar es Salaam SMEs

Abstract

A study was conducted to assess quality stability of cereal flours processed by food processingSMEs in Dar es Salaam. This product is obtained by mixing various cereal grains and isconsidered as of higher nutritional values in Tanzania. The shelf-life was predicted bydetermining water activity (a w ) and moisture content (MC) levels and plotting the water sorptionisotherms (MSI). Ninety per cent of investigated samples (N=78) were found packaged in thematerials of various quality conditions. It was found that the packaging materials mostly used isplastic films (63%), paper packets/bags (26%), hard papers (3%), plastic jars (1%) andcombination of paper packets/boards inserted with plastic film (7%). Water sorption isothermswere plotted for single and multiple ingredient products. The highest levels of a w were observedfor products in paper bags with 0.63 (a w ) and 0.13 MC (kg water/kg solids). Plastic films andjars had intermediate levels at 0.52 (a w ) and 0.042 MC (kg water/kg solids), and combined paperpackets/boards with plastic films had lowest levels at 0.43 (a w ) and 0.038 MC (kg water/kgsolids) exhibiting highest stability of products packaged in these materials. Relative humidityand temperature at sampling locations ranged from 80 to 94% and 30 to 34oC, respectively.Multiple ingredient products showed the lowest a w and MC levels, whereas single ingredientflours possessed higher a w and MC values. Generally, the package system comprising paperboard (or hard paper/box) and plastic bag (plastic film) was the most stable followed by plasticfilms, and paper bag by far.